This paper introduces a novel optimization approach called Recuperated Seed Search Optimization(RSSO),designed to address challenges in solving mechanical engineering design problems.Many optimization techniques strug...This paper introduces a novel optimization approach called Recuperated Seed Search Optimization(RSSO),designed to address challenges in solving mechanical engineering design problems.Many optimization techniques struggle with slow convergence and suboptimal solutions due to complex,nonlinear natures.The Sperm Swarm Optimization(SSO)algorithm,which mimics the sperm’s movement to reach an egg,is one such technique.To improve SSO,researchers combined it with three strategies:opposition-based learning(OBL),Cauchy mutation(CM),and position clamping.OBL introduces diversity to SSO by exploring opposite solutions,speeding up convergence.CM enhances both exploration and exploitation capabilities throughout the optimization process.This combined approach,RSSO,has been rigorously tested on standard benchmark functions,real-world engineering problems,and through statistical analysis(Wilcoxon test).The results demonstrate that RSSO significantly outperforms other optimization algorithms,achieving faster convergence and better solutions.The paper details the RSSO algorithm,discusses its implementation,and presents comparative results that validate its effectiveness in solving complex engineering design challenges.展开更多
It is discussed that a tangential force T induces a self-excited vibration in the motion ofspindle blades of a ring spinning frame.Depending on the relative magnitude of the tangentialforce compared with the tangentia...It is discussed that a tangential force T induces a self-excited vibration in the motion ofspindle blades of a ring spinning frame.Depending on the relative magnitude of the tangentialforce compared with the tangential damping force the motion of blade is either stable orunstable.The chief factors causing the self-excited vibration can also be traced from the charac-ter of the experimental locus.展开更多
The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary cha...The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary challenges that must be addressed.For example,although bredigite(Br)has shown great potential for application in bone tissue engineering,it easily fails in replacement.In the present work,these challenges are addressed by reinforcing the Br matrix with nanosheets of graphene oxide(rGO)that have been reduced by bovine serum albumin(BSA)in order to enhance the mechanical properties and biological behavior.The reduction of graphene oxide by BSA improves the water stability of the nanosheets and provides an electrostatic interaction between theBSA-rGO nanosheets and theBr particles.The high thermal conductivity of theBSA-rGO nanosheets decreases the porosity of the Br by transferring heat to the core of the tablet.Furthermore,the addition of BSA-rGO nanosheets into the Br matrix enhances the adhesion of G-292 cells on the surface of the tablets.These findings suggest that the tablet consisting of BSA-rGO-reinforced Br has encouraging potential for application in bone tissue engineering.展开更多
Mechanical properties of ukam, banana, sisal, coconut, hemp and e-glass fibre reinforced laminates were evaluated to assess the possibility of using it as new material in engineering applications. Samples were fabrica...Mechanical properties of ukam, banana, sisal, coconut, hemp and e-glass fibre reinforced laminates were evaluated to assess the possibility of using it as new material in engineering applications. Samples were fabricated by the hand lay-up process (30:70 fibre and matrix ratio by weight) and the properties evaluated using the INSTRON material testing system. The mechanical properties were tested and showed that glass laminate has the maximum tensile strength of 63 MPa, bending strength of 0.5 MPa, compressive strength of 37.75 MPa and the impact strength of 17.82 J/m2. The ukam plant fibre laminate has the maximum tensile strength of 16.25 MPa and the impact strength of 9.8J/m among the natural fibres;the sisal laminate has the maximum compressive strength of 42 MPa and maximum bending strength of 0.0036 MPa among the natural fibres. Results indicated that natural fibres are of interest for low-cost engineering applications and can compete with artificial glass fibres (E-glass fibre) when a high stiffness per unit weight is desirable. Results also indicated that future research towards significant improvements in tensile and impact strength of these types of composites should focus on the optimisation of fibre strength rather than interfacial bond strength.展开更多
Process engineering has been seen as one of the vital tools for improving surface coating phenomena for advance application. In an attempt to improve the mechanical, physical and chemical performance of the steel stru...Process engineering has been seen as one of the vital tools for improving surface coating phenomena for advance application. In an attempt to improve the mechanical, physical and chemical performance of the steel structure for ex-tended application, Zn-CeO2/ZnCeO2-Al2SiO5 thin film composite was fabri-cated on mild steel using direct electrolytic route. Process variation of Al2SiO5 particulate ranges from 5 to 15 g per litre. The embedded coating was charac-terized using Scanning electron microscope (SEM). The chemical effect of the developed alloy was characterized through linear potentiodynamic polarization experiment and the performances of samples were examined in simulated 3.5% sodium chloride. The microhardness verification study proves that there is sig-nificant improvement in hardness trend. The tribological assessment indicated that there is less plastic deformation as a result of the counter body. In all, Zn-CeO2/Zn-CeO2-Al2SiO5 exhibits good stability, with agglomeration and great built up of crystal at the interface.展开更多
Dynamics is the foundation of undergraduate study in mechanical engineering. If you are good in dynamics, you will be good on all other courses. Advanced dynamics is the foundation for graduate study. The author taugh...Dynamics is the foundation of undergraduate study in mechanical engineering. If you are good in dynamics, you will be good on all other courses. Advanced dynamics is the foundation for graduate study. The author taught advanced dynamics for more than ten years, this is the author＇s observation. Why it is so？ Because the course of advanced dynamics covers usually many mathematical fundamentals such as vectors, tensors, matrices and rotation operators; principles and applications in dynamics from particle dynamics to rigid body motion, from small oscillation to vibration of systems with multiple degrees of freedom, the author＇s course covers also special relativity theory. They are very innovative. And they set the foundation for the study of all the graduate courses. Science is always in progress, dynamics is in the same form. Just say a few examples to illustrate the frontier of dynamics： missile shooting missile is important in our defense, the author covered this as an example in particle dynamics. Space ship travels from Earth to Mars is another example. Several rotational motions with different axes can be combined to one through the use of rotation operator. This is important because it usually can save time. All these examples will be included in this paper in some details.展开更多
Titanium(Ti)and its alloys are frequently utilized as critical components in a variety of engineering ap-plications because of their high specific strength and excellent corrosion resistance.Compared to conven-tional ...Titanium(Ti)and its alloys are frequently utilized as critical components in a variety of engineering ap-plications because of their high specific strength and excellent corrosion resistance.Compared to conven-tional surface strengthening technologies,laser shock peening(LSP)has increasingly attracted attention from researchers and industries,since it significantly improves the surface strength,biocompatibility,fa-tigue resistance,and anti-corrosion ability of Ti and its alloys.Despite numerous studies that have been carried out to elucidate the effects of LSP on microstructural evolution and mechanical properties of Ti and its alloys in recent years,a comprehensive review of recent advancements in the field of Ti and its alloys subjected to LSP is still lacking.In this review,the standard LSP and the novel process designs of LSP assisted by thermal,cryogenic,electropulsing and magnetic fields are discussed and compared.Microstructural evolution,with focuses on the dislocation dynamics,deformation twinning,grain refine-ment and surface amorphization,during LSP processing of Ti alloys is reviewed.Furthermore,the en-hanced engineering performance of the L SP-processed(L SPed)Ti alloys,including surface hardness,wear resistance,fatigue life and corrosion resistance are summarized.Finally,this review concludes by present-ing an overview of the current challenges encountered in this field and offering insights into anticipated future trends.展开更多
Control of the columnar to equiaxed transition(CET)is a major challenge in additively manufacturedβtitanium alloys.In this work,the promotion of CET was successfully achieved through in-situ fabrication of Ti-5Cu(wt....Control of the columnar to equiaxed transition(CET)is a major challenge in additively manufacturedβtitanium alloys.In this work,the promotion of CET was successfully achieved through in-situ fabrication of Ti-5Cu(wt.%)alloys with additions of 5,15,and 25 wt.%Nb using elemental Ti,Cu,and Nb powders by employing laser powder bed fusion(LPBF).The alloy containing 5 wt.%Nb consisted ofαlamellae,Ti2 Cu precipitates,and unmeltedβ-Nb inclusions,whereas the 25 wt.%Nb alloy consisted of equiaxedβgrains,ωprecipitates,and Ti2 Cu precipitates at the grain boundaries.In terms of mechanical proper-ties,despite the presence of Nb inclusions and liquation cracks in the 5 wt.%Nb alloy,it showed a yield strength of 1051±40 MPa and an elongation of 5.2%±1.3%.Both the strength and ductility decreased with increasing Nb content,e.g.,the 25 wt.%Nb alloy exhibited a yield strength of 808±53 MPa and an elongation of 1.6%±0.2%.As the Nb content increased from 5 to 25 wt.%,the Young’s modulus decreased from 110 to 65 GPa.The 25 wt.%Nb alloy showed a high ratio of hardness to Young’s mod-ulus(H/E)and yield pressure(H3/E2).However,due to its brittle nature,the material manifested high wear rates.These findings provide a basis for the future development of novel low-modulus isotropicβ-titanium alloys using LPBF.展开更多
Magnesium(Mg)-based bioresorbable stents represent a potentially groundbreaking advancement in cardiovascular therapy;offering tem-porary vessel support and complete biodegradability—addressing limitations of traditi...Magnesium(Mg)-based bioresorbable stents represent a potentially groundbreaking advancement in cardiovascular therapy;offering tem-porary vessel support and complete biodegradability—addressing limitations of traditional stents like in-stent restenosis and long-term com-plications.However,challenges such as rapid corrosion and suboptimal endothelialisation have hindered their clinical adoption.This review highlights the latest breakthroughs in surface modification,alloying,and coating strategies to enhance the mechanical integrity,corrosion resistance,and biocompatibility of Mg-based stents.Key surface engineering techniques,including polymer and bioactive coatings,are ex-amined for their role in promoting endothelial healing and minimising inflammatory responses.Future directions are proposed,focusing on personalised stent designs to optimize efficacy and long-term outcomes,positioning Mg-based stents as a transformative solution in interventional cardiology.展开更多
The functionally graded materials(FGMs)are obtained by various processes.Although a few FGMs are obtained naturally,such as oyster,pearl,and bamboo,additive manufacturing(AM),known as 3D printing,is a net-shaped manuf...The functionally graded materials(FGMs)are obtained by various processes.Although a few FGMs are obtained naturally,such as oyster,pearl,and bamboo,additive manufacturing(AM),known as 3D printing,is a net-shaped manufacturing process employed to manufacture complex 3D objects without tools,molds,assembly,and joining.Currently,commercial AM techniques mostly use homogeneous composition with simplified geometric descriptions,employing a single material across the entire component to achieve functional graded additive manufacturing(FGAM),in contrast to multi-material FGAM with heterogeneous structures.FGMs are widely used in various fields due to their mechanical property advantages.Because FGM plays a significant role in the industrial production,the characteristics and mechanical behaviour of FGMs prepared by AM were reviewed.In this review,the research on FGMs and AM over the past 30 years was reviewed,suggesting that future researchers should focus on the application of artificial intelligence and machine learning technologies in industry to optimize the process parameters of different gradient systems.展开更多
Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how str...Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how stress affects lifespan,this review offers the first comprehensive,multiscale comparison of strategies that optimize geometry to improve fatigue performance.This includes everything from microscopic features like the shape of graphite nodules to large-scale design elements such as fillets,notches,and overall structural layouts.We analyze and combine various methods,including topology and shape optimization,the ability of additive manufacturing to finetune internal geometries,and reliability-based design approaches.A key new contribution is our proposal of a standard way to evaluate geometry-focused fatigue design,allowing for consistent comparison and encouraging validation across different fields.Furthermore,we highlight important areas for future research,such as incorporating manufacturing flaws,using multiscale models,and integrating machine learning techniques.This work is the first to provide a broad geometric viewpoint in fatigue engineering,laying the groundwork for future design methods that are driven by data and centered on reliability.展开更多
The synthesis of carbon supporter/nanoscale high-entropy alloys(HEAs)electromagnetic response composites by carbothermal shock method has been identified as an advanced strategy for the collaborative competition engin...The synthesis of carbon supporter/nanoscale high-entropy alloys(HEAs)electromagnetic response composites by carbothermal shock method has been identified as an advanced strategy for the collaborative competition engineering of conductive/dielectric genes.Electron migration modes within HEAs as manipulated by the electronegativity,valence electron configurations and molar proportions of constituent elements determine the steady state and efficiency of equivalent dipoles.Herein,enlightened by skin-like effect,a reformative carbothermal shock method using carbonized cellulose paper(CCP)as carbon supporter is used to preserve the oxygencontaining functional groups(O·)of carbonized cellulose fibers(CCF).Nucleation of HEAs and construction of emblematic shell-core CCF/HEAs heterointerfaces are inextricably linked to carbon metabolism induced by O·.Meanwhile,the electron migration mode of switchable electronrich sites promotes the orientation polarization of anisotropic equivalent dipoles.By virtue of the reinforcement strategy,CCP/HEAs composite prepared by 35%molar ratio of Mn element(CCP/HEAs-Mn_(2.15))achieves efficient electromagnetic wave(EMW)absorption of−51.35 dB at an ultra-thin thickness of 1.03 mm.The mechanisms of the resulting dielectric properties of HEAs-based EMW absorbing materials are elucidated by combining theoretical calculations with experimental characterizations,which provide theoretical bases and feasible strategies for the simulation and practical application of electromagnetic functional devices(e.g.,ultra-wideband bandpass filter).展开更多
This study investigates the impact of welding heat input on weldments of modified 9Cr-1Mo(P91)steel,a high-strength material that requires high-energy welding processes like submerged arc welding.In the as-welded cond...This study investigates the impact of welding heat input on weldments of modified 9Cr-1Mo(P91)steel,a high-strength material that requires high-energy welding processes like submerged arc welding.In the as-welded condition,P91 steel welds primarily consist of untempered martensite,which transforms into tempered martensite during post-weld heat treatment(PWHT).Electron spectro-scopy analysis reveals the presence of M_(23)C_(6) and MX carbonitride precipitates at grain boundaries.Increasing the heat input leads to greater quantities of precipitates in the prior austenite grain boundaries,which can affect material properties.Weldment hardness profiles exhibit modest improvements,while ultimate tensile strength and toughness decrease with higher welding heat input,poten-tially due to the formation of a ferritic phase.Residual stress distributions are noticeably influenced by the welding heat input level.展开更多
Assessing the vulnerability of a platform is crucial in its design.In fact,the results obtained from vulnerability analyses provide valuable information,leading to precise design choices or corrective solutions that e...Assessing the vulnerability of a platform is crucial in its design.In fact,the results obtained from vulnerability analyses provide valuable information,leading to precise design choices or corrective solutions that enhance the platform's chances of surviving different scenarios.Such scenarios can involve various types of threats that can affect the platform's survivability.Among such,blast waves impacting the platform's structure represent critical conditions that have not yet been studied in detail.That is,frameworks for vulnerability assessment that can deal with blast loading have not been presented yet.In this context,this work presents a fast-running engineering tool that can quantify the risk that a structure fails when it is subjected to blast loading from the detonation of high explosive-driven threats detonating at various distances from the structure itself.The tool has been implemented in an in-house software that calculates vulnerability to various impacting objects,and its capabilities have been shown through a simplified,yet realistic,case study.The novelty of this research lies in the development of an integrated computational environment capable of calculating the platform's vulnerability to blast waves,without the need for running expensive finite element simulations.In fact,the proposed tool is fully based on analytical models integrated with a probabilistic approach for vulnerability calculation.展开更多
The precise computation of nanoelectromechanical switches’(NEMS)multi-physical interactions requires advanced numerical models and is a crucial part of the development of micro-and nano-systems.This paper presents a ...The precise computation of nanoelectromechanical switches’(NEMS)multi-physical interactions requires advanced numerical models and is a crucial part of the development of micro-and nano-systems.This paper presents a novel compound numerical method to study the instability of a functionally graded(FG)beam-type NEMS,considering surface elasticity effects as stated by Gurtin-Murdoch theory in an Euler-Bernoulli beam.The presented method is based on a combination of the Method of Adjoints(MoA)together with the Bézier-based multistep technique.By utilizing the MoA,a boundary value problem(BVP)is turned into an initial value problem(IVP).The resulting IVP is then solved by employing a cost-efficient multi-step process.It is demonstrated that the mentioned method can arrive at a high level of accuracy.Furthermore,it is revealed that the stability of the presented methodology is far better than that of other common multi-step methods,such as Adams-Bashforth,particularly at higher step sizes.Finally,the effects of axially functionally graded(FG)properties on the pull-in phenomenon and the main design parameters of NEMS,including the detachment length,are inspected.It was shown that the main parameter of design is the modulus of elasticity of the material,as Silver(Ag),which had better mechanical properties,showed almost a 6%improvement compared to aluminum(Al).However,by applying the correct amount of material with sturdier surface parameters,such as Aluminum(Al),at certain points,the nanobeams’functionality can be improved even further by around 1.5%.展开更多
The mechanical behaviour of Titanium-based Fiber Metal Laminates(FMLs)reinforced with Kevlar,Jute and the novel woven(Kevlar+Jute)fiber mat were evaluated through tensile,flexural,Charpy impact,and drop-weight tests.T...The mechanical behaviour of Titanium-based Fiber Metal Laminates(FMLs)reinforced with Kevlar,Jute and the novel woven(Kevlar+Jute)fiber mat were evaluated through tensile,flexural,Charpy impact,and drop-weight tests.The FMLs were fabricated with various stacking configurations(2/1,3/2,4/3,and 5/4)to examine their influence on mechanical properties.Kevlar-reinforced laminates consistently demonstrated superior tensile and flexural strengths,with the highest tensile strength of 772 MPa observed in the 3/2 configuration,attributed to Kevlar's excellent load-bearing capacity.Jute-reinforced laminates exhibited lower performance due to poor bonding and early delamination,while the FMLs reinforced with woven(Kevlar+Jute)fiber mat achieved a balance between mechanical strength and cost-effectiveness by attaining a tensile strength of 718 MPa in the 3/2 configuration.Impact energy absorption results revealed that Kevlar-reinforced FMLs provided the highest energy absorption under Charpy tests,reaching 13.5 J in the 3/2 configuration.The 4/3 configu ration exhibited superior resistance under drop-weight impacts,absorbing 104.7 J of energy.Failure analysis using SEM revealed key mechanisms such as fiber debonding,delamination,and fiber pull-out,with increased severity observed in laminates with a higher number of fiber-epoxy layers,especially in the 5/4 configuration.This study highlights the potential of Kevlar-Jute hybrid fiber-reinforced FMLs for applications requiring high mechanical performance and impact resistance.Future research should explore advanced surface treatments and the environmental durability of these laminates for aerospace and automotive applications.展开更多
In this study,the effect of Tin(Sn)addition on the microstructure,mechanical properties,and wear resistance of pure magnesium(Mg)was examined.Mg-Sn alloys were synthesized using stir casting technique with Sn concentr...In this study,the effect of Tin(Sn)addition on the microstructure,mechanical properties,and wear resistance of pure magnesium(Mg)was examined.Mg-Sn alloys were synthesized using stir casting technique with Sn concentrations of 2.5%,5%,and 7.5% by weight.The specimens were prepared as per ASTM standards for their evaluation.Higher Sn concentrations result in a reduced volume fraction of the eutectic phase,while Mg_(2)Sn precipitates are observed in alloys with 5% or more Sn.Scanning electron microscopy(SEM)analysis of the Mg-7.5wt.%Sn alloy reveals the presence of Mg(OH)_(2),with X-ray diffraction(XRD)confirming an oxygen content of 18% by weight.The addition of Sn minimizes casting porosity,enhancing the quality of the alloys.The findings demonstrate a positive correlation between increasing Sn content and enhanced strength and wear resistance.The Mg-7.5wt.%Sn alloy exhibits significantly enhanced tensile properties attributed to grain refinement and the formation of well-defined grain boundaries compared to alloys with lower Sn additions(2.5% and 5%),although a slight reduction in microhardness is observed.Tribological evaluation indicates reduced wear and friction,suggesting better surface performance.This research underscores the complex interplay between Sn content,microstructural evolution,and the resulting mechanical and tribological performance of Mg-Sn alloys.展开更多
Metallic lattice structures represent advanced architected materials delivering exceptional properties with promising lightweight potential.With the rapid advancement of additive manufacturing,these structures have ga...Metallic lattice structures represent advanced architected materials delivering exceptional properties with promising lightweight potential.With the rapid advancement of additive manufacturing,these structures have garnered increasing research interest.However,most metallic lattice structures generally exhibit anisotropic characteristics,which limits their application ranges.Additionally,a limited number of studies have successfully developed precise mechanical models,which have undergone experimental validation,for the purpose of describing the mechanical response exhibited by additively manufactured metallic lattice structures.In this study,Kelvin lattice structures with varying porosities were systematically designed and fabricated using laser powder bed fusion(LPBF)technology.By integrating finite element simulations with experimental characterization,an enhanced mechanical model was developed through a modification of the Gibson-Ashby model,providing an accurate quantitative description of the relationship between porosity and mechanical properties.The results show that the revised mechanical model can accurately describe the relationship between the geometric parameters and properties of metallic lattice structures.Specifically,the designed Kelvin lattice structures exhibit a smooth stress-strain curve with an obvious yield platform,demonstrating isotropic mechanical properties in all the three spatial directions.This enhances their suitability for complex loading conditions.Meanwhile,the microstructure and manufacturing accuracy of the Kelvin lattice structures were observed and analyzed by micro computed tomography.The results show that the fabricated metallic lattice structures achieved precise dimensional control and optimal densification.This study presents the complete process involved in modeling the Kelvin structure,including its conceptualization,manufacturing,implementation,and ultimately,disposal.展开更多
With the growing importance of wearable and portable electronics in modern society and industry,researchers from all over the world have reported on advances in energy harvesting and self-powered sensing technologies....With the growing importance of wearable and portable electronics in modern society and industry,researchers from all over the world have reported on advances in energy harvesting and self-powered sensing technologies.The current review discusses recent developments in triboelectric platforms from a manufacturing perspective,including material,design,application,and industrialization.Manufacturing is an essential component of both industry and technology.The use of a proper manufacturing process enables cutting-edge technology in a lab-scale stage to progress to commercialization and popularization with scalability,availability,commercial advantage,and consistent quality.Furthermore,much literature has emphasized that the most powerful advantage of the triboelectric platform is its wide range of available materials and simple working mechanism,both of which are important characteristics in manufacturing engineering.As a result,different manufacturing processes can be implemented as needed.Because the practical process can have a synergetic effect on the fundamental development,resulting in the growth of both,the development of the triboelectric platform from the standpoint of manufacturing engineering can be further advanced.However,research into the development of a productive manufacturing process is still in its early stages in the field of triboelectric platforms.This review looks at the various manufacturing technologies used in previous studies and discusses the potential benefits of the appropriate process for triboelectric platforms.Given its unique strength,which includes a diverse material selection and a simple working mechanism,the triboelectric platform can use a variety of manufacturing technologies and the process can be optimized as needed.Numerous research groups have clearly demonstrated the triboelectric platform's advantages.As a result,using appropriate manufacturing processes can accelerate the technological advancement of triboelectric platforms in a variety of research and industrial fields by allowing them to move beyond the lab-scale fabrication stage.展开更多
In the present study,the mechanical and ballistic properties of friction stir welded(FSW)aluminum alloy(AA5754)samples were investigated,both untreated and cryogenically treated,when impacted by a 7.62 mm armour-pierc...In the present study,the mechanical and ballistic properties of friction stir welded(FSW)aluminum alloy(AA5754)samples were investigated,both untreated and cryogenically treated,when impacted by a 7.62 mm armour-piercing(AP)bullet at an impact velocity of 682±20 m/s.The FSW technique was used to prepare the welded samples for AA5754,with an axial force of 7 kN,a feed rate of 20 mm/min,and a speed of 1200 rpm.The cryogenic treatments performed after welding,including deep cryogenic treatment(DCT)at196℃ and shallow cryogenic treatment(SCT)at80℃,for 6 and 72 h,respectively.The microstructure and mechanical characteristics of cryogenically treated and untreated joints were examined.The cryogenic treatment refined the grain size(1.05 μm)and enhanced the microhardness(93 Hv).Moreover,DCT-FSW significantly improved the tensile strength(13.93%)and impact strength(8.45%)compared to untreated FSW sample.Additionally,in untreated FSW samples,the fracture behaviour varied:the impact fracture mode primarily exhibited ductile failure,while the tensile fracture exhibited a mixed fracture mode.In contrast,the tensile and impact fracture modes of the DCT-FSWwere dominated by a ductile failure mode.The DCT-FSW target demonstrated a lower depth of penetration(DOP)of 31 mm compared to the SCT-FSWand untreated FSW targets.Post-ballistic SEM analysis in the crater region of all three zones revealed the formation of frictional grooves,small cracks,and adiabatic shear bands(ASBs).展开更多
文摘This paper introduces a novel optimization approach called Recuperated Seed Search Optimization(RSSO),designed to address challenges in solving mechanical engineering design problems.Many optimization techniques struggle with slow convergence and suboptimal solutions due to complex,nonlinear natures.The Sperm Swarm Optimization(SSO)algorithm,which mimics the sperm’s movement to reach an egg,is one such technique.To improve SSO,researchers combined it with three strategies:opposition-based learning(OBL),Cauchy mutation(CM),and position clamping.OBL introduces diversity to SSO by exploring opposite solutions,speeding up convergence.CM enhances both exploration and exploitation capabilities throughout the optimization process.This combined approach,RSSO,has been rigorously tested on standard benchmark functions,real-world engineering problems,and through statistical analysis(Wilcoxon test).The results demonstrate that RSSO significantly outperforms other optimization algorithms,achieving faster convergence and better solutions.The paper details the RSSO algorithm,discusses its implementation,and presents comparative results that validate its effectiveness in solving complex engineering design challenges.
文摘It is discussed that a tangential force T induces a self-excited vibration in the motion ofspindle blades of a ring spinning frame.Depending on the relative magnitude of the tangentialforce compared with the tangential damping force the motion of blade is either stable orunstable.The chief factors causing the self-excited vibration can also be traced from the charac-ter of the experimental locus.
基金Thiswork is financially supported by IranUniversity of Science and Technology(IUST)and Motamed Cancer Institute(ACECR).
文摘The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary challenges that must be addressed.For example,although bredigite(Br)has shown great potential for application in bone tissue engineering,it easily fails in replacement.In the present work,these challenges are addressed by reinforcing the Br matrix with nanosheets of graphene oxide(rGO)that have been reduced by bovine serum albumin(BSA)in order to enhance the mechanical properties and biological behavior.The reduction of graphene oxide by BSA improves the water stability of the nanosheets and provides an electrostatic interaction between theBSA-rGO nanosheets and theBr particles.The high thermal conductivity of theBSA-rGO nanosheets decreases the porosity of the Br by transferring heat to the core of the tablet.Furthermore,the addition of BSA-rGO nanosheets into the Br matrix enhances the adhesion of G-292 cells on the surface of the tablets.These findings suggest that the tablet consisting of BSA-rGO-reinforced Br has encouraging potential for application in bone tissue engineering.
文摘Mechanical properties of ukam, banana, sisal, coconut, hemp and e-glass fibre reinforced laminates were evaluated to assess the possibility of using it as new material in engineering applications. Samples were fabricated by the hand lay-up process (30:70 fibre and matrix ratio by weight) and the properties evaluated using the INSTRON material testing system. The mechanical properties were tested and showed that glass laminate has the maximum tensile strength of 63 MPa, bending strength of 0.5 MPa, compressive strength of 37.75 MPa and the impact strength of 17.82 J/m2. The ukam plant fibre laminate has the maximum tensile strength of 16.25 MPa and the impact strength of 9.8J/m among the natural fibres;the sisal laminate has the maximum compressive strength of 42 MPa and maximum bending strength of 0.0036 MPa among the natural fibres. Results indicated that natural fibres are of interest for low-cost engineering applications and can compete with artificial glass fibres (E-glass fibre) when a high stiffness per unit weight is desirable. Results also indicated that future research towards significant improvements in tensile and impact strength of these types of composites should focus on the optimisation of fibre strength rather than interfacial bond strength.
文摘Process engineering has been seen as one of the vital tools for improving surface coating phenomena for advance application. In an attempt to improve the mechanical, physical and chemical performance of the steel structure for ex-tended application, Zn-CeO2/ZnCeO2-Al2SiO5 thin film composite was fabri-cated on mild steel using direct electrolytic route. Process variation of Al2SiO5 particulate ranges from 5 to 15 g per litre. The embedded coating was charac-terized using Scanning electron microscope (SEM). The chemical effect of the developed alloy was characterized through linear potentiodynamic polarization experiment and the performances of samples were examined in simulated 3.5% sodium chloride. The microhardness verification study proves that there is sig-nificant improvement in hardness trend. The tribological assessment indicated that there is less plastic deformation as a result of the counter body. In all, Zn-CeO2/Zn-CeO2-Al2SiO5 exhibits good stability, with agglomeration and great built up of crystal at the interface.
文摘Dynamics is the foundation of undergraduate study in mechanical engineering. If you are good in dynamics, you will be good on all other courses. Advanced dynamics is the foundation for graduate study. The author taught advanced dynamics for more than ten years, this is the author＇s observation. Why it is so？ Because the course of advanced dynamics covers usually many mathematical fundamentals such as vectors, tensors, matrices and rotation operators; principles and applications in dynamics from particle dynamics to rigid body motion, from small oscillation to vibration of systems with multiple degrees of freedom, the author＇s course covers also special relativity theory. They are very innovative. And they set the foundation for the study of all the graduate courses. Science is always in progress, dynamics is in the same form. Just say a few examples to illustrate the frontier of dynamics： missile shooting missile is important in our defense, the author covered this as an example in particle dynamics. Space ship travels from Earth to Mars is another example. Several rotational motions with different axes can be combined to one through the use of rotation operator. This is important because it usually can save time. All these examples will be included in this paper in some details.
基金supported by the National Key R&D Plan of China(No.2022YFB3705603)the National Natural Science Foundation of China(No.52101046)+1 种基金the Excellent Youth Overseas Project of National Science and Natural Foundation of China,the Baowu Special Metallurgy Cooperation Limited(No.22H010101336)the Medicine-Engineering Interdisciplinary Project of Shanghai Jiao Tong University(No.YG2022QN076).
文摘Titanium(Ti)and its alloys are frequently utilized as critical components in a variety of engineering ap-plications because of their high specific strength and excellent corrosion resistance.Compared to conven-tional surface strengthening technologies,laser shock peening(LSP)has increasingly attracted attention from researchers and industries,since it significantly improves the surface strength,biocompatibility,fa-tigue resistance,and anti-corrosion ability of Ti and its alloys.Despite numerous studies that have been carried out to elucidate the effects of LSP on microstructural evolution and mechanical properties of Ti and its alloys in recent years,a comprehensive review of recent advancements in the field of Ti and its alloys subjected to LSP is still lacking.In this review,the standard LSP and the novel process designs of LSP assisted by thermal,cryogenic,electropulsing and magnetic fields are discussed and compared.Microstructural evolution,with focuses on the dislocation dynamics,deformation twinning,grain refine-ment and surface amorphization,during LSP processing of Ti alloys is reviewed.Furthermore,the en-hanced engineering performance of the L SP-processed(L SPed)Ti alloys,including surface hardness,wear resistance,fatigue life and corrosion resistance are summarized.Finally,this review concludes by present-ing an overview of the current challenges encountered in this field and offering insights into anticipated future trends.
基金the National Natural Science Foun-dation of China(Grant Nos.12374022,U23A20540)the Natu-ral Science Foundation of Hunan Province for Distinguished Young Scholars(Grant No.2023JJ10075)+3 种基金the China Postdoctoral Science Foundation(Grant Nos.GZC20241335,2024MD753962)the YueLuShan Center Industrial Innovation(Grant No.2024YCII0106)the Scientific and Technological Project of Yunnan Precious Met-als Laboratory(Grant No.YPML-2023050247)the Central South University Research Programme of Advanced Interdisci-plinary Studies(Grant No.2023QYJC039).
文摘Control of the columnar to equiaxed transition(CET)is a major challenge in additively manufacturedβtitanium alloys.In this work,the promotion of CET was successfully achieved through in-situ fabrication of Ti-5Cu(wt.%)alloys with additions of 5,15,and 25 wt.%Nb using elemental Ti,Cu,and Nb powders by employing laser powder bed fusion(LPBF).The alloy containing 5 wt.%Nb consisted ofαlamellae,Ti2 Cu precipitates,and unmeltedβ-Nb inclusions,whereas the 25 wt.%Nb alloy consisted of equiaxedβgrains,ωprecipitates,and Ti2 Cu precipitates at the grain boundaries.In terms of mechanical proper-ties,despite the presence of Nb inclusions and liquation cracks in the 5 wt.%Nb alloy,it showed a yield strength of 1051±40 MPa and an elongation of 5.2%±1.3%.Both the strength and ductility decreased with increasing Nb content,e.g.,the 25 wt.%Nb alloy exhibited a yield strength of 808±53 MPa and an elongation of 1.6%±0.2%.As the Nb content increased from 5 to 25 wt.%,the Young’s modulus decreased from 110 to 65 GPa.The 25 wt.%Nb alloy showed a high ratio of hardness to Young’s mod-ulus(H/E)and yield pressure(H3/E2).However,due to its brittle nature,the material manifested high wear rates.These findings provide a basis for the future development of novel low-modulus isotropicβ-titanium alloys using LPBF.
文摘Magnesium(Mg)-based bioresorbable stents represent a potentially groundbreaking advancement in cardiovascular therapy;offering tem-porary vessel support and complete biodegradability—addressing limitations of traditional stents like in-stent restenosis and long-term com-plications.However,challenges such as rapid corrosion and suboptimal endothelialisation have hindered their clinical adoption.This review highlights the latest breakthroughs in surface modification,alloying,and coating strategies to enhance the mechanical integrity,corrosion resistance,and biocompatibility of Mg-based stents.Key surface engineering techniques,including polymer and bioactive coatings,are ex-amined for their role in promoting endothelial healing and minimising inflammatory responses.Future directions are proposed,focusing on personalised stent designs to optimize efficacy and long-term outcomes,positioning Mg-based stents as a transformative solution in interventional cardiology.
文摘The functionally graded materials(FGMs)are obtained by various processes.Although a few FGMs are obtained naturally,such as oyster,pearl,and bamboo,additive manufacturing(AM),known as 3D printing,is a net-shaped manufacturing process employed to manufacture complex 3D objects without tools,molds,assembly,and joining.Currently,commercial AM techniques mostly use homogeneous composition with simplified geometric descriptions,employing a single material across the entire component to achieve functional graded additive manufacturing(FGAM),in contrast to multi-material FGAM with heterogeneous structures.FGMs are widely used in various fields due to their mechanical property advantages.Because FGM plays a significant role in the industrial production,the characteristics and mechanical behaviour of FGMs prepared by AM were reviewed.In this review,the research on FGMs and AM over the past 30 years was reviewed,suggesting that future researchers should focus on the application of artificial intelligence and machine learning technologies in industry to optimize the process parameters of different gradient systems.
文摘Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how stress affects lifespan,this review offers the first comprehensive,multiscale comparison of strategies that optimize geometry to improve fatigue performance.This includes everything from microscopic features like the shape of graphite nodules to large-scale design elements such as fillets,notches,and overall structural layouts.We analyze and combine various methods,including topology and shape optimization,the ability of additive manufacturing to finetune internal geometries,and reliability-based design approaches.A key new contribution is our proposal of a standard way to evaluate geometry-focused fatigue design,allowing for consistent comparison and encouraging validation across different fields.Furthermore,we highlight important areas for future research,such as incorporating manufacturing flaws,using multiscale models,and integrating machine learning techniques.This work is the first to provide a broad geometric viewpoint in fatigue engineering,laying the groundwork for future design methods that are driven by data and centered on reliability.
基金Financial support from the National Natural Science Foundation of China(52372289,52102368,52231007,12327804,T2321003,22088101,22178037 and U22A20424)Regional Joint Fund for Basic Research and Applied Basic Research of Guangdong Province(No.2020A1515110905)+1 种基金Guangdong Special Fund for key Areas(20237DZX3042)Shenzhen Stable Support Project,Liaoning Revitalization Talents Program(XLYC2002114)are highly appreciated.
文摘The synthesis of carbon supporter/nanoscale high-entropy alloys(HEAs)electromagnetic response composites by carbothermal shock method has been identified as an advanced strategy for the collaborative competition engineering of conductive/dielectric genes.Electron migration modes within HEAs as manipulated by the electronegativity,valence electron configurations and molar proportions of constituent elements determine the steady state and efficiency of equivalent dipoles.Herein,enlightened by skin-like effect,a reformative carbothermal shock method using carbonized cellulose paper(CCP)as carbon supporter is used to preserve the oxygencontaining functional groups(O·)of carbonized cellulose fibers(CCF).Nucleation of HEAs and construction of emblematic shell-core CCF/HEAs heterointerfaces are inextricably linked to carbon metabolism induced by O·.Meanwhile,the electron migration mode of switchable electronrich sites promotes the orientation polarization of anisotropic equivalent dipoles.By virtue of the reinforcement strategy,CCP/HEAs composite prepared by 35%molar ratio of Mn element(CCP/HEAs-Mn_(2.15))achieves efficient electromagnetic wave(EMW)absorption of−51.35 dB at an ultra-thin thickness of 1.03 mm.The mechanisms of the resulting dielectric properties of HEAs-based EMW absorbing materials are elucidated by combining theoretical calculations with experimental characterizations,which provide theoretical bases and feasible strategies for the simulation and practical application of electromagnetic functional devices(e.g.,ultra-wideband bandpass filter).
文摘This study investigates the impact of welding heat input on weldments of modified 9Cr-1Mo(P91)steel,a high-strength material that requires high-energy welding processes like submerged arc welding.In the as-welded condition,P91 steel welds primarily consist of untempered martensite,which transforms into tempered martensite during post-weld heat treatment(PWHT).Electron spectro-scopy analysis reveals the presence of M_(23)C_(6) and MX carbonitride precipitates at grain boundaries.Increasing the heat input leads to greater quantities of precipitates in the prior austenite grain boundaries,which can affect material properties.Weldment hardness profiles exhibit modest improvements,while ultimate tensile strength and toughness decrease with higher welding heat input,poten-tially due to the formation of a ferritic phase.Residual stress distributions are noticeably influenced by the welding heat input level.
文摘Assessing the vulnerability of a platform is crucial in its design.In fact,the results obtained from vulnerability analyses provide valuable information,leading to precise design choices or corrective solutions that enhance the platform's chances of surviving different scenarios.Such scenarios can involve various types of threats that can affect the platform's survivability.Among such,blast waves impacting the platform's structure represent critical conditions that have not yet been studied in detail.That is,frameworks for vulnerability assessment that can deal with blast loading have not been presented yet.In this context,this work presents a fast-running engineering tool that can quantify the risk that a structure fails when it is subjected to blast loading from the detonation of high explosive-driven threats detonating at various distances from the structure itself.The tool has been implemented in an in-house software that calculates vulnerability to various impacting objects,and its capabilities have been shown through a simplified,yet realistic,case study.The novelty of this research lies in the development of an integrated computational environment capable of calculating the platform's vulnerability to blast waves,without the need for running expensive finite element simulations.In fact,the proposed tool is fully based on analytical models integrated with a probabilistic approach for vulnerability calculation.
文摘The precise computation of nanoelectromechanical switches’(NEMS)multi-physical interactions requires advanced numerical models and is a crucial part of the development of micro-and nano-systems.This paper presents a novel compound numerical method to study the instability of a functionally graded(FG)beam-type NEMS,considering surface elasticity effects as stated by Gurtin-Murdoch theory in an Euler-Bernoulli beam.The presented method is based on a combination of the Method of Adjoints(MoA)together with the Bézier-based multistep technique.By utilizing the MoA,a boundary value problem(BVP)is turned into an initial value problem(IVP).The resulting IVP is then solved by employing a cost-efficient multi-step process.It is demonstrated that the mentioned method can arrive at a high level of accuracy.Furthermore,it is revealed that the stability of the presented methodology is far better than that of other common multi-step methods,such as Adams-Bashforth,particularly at higher step sizes.Finally,the effects of axially functionally graded(FG)properties on the pull-in phenomenon and the main design parameters of NEMS,including the detachment length,are inspected.It was shown that the main parameter of design is the modulus of elasticity of the material,as Silver(Ag),which had better mechanical properties,showed almost a 6%improvement compared to aluminum(Al).However,by applying the correct amount of material with sturdier surface parameters,such as Aluminum(Al),at certain points,the nanobeams’functionality can be improved even further by around 1.5%.
基金the aid of Research and Development Fund-Seed Money provided by Vel Tech Rangarajan Dr.Sagunthala R&D Institute of Science and Technology。
文摘The mechanical behaviour of Titanium-based Fiber Metal Laminates(FMLs)reinforced with Kevlar,Jute and the novel woven(Kevlar+Jute)fiber mat were evaluated through tensile,flexural,Charpy impact,and drop-weight tests.The FMLs were fabricated with various stacking configurations(2/1,3/2,4/3,and 5/4)to examine their influence on mechanical properties.Kevlar-reinforced laminates consistently demonstrated superior tensile and flexural strengths,with the highest tensile strength of 772 MPa observed in the 3/2 configuration,attributed to Kevlar's excellent load-bearing capacity.Jute-reinforced laminates exhibited lower performance due to poor bonding and early delamination,while the FMLs reinforced with woven(Kevlar+Jute)fiber mat achieved a balance between mechanical strength and cost-effectiveness by attaining a tensile strength of 718 MPa in the 3/2 configuration.Impact energy absorption results revealed that Kevlar-reinforced FMLs provided the highest energy absorption under Charpy tests,reaching 13.5 J in the 3/2 configuration.The 4/3 configu ration exhibited superior resistance under drop-weight impacts,absorbing 104.7 J of energy.Failure analysis using SEM revealed key mechanisms such as fiber debonding,delamination,and fiber pull-out,with increased severity observed in laminates with a higher number of fiber-epoxy layers,especially in the 5/4 configuration.This study highlights the potential of Kevlar-Jute hybrid fiber-reinforced FMLs for applications requiring high mechanical performance and impact resistance.Future research should explore advanced surface treatments and the environmental durability of these laminates for aerospace and automotive applications.
文摘In this study,the effect of Tin(Sn)addition on the microstructure,mechanical properties,and wear resistance of pure magnesium(Mg)was examined.Mg-Sn alloys were synthesized using stir casting technique with Sn concentrations of 2.5%,5%,and 7.5% by weight.The specimens were prepared as per ASTM standards for their evaluation.Higher Sn concentrations result in a reduced volume fraction of the eutectic phase,while Mg_(2)Sn precipitates are observed in alloys with 5% or more Sn.Scanning electron microscopy(SEM)analysis of the Mg-7.5wt.%Sn alloy reveals the presence of Mg(OH)_(2),with X-ray diffraction(XRD)confirming an oxygen content of 18% by weight.The addition of Sn minimizes casting porosity,enhancing the quality of the alloys.The findings demonstrate a positive correlation between increasing Sn content and enhanced strength and wear resistance.The Mg-7.5wt.%Sn alloy exhibits significantly enhanced tensile properties attributed to grain refinement and the formation of well-defined grain boundaries compared to alloys with lower Sn additions(2.5% and 5%),although a slight reduction in microhardness is observed.Tribological evaluation indicates reduced wear and friction,suggesting better surface performance.This research underscores the complex interplay between Sn content,microstructural evolution,and the resulting mechanical and tribological performance of Mg-Sn alloys.
基金financially supported by the Liaoning Province Applied Fundamental Research Program (No.2023JH2/101700039)Liaoning Province Natural Science Foundation (No.2023-MSLH-328).
文摘Metallic lattice structures represent advanced architected materials delivering exceptional properties with promising lightweight potential.With the rapid advancement of additive manufacturing,these structures have garnered increasing research interest.However,most metallic lattice structures generally exhibit anisotropic characteristics,which limits their application ranges.Additionally,a limited number of studies have successfully developed precise mechanical models,which have undergone experimental validation,for the purpose of describing the mechanical response exhibited by additively manufactured metallic lattice structures.In this study,Kelvin lattice structures with varying porosities were systematically designed and fabricated using laser powder bed fusion(LPBF)technology.By integrating finite element simulations with experimental characterization,an enhanced mechanical model was developed through a modification of the Gibson-Ashby model,providing an accurate quantitative description of the relationship between porosity and mechanical properties.The results show that the revised mechanical model can accurately describe the relationship between the geometric parameters and properties of metallic lattice structures.Specifically,the designed Kelvin lattice structures exhibit a smooth stress-strain curve with an obvious yield platform,demonstrating isotropic mechanical properties in all the three spatial directions.This enhances their suitability for complex loading conditions.Meanwhile,the microstructure and manufacturing accuracy of the Kelvin lattice structures were observed and analyzed by micro computed tomography.The results show that the fabricated metallic lattice structures achieved precise dimensional control and optimal densification.This study presents the complete process involved in modeling the Kelvin structure,including its conceptualization,manufacturing,implementation,and ultimately,disposal.
基金supported by the National Research Foundation of Korea(NRF)(No.2021R1C1C2009703)supported by the National Research Foundation of Korea(NRF)Grant funded by the Korea government(MSIT)(RS-2024-00344920)supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)Grant funded by the Ministry of Trade,Industry and Energy of Korea(No.RS2023-00244330)。
文摘With the growing importance of wearable and portable electronics in modern society and industry,researchers from all over the world have reported on advances in energy harvesting and self-powered sensing technologies.The current review discusses recent developments in triboelectric platforms from a manufacturing perspective,including material,design,application,and industrialization.Manufacturing is an essential component of both industry and technology.The use of a proper manufacturing process enables cutting-edge technology in a lab-scale stage to progress to commercialization and popularization with scalability,availability,commercial advantage,and consistent quality.Furthermore,much literature has emphasized that the most powerful advantage of the triboelectric platform is its wide range of available materials and simple working mechanism,both of which are important characteristics in manufacturing engineering.As a result,different manufacturing processes can be implemented as needed.Because the practical process can have a synergetic effect on the fundamental development,resulting in the growth of both,the development of the triboelectric platform from the standpoint of manufacturing engineering can be further advanced.However,research into the development of a productive manufacturing process is still in its early stages in the field of triboelectric platforms.This review looks at the various manufacturing technologies used in previous studies and discusses the potential benefits of the appropriate process for triboelectric platforms.Given its unique strength,which includes a diverse material selection and a simple working mechanism,the triboelectric platform can use a variety of manufacturing technologies and the process can be optimized as needed.Numerous research groups have clearly demonstrated the triboelectric platform's advantages.As a result,using appropriate manufacturing processes can accelerate the technological advancement of triboelectric platforms in a variety of research and industrial fields by allowing them to move beyond the lab-scale fabrication stage.
文摘In the present study,the mechanical and ballistic properties of friction stir welded(FSW)aluminum alloy(AA5754)samples were investigated,both untreated and cryogenically treated,when impacted by a 7.62 mm armour-piercing(AP)bullet at an impact velocity of 682±20 m/s.The FSW technique was used to prepare the welded samples for AA5754,with an axial force of 7 kN,a feed rate of 20 mm/min,and a speed of 1200 rpm.The cryogenic treatments performed after welding,including deep cryogenic treatment(DCT)at196℃ and shallow cryogenic treatment(SCT)at80℃,for 6 and 72 h,respectively.The microstructure and mechanical characteristics of cryogenically treated and untreated joints were examined.The cryogenic treatment refined the grain size(1.05 μm)and enhanced the microhardness(93 Hv).Moreover,DCT-FSW significantly improved the tensile strength(13.93%)and impact strength(8.45%)compared to untreated FSW sample.Additionally,in untreated FSW samples,the fracture behaviour varied:the impact fracture mode primarily exhibited ductile failure,while the tensile fracture exhibited a mixed fracture mode.In contrast,the tensile and impact fracture modes of the DCT-FSWwere dominated by a ductile failure mode.The DCT-FSW target demonstrated a lower depth of penetration(DOP)of 31 mm compared to the SCT-FSWand untreated FSW targets.Post-ballistic SEM analysis in the crater region of all three zones revealed the formation of frictional grooves,small cracks,and adiabatic shear bands(ASBs).
