For the 110 mining method,it is challenging to accurately calculate the support resistance of the roadway due to the lack of understanding of the dynamic movement of the overlying strata in this method.The consequenti...For the 110 mining method,it is challenging to accurately calculate the support resistance of the roadway due to the lack of understanding of the dynamic movement of the overlying strata in this method.The consequential excessive support results in a significant increase in the cost of roadway support.The authors explored the overlying strata movement and roadway deformation of the gob-entry retaining in the 110 mining method to solve this problem.First,the typical stages of the roof-cutting gob-side entry were defined.Second,the mechanical model and calculation formula of the support resistance on the roof were explored.Then,using numerical simulation software,the starting ranges of the specific supports at different stages were verified and the feasibility of the support scheme was examined.Finally,combined with the field measurement data,the stress and the deformation of the gob roadway at different stages under the influence of two mining processes in the 110 mining method were obtained.The numerical simulation results obtained are consistent with the field test results,providing a theoretical basis for precision support at different stages by the 110 mining method.展开更多
The dynamics of liquid sloshing in a spherical tank with spacer under low gravity was investigated. By extending the characteristic functions, the frequencies of liquid free sloshing, reaction force and moments on th...The dynamics of liquid sloshing in a spherical tank with spacer under low gravity was investigated. By extending the characteristic functions, the frequencies of liquid free sloshing, reaction force and moments on the wall of tank were obtained. By mechanical equivalent principle, the equivalent models of spring vibrator damper of liquid sloshing were given. The numerical results obtained show when a spacer is inserted in the tank, the sloshing frequency of liquid and the sloshing mass of liquid will decrease.展开更多
Multi-stage SRV fracturing in horizontal wells is a new technology developed at home and abroad in recent years to effectively develop shale gas or low-permeability reservoirs,but on the other hand makes the mechanica...Multi-stage SRV fracturing in horizontal wells is a new technology developed at home and abroad in recent years to effectively develop shale gas or low-permeability reservoirs,but on the other hand makes the mechanical environment of fracturing strings more complicated at the same time.In view of this,based on the loading features of tubing strings during the multi-stage fracturing of a horizontal well,mechanical models were established for three working cases of multiple packer setting,open differential-pressure sliding sleeve,and open ball-injection sliding sleeve under a hold-down packer.Moreover,mathematical models were respectively built for the above three cases.According to the Lame formula and Von Mises stress calculation formula for the thick-walled cylinder in the theory of elastic mechanics,a mathematical model was also established to calculate the equivalent stress for tubing string safety evaluation when the fracturing string was under the combined action of inner pressure,external squeezing force and axial stress,and another mathematical model was built for the mechanical strength and safety evaluation of multi-stage fracturing strings.In addition,a practical software was developed for the mechanical safety evaluation of horizontal well multi-stage fracturing strings according to the mathematical model developed for the mechanical calculation of the multi-packer string in horizontal wells.The research results were applied and verified in a gas well of Tahe Oilfield in the Tarim Basin with excellent effects,providing a theoretical basis and a simple and reliable technical means for optimal design and safety evaluation of safe operational parameters of multistage fracturing strings in horizontal wells.展开更多
We propose an integrated method of data-driven and mechanism models for well logging formation evaluation,explicitly focusing on predicting reservoir parameters,such as porosity and water saturation.Accurately interpr...We propose an integrated method of data-driven and mechanism models for well logging formation evaluation,explicitly focusing on predicting reservoir parameters,such as porosity and water saturation.Accurately interpreting these parameters is crucial for effectively exploring and developing oil and gas.However,with the increasing complexity of geological conditions in this industry,there is a growing demand for improved accuracy in reservoir parameter prediction,leading to higher costs associated with manual interpretation.The conventional logging interpretation methods rely on empirical relationships between logging data and reservoir parameters,which suffer from low interpretation efficiency,intense subjectivity,and suitability for ideal conditions.The application of artificial intelligence in the interpretation of logging data provides a new solution to the problems existing in traditional methods.It is expected to improve the accuracy and efficiency of the interpretation.If large and high-quality datasets exist,data-driven models can reveal relationships of arbitrary complexity.Nevertheless,constructing sufficiently large logging datasets with reliable labels remains challenging,making it difficult to apply data-driven models effectively in logging data interpretation.Furthermore,data-driven models often act as“black boxes”without explaining their predictions or ensuring compliance with primary physical constraints.This paper proposes a machine learning method with strong physical constraints by integrating mechanism and data-driven models.Prior knowledge of logging data interpretation is embedded into machine learning regarding network structure,loss function,and optimization algorithm.We employ the Physically Informed Auto-Encoder(PIAE)to predict porosity and water saturation,which can be trained without labeled reservoir parameters using self-supervised learning techniques.This approach effectively achieves automated interpretation and facilitates generalization across diverse datasets.展开更多
The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclea...The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants.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
The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deci...The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deciphering their adhesion mechanism.This study developed a contact mechanics model based on van der Waals forces and frictional self-locking effects,incorporating both the spatular pad and spatular shaft of the gecko’s foot microstructures.Building on this foundation,a discrete element simulation model was established using the bonding method to replicate the contact between the gecko's spatula and different surfaces.The dynamic adhesion and detaching processes under normal and tangential external forces were simulated,allowing for the analysis of variation curves of normal and tangential adhesion forces at different detaching angles.This provided insights into the directional adhesion mechanics of the gecko's spatula.Furthermore,a force measurement system was constructed using a multi-degree-of-freedom nano-manipulator and an atomic force microscope within a scanning electron microscope.This system was used to experimentally test the adhesion characteristics of the gecko’s foot microstructures,validating the accuracy of the proposed adhesion mechanics model.展开更多
According to the structure of the hohl schaft kegel（HSK） tooling system and its working principle, a mechanical model of the HSK tooling system is established. Major factors influencing the stiffness of the system a...According to the structure of the hohl schaft kegel（HSK） tooling system and its working principle, a mechanical model of the HSK tooling system is established. Major factors influencing the stiffness of the system are analyzed and the relationship between the load and the manufacturing quality is obtained. The basic rule of the stiffness variation is presented and the theoretical analysis is in a good agreement with experimental results. The dynamic stiffness must also be considered to evaluate the performance of the tooling system besides the staticstiffness. Finally, the selecting principles of the HSK types are proposed and their optimum operating conditions are established.展开更多
According to the cutting characteristics of progressive spiral movement by rotary cutting of the disc cutter, using the broken theory of interaction of compression and shearing, the three-axis force rotary cutting mec...According to the cutting characteristics of progressive spiral movement by rotary cutting of the disc cutter, using the broken theory of interaction of compression and shearing, the three-axis force rotary cutting mechanical model of disc cutter was established and the influence of installation radius, the phase difference and the cutter space on the mechanics of disc cutter were analyzed. The results show that on the same radial line of tunneling interface, the boring distance of cutting tools installed on a different radius is not equal. The cutting radial line of tunneling interface is a polyline and its height is determined by phase angle and penetration of cutting tools. Both phase difference and the installation radius between adjacent disc cutters have little effect on the vertical force and rolling force, but increase with the increase in cutter spacing. In addition, when increasing phase difference and cutter space bilaterally, and reducing installation radius simultaneously, the lateral force would be improved. Related results have been verified onl O0 t rotary tool cutting test platform.展开更多
With the increase of domestic gas consumption in cities and towns in China,gas explo-sion accidents happened rather frequently,and many structures were damaged greatly.Rational physical design could protect structures...With the increase of domestic gas consumption in cities and towns in China,gas explo-sion accidents happened rather frequently,and many structures were damaged greatly.Rational physical design could protect structures from being destroyed,but the character of explosion load must be learned firstly by establishing a correct mechanical model to simulate vented gas explo-sions.The explosion process has been studied for many years towards the safety of chemical in-dustry equipments.The key problem of these studies was the equations usually involved some ad-justable parameters that must be evaluated by experimental data,and the procedure of calculation was extremely complicated,so the reliability of these studies was seriously limited.Based on these studies,a simple mathematical model was established in this paper by using energy conservation,mass conservation,gas state equation,adiabatic compression equation and gas venting equation.Explosion load must be estimated by considering the room layout; the rate of pressure rise was then corrected by using a turbulence factor,so the pressure-time curve could be obtained.By using this method,complicated calculation was avoided,while experimental and calculated results fitted fairly well.Some pressure-time curves in a typical rectangular room were calculated to inves-tigate the influences of different ignition locations,gas thickness,concentration,room size and venting area on the explosion pressure.The results indicated that: it was the most dangerous con-dition when being ignited in the geometry centre of the room; the greater the burning velocity,the worse the venting effect; the larger the venting pressure,the higher the peak pressure; the larger the venting area,the lower the peak pressure.展开更多
With the help of plant roots, slope vegetation makes the slope soil mass become a composite material of soil and roots, and thus enhances shear strength of the slope soil mass and stability of the slope. However, the ...With the help of plant roots, slope vegetation makes the slope soil mass become a composite material of soil and roots, and thus enhances shear strength of the slope soil mass and stability of the slope. However, the related studies at present are still qualitative. In this paper, quantitative analysis of the interaction between roots and soil mass are made. By the analysis of the interaction between herbaceous plant roots including lateral roots of woody plants and rock and soil mass, a mechanical model of the interaction between frictional roots and soil is established, and its correctness is shown. A mechanical model of the interaction between anchorage root, namely, woody plant taproot, and soil is also established. The establishment of the models provides a useful means in quantitative analysis of the interaction between plant roots and soil, and has practical values.展开更多
Many physical experiments have shown that the domain switching in a ferroelectric material is a complicated evolution process of the domain wall with the variation of stress and electric field. According to this mecha...Many physical experiments have shown that the domain switching in a ferroelectric material is a complicated evolution process of the domain wall with the variation of stress and electric field. According to this mechanism, the volume fraction of the domain switching is introduced in the constitutive law of ferroelectric ceramic and used to study the nonlinear constitutive behavior of ferroelectric body in this paper. The principle of stationary total energy is put forward in which the basic unknown quantities are the displacement ui, electric displacement Di and volume fraction pI of the domain switching for the variant I. Mechanical field equation and a new domain switching criterion are obtained from the principle of stationary total energy. The domain switching criterion proposed in this paper is an expansion and development of the energy criterion. On the basis of the domain switching criterion, a set of linear algebraic equations for the volume fraction PI of domain switching is obtained, in which the coefficients of the linear algebraic equations only contain the unknown strain and electric fields. Then a single domain mechanical model is proposed in this paper. The poled ferroelectric specimen is considered as a transversely isotropic single domain. By using the partial experimental results, the hardening relation between the driving force of domain switching and the volume fraction of domain switching can be calibrated. Then the electromechanical response can be calculated on the basis of the calibrated hardening relation. The results involve the electric butterfly shaped curves of axial strain versus axial electric field, the hysteresis loops of electric displacement versus electric filed and the evo- lution process of the domain switching in the ferroelectric specimens under uniaxial coupled stress and electric field loading. The present theoretic prediction agrees reasonably with the experimental results given by Lynch.展开更多
Drying （conditioning） is an important procedure to prevent hydrate formation during gas pipeline gas-up and to protect pipelines against corrosion. The air-drying method is preferred in offshore gas pipelines pre-co...Drying （conditioning） is an important procedure to prevent hydrate formation during gas pipeline gas-up and to protect pipelines against corrosion. The air-drying method is preferred in offshore gas pipelines pre-commissioning. The air-drying process of gas pipelines commonly includes two steps, air purging and soak test. The mass conservation and the phase equilibrium theory are applied to setting up the mathematical models of air purging, which can be used to simulate dry airflow rate and drying time. Fick diffusion law is applied to setting up the mathematical model of soak test, which can predict the water vapor concentration distribution. The results calculated from the purging model and the soak test model are in good agreement with the experimental data in the DF 1-1 offshore production pipeline conditioning. The models are verified to be available for the air-drying project design of offshore gas pipelines. Some proposals for airdrying engineering and operational procedures are put forward by analyzing the air-drying process of DFI-1 gasexporting pipelines.展开更多
Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensiona...Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensional high-stress and even causing disasters.Therefore,a novel complex true triaxial static-dynamic combined loading method reflecting underground excavation damage and then frequent intermittent disturbance failure is proposed.True triaxial static compression and intermittent disturbance tests are carried out on monzogabbro.The effects of intermediate principal stress and amplitude on the strength characteristics,deformation characteristics,failure characteristics,and precursors of monzogabbro are analyzed,intermediate principal stress and amplitude increase monzogabbro strength and tensile fracture mechanism.Rapid increases in microseismic parameters during rock loading can be precursors for intermittent rock disturbance.Based on the experimental result,the new damage fractional elements and method with considering crack initiation stress and crack unstable stress as initiation and acceleration condition of intermittent disturbance irreversible deformation are proposed.A novel three-dimensional disturbance fractional deterioration model considering the intermediate principal stress effect and intermittent disturbance damage effect is established,and the model predicted results align well with the experimental results.The sensitivity of stress states and model parameters is further explored,and the intermittent disturbance behaviors at different f are predicted.This study provides valuable theoretical bases for the stability analysis of deep mining engineering under dynamic loads.展开更多
A new unified macro- and micro-mechanics failure analysis method for composite structures was developed in order to take the effects of composite micro structure into consideration. In this method, the macro stress di...A new unified macro- and micro-mechanics failure analysis method for composite structures was developed in order to take the effects of composite micro structure into consideration. In this method, the macro stress distribution of composite structure was calculated by commercial finite element analysis software. According to the macro stress distribution, the damage point was searched and the micro-stress distribution was calculated by reformulated finite-volume direct averaging micromechanics （FVDAM）, which was a multi-scale finite element method for composite. The micro structure failure modes were estimated with the failure strength of constituents. A unidirectional composite plate with a circular hole in the center under two kinds of loads was analyzed with the traditional macro-mechanical failure analysis method and the unified macro- and micro-mechanics failure analysis method. The results obtained by the two methods are consistent, which show this new method＇s accuracy and efficiency.展开更多
ln-situ experiments were conducted to investigate the mechanical properties of the soil-rock mixture in the internal dump of the Shengli #1 Surface Coal Mine, China. Based on the experimental results, this study used ...ln-situ experiments were conducted to investigate the mechanical properties of the soil-rock mixture in the internal dump of the Shengli #1 Surface Coal Mine, China. Based on the experimental results, this study used comparative analysis and found that the shear strength of the soil-rock mixture in the dump was greater than the residual shear strength of the original rock. The results showed that the material presented in the dump as large blocks was the main factor affecting the strength of the soil-rock mixture, Numerical simulation was carried out for the analyses of three factors： different combinations of shear failure, rolling failure along with different large-block radius ratios, and mixture densities. The results illustrated that the cohesion and angle of internal friction of the soil-rock mixture are 12 kPa and 32.26°. However, in some cases the bench angle in the dump was controlled by a coupling relationship of rocks in the material. Finally, the stability of a soil slope showed a linear relationship with the large-block radius ratio and the bulk density.展开更多
An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindri...An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindrical lithium-ion battery consists of a spring-damping parallel unit.Therefore,a spring-damping parallel unit connecting a damping unit in series is selected to construct the constitutive characteristics of the battery under mechanical abuse.Comparison results show that the equivalent mechanical model can more effectively describe the mechanical properties of the batteries than most cubic fitting models,of which the average relative error of the equivalent mechanical model under different states-of-charge is less than 6.75%.Combined with the proposed equivalent mechanical model,the failure process of the batteries was simulated and analyzed using LS-Dyna and HyperWorks.Under rigid rod tests,failure occurred at the core and bottom of the batteries;under hemispherical punch tests,failure occurred at the core and top,consistent with the experimental results.The average prediction error for the failure displacement under different abuse conditions is less than 4%in the simulations.The equivalent mechanical model requires only a few parameters and can be recognized easily.In the future,the model can be used in safety warning devices based on mechanical penetration.展开更多
A mechanical model of liquid crystals （LCs） is applied to study the polymorphism of homologous series of terphenyl compounds. With a senti-experimental molecular orbit method, we calculate the moment of inertia whic...A mechanical model of liquid crystals （LCs） is applied to study the polymorphism of homologous series of terphenyl compounds. With a senti-experimental molecular orbit method, we calculate the moment of inertia which represents the rotation state to describe the phase transition temperature obtained from experimental data. We propose a novel explanation of the phase sequence or polymorphism of LC materials using the two key parameters, the moment of inertia and critical rotational velocity. The effect of molecular polarity on the appearance of liquid crystalline is also discussed.展开更多
Axial compression stress, produced by the pre-tightening force of a bolt, is a necessary condition for surrounding rock to form a whole structure. For this study, we built a mechanical model for an end-anchorage bolt,...Axial compression stress, produced by the pre-tightening force of a bolt, is a necessary condition for surrounding rock to form a whole structure. For this study, we built a mechanical model for an end-anchorage bolt, which represented the effect of a bolt on the surrounding rock in roadways in order to obtain its elastic solution. Simultaneously, we analyzed factors affecting the axial compression of the bolt on the surrounding rock and obtained the axial stress contours of the anchorage area through this elastic solution. The results indicate that 1) the axial compression stress in the anchorage area is proportional to the pre-tightening force and confirms the rule that stress declines sharply with the increase in axial distance from the bolt, with an effective stress radius of 1 m; 2) the maximum axial compression stress declines first and then rises with the increase in depth from the surface of the anchorage surrounding rock and 3) the size of the axial compression area is mainly determined by the length of the bolt.展开更多
The mechanical behavior of underground pipe gallery is a key research issue due to the static/dynamic states which exist in a ground fissure area.This study took an underground pipe gallery project in Xi’an,China as ...The mechanical behavior of underground pipe gallery is a key research issue due to the static/dynamic states which exist in a ground fissure area.This study took an underground pipe gallery project in Xi’an,China as the research object.We analyzed the stress/strain characteristics of the pipe gallery structure and surrounding soil under static/dynamic conditions by the numerical simulation methods in detail.Based on the results,we proposed a theoretical calculation model for the pipe gallery structure considering the influence of the ground fissure,and combined with engineering examples for calculation and discussion.Subsequent results showed that:(1)the effective activity range of ground fissure on the deformation of the pipe gallery structure was mainly from 0.0 m(horizontal direction of ground fissure)to 32.0 m.In activity range,the pipe gallery structure is prone to failure,owing to the large soil deformation in the vertical direction;(2)with the increase of ground fissure settlement,a stress reduction area near the ground fissure appeared at the bottom of the hanging wall of the pipe gallery structure,and a local void phenomenon was revealed.The length of the local void is 6.0 m to 8.0 m under the maximum settlement(0.8 m)of the ground fissure;(3)Compared with the static conditions,the vertical and horizontal displacements of the pipe gallery structure and surrounding soil under the seismic action were little,and there were tensioncompression and torsion-shear effects in corner of the square pipe gallery structure(with a stress concentration phenomenon).The deformation law of pipe gallery structure and surrounding soil considering ground fissure and the theoretical model of pipe gallery structure established in this paper can provide reference for practical engineering.展开更多
基金Project(51674265) supported by the National Natural Science Foundation of ChinaProjects(2018YFC0603705,2016YFC0600901) supported by the State Key Research Development Program of ChinaProject supported by the Yueqi Outstanding Scholar Award Program of China University of Mining&Technology,Beijing,China。
文摘For the 110 mining method,it is challenging to accurately calculate the support resistance of the roadway due to the lack of understanding of the dynamic movement of the overlying strata in this method.The consequential excessive support results in a significant increase in the cost of roadway support.The authors explored the overlying strata movement and roadway deformation of the gob-entry retaining in the 110 mining method to solve this problem.First,the typical stages of the roof-cutting gob-side entry were defined.Second,the mechanical model and calculation formula of the support resistance on the roof were explored.Then,using numerical simulation software,the starting ranges of the specific supports at different stages were verified and the feasibility of the support scheme was examined.Finally,combined with the field measurement data,the stress and the deformation of the gob roadway at different stages under the influence of two mining processes in the 110 mining method were obtained.The numerical simulation results obtained are consistent with the field test results,providing a theoretical basis for precision support at different stages by the 110 mining method.
基金Project support by the Scientific Research Foundation of Anhui (Grant No:00021090) and the Science Foundation of Jiangsu Higher Education (Grant No:02KJD13004).
文摘The dynamics of liquid sloshing in a spherical tank with spacer under low gravity was investigated. By extending the characteristic functions, the frequencies of liquid free sloshing, reaction force and moments on the wall of tank were obtained. By mechanical equivalent principle, the equivalent models of spring vibrator damper of liquid sloshing were given. The numerical results obtained show when a spacer is inserted in the tank, the sloshing frequency of liquid and the sloshing mass of liquid will decrease.
基金Foundation for Doctors from the Chinese Ministry of Education(No.20135121110005)National Major Science&Technology Project“Key technology for well bores in marine carbonate reservoirs”(No.2011ZX05005-006).
文摘Multi-stage SRV fracturing in horizontal wells is a new technology developed at home and abroad in recent years to effectively develop shale gas or low-permeability reservoirs,but on the other hand makes the mechanical environment of fracturing strings more complicated at the same time.In view of this,based on the loading features of tubing strings during the multi-stage fracturing of a horizontal well,mechanical models were established for three working cases of multiple packer setting,open differential-pressure sliding sleeve,and open ball-injection sliding sleeve under a hold-down packer.Moreover,mathematical models were respectively built for the above three cases.According to the Lame formula and Von Mises stress calculation formula for the thick-walled cylinder in the theory of elastic mechanics,a mathematical model was also established to calculate the equivalent stress for tubing string safety evaluation when the fracturing string was under the combined action of inner pressure,external squeezing force and axial stress,and another mathematical model was built for the mechanical strength and safety evaluation of multi-stage fracturing strings.In addition,a practical software was developed for the mechanical safety evaluation of horizontal well multi-stage fracturing strings according to the mathematical model developed for the mechanical calculation of the multi-packer string in horizontal wells.The research results were applied and verified in a gas well of Tahe Oilfield in the Tarim Basin with excellent effects,providing a theoretical basis and a simple and reliable technical means for optimal design and safety evaluation of safe operational parameters of multistage fracturing strings in horizontal wells.
基金supported by National Key Research and Development Program (2019YFA0708301)National Natural Science Foundation of China (51974337)+2 种基金the Strategic Cooperation Projects of CNPC and CUPB (ZLZX2020-03)Science and Technology Innovation Fund of CNPC (2021DQ02-0403)Open Fund of Petroleum Exploration and Development Research Institute of CNPC (2022-KFKT-09)
文摘We propose an integrated method of data-driven and mechanism models for well logging formation evaluation,explicitly focusing on predicting reservoir parameters,such as porosity and water saturation.Accurately interpreting these parameters is crucial for effectively exploring and developing oil and gas.However,with the increasing complexity of geological conditions in this industry,there is a growing demand for improved accuracy in reservoir parameter prediction,leading to higher costs associated with manual interpretation.The conventional logging interpretation methods rely on empirical relationships between logging data and reservoir parameters,which suffer from low interpretation efficiency,intense subjectivity,and suitability for ideal conditions.The application of artificial intelligence in the interpretation of logging data provides a new solution to the problems existing in traditional methods.It is expected to improve the accuracy and efficiency of the interpretation.If large and high-quality datasets exist,data-driven models can reveal relationships of arbitrary complexity.Nevertheless,constructing sufficiently large logging datasets with reliable labels remains challenging,making it difficult to apply data-driven models effectively in logging data interpretation.Furthermore,data-driven models often act as“black boxes”without explaining their predictions or ensuring compliance with primary physical constraints.This paper proposes a machine learning method with strong physical constraints by integrating mechanism and data-driven models.Prior knowledge of logging data interpretation is embedded into machine learning regarding network structure,loss function,and optimization algorithm.We employ the Physically Informed Auto-Encoder(PIAE)to predict porosity and water saturation,which can be trained without labeled reservoir parameters using self-supervised learning techniques.This approach effectively achieves automated interpretation and facilitates generalization across diverse datasets.
基金National Natural Science Foundation of China(12135008,12132005)。
文摘The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants.
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funded by The National Key R&D Program of China(2023YFC2205600)Open Project of Space Structure and Mechanism Technology Laboratory of China Aerospace Science and Technology Group Co.,Ltd.(YY-F805202312005)+1 种基金HIT Youth Scientist Laboratory Project,Postdoctoral Fellowship Program of CPSF(GZB20230259)the China Postdoctoral Science Foundation(2023TQ0133)(2023M731288).
文摘The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deciphering their adhesion mechanism.This study developed a contact mechanics model based on van der Waals forces and frictional self-locking effects,incorporating both the spatular pad and spatular shaft of the gecko’s foot microstructures.Building on this foundation,a discrete element simulation model was established using the bonding method to replicate the contact between the gecko's spatula and different surfaces.The dynamic adhesion and detaching processes under normal and tangential external forces were simulated,allowing for the analysis of variation curves of normal and tangential adhesion forces at different detaching angles.This provided insights into the directional adhesion mechanics of the gecko's spatula.Furthermore,a force measurement system was constructed using a multi-degree-of-freedom nano-manipulator and an atomic force microscope within a scanning electron microscope.This system was used to experimentally test the adhesion characteristics of the gecko’s foot microstructures,validating the accuracy of the proposed adhesion mechanics model.
文摘According to the structure of the hohl schaft kegel（HSK） tooling system and its working principle, a mechanical model of the HSK tooling system is established. Major factors influencing the stiffness of the system are analyzed and the relationship between the load and the manufacturing quality is obtained. The basic rule of the stiffness variation is presented and the theoretical analysis is in a good agreement with experimental results. The dynamic stiffness must also be considered to evaluate the performance of the tooling system besides the staticstiffness. Finally, the selecting principles of the HSK types are proposed and their optimum operating conditions are established.
基金Project(2007CB714002) supported by the National Basic Research Program of ChinaProject(51074180) supported by the National Natural Science Foundation of ChinaProject(2010FJ1002) supported by Hunan Municipal Science and Technology Program,China
文摘According to the cutting characteristics of progressive spiral movement by rotary cutting of the disc cutter, using the broken theory of interaction of compression and shearing, the three-axis force rotary cutting mechanical model of disc cutter was established and the influence of installation radius, the phase difference and the cutter space on the mechanics of disc cutter were analyzed. The results show that on the same radial line of tunneling interface, the boring distance of cutting tools installed on a different radius is not equal. The cutting radial line of tunneling interface is a polyline and its height is determined by phase angle and penetration of cutting tools. Both phase difference and the installation radius between adjacent disc cutters have little effect on the vertical force and rolling force, but increase with the increase in cutter spacing. In addition, when increasing phase difference and cutter space bilaterally, and reducing installation radius simultaneously, the lateral force would be improved. Related results have been verified onl O0 t rotary tool cutting test platform.
文摘With the increase of domestic gas consumption in cities and towns in China,gas explo-sion accidents happened rather frequently,and many structures were damaged greatly.Rational physical design could protect structures from being destroyed,but the character of explosion load must be learned firstly by establishing a correct mechanical model to simulate vented gas explo-sions.The explosion process has been studied for many years towards the safety of chemical in-dustry equipments.The key problem of these studies was the equations usually involved some ad-justable parameters that must be evaluated by experimental data,and the procedure of calculation was extremely complicated,so the reliability of these studies was seriously limited.Based on these studies,a simple mathematical model was established in this paper by using energy conservation,mass conservation,gas state equation,adiabatic compression equation and gas venting equation.Explosion load must be estimated by considering the room layout; the rate of pressure rise was then corrected by using a turbulence factor,so the pressure-time curve could be obtained.By using this method,complicated calculation was avoided,while experimental and calculated results fitted fairly well.Some pressure-time curves in a typical rectangular room were calculated to inves-tigate the influences of different ignition locations,gas thickness,concentration,room size and venting area on the explosion pressure.The results indicated that: it was the most dangerous con-dition when being ignited in the geometry centre of the room; the greater the burning velocity,the worse the venting effect; the larger the venting pressure,the higher the peak pressure; the larger the venting area,the lower the peak pressure.
基金Project supported by the National Natural Science Foundation of China (No. 10672191)the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20090211110016)the Natural Science Foundation of Gansu Province of China (No. 096RJZA048)
文摘With the help of plant roots, slope vegetation makes the slope soil mass become a composite material of soil and roots, and thus enhances shear strength of the slope soil mass and stability of the slope. However, the related studies at present are still qualitative. In this paper, quantitative analysis of the interaction between roots and soil mass are made. By the analysis of the interaction between herbaceous plant roots including lateral roots of woody plants and rock and soil mass, a mechanical model of the interaction between frictional roots and soil is established, and its correctness is shown. A mechanical model of the interaction between anchorage root, namely, woody plant taproot, and soil is also established. The establishment of the models provides a useful means in quantitative analysis of the interaction between plant roots and soil, and has practical values.
基金The project supported by the National Natural Science Foundation of China(10572138)
文摘Many physical experiments have shown that the domain switching in a ferroelectric material is a complicated evolution process of the domain wall with the variation of stress and electric field. According to this mechanism, the volume fraction of the domain switching is introduced in the constitutive law of ferroelectric ceramic and used to study the nonlinear constitutive behavior of ferroelectric body in this paper. The principle of stationary total energy is put forward in which the basic unknown quantities are the displacement ui, electric displacement Di and volume fraction pI of the domain switching for the variant I. Mechanical field equation and a new domain switching criterion are obtained from the principle of stationary total energy. The domain switching criterion proposed in this paper is an expansion and development of the energy criterion. On the basis of the domain switching criterion, a set of linear algebraic equations for the volume fraction PI of domain switching is obtained, in which the coefficients of the linear algebraic equations only contain the unknown strain and electric fields. Then a single domain mechanical model is proposed in this paper. The poled ferroelectric specimen is considered as a transversely isotropic single domain. By using the partial experimental results, the hardening relation between the driving force of domain switching and the volume fraction of domain switching can be calibrated. Then the electromechanical response can be calculated on the basis of the calibrated hardening relation. The results involve the electric butterfly shaped curves of axial strain versus axial electric field, the hysteresis loops of electric displacement versus electric filed and the evo- lution process of the domain switching in the ferroelectric specimens under uniaxial coupled stress and electric field loading. The present theoretic prediction agrees reasonably with the experimental results given by Lynch.
文摘Drying （conditioning） is an important procedure to prevent hydrate formation during gas pipeline gas-up and to protect pipelines against corrosion. The air-drying method is preferred in offshore gas pipelines pre-commissioning. The air-drying process of gas pipelines commonly includes two steps, air purging and soak test. The mass conservation and the phase equilibrium theory are applied to setting up the mathematical models of air purging, which can be used to simulate dry airflow rate and drying time. Fick diffusion law is applied to setting up the mathematical model of soak test, which can predict the water vapor concentration distribution. The results calculated from the purging model and the soak test model are in good agreement with the experimental data in the DF 1-1 offshore production pipeline conditioning. The models are verified to be available for the air-drying project design of offshore gas pipelines. Some proposals for airdrying engineering and operational procedures are put forward by analyzing the air-drying process of DFI-1 gasexporting pipelines.
基金the financial support from the National Natural Science Foundation of China(No.52109119)the Guangxi Natural Science Foundation(No.2021GXNSFBA075030)+2 种基金the Guangxi Science and Technology Project(No.Guike AD20325002)the Chinese Postdoctoral Science Fund Project(No.2022 M723408)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(China Institute of Water Resources and Hydropower Research)(No.IWHR-SKL-202202).
文摘Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensional high-stress and even causing disasters.Therefore,a novel complex true triaxial static-dynamic combined loading method reflecting underground excavation damage and then frequent intermittent disturbance failure is proposed.True triaxial static compression and intermittent disturbance tests are carried out on monzogabbro.The effects of intermediate principal stress and amplitude on the strength characteristics,deformation characteristics,failure characteristics,and precursors of monzogabbro are analyzed,intermediate principal stress and amplitude increase monzogabbro strength and tensile fracture mechanism.Rapid increases in microseismic parameters during rock loading can be precursors for intermittent rock disturbance.Based on the experimental result,the new damage fractional elements and method with considering crack initiation stress and crack unstable stress as initiation and acceleration condition of intermittent disturbance irreversible deformation are proposed.A novel three-dimensional disturbance fractional deterioration model considering the intermediate principal stress effect and intermittent disturbance damage effect is established,and the model predicted results align well with the experimental results.The sensitivity of stress states and model parameters is further explored,and the intermittent disturbance behaviors at different f are predicted.This study provides valuable theoretical bases for the stability analysis of deep mining engineering under dynamic loads.
基金co-supported by National Basic Research Program of China, National Natural Science Foundation of China(No. 51075204)Aeronautical Science Foundation of China (No.2009ZB52028, No. 2012ZB52026)+1 种基金Research Fund for the Doctoral Program of Higher Education of China (No. 20070287039)NUAA Research Funding (No. NZ2012106)
文摘A new unified macro- and micro-mechanics failure analysis method for composite structures was developed in order to take the effects of composite micro structure into consideration. In this method, the macro stress distribution of composite structure was calculated by commercial finite element analysis software. According to the macro stress distribution, the damage point was searched and the micro-stress distribution was calculated by reformulated finite-volume direct averaging micromechanics （FVDAM）, which was a multi-scale finite element method for composite. The micro structure failure modes were estimated with the failure strength of constituents. A unidirectional composite plate with a circular hole in the center under two kinds of loads was analyzed with the traditional macro-mechanical failure analysis method and the unified macro- and micro-mechanics failure analysis method. The results obtained by the two methods are consistent, which show this new method＇s accuracy and efficiency.
基金financially supported by the Key Program of the National Natural Science Foundation of China(No.51574222)National Natural Science Foundation of China(No.51034005)+1 种基金Program for New Century Excellent Talents in University of China(No.NCET-13-1022)National Key Research and Development Plan of China(No.2016YFC0501103)
文摘ln-situ experiments were conducted to investigate the mechanical properties of the soil-rock mixture in the internal dump of the Shengli #1 Surface Coal Mine, China. Based on the experimental results, this study used comparative analysis and found that the shear strength of the soil-rock mixture in the dump was greater than the residual shear strength of the original rock. The results showed that the material presented in the dump as large blocks was the main factor affecting the strength of the soil-rock mixture, Numerical simulation was carried out for the analyses of three factors： different combinations of shear failure, rolling failure along with different large-block radius ratios, and mixture densities. The results illustrated that the cohesion and angle of internal friction of the soil-rock mixture are 12 kPa and 32.26°. However, in some cases the bench angle in the dump was controlled by a coupling relationship of rocks in the material. Finally, the stability of a soil slope showed a linear relationship with the large-block radius ratio and the bulk density.
基金Supported by National Key R&D Program of China(Grant No.2017YFB0103801).
文摘An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindrical lithium-ion battery consists of a spring-damping parallel unit.Therefore,a spring-damping parallel unit connecting a damping unit in series is selected to construct the constitutive characteristics of the battery under mechanical abuse.Comparison results show that the equivalent mechanical model can more effectively describe the mechanical properties of the batteries than most cubic fitting models,of which the average relative error of the equivalent mechanical model under different states-of-charge is less than 6.75%.Combined with the proposed equivalent mechanical model,the failure process of the batteries was simulated and analyzed using LS-Dyna and HyperWorks.Under rigid rod tests,failure occurred at the core and bottom of the batteries;under hemispherical punch tests,failure occurred at the core and top,consistent with the experimental results.The average prediction error for the failure displacement under different abuse conditions is less than 4%in the simulations.The equivalent mechanical model requires only a few parameters and can be recognized easily.In the future,the model can be used in safety warning devices based on mechanical penetration.
文摘A mechanical model of liquid crystals （LCs） is applied to study the polymorphism of homologous series of terphenyl compounds. With a senti-experimental molecular orbit method, we calculate the moment of inertia which represents the rotation state to describe the phase transition temperature obtained from experimental data. We propose a novel explanation of the phase sequence or polymorphism of LC materials using the two key parameters, the moment of inertia and critical rotational velocity. The effect of molecular polarity on the appearance of liquid crystalline is also discussed.
基金Projects are the National Basic Research Program of China (No.2007CB209400)the 111 Project (No.B07028)the National Natural Science Foundation of China (Nos.50634050 and 50904065)
文摘Axial compression stress, produced by the pre-tightening force of a bolt, is a necessary condition for surrounding rock to form a whole structure. For this study, we built a mechanical model for an end-anchorage bolt, which represented the effect of a bolt on the surrounding rock in roadways in order to obtain its elastic solution. Simultaneously, we analyzed factors affecting the axial compression of the bolt on the surrounding rock and obtained the axial stress contours of the anchorage area through this elastic solution. The results indicate that 1) the axial compression stress in the anchorage area is proportional to the pre-tightening force and confirms the rule that stress declines sharply with the increase in axial distance from the bolt, with an effective stress radius of 1 m; 2) the maximum axial compression stress declines first and then rises with the increase in depth from the surface of the anchorage surrounding rock and 3) the size of the axial compression area is mainly determined by the length of the bolt.
基金funding of the National Natural Science Foundation of China(No.41702346 and No.42072319)the Science and Technology Plan Project of Shaanxi,China(No.2020SF-431)。
文摘The mechanical behavior of underground pipe gallery is a key research issue due to the static/dynamic states which exist in a ground fissure area.This study took an underground pipe gallery project in Xi’an,China as the research object.We analyzed the stress/strain characteristics of the pipe gallery structure and surrounding soil under static/dynamic conditions by the numerical simulation methods in detail.Based on the results,we proposed a theoretical calculation model for the pipe gallery structure considering the influence of the ground fissure,and combined with engineering examples for calculation and discussion.Subsequent results showed that:(1)the effective activity range of ground fissure on the deformation of the pipe gallery structure was mainly from 0.0 m(horizontal direction of ground fissure)to 32.0 m.In activity range,the pipe gallery structure is prone to failure,owing to the large soil deformation in the vertical direction;(2)with the increase of ground fissure settlement,a stress reduction area near the ground fissure appeared at the bottom of the hanging wall of the pipe gallery structure,and a local void phenomenon was revealed.The length of the local void is 6.0 m to 8.0 m under the maximum settlement(0.8 m)of the ground fissure;(3)Compared with the static conditions,the vertical and horizontal displacements of the pipe gallery structure and surrounding soil under the seismic action were little,and there were tensioncompression and torsion-shear effects in corner of the square pipe gallery structure(with a stress concentration phenomenon).The deformation law of pipe gallery structure and surrounding soil considering ground fissure and the theoretical model of pipe gallery structure established in this paper can provide reference for practical engineering.
