Cells interact with the extracellular matrix and generate traction forces,which play fundamental roles in many cytological activities,such as migration and differentiation.The quanti fication of these traction forces ...Cells interact with the extracellular matrix and generate traction forces,which play fundamental roles in many cytological activities,such as migration and differentiation.The quanti fication of these traction forces is a prerequisite for understanding the interaction and regulation between force and functions,which can be accomplished by traction force microscopy(TFM).In TFM,the forces are determined by tracking the displacement of fiducial markers through optical microscopy.The type of fiducial marker,microscopy modality,and image processing algorithms are key factors determining the final resolution of TFM.This review summarizes efforts in three aspects to enhance the performance of TFM and discusses the challenges of further development,particularly from an optical view.展开更多
The development of wearable electronics necessitates flexible and robust energy storage components to enhance comfort and battery longevity.The key to flexible batteries is improving electrochemical stability during d...The development of wearable electronics necessitates flexible and robust energy storage components to enhance comfort and battery longevity.The key to flexible batteries is improving electrochemical stability during deformation,which demands mechanical analysis for optimized design and manufacturing.This paper summarizes the progress of flexible batteries from a mechanical perspective,highlighting highly deformable structures such as fiber,wave,origami,and rigid-supple integrated designs.We discuss mechanical performance characterization and existing evaluation criteria for battery flexibility,along with simulation modeling and testing methods.Furthermore,we analyze mechano-electrochemical coupling,reviewing theoretical models that simulate mechanical and electrochemical behavior under various loads and introduce coupling tests that assess electrochemical performance during deformation.Finally,we suggest future research directions to advance flexible energy storage devices.展开更多
The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread att...The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread attention from researchers.In this paper,the deformation and buckling behaviors of a circular arch subject to compression by a rigid plate are investigated with a planar elastic rod model that incorporates tension,shearing,and bending.In comparison with the existing models that solely consider the bending energy,the deflection curve,the internal force distribution,and the critical load of the present model show good agreement with the finite element results.Through the dimensional analysis and order-of-magnitude estimation,we examine the factors influencing the critical load.The study reveals that the semi-central angle of the arch has the most significant effect.The dimensionless geometric parameter describing arch slenderness becomes prominent when the semi-central angle is less than 30°,while Poisson's ratio and the cross-sectional shear correction factor exhibit negligible influence.Furthermore,the variation in the proportions of strain energy components during critical buckling is presented with respect to the semi-central angle and the geometric parameter,thereby delineating the applicable ranges of both the original model(OM)and the modified model(MM).展开更多
Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenizatio...Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenization methods based on the classical elasticity theory struggle to accurately describe the non-classical mechanical behaviors of lattice materials,especially when dealing with complex unit-cell geometries featured by non-symmetric configurations or non-single central node connections.In response to this limitation,this study establishes a generalized homogenization model based on the micropolar theory framework,employing Hill's boundary conditions to precisely predict the equivalent moduli of complex lattice materials.By introducing the independent rotational degree of freedom(DOF)characteristic of the micropolar theory,the proposed model successfully overcomes the limitation of conventional methods in accurately describing the asymmetric deformation and scale effects.We initially calculate the constitutive relations of two-dimensional(2D)cross-shaped multi-node chiral lattices and subsequently extend the method to three-dimensional(3D)lattices,successfully predicting the mechanical properties of both traditional and eccentric body-centered cubic(BCC)lattices.The theoretical model is validated through the finite element numerical verification which shows excellent consistency with the theoretical predictions.A further parametric study investigates the influence of geometric parameters,revealing the underlying size-effect mechanism.This paper provides a reliable theoretical tool for the design and property optimization of complex lattice materials.展开更多
The Kapitza resistance is of fundamental importance for the thermal stability of the interface between the ceramic top coat and the thermal growth oxide layer in the thermal barrier coating structure,which is widely u...The Kapitza resistance is of fundamental importance for the thermal stability of the interface between the ceramic top coat and the thermal growth oxide layer in the thermal barrier coating structure,which is widely used to protect high-temperature components in current gas turbine engines.The top coat typically consists of the ZrO_(2)partially stabilized by 8%Y2O3(YSZ),and the main component of the thermal growth oxide isα-Al_(2)O_(3).In this work,the Kapitza resistance is found to be a small value of 0.69 m^(2)K/GW for the YSZ/α-Al_(2)O_(3)interface based on the heat dissipation simulation method.It indicates that the localization of thermal energy is rather weak,which is beneficial for the thermal stability of the YSZ/α-Al_(2)O_(3)interface.This Kapitza resistance can be further reduced to 0.50 m^(2)K/GW by a mechanical or thermal compressive strain of 8%.To explore the underlying mechanism for this strain effect,we analyze the phonon vibration and the microscopic deformation in the interface region.It is revealed that the interface becomes denser through the compression-induced twisting of some Al-O_(zr)and A1-O_(Al)chemical bonds in the interface region,which is responsible for the reduction in the Kapitza resistance.The temperature effect and crystal size effect on the Kapitza resistance of the YSZ/α-Al_(2)O_(3)interface are also systematically studied.These findings shall provide valuable information for further understanding of the thermal conductivity and thermal stability of the thermal barrier coating structures.展开更多
Recently, intelligent or smart materials and structures have been received more and more attention due to their distinguished multi-field coupling properties and wide applications in aerospace, automobiles, civil stru...Recently, intelligent or smart materials and structures have been received more and more attention due to their distinguished multi-field coupling properties and wide applications in aerospace, automobiles, civil structures, medical devices, information storage, energy harvesting and so on. It is of academic challenge to fully understand the complex multi-field coupling behaviors of various smart materials and structures, and of engineering sig- nificance to enhance the performance and reliability of these materials and structures in industrial applications. The papers in the special topic of Mechanics of Intelligent Materials and Structures focus on the understanding of the electromechanical, magneto-elastic, and magneto-rheological coupling behav- iors and properties of smart materials and structures for applications in vibration control, resonators, and various functional devices.展开更多
Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of...Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.展开更多
The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the in...The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the interface performances of the engineering structures.In this paper,a contact model is established,which is suitable for tensile and bending deformed contact surfaces.Four contact forms of asperities are proposed,and their distribution characteristics are analyzed.This model reveals the mechanism of friction generation from the perspective of the force balance of asperity.The results show the contact behaviors of the deformed contact surface are significantly different from that of the plane contact,which is mainly reflected in the change in the number of contact asperities and the real contact area.This study suggests that the real contact area of the interface can be altered by applying tensile and bending strains,thereby regulating its contact mechanics and conductive behavior.展开更多
Tension-compression asymmetry is a critical concern for magnesium(Mg)alloys,particularly in automo-tive crash structures.This study systematically examines the tension-compression asymmetry of a cast Mg-Gd-Y alloy at ...Tension-compression asymmetry is a critical concern for magnesium(Mg)alloys,particularly in automo-tive crash structures.This study systematically examines the tension-compression asymmetry of a cast Mg-Gd-Y alloy at various strain rates.Experimental results indicate symmetric yielding stress under both tension and compression at all strain rates,along with a reduction in the tension-compression asym-metry of ultimate stress and plastic strain as the strain rate increases.This trend arises from an unusual strain rate-dependent tension-compression asymmetry,characterized by strain rate toughening in tension and negligible strain rate effect in compression.The differing behavior is linked to the distinct twinning mechanisms under tension and compression.The suppression of twinning under tension contributes to the positive strain rate dependence of pyramidal slip,whereas the activation of abundant twins during compression means that pyramidal slip is unnecessary to accommodate c-axis strain,leading to the ab-sence of a strain rate effect in compression.Abundant twins nucleate consistently from yielding to 2%strain,but only after basal and prismaticslip have mediated microplasticity,suggesting that these slip systems reduce the nucleation stress for twinning during compression,resulting in a lower activation stress for twinning compared to tension.This study provides new insights into micromechanisms of the tension-compression asymmetry in cast Mg-Gd-Y alloys and offers practical guidance for the application of these materials in critical components that must endure both tension and compression under varying strain rates.展开更多
This study presents a coupled thermo-hydro-mechanical-fatigue(THM-F)model,developed based on variational phase-field fatigue theory,to simulate the freeze-thaw(F-T)damage process in concrete.The fracture phasefield mo...This study presents a coupled thermo-hydro-mechanical-fatigue(THM-F)model,developed based on variational phase-field fatigue theory,to simulate the freeze-thaw(F-T)damage process in concrete.The fracture phasefield model incorporates the F-T fatigue mechanism driven by energy dissipation during the free energy growth stage.Using microscopic inclusion theory,we derive an evolution model of pore size distribution(PSD)for concrete under F-T cycles by treating pore water as columnar inclusions.Drawing upon pore ice crystal theory,calculation models that account for concrete PSD characteristics are established to determine ice saturation,permeability coefficient,and pore pressure.To enhance computational accuracy,a segmented Gaussian integration strategy based on aperture levels is employed.The pore pressure estimation model is applied to assess the frost resistance of concrete with varying air-entraining agent contents,confirming that optimal air-entrainment significantly improves pore structure and lowers the overall freezing point of pore ice.The derived permeability coefficient and pore pressure estimation models are integrated into the THM-F coupled framework,which employs a staggered iterative solution scheme for efficient simulation.Mesoscale numerical examples of concrete demonstrate that the proposed THM-F model effectively captures structural degradation and accurately tracks the procession of F-T-induced fatigue cracks.Validations against experimental measurements,including temperature variations,stress-strain curves,and strain history,shows excellent agreement,underscoring the model’s accuracy and applicability.This study provides a robust theoretical and computational framework for quantitative analysis of coupled F-T-fatigue damage in concrete.展开更多
Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applicat...Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applications such as trapped field magnets.However,for such large-grain superconductor bulks,there are lots of voids and cracks forming during the process of melting preparation,and some of them can be up to hundreds of microns or even millimeters in size.Consequently,these larger size voids/cracks pose a great threat to the strength of the bulks due to the inherent brittleness of superconductor REBCO materials.In order to ensure the operational safety of related superconducting devices with bulk superconductors,it is firstly important to accurately detect these voids/cracks in them.In this paper,we proposed a method for quantitatively evaluating multiple voids/cracks in bulk superconductors through the magnetic field and displacement response signals at superconductor bulk surface.The proposed method utilizes a damage index constructed from the magnetic field signals and displacement responses to identify the number and preliminary location of multiple defects.By dividing the detection area into subdomains and combining the magnetic field signals with displacement responses within each subdomain,a particle swarm algorithm was employed to evaluate the location and size parameters of the defects.In contrast to other evaluation methods using only magnetic field or displacement response signals,the combined evaluation method using both signals can identify the number of cracks effectively.Numerical studies demonstrate that the morphology of voids and cracks reconstructed using the proposed algorithm ideally matches real defects and is applicable to cases where voids and cracks coexist.This study provides a theoretical basis for the quantitative detection of voids/cracks in bulk superconductors.展开更多
Accurately predicting the mechanical behavior of pure metals at different radiation doses and prescribing the microstructure evolutions,such as the dislocation structures,remain challenging.This work introduces a 3D h...Accurately predicting the mechanical behavior of pure metals at different radiation doses and prescribing the microstructure evolutions,such as the dislocation structures,remain challenging.This work introduces a 3D hybrid numerical simulation scheme that integrates finite element(FE)and finite difference(FD)modules.The FE module is used to implement the crystal plasticity model,while the FD module is used to solve the reaction-diffusion model regarding dislocation nucleation and transportation.Our hybrid model successfully replicates the mechanical behavior of pristine Cu single crystals and provides details of dislocation cell structures that agree with the experimental observation.Furthermore,the model effectively reflects the irradiation hardening effects for Cu single crystals and demonstrates the formation of dislocation channels and shear band type of strain localization.Our work offers an effective approach for predicting the mechanical responses and the safety evaluation of pure metals in extreme working conditions.展开更多
Surface energy is essential to the understanding of micro-mechanics for heterogeneous composites.To investigate the effective elasticity and fracture behaviors,we derive an effective surface energy based on Eshelby’s...Surface energy is essential to the understanding of micro-mechanics for heterogeneous composites.To investigate the effective elasticity and fracture behaviors,we derive an effective surface energy based on Eshelby’s equivalent inclusion theory.Within a unified theoretical framework,the effective surface energy predicts the fundamentals from elasticity to fracture,and reproduces classical homogenization methods and phase field models.The influences of elastic heterogeneity and size effects are analyzed in depth.Using the surface energy formulation,a computational model is developed by minimizing the deviation of effective elastic modulus from experimental observation.To validate our theoretical prediction,numerical simulations under tension and shear loadings for monodisperse and bidisperse particulate systems are performed,which agree well with experimental evidences.Local debondings nucleate and initiate at the inclusion-matrix interfaces,then develop into multiple interacting cracks and shear bands,thereby greatly promotes the process of fracture.展开更多
Controllable shock wave fracturing is an innovative engineering technique used for shale reservoir fracturing and reformation.Understanding the anisotropic fracture mechanism of shale under impact loading is vital for...Controllable shock wave fracturing is an innovative engineering technique used for shale reservoir fracturing and reformation.Understanding the anisotropic fracture mechanism of shale under impact loading is vital for optimizing shock wave fracturing equipment and enhancing shale oil production.In this study,using the well-known notched semi-circular bend(NSCB)sample and the novel double-edge notched flattened Brazilian disc(DNFBD)sample combined with a split Hopkinson pressure bar(SHPB),various dynamic anisotropic fracture properties of Lushan shale,including failure characteristics,fracture toughness,energy dissipation and crack propagation velocity,are comprehensively compared and discussed under mode Ⅰ and mode Ⅱ fracture scenarios.First,using a newly modified fracture criterion considering the strength anisotropy of shale,the DNFBD specimen is predicted to be a robust method for true mode Ⅱ fracture of anisotropic shale rocks.Our experimental results show that the dynamic mode Ⅱ fracture of shale induces a rougher and more complex fracture morphology and performs a higher fracture toughness or fracture energy compared to dynamic mode Ⅰ fracture.The minimal fracture toughness or fracture energy occurs in the Short-transverse orientation,while the maximal ones occur in the Divider orientation.In addition,it is interesting to find that the mode Ⅱ fracture toughness anisotropy index decreases more slowly than that in the mode Ⅰ fracture scenario.These results provide significant insights for understanding the different dynamic fracture mechanisms of anisotropic shale rocks under impact loading and have some beneficial implications for the controllable shock wave fracturing technique.展开更多
Bionic X-shaped vibration isolators have been widely employed in aerospace and other industrial fields,but the stiffness properties of classic X-shaped structures limit the vibration isolation ability for low frequenc...Bionic X-shaped vibration isolators have been widely employed in aerospace and other industrial fields,but the stiffness properties of classic X-shaped structures limit the vibration isolation ability for low frequencies.An innovative bionic quasi-zero stiffness(QZS)vibration isolator(BQZSVI),which can broaden the QZS range of a classic X-shaped isolator and can bring it closer to the equilibrium position,is proposed.The BQZSVI consists of an X-shaped structure as the bone fabric of lower limbs and a nonlinear magnetic loop device simulating the leg muscle.Based on static calculation,the stiffness characteristic of the structure is confirmed.The governing equations of motion of the BQZSVI structure are established in the framework of the Lagrange equation,and the harmonic balance method(HBM)is adopted to obtain the transmissibility responses.The results show that the BQZSVI can provide a more accessible and broader range of QZS.In the dynamic manifestation,the introduction of the BQZSVI can reduce the amplitude of a classic X-shaped vibration isolator by 65.7%,and bring down the initial vibration isolation frequency from 7.43 Hz to 2.39 Hz.In addition,a BQZSVI prototype is designed and fabricated,and the exactitude of the theoretical analysis method is proven by means of experiments.展开更多
Lithium ion batteries are important for new energy technologies and manufacturing systems.However,enhancing their capacity and cycling stability poses a significant challenge.This study proposes a novel method,i.e.,mo...Lithium ion batteries are important for new energy technologies and manufacturing systems.However,enhancing their capacity and cycling stability poses a significant challenge.This study proposes a novel method,i.e.,modifying current collectors with perforations,to address these issues.Lithium ion batteries with mechanically perforated current collectors are prepared and tested with charge/discharge cycles,revealing superior capacity as well as enhanced electrochemical stability over cycles.Impedance spectroscopy,scanning electron microscopy,and peeling tests are conducted to investigate the underlying mechanisms.Higher peel resistance,minimized interface cracking,and reduced electrical impedance are found in the perforated electrodes after cycles.Investigations indicate that the perforation holes on current collectors allow the active materials coating on the two sides of the current collector to bind together and,thus,lead to enhanced adhesion between the current collector and active layer.Mechanical simulation illustrates the role of perforated current collectors in curbing interface cracking during lithiation,while electrochemical simulation shows that the interfacial cracking hinders the diffusion of lithium ions,thereby increasing battery impedance and reducing the cyclic performance.This investigation reveals the potential of designing non-active battery components to enhance battery performance,advocating a nuanced approach to battery design emphasizing structural integrity and interface optimization.展开更多
This study investigates the dynamic compressive behavior of three periodic lattice structures fabricated from Ti-6Al-4V titanium alloy,each with distinct topologies:simple cubic(SC),body-centered cubic(BCC),and face-c...This study investigates the dynamic compressive behavior of three periodic lattice structures fabricated from Ti-6Al-4V titanium alloy,each with distinct topologies:simple cubic(SC),body-centered cubic(BCC),and face-centered cubic(FCC).Dynamic compression experiments were conducted using a Split Hopkinson Pressure Bar(SHPB)system,complemented by high-speed imaging to capture real-time deformation and failure mechanisms under impact loading.The influence of cell topology,relative density,and strain rate on dynamic mechanical properties,failure behavior,and stress wave propagation was systematically examined.Finite element modeling was performed,and the simulated results showed good agreement with experimental data.The findings reveal that the dynamic mechanical properties of the lattice structures are generally insensitive to strain rate variations,while failure behavior is predominantly governed by structural configuration.The SC structure exhibited strut buckling and instability-induced fracture,whereas the BCC and FCC structures displayed layer-by-layer crushing with lower strain rate sensitivity.Regarding stress wave propagation,all structures demonstrated significant attenuation capabilities,with the BCC structure achieving the greatest reduction in transmitted wave amplitude and energy.Across all configurations,wave reflection was identified as the primary energy dissipation mechanism.These results provide critical insights into the design of lattice structures for impact mitigation and energy absorption applications.展开更多
Near-αtitanium(Ti)alloys are promising high-temperature(HT)structural materials for aerospace and automotive applications due to their superior specific HT strength and creep resistance.Nevertheless,improving the syn...Near-αtitanium(Ti)alloys are promising high-temperature(HT)structural materials for aerospace and automotive applications due to their superior specific HT strength and creep resistance.Nevertheless,improving the synergy between strength and ductility at HTs,and thereby expanding the operating tem-perature range,remains a key challenge in advancing the HT application potential of near-αTi alloys.Herein,a novel in-situ silicide modulation strategy is proposed to achieve superior high-temperature strength and ductility synergy in near-αTi alloys.Specifically,this strategy is realized through fabricating hypoeutectoid and hypereutectoid TA15 alloys(Ti-6.5Al-2Zr-1Mo-1V,wt.%)containing 0.5 wt.%and 1.0 wt.%silicon(Si)via spark plasma sintering(SPS).Results indicate that Si alloying significantly enhances the HT strength of the TA15 alloy without compromising its HT ductility.At 500℃,TA15 alloy with 1.0 wt.%Si achieves a tensile strength of 937.8 MPa with a break elongation of 17.5%,showing superior strength-ductility synergy over most commercial near-αTi alloys and Ti matrix composites.The superior HT strength-ductility synergy of the Si-containing alloys is attributed both to the silicides in-situ formed during SPS and to additional silicides in-situ formed during HT deformation.Additionally,adding 1.0 wt.%Si into TA15 alloy deteriorated the room-temperature ductility while having no adverse effect on the HT ductility,highlighting the temperature-dependent effects of intergranular silicides on mechanical proper-ties.Furthermore,quantitative analysis of HT strengthening mechanisms is performed,providing insights for designing near-αTi alloys for HT structural applications.展开更多
Titanium-silicon(Ti-Si)alloy system shows significant potential for aerospace and automotive applications due to its superior specific strength,creep resistance,and oxidation resistance.For Si-containing Ti alloys,the...Titanium-silicon(Ti-Si)alloy system shows significant potential for aerospace and automotive applications due to its superior specific strength,creep resistance,and oxidation resistance.For Si-containing Ti alloys,the sufficient content of Si is critical for achieving these favorable performances,while excessive Si addition will result in mechanical brittleness.Herein,both physical experiments and finite element(FE)simulations are employed to investigate the micro-mechanisms of Si alloying in tailoring the mechanical properties of Ti alloys.Four typical states of Si-containing Ti alloys(solid solution state,hypoeutectoid state,near-eutectoid state,hypereutectoid state)with varying Si content(0.3-1.2 wt.%)were fabricated via in-situ alloying spark plasma sintering.Experimental results indicate that in-situ alloying of 0.6 wt.%Si enhances the alloy’s strength and ductility simultaneously due to the formation of fine and uniformly dispersed Ti_(5)Si_(3)particles,while higher content of Si(0.9 and 1.2 wt.%)results in coarser primary Ti_(5)Si_(3)agglomerations,deteriorating the ductility.FE simulations support these findings,highlighting the finer and more uniformly distributed Ti_(5)Si_(3)particles contribute to less stress concentration and promote uniform deformation across the matrix,while agglomerated Ti_(5)Si_(3)particles result in increased local stress concentrations,leading to higher chances of particle fracture and reduced ductility.This study not only elucidates the micro-mechanisms of in-situ Si alloying for tailoring the mechanical properties of Ti alloys but also aids in optimizing the design of high-performance Si-containing Ti alloys.展开更多
Fluid-conveying pipes generally face combined excitations caused by periodic loads and random noises.Gaussian white noise is a common random noise excitation.This study investigates the random vibration response of a ...Fluid-conveying pipes generally face combined excitations caused by periodic loads and random noises.Gaussian white noise is a common random noise excitation.This study investigates the random vibration response of a simply-supported pipe conveying fluid under combined harmonic and Gaussian white noise excitations.According to the generalized Hamilton’s principle,the dynamic model of the pipe conveying fluid under combined harmonic and Gaussian white noise excitations is established.Subsequently,the averaged stochastic differential equations and Fokker–Planck–Kolmogorov(FPK)equations of the pipe conveying fluid subjected to combined excitations are acquired by the modified stochastic averaging method.The effectiveness of the analysis results is verified through the Monte Carlo method.The effects of fluid speed,noise intensity,amplitude of harmonic excitation,and damping factor on the probability density functions of amplitude,displacement,as well as velocity are discussed in detail.The results show that with an increase in fluid speed or noise intensity,the possible greatest amplitude for the fluid-conveying pipe increases,and the possible greatest displacement and velocity also increase.With an increase in the amplitude of harmonic excitation or damping factor,the possible greatest amplitude for the pipe decreases,and the possible greatest displacement and velocity also decrease.展开更多
基金supported by the Major Research Instrument Development Project of the National Natural Science Foundation of China(32527801)the National Natural Science Foundation of China(32301168)+1 种基金the Ningbo Natural Science Foundation of China(2023J351)the Yongjiang Innovative Talents Project of Ningbo City(2024A-172-G).
文摘Cells interact with the extracellular matrix and generate traction forces,which play fundamental roles in many cytological activities,such as migration and differentiation.The quanti fication of these traction forces is a prerequisite for understanding the interaction and regulation between force and functions,which can be accomplished by traction force microscopy(TFM).In TFM,the forces are determined by tracking the displacement of fiducial markers through optical microscopy.The type of fiducial marker,microscopy modality,and image processing algorithms are key factors determining the final resolution of TFM.This review summarizes efforts in three aspects to enhance the performance of TFM and discusses the challenges of further development,particularly from an optical view.
基金funded by the National Natural Science Foundation of China(No.12102244)the Open Fund of Hubei Longzhong Laboratory(No.2022KF-12)supported by the Laboratory of Flexible Electronics Technology at Tsinghua University.
文摘The development of wearable electronics necessitates flexible and robust energy storage components to enhance comfort and battery longevity.The key to flexible batteries is improving electrochemical stability during deformation,which demands mechanical analysis for optimized design and manufacturing.This paper summarizes the progress of flexible batteries from a mechanical perspective,highlighting highly deformable structures such as fiber,wave,origami,and rigid-supple integrated designs.We discuss mechanical performance characterization and existing evaluation criteria for battery flexibility,along with simulation modeling and testing methods.Furthermore,we analyze mechano-electrochemical coupling,reviewing theoretical models that simulate mechanical and electrochemical behavior under various loads and introduce coupling tests that assess electrochemical performance during deformation.Finally,we suggest future research directions to advance flexible energy storage devices.
基金Project supported by the National Natural Science Foundation of China(Nos.124B2043,U2241267,12172155,and 12302278)the Science and Technology Leading Talent Project of Gansu Province of China(No.23ZDKA0009)the Natural Science Foundation of Gansu Province of China(Nos.24JRRA473 and 24JRRA489)。
文摘The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread attention from researchers.In this paper,the deformation and buckling behaviors of a circular arch subject to compression by a rigid plate are investigated with a planar elastic rod model that incorporates tension,shearing,and bending.In comparison with the existing models that solely consider the bending energy,the deflection curve,the internal force distribution,and the critical load of the present model show good agreement with the finite element results.Through the dimensional analysis and order-of-magnitude estimation,we examine the factors influencing the critical load.The study reveals that the semi-central angle of the arch has the most significant effect.The dimensionless geometric parameter describing arch slenderness becomes prominent when the semi-central angle is less than 30°,while Poisson's ratio and the cross-sectional shear correction factor exhibit negligible influence.Furthermore,the variation in the proportions of strain energy components during critical buckling is presented with respect to the semi-central angle and the geometric parameter,thereby delineating the applicable ranges of both the original model(OM)and the modified model(MM).
基金Project supported by the National Natural Science Foundation of China(No.12472077)the supports from Shanghai Gaofeng Project for University Academic Program Development,Fundamental Research Funds for the Central Universities(No.22120240353).
文摘Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenization methods based on the classical elasticity theory struggle to accurately describe the non-classical mechanical behaviors of lattice materials,especially when dealing with complex unit-cell geometries featured by non-symmetric configurations or non-single central node connections.In response to this limitation,this study establishes a generalized homogenization model based on the micropolar theory framework,employing Hill's boundary conditions to precisely predict the equivalent moduli of complex lattice materials.By introducing the independent rotational degree of freedom(DOF)characteristic of the micropolar theory,the proposed model successfully overcomes the limitation of conventional methods in accurately describing the asymmetric deformation and scale effects.We initially calculate the constitutive relations of two-dimensional(2D)cross-shaped multi-node chiral lattices and subsequently extend the method to three-dimensional(3D)lattices,successfully predicting the mechanical properties of both traditional and eccentric body-centered cubic(BCC)lattices.The theoretical model is validated through the finite element numerical verification which shows excellent consistency with the theoretical predictions.A further parametric study investigates the influence of geometric parameters,revealing the underlying size-effect mechanism.This paper provides a reliable theoretical tool for the design and property optimization of complex lattice materials.
基金the National Natural Science Foundation of China(Grant Nos.11822206 and 12072182)Innovation Program of the Shanghai Municipal Education Commission(Grant No.2017-01-07-00-09-E00019)。
文摘The Kapitza resistance is of fundamental importance for the thermal stability of the interface between the ceramic top coat and the thermal growth oxide layer in the thermal barrier coating structure,which is widely used to protect high-temperature components in current gas turbine engines.The top coat typically consists of the ZrO_(2)partially stabilized by 8%Y2O3(YSZ),and the main component of the thermal growth oxide isα-Al_(2)O_(3).In this work,the Kapitza resistance is found to be a small value of 0.69 m^(2)K/GW for the YSZ/α-Al_(2)O_(3)interface based on the heat dissipation simulation method.It indicates that the localization of thermal energy is rather weak,which is beneficial for the thermal stability of the YSZ/α-Al_(2)O_(3)interface.This Kapitza resistance can be further reduced to 0.50 m^(2)K/GW by a mechanical or thermal compressive strain of 8%.To explore the underlying mechanism for this strain effect,we analyze the phonon vibration and the microscopic deformation in the interface region.It is revealed that the interface becomes denser through the compression-induced twisting of some Al-O_(zr)and A1-O_(Al)chemical bonds in the interface region,which is responsible for the reduction in the Kapitza resistance.The temperature effect and crystal size effect on the Kapitza resistance of the YSZ/α-Al_(2)O_(3)interface are also systematically studied.These findings shall provide valuable information for further understanding of the thermal conductivity and thermal stability of the thermal barrier coating structures.
文摘Recently, intelligent or smart materials and structures have been received more and more attention due to their distinguished multi-field coupling properties and wide applications in aerospace, automobiles, civil structures, medical devices, information storage, energy harvesting and so on. It is of academic challenge to fully understand the complex multi-field coupling behaviors of various smart materials and structures, and of engineering sig- nificance to enhance the performance and reliability of these materials and structures in industrial applications. The papers in the special topic of Mechanics of Intelligent Materials and Structures focus on the understanding of the electromechanical, magneto-elastic, and magneto-rheological coupling behav- iors and properties of smart materials and structures for applications in vibration control, resonators, and various functional devices.
基金supported by the National Natural Science Foundation of China(12072136).
文摘Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.
基金This work are supported by the Natural Science Foundation of China General Program(Grant No.12272157)the Natural Science Foundation of China Major Program(Grant No.12327901)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2023-ey05)the 111 Project(Grant No.B14044).
文摘The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the interface performances of the engineering structures.In this paper,a contact model is established,which is suitable for tensile and bending deformed contact surfaces.Four contact forms of asperities are proposed,and their distribution characteristics are analyzed.This model reveals the mechanism of friction generation from the perspective of the force balance of asperity.The results show the contact behaviors of the deformed contact surface are significantly different from that of the plane contact,which is mainly reflected in the change in the number of contact asperities and the real contact area.This study suggests that the real contact area of the interface can be altered by applying tensile and bending strains,thereby regulating its contact mechanics and conductive behavior.
基金the National Natural Science Foundation of China(grant Nos.11988102,52301146,51301173,51531002,52171055,52371037,51601193)the National Key Research and Development Program of China(grant No.2016YFB0301104)+1 种基金the Fundamental Research Funds for the Central Universities(grant No.2023JG007)China Postdoctoral Science Foundation(grant No.8206300226).
文摘Tension-compression asymmetry is a critical concern for magnesium(Mg)alloys,particularly in automo-tive crash structures.This study systematically examines the tension-compression asymmetry of a cast Mg-Gd-Y alloy at various strain rates.Experimental results indicate symmetric yielding stress under both tension and compression at all strain rates,along with a reduction in the tension-compression asym-metry of ultimate stress and plastic strain as the strain rate increases.This trend arises from an unusual strain rate-dependent tension-compression asymmetry,characterized by strain rate toughening in tension and negligible strain rate effect in compression.The differing behavior is linked to the distinct twinning mechanisms under tension and compression.The suppression of twinning under tension contributes to the positive strain rate dependence of pyramidal slip,whereas the activation of abundant twins during compression means that pyramidal slip is unnecessary to accommodate c-axis strain,leading to the ab-sence of a strain rate effect in compression.Abundant twins nucleate consistently from yielding to 2%strain,but only after basal and prismaticslip have mediated microplasticity,suggesting that these slip systems reduce the nucleation stress for twinning during compression,resulting in a lower activation stress for twinning compared to tension.This study provides new insights into micromechanisms of the tension-compression asymmetry in cast Mg-Gd-Y alloys and offers practical guidance for the application of these materials in critical components that must endure both tension and compression under varying strain rates.
基金supported by the National Natural Science Foundation of China(Grant Nos.11932006 and 12172121).
文摘This study presents a coupled thermo-hydro-mechanical-fatigue(THM-F)model,developed based on variational phase-field fatigue theory,to simulate the freeze-thaw(F-T)damage process in concrete.The fracture phasefield model incorporates the F-T fatigue mechanism driven by energy dissipation during the free energy growth stage.Using microscopic inclusion theory,we derive an evolution model of pore size distribution(PSD)for concrete under F-T cycles by treating pore water as columnar inclusions.Drawing upon pore ice crystal theory,calculation models that account for concrete PSD characteristics are established to determine ice saturation,permeability coefficient,and pore pressure.To enhance computational accuracy,a segmented Gaussian integration strategy based on aperture levels is employed.The pore pressure estimation model is applied to assess the frost resistance of concrete with varying air-entraining agent contents,confirming that optimal air-entrainment significantly improves pore structure and lowers the overall freezing point of pore ice.The derived permeability coefficient and pore pressure estimation models are integrated into the THM-F coupled framework,which employs a staggered iterative solution scheme for efficient simulation.Mesoscale numerical examples of concrete demonstrate that the proposed THM-F model effectively captures structural degradation and accurately tracks the procession of F-T-induced fatigue cracks.Validations against experimental measurements,including temperature variations,stress-strain curves,and strain history,shows excellent agreement,underscoring the model’s accuracy and applicability.This study provides a robust theoretical and computational framework for quantitative analysis of coupled F-T-fatigue damage in concrete.
基金supported by the National Natural Science Foundation of China(Grant Nos.12232005 and 12072101).
文摘Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applications such as trapped field magnets.However,for such large-grain superconductor bulks,there are lots of voids and cracks forming during the process of melting preparation,and some of them can be up to hundreds of microns or even millimeters in size.Consequently,these larger size voids/cracks pose a great threat to the strength of the bulks due to the inherent brittleness of superconductor REBCO materials.In order to ensure the operational safety of related superconducting devices with bulk superconductors,it is firstly important to accurately detect these voids/cracks in them.In this paper,we proposed a method for quantitatively evaluating multiple voids/cracks in bulk superconductors through the magnetic field and displacement response signals at superconductor bulk surface.The proposed method utilizes a damage index constructed from the magnetic field signals and displacement responses to identify the number and preliminary location of multiple defects.By dividing the detection area into subdomains and combining the magnetic field signals with displacement responses within each subdomain,a particle swarm algorithm was employed to evaluate the location and size parameters of the defects.In contrast to other evaluation methods using only magnetic field or displacement response signals,the combined evaluation method using both signals can identify the number of cracks effectively.Numerical studies demonstrate that the morphology of voids and cracks reconstructed using the proposed algorithm ideally matches real defects and is applicable to cases where voids and cracks coexist.This study provides a theoretical basis for the quantitative detection of voids/cracks in bulk superconductors.
基金supported by the National Natural Science Foundation of China(Grant Nos.12325202,12172005,and 11988102)。
文摘Accurately predicting the mechanical behavior of pure metals at different radiation doses and prescribing the microstructure evolutions,such as the dislocation structures,remain challenging.This work introduces a 3D hybrid numerical simulation scheme that integrates finite element(FE)and finite difference(FD)modules.The FE module is used to implement the crystal plasticity model,while the FD module is used to solve the reaction-diffusion model regarding dislocation nucleation and transportation.Our hybrid model successfully replicates the mechanical behavior of pristine Cu single crystals and provides details of dislocation cell structures that agree with the experimental observation.Furthermore,the model effectively reflects the irradiation hardening effects for Cu single crystals and demonstrates the formation of dislocation channels and shear band type of strain localization.Our work offers an effective approach for predicting the mechanical responses and the safety evaluation of pure metals in extreme working conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.12172062 and 12588201).
文摘Surface energy is essential to the understanding of micro-mechanics for heterogeneous composites.To investigate the effective elasticity and fracture behaviors,we derive an effective surface energy based on Eshelby’s equivalent inclusion theory.Within a unified theoretical framework,the effective surface energy predicts the fundamentals from elasticity to fracture,and reproduces classical homogenization methods and phase field models.The influences of elastic heterogeneity and size effects are analyzed in depth.Using the surface energy formulation,a computational model is developed by minimizing the deviation of effective elastic modulus from experimental observation.To validate our theoretical prediction,numerical simulations under tension and shear loadings for monodisperse and bidisperse particulate systems are performed,which agree well with experimental evidences.Local debondings nucleate and initiate at the inclusion-matrix interfaces,then develop into multiple interacting cracks and shear bands,thereby greatly promotes the process of fracture.
基金supported by the National Natural Science Foundation of China(Grant No.12302500)the National Key Research and Development Program of China(Grant No.2020YFA0710503)Postdoctoral Fellowship Program(Grade B)of China Postdoctoral Science Foundation(Grant No.GBZ20230022).
文摘Controllable shock wave fracturing is an innovative engineering technique used for shale reservoir fracturing and reformation.Understanding the anisotropic fracture mechanism of shale under impact loading is vital for optimizing shock wave fracturing equipment and enhancing shale oil production.In this study,using the well-known notched semi-circular bend(NSCB)sample and the novel double-edge notched flattened Brazilian disc(DNFBD)sample combined with a split Hopkinson pressure bar(SHPB),various dynamic anisotropic fracture properties of Lushan shale,including failure characteristics,fracture toughness,energy dissipation and crack propagation velocity,are comprehensively compared and discussed under mode Ⅰ and mode Ⅱ fracture scenarios.First,using a newly modified fracture criterion considering the strength anisotropy of shale,the DNFBD specimen is predicted to be a robust method for true mode Ⅱ fracture of anisotropic shale rocks.Our experimental results show that the dynamic mode Ⅱ fracture of shale induces a rougher and more complex fracture morphology and performs a higher fracture toughness or fracture energy compared to dynamic mode Ⅰ fracture.The minimal fracture toughness or fracture energy occurs in the Short-transverse orientation,while the maximal ones occur in the Divider orientation.In addition,it is interesting to find that the mode Ⅱ fracture toughness anisotropy index decreases more slowly than that in the mode Ⅰ fracture scenario.These results provide significant insights for understanding the different dynamic fracture mechanisms of anisotropic shale rocks under impact loading and have some beneficial implications for the controllable shock wave fracturing technique.
基金Project supported by the National Natural Science Foundation of China(No.U23A2066)the Liaoning Revitalization Talents Program of China(No.XLYC2202032)。
文摘Bionic X-shaped vibration isolators have been widely employed in aerospace and other industrial fields,but the stiffness properties of classic X-shaped structures limit the vibration isolation ability for low frequencies.An innovative bionic quasi-zero stiffness(QZS)vibration isolator(BQZSVI),which can broaden the QZS range of a classic X-shaped isolator and can bring it closer to the equilibrium position,is proposed.The BQZSVI consists of an X-shaped structure as the bone fabric of lower limbs and a nonlinear magnetic loop device simulating the leg muscle.Based on static calculation,the stiffness characteristic of the structure is confirmed.The governing equations of motion of the BQZSVI structure are established in the framework of the Lagrange equation,and the harmonic balance method(HBM)is adopted to obtain the transmissibility responses.The results show that the BQZSVI can provide a more accessible and broader range of QZS.In the dynamic manifestation,the introduction of the BQZSVI can reduce the amplitude of a classic X-shaped vibration isolator by 65.7%,and bring down the initial vibration isolation frequency from 7.43 Hz to 2.39 Hz.In addition,a BQZSVI prototype is designed and fabricated,and the exactitude of the theoretical analysis method is proven by means of experiments.
基金supported by the National Natural Science Foundation of China under Grant Nos.12172205,11872236,and 12072183.
文摘Lithium ion batteries are important for new energy technologies and manufacturing systems.However,enhancing their capacity and cycling stability poses a significant challenge.This study proposes a novel method,i.e.,modifying current collectors with perforations,to address these issues.Lithium ion batteries with mechanically perforated current collectors are prepared and tested with charge/discharge cycles,revealing superior capacity as well as enhanced electrochemical stability over cycles.Impedance spectroscopy,scanning electron microscopy,and peeling tests are conducted to investigate the underlying mechanisms.Higher peel resistance,minimized interface cracking,and reduced electrical impedance are found in the perforated electrodes after cycles.Investigations indicate that the perforation holes on current collectors allow the active materials coating on the two sides of the current collector to bind together and,thus,lead to enhanced adhesion between the current collector and active layer.Mechanical simulation illustrates the role of perforated current collectors in curbing interface cracking during lithiation,while electrochemical simulation shows that the interfacial cracking hinders the diffusion of lithium ions,thereby increasing battery impedance and reducing the cyclic performance.This investigation reveals the potential of designing non-active battery components to enhance battery performance,advocating a nuanced approach to battery design emphasizing structural integrity and interface optimization.
基金supported by the National Natural Science Foundations of China(No.11972267 and 11802214)the Fundamental Research Funds for the Central Universities(No.104972024JYS0022)the Open Fund of the Hubei Longzhong Laboratory(No.2024KF-30).
文摘This study investigates the dynamic compressive behavior of three periodic lattice structures fabricated from Ti-6Al-4V titanium alloy,each with distinct topologies:simple cubic(SC),body-centered cubic(BCC),and face-centered cubic(FCC).Dynamic compression experiments were conducted using a Split Hopkinson Pressure Bar(SHPB)system,complemented by high-speed imaging to capture real-time deformation and failure mechanisms under impact loading.The influence of cell topology,relative density,and strain rate on dynamic mechanical properties,failure behavior,and stress wave propagation was systematically examined.Finite element modeling was performed,and the simulated results showed good agreement with experimental data.The findings reveal that the dynamic mechanical properties of the lattice structures are generally insensitive to strain rate variations,while failure behavior is predominantly governed by structural configuration.The SC structure exhibited strut buckling and instability-induced fracture,whereas the BCC and FCC structures displayed layer-by-layer crushing with lower strain rate sensitivity.Regarding stress wave propagation,all structures demonstrated significant attenuation capabilities,with the BCC structure achieving the greatest reduction in transmitted wave amplitude and energy.Across all configurations,wave reflection was identified as the primary energy dissipation mechanism.These results provide critical insights into the design of lattice structures for impact mitigation and energy absorption applications.
基金supported by the Natural Science Foundation of Hunan Province(No.2023JJ40353)the National Key Research and Development Program of China(No.2019YFE03120001).
文摘Near-αtitanium(Ti)alloys are promising high-temperature(HT)structural materials for aerospace and automotive applications due to their superior specific HT strength and creep resistance.Nevertheless,improving the synergy between strength and ductility at HTs,and thereby expanding the operating tem-perature range,remains a key challenge in advancing the HT application potential of near-αTi alloys.Herein,a novel in-situ silicide modulation strategy is proposed to achieve superior high-temperature strength and ductility synergy in near-αTi alloys.Specifically,this strategy is realized through fabricating hypoeutectoid and hypereutectoid TA15 alloys(Ti-6.5Al-2Zr-1Mo-1V,wt.%)containing 0.5 wt.%and 1.0 wt.%silicon(Si)via spark plasma sintering(SPS).Results indicate that Si alloying significantly enhances the HT strength of the TA15 alloy without compromising its HT ductility.At 500℃,TA15 alloy with 1.0 wt.%Si achieves a tensile strength of 937.8 MPa with a break elongation of 17.5%,showing superior strength-ductility synergy over most commercial near-αTi alloys and Ti matrix composites.The superior HT strength-ductility synergy of the Si-containing alloys is attributed both to the silicides in-situ formed during SPS and to additional silicides in-situ formed during HT deformation.Additionally,adding 1.0 wt.%Si into TA15 alloy deteriorated the room-temperature ductility while having no adverse effect on the HT ductility,highlighting the temperature-dependent effects of intergranular silicides on mechanical proper-ties.Furthermore,quantitative analysis of HT strengthening mechanisms is performed,providing insights for designing near-αTi alloys for HT structural applications.
基金supported by the Natural Science Foundation of Hunan Province(Grant No.2023JJ40353)the National Key Research and Development Program of China(No.2019YFE03120001).
文摘Titanium-silicon(Ti-Si)alloy system shows significant potential for aerospace and automotive applications due to its superior specific strength,creep resistance,and oxidation resistance.For Si-containing Ti alloys,the sufficient content of Si is critical for achieving these favorable performances,while excessive Si addition will result in mechanical brittleness.Herein,both physical experiments and finite element(FE)simulations are employed to investigate the micro-mechanisms of Si alloying in tailoring the mechanical properties of Ti alloys.Four typical states of Si-containing Ti alloys(solid solution state,hypoeutectoid state,near-eutectoid state,hypereutectoid state)with varying Si content(0.3-1.2 wt.%)were fabricated via in-situ alloying spark plasma sintering.Experimental results indicate that in-situ alloying of 0.6 wt.%Si enhances the alloy’s strength and ductility simultaneously due to the formation of fine and uniformly dispersed Ti_(5)Si_(3)particles,while higher content of Si(0.9 and 1.2 wt.%)results in coarser primary Ti_(5)Si_(3)agglomerations,deteriorating the ductility.FE simulations support these findings,highlighting the finer and more uniformly distributed Ti_(5)Si_(3)particles contribute to less stress concentration and promote uniform deformation across the matrix,while agglomerated Ti_(5)Si_(3)particles result in increased local stress concentrations,leading to higher chances of particle fracture and reduced ductility.This study not only elucidates the micro-mechanisms of in-situ Si alloying for tailoring the mechanical properties of Ti alloys but also aids in optimizing the design of high-performance Si-containing Ti alloys.
基金supported by the National Natural Science Foundation of China(Nos.12272211 and 12072181).
文摘Fluid-conveying pipes generally face combined excitations caused by periodic loads and random noises.Gaussian white noise is a common random noise excitation.This study investigates the random vibration response of a simply-supported pipe conveying fluid under combined harmonic and Gaussian white noise excitations.According to the generalized Hamilton’s principle,the dynamic model of the pipe conveying fluid under combined harmonic and Gaussian white noise excitations is established.Subsequently,the averaged stochastic differential equations and Fokker–Planck–Kolmogorov(FPK)equations of the pipe conveying fluid subjected to combined excitations are acquired by the modified stochastic averaging method.The effectiveness of the analysis results is verified through the Monte Carlo method.The effects of fluid speed,noise intensity,amplitude of harmonic excitation,and damping factor on the probability density functions of amplitude,displacement,as well as velocity are discussed in detail.The results show that with an increase in fluid speed or noise intensity,the possible greatest amplitude for the fluid-conveying pipe increases,and the possible greatest displacement and velocity also increase.With an increase in the amplitude of harmonic excitation or damping factor,the possible greatest amplitude for the pipe decreases,and the possible greatest displacement and velocity also decrease.
