Existing analytical methods of buried steel pipelines subjected to active strike-slip faults depended on a number of simplifications.To study the failure mechanism more accurately,a refined strain analytical methodolo...Existing analytical methods of buried steel pipelines subjected to active strike-slip faults depended on a number of simplifications.To study the failure mechanism more accurately,a refined strain analytical methodology was proposed,taking the nonlinear characteristics of soil-pipeline interaction and pipe steel into account.Based on the elastic-beam and beam-on-elastic-foundation theories,the position of pipe potential destruction and the strain and deformation distributions along the pipeline were derived.Compared with existing analytical methods and three-dimensional nonlinear finite element analysis,the maximum axial total strains of pipe from the analytical methodology presented are in good agreement with the finite element results at small and intermediate fault movements and become gradually more conservative at large fault displacements.The position of pipe potential failure and the deformation distribution along the pipeline are fairly consistent with the finite element results.展开更多
Based on viscoelastic Kelvin.model and：nonlocal relationship of strain and stress, a nonlocal constitutive relationshila of viscoelasticity is obtained and the strain response of a bar in tension is studied, By trans...Based on viscoelastic Kelvin.model and：nonlocal relationship of strain and stress, a nonlocal constitutive relationshila of viscoelasticity is obtained and the strain response of a bar in tension is studied, By transforming governing equation of the strain analysis into Volterra integration form and by choosing a symmetric exponential form of kernel function and adapting Neumann series, the closed-form s.olution of strain field of the bar is obtained.： The creep process of the bar is presented： When time approaches infinite, the strain of bar is equal to the one of nonlocal elasticity展开更多
The experiment regarding material determination of a vehicle part was conducted.The experiment on stamping production of a part using the steels A,B and C was made.The strain data on the deformed parts were measured.T...The experiment regarding material determination of a vehicle part was conducted.The experiment on stamping production of a part using the steels A,B and C was made.The strain data on the deformed parts were measured.The forming limit diagrams for the steels were examined and evaluated.The results show that three steels are unsuitable for this stamping part.The desired material properties with an optimal strain hardening exponent value were determined using experimental and analytical methods.The steel D was chosen as a desired material.The results show that the steel D is appropriate for mass production.In addition,the feasibility of the application of thinner material to this part was studied.The validity of the material selection was verified theoretically and experimentally.展开更多
In order to predict the life of engineering structures, it is necessary to investigate the strain distribution in notched members. In gineral, the Uauschinger Effect of materials under cyclic loading is not negligible...In order to predict the life of engineering structures, it is necessary to investigate the strain distribution in notched members. In gineral, the Uauschinger Effect of materials under cyclic loading is not negligible, and so the anisolropic hardening model has been suggested. From the comparison between the calculated and experimental results in this paper, we can see that even the linear kinematic hardening model is quite suitable for strain analysis under cyclic loading.展开更多
Fiber metal laminates have many advantages over traditional laminates （e.g., any type of fiber and resin material can be placed anywhere between the metallic layers without risk of failure of the composite fabric she...Fiber metal laminates have many advantages over traditional laminates （e.g., any type of fiber and resin material can be placed anywhere between the metallic layers without risk of failure of the composite fabric sheets）. Furthermore, the process requirements to strictly control the temperature and punch force in fiber metal laminates are also less stringent than those in traditional laminates. To further explore the novel method, this study conducts a finite element method-based （FEM-based） strain analysis on multilayer blanks by using the 3A method. Different forming modes such as wrinkling and fracture are discussed by using experimental and numerical studies. Hydroforming is used for multilayer forming. The Barlat 2000 yield criteria and DYNAFORM/LS-DYNA are used for the simulations. Optimal process parameters are determined on the basis of fixed die-binder gap and variable cavity pressure. The results of this study will enhance the knowledge on the mechanics of multilayer structures formed by using the 3A method and expand its commercial applications.展开更多
Enterococci bacteria are important in environmental, food and clinical microbiology. Enterococcus faecium is a nosocomial pathogen that causes bacteremia, endocarditis and other infections. It is among the most preval...Enterococci bacteria are important in environmental, food and clinical microbiology. Enterococcus faecium is a nosocomial pathogen that causes bacteremia, endocarditis and other infections. It is among the most prevalent organisms encountered in hospital-associated infections accounting for approximately 12% of nosocomial infections in the USA （Linden and Miller, 1999）. However, certain strains of E. faecium are not only non-pathogenic but also have beneficial effects on human health with probiotic potential. For example, E. faecium T-110 is a consortium member in several probiotic products including BIO-THREE~ which is widely prescribed for human, animal and aqua-cultural use. This strain was originally developed by TOA Pharmaceuticals in Japan, and later used in the probiotic products of several other companies.展开更多
The flip chip package is a kind of advanced electri ca l packages. Due to the requirement of miniaturization, lower weight, higher dens ity and higher performance in the advanced electric package, it is expected that ...The flip chip package is a kind of advanced electri ca l packages. Due to the requirement of miniaturization, lower weight, higher dens ity and higher performance in the advanced electric package, it is expected that flip chip package will soon be a mainstream technology. The silicon chip is dir ectly connected to printing circuit substrate by SnPb solder joints. Also, the u nderfill, a composite of polymer and silica particles, is filled in the gap betw een the chip and substrate around the solder joints to improve the reliabili ty of solder joints. When flip chip package specimen is tested with thermal cycl ing, the cyclic stress/strain response that exists at the underfill interfaces and solder joints may result in interfacial crack initiation and propagation. Therefore, the chip cracking and the interfacial delamination between underfill and chip corner have been investigated in many studies. Also, most researches h ave focused on the effect of fatigue and creep properties of solder joint induce d by the plastic strain alternation and accumulation. The nuderfill must have lo w viscosity in the liquid state and good adhesion to the interface after solidif ying. Also, the mechanical behavior of such epoxy material has much dependen ce on temperature in its glass transition temperature range that is usually cove red by the temperature range of thermal cycling test. Therefore, the materia l behavior of underfill exists a significant non-linearity and the assumption o f linear elastic can lack for accuracy in numerical analysis. Through numerical analysis, this study had some comparisons about the effect of linear and non -linear properties of underfill on strain behaviors around the interface of fli p chip assembly. Especially, the deformation tendency inside solder bumps could be predicted. Also, it is worthily mentioned that we have pointed out which comp onent of plastic strain, thus, either normal or shear, has dominant influence to the fatigue and creep of solder bump, which have not brought up before. About the numerical analysis to the thermal plastic strain occurs in flip chip i nterconnection during thermal cycling test, a commercial finite element software , namely, ANSYS, was employed to simulate the thermal cycling test obeyed by MIL-STD-883C. The temperatures of thermal cycling ranged from -55 ℃ to 125 ℃ with ramp rate of 36 ℃/min and a dwell time of 25 min at peak temperature. T he schematic drawing of diagonal cross-section of flip chip package composed of FR-4 substrate, silicon chip, underfill and solder bump was shown as Fig.1. Th e numerical model was two-dimensional (2-D) with plane strain assumption and o nly one half of the cross-section was modeled due to geometry symmetry. The dim ensions and boundary conditions of numerical model were shown in Fig.2. The symm etric boundary conditions were applied along the left edge of the model, and the left bottom corner was additional constrained in vertical direction to prevent body motion. The finite element meshes of overall and local numerical model was shown as Fig.3. In this study, two cases of material model were used to describe the material behavior of the underfill: the case1 was linear elastic model that assumed Young’s Modulus (E) and thermal expansion coefficient (CTE) were consta nt during thermal cycling; the case2 was MKIN model (in ANSYS) that had nonlinea r temperature-dependent stress-strain relationship and temperature-dependent CTE. The material model applied to the solder bump was ANAND model (in ANSYS) th at described time-dependent plasticity phenomenon of viscoplastic material. Bot h the FR-4 substrate and silicon chip were assumed as temperature-independent elastic material; moreover, FR-4 substrate is orthotropic while silicon chip is isotropic. From the comparison between numerical results of linear and nonlinear material a ssumption of underfill, (i.e. case1 and case2), the quantities of plastic strain around the interconnection from case1 are higher than that in case2. Thus, the linear展开更多
In this paper, the stress-strain curve of material is fitted by polygonal line composed of three lines. According to the theory of proportional loading in elastoplasticity, we simplify the complete stress-strain relat...In this paper, the stress-strain curve of material is fitted by polygonal line composed of three lines. According to the theory of proportional loading in elastoplasticity, we simplify the complete stress-strain relations, which are given by the increment theory of elastoplasticity. Thus, the finite element equation with the solution of displacement is derived. The assemblage elastoplastic stiffness matrix can be obtained by adding something to the elastic matrix, hence it will shorten the computing time. The determination of every loading increment follows the von Mises yield criteria. The iterative method is used in computation. It omits the redecomposition of the assemblage stiffness matrix and it will step further to shorten the computing time. Illustrations are given to the high-order element application departure from proportional loading, the computation of unloading fitting to the curve and the problem of load estimation.展开更多
The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret...The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret the relationship between the different lithologies and the tectonic setting,in order to elucidate the nature of kinematic analysis in the Halaban region.The kinematic analyses were applied to feldspar porphyroclasts,quartz and hornblende for twenty-six samples.The kinematic vorticity number(Wm)for deformed rocks in the study area ranged from~0.6 to 0.9.The direction of the long axes for finite strain data(X axes)revealed a WNW trend with shallow dipping.The direction of the short axes for finite strain data(Z axes)were represented by vertical with associated horizontal foliation.The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region.Furthermore,our finite strain data shows no significant volume change during deformation.The subhorizontal foliation was synchronized with thrusting and deformation.Furthermore,throughout the overlying nappes,the same attitudes of tectonic contacts are observable,the nappes in the orogens being formed from simple shear deformation.展开更多
In order to study contemporary crustal movement of Antarctic,China has not only constructed the deformation monitoring network in West Antarctic Fildes strait region,but also monitored the network by using DI-20 Geodi...In order to study contemporary crustal movement of Antarctic,China has not only constructed the deformation monitoring network in West Antarctic Fildes strait region,but also monitored the network by using DI-20 Geodimeter and GPS instruments,and participated the Antarctic GPS Campaign Observation organized by SCAR as well.During mathematics processing of crustal horizontal deformation observations,a method to bring deformation parameters into the error equations of observations is discussed in this paper.Several classical deformation models,such as rigid body displacement and strain,are introduced in detail.By analyzing the reference datum of statistical geodetic network,a conclusion is drawn that it is unfit to use rank-defected reference datum for the crustal deformation analysis,and another method is developed to set up different additional weight matrix for every different kind of parameter,the classical adjustment and rank-defected adjustment are well unified.Two methods of considering or non-considering the relation between point parameters and deformation parameters are compared,and the former is more appropriate than the latter.A series of programs are developed to implementing the method mentioned above and the analysis of West Antarctic Fileds deformation monitoring network.It is also involved GPS data processing and analysis of deformation results in the paper.The research results indicate that it seems exacting displacement in Fildes rift region,but the displacement is not large,just a little rift shear movement.展开更多
In order to research contemporary crustal movement of Antarctica, China has constructed the deformation monitoring network in the Fildes Strait region,West Antarctica, monitored the network by using DI 20 geodimeter...In order to research contemporary crustal movement of Antarctica, China has constructed the deformation monitoring network in the Fildes Strait region,West Antarctica, monitored the network by using DI 20 geodimeter and GPS instruments, and participated the Antarctic GPS Campaign Observation organized by SCAR as well. During mathematics processing of crustal horizontal deformation observations,a method to bring deformation parameters into the error equations of observations is discussed in this paper. Several classical deformation models,such as rigid body displacement and strain,are introduced. By analyzing the reference datum of static and dynamic geodetic network,the method is developed to set up different additional weight matrix for every different kind of parameter. A series of programs are developed to implementing the method mentioned above and the analysis of West Antarctic Fildes Strait deformation monitoring network. Discussion is also made of GPS monitoring data by using the principle of monitoring network strain analysis in the paper. The research results indicate that the displacement did occur in Fildes rift region,but the displacement was not large,just a slight rift shear movement.展开更多
The cyclic stress-strain responses (CSSR), Neuber's rule (NR) and cyclic strain-life relation (CSLR) are treated as probabilistic curves in local stress and strain method of low cycle fatigue analysis. The randomn...The cyclic stress-strain responses (CSSR), Neuber's rule (NR) and cyclic strain-life relation (CSLR) are treated as probabilistic curves in local stress and strain method of low cycle fatigue analysis. The randomness of loading and the theory of fatigue damage accumulation (TOFDA) are considered. The probabilistic analysis of local stress, local strain and fatigue life are constructed based on the first-order Taylor's series expansions. Through this method proposed fatigue reliability analysis can be accomplished.展开更多
At a sampling rate of 100 samples per second,the YRY-4 four-gauge borehole strainmeters（FGBS） are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a...At a sampling rate of 100 samples per second,the YRY-4 four-gauge borehole strainmeters（FGBS） are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a high sampling rate, data from the YRY-4 strainmeters demonstrate fairly satisfactory self-consistency. The strain tensor seismograms demonstrate the senses of motion of P waves, that is, the type of seismic wave travels in the direction of the maximum normal strain change. The observed strain patterns of S waves significantly differ from those of P waves and should contain information about the source mechanism. Spectrum analysis shows that the strain seismograms are consistent with conventional broadband seismograms from the same site.展开更多
With mean yield（MY）criterion,an analytical solution of the collapse load for a defect-free pipe elbow under internal pressure is first obtained.It is a function of ratio of thickness to radius t0/r0,strain hardening...With mean yield（MY）criterion,an analytical solution of the collapse load for a defect-free pipe elbow under internal pressure is first obtained.It is a function of ratio of thickness to radius t0/r0,strain hardening exponent n,curvature influence factor mand ultimate tensile strength.The collapse load increases with the increase of m,and it is the same as the burst pressure of straight pipe if m=1is assumed.The MY-based solution is compared with those based on Tresca,Mises and twin shear stress（TSS）yield criteria,and the comparison indicates that Tresca and twin shear stress yield criteria predict a lower bound and an upper bound to the collapse load respectively.However,the MY-based solution lies just between the TSS and Tresca solutions,and almost has the same precision with the Mises solution.展开更多
In order to understand failure mechanisms of the tunnel excavated in the stratified rock masses in deep mine, the physical modeling experiment by using the large-scale model was carried out. The field case simulated i...In order to understand failure mechanisms of the tunnel excavated in the stratified rock masses in deep mine, the physical modeling experiment by using the large-scale model was carried out. The field case simulated in the experiment is a main connection tunnel located at depth of 1000 m in Qishan coal mine,Xuzhou mining district. Tunnel deformation was monitored by using strain gauges and a video camera simultaneously. Crack initiation and propagation process during the test were analyzed based on image analysis of the captured video photographs. At the same time, deformation process of the key monitoring points around the tunnel section is given by the monitored strain plots. Under the increasing external loads, crack initiation occurs firstly on the left wall of the tunnel, then on the immediate roof.Complete failure of the tunnel occurs as a result of the slippage of the rock layers along the interfaces.展开更多
Nano domain Al substituted Zinc ferrite was prepared by chemical route using Ethylene Diamine as ligand.High purity precursors nitrate salts of Zinc,Fe(3+),Al(3+)were utilized along with citric acid which acts as both...Nano domain Al substituted Zinc ferrite was prepared by chemical route using Ethylene Diamine as ligand.High purity precursors nitrate salts of Zinc,Fe(3+),Al(3+)were utilized along with citric acid which acts as both fuel and complexing agent.Two different molar ratios of Zn(2+):(Fe3+):Al(3+)is 1:1.5:0.5 and 1:1.25:0.75.After ensuring proper mix of the solution Ethylene diamine was added dropwise to form a gel like mass with proper pH control.Before annealing,thermal analysis was carried to determine the crystallization/phase transition zone.Drying was carried in several stages.Initially,gel like mass was obtained after drying at 40°C while pH was about 7.Drying of gel was carried in oil bath at about 90°C and powdered mass obtained was grinded followed by auto combustion at 150°C for 60 minutes before annealing at 150°C,350°C,650°C,950°C for 2 hours to ensure the phase formation.Crystallite size,lattice strain and lattice parameters were studied from XRD analysis.展开更多
The experiment regarding material determination of a vehicle part was conducted. The experiment on stamping production of a part using the steels A, B and C was made. The strain data on the deformed parts were measure...The experiment regarding material determination of a vehicle part was conducted. The experiment on stamping production of a part using the steels A, B and C was made. The strain data on the deformed parts were measured. The forming limit diagrams for the steels were examined and evaluated. The results show that three steels are unsuitable for this stamping part. The desired material properties with an optimal strain hardening exponent value were determined using experimental and analytical methods. The steel D was chosen as a desired material. The results show that the steel D is appropriate for mass production. In addition, the feasibility of the application of thinner material to this part was studied. The validity of the material selection was verified theoretically and experimentally.展开更多
We present a computational framework for the study of cardiac motion.The bio-mechanical model captures the passive and active properties of the cardiac tissue as well as the fiber architecture.We focus on the analysis...We present a computational framework for the study of cardiac motion.The bio-mechanical model captures the passive and active properties of the cardiac tissue as well as the fiber architecture.We focus on the analysis of deformations of a beating left ventricle(LV),comparing numerical simulations with real data acquired by echocardiography.The goal is to determine the clinical relevance of the LV strains pattern and to investigate the relationships between that pattern and the arrangement of myocardial fibers.The proposed framework could in principle be used for a wide range of clinical applications.展开更多
The bending strength of microfabricated polysilicon beams was measured by beam bending using a nanoindenter. Also, the tensile strength of microfabricated polysilicon thin ?lms was measured by tensile testing with a...The bending strength of microfabricated polysilicon beams was measured by beam bending using a nanoindenter. Also, the tensile strength of microfabricated polysilicon thin ?lms was measured by tensile testing with a new microtensile test device. It was found that the bending strength and tensile strength of polysilicon microstructures exerts size e?ect on the size of the specimens. In such cases, the size e?ect can be traced back to the ratio of surface area to volume as the governing parameter. A statistical analysis of the bending strength for various specimen sizes shows that the average bending strength of polysilicon microcantilever beams is 2.885 ± 0.408 GPa. The measured average value of Young’s modulus, 164 ± 1.2 GPa, falls within the theoretical bounds. The average fracture tensile strength is 1.36 GPa with a standard deviation of 0.14 GPa, and the Weibull modulus is 10.4 -11.7, respectively. The tensile testing of 40 specimens on failure results in a recommendation for design that the nominal strain be maintained below 0.0057.展开更多
基金Project(50439010) supported by the National Natural Science Foundation of ChinaProject(DUT10ZD201) supported by the Fundamental Research Funds for the Central Universities in China
文摘Existing analytical methods of buried steel pipelines subjected to active strike-slip faults depended on a number of simplifications.To study the failure mechanism more accurately,a refined strain analytical methodology was proposed,taking the nonlinear characteristics of soil-pipeline interaction and pipe steel into account.Based on the elastic-beam and beam-on-elastic-foundation theories,the position of pipe potential destruction and the strain and deformation distributions along the pipeline were derived.Compared with existing analytical methods and three-dimensional nonlinear finite element analysis,the maximum axial total strains of pipe from the analytical methodology presented are in good agreement with the finite element results at small and intermediate fault movements and become gradually more conservative at large fault displacements.The position of pipe potential failure and the deformation distribution along the pipeline are fairly consistent with the finite element results.
基金Project supported by the Science Foundation ofNational University of Defense Technology(No.JC0601-01)
文摘Based on viscoelastic Kelvin.model and：nonlocal relationship of strain and stress, a nonlocal constitutive relationshila of viscoelasticity is obtained and the strain response of a bar in tension is studied, By transforming governing equation of the strain analysis into Volterra integration form and by choosing a symmetric exponential form of kernel function and adapting Neumann series, the closed-form s.olution of strain field of the bar is obtained.： The creep process of the bar is presented： When time approaches infinite, the strain of bar is equal to the one of nonlocal elasticity
文摘The experiment regarding material determination of a vehicle part was conducted.The experiment on stamping production of a part using the steels A,B and C was made.The strain data on the deformed parts were measured.The forming limit diagrams for the steels were examined and evaluated.The results show that three steels are unsuitable for this stamping part.The desired material properties with an optimal strain hardening exponent value were determined using experimental and analytical methods.The steel D was chosen as a desired material.The results show that the steel D is appropriate for mass production.In addition,the feasibility of the application of thinner material to this part was studied.The validity of the material selection was verified theoretically and experimentally.
文摘In order to predict the life of engineering structures, it is necessary to investigate the strain distribution in notched members. In gineral, the Uauschinger Effect of materials under cyclic loading is not negligible, and so the anisolropic hardening model has been suggested. From the comparison between the calculated and experimental results in this paper, we can see that even the linear kinematic hardening model is quite suitable for strain analysis under cyclic loading.
文摘Fiber metal laminates have many advantages over traditional laminates （e.g., any type of fiber and resin material can be placed anywhere between the metallic layers without risk of failure of the composite fabric sheets）. Furthermore, the process requirements to strictly control the temperature and punch force in fiber metal laminates are also less stringent than those in traditional laminates. To further explore the novel method, this study conducts a finite element method-based （FEM-based） strain analysis on multilayer blanks by using the 3A method. Different forming modes such as wrinkling and fracture are discussed by using experimental and numerical studies. Hydroforming is used for multilayer forming. The Barlat 2000 yield criteria and DYNAFORM/LS-DYNA are used for the simulations. Optimal process parameters are determined on the basis of fixed die-binder gap and variable cavity pressure. The results of this study will enhance the knowledge on the mechanics of multilayer structures formed by using the 3A method and expand its commercial applications.
文摘Enterococci bacteria are important in environmental, food and clinical microbiology. Enterococcus faecium is a nosocomial pathogen that causes bacteremia, endocarditis and other infections. It is among the most prevalent organisms encountered in hospital-associated infections accounting for approximately 12% of nosocomial infections in the USA （Linden and Miller, 1999）. However, certain strains of E. faecium are not only non-pathogenic but also have beneficial effects on human health with probiotic potential. For example, E. faecium T-110 is a consortium member in several probiotic products including BIO-THREE~ which is widely prescribed for human, animal and aqua-cultural use. This strain was originally developed by TOA Pharmaceuticals in Japan, and later used in the probiotic products of several other companies.
文摘The flip chip package is a kind of advanced electri ca l packages. Due to the requirement of miniaturization, lower weight, higher dens ity and higher performance in the advanced electric package, it is expected that flip chip package will soon be a mainstream technology. The silicon chip is dir ectly connected to printing circuit substrate by SnPb solder joints. Also, the u nderfill, a composite of polymer and silica particles, is filled in the gap betw een the chip and substrate around the solder joints to improve the reliabili ty of solder joints. When flip chip package specimen is tested with thermal cycl ing, the cyclic stress/strain response that exists at the underfill interfaces and solder joints may result in interfacial crack initiation and propagation. Therefore, the chip cracking and the interfacial delamination between underfill and chip corner have been investigated in many studies. Also, most researches h ave focused on the effect of fatigue and creep properties of solder joint induce d by the plastic strain alternation and accumulation. The nuderfill must have lo w viscosity in the liquid state and good adhesion to the interface after solidif ying. Also, the mechanical behavior of such epoxy material has much dependen ce on temperature in its glass transition temperature range that is usually cove red by the temperature range of thermal cycling test. Therefore, the materia l behavior of underfill exists a significant non-linearity and the assumption o f linear elastic can lack for accuracy in numerical analysis. Through numerical analysis, this study had some comparisons about the effect of linear and non -linear properties of underfill on strain behaviors around the interface of fli p chip assembly. Especially, the deformation tendency inside solder bumps could be predicted. Also, it is worthily mentioned that we have pointed out which comp onent of plastic strain, thus, either normal or shear, has dominant influence to the fatigue and creep of solder bump, which have not brought up before. About the numerical analysis to the thermal plastic strain occurs in flip chip i nterconnection during thermal cycling test, a commercial finite element software , namely, ANSYS, was employed to simulate the thermal cycling test obeyed by MIL-STD-883C. The temperatures of thermal cycling ranged from -55 ℃ to 125 ℃ with ramp rate of 36 ℃/min and a dwell time of 25 min at peak temperature. T he schematic drawing of diagonal cross-section of flip chip package composed of FR-4 substrate, silicon chip, underfill and solder bump was shown as Fig.1. Th e numerical model was two-dimensional (2-D) with plane strain assumption and o nly one half of the cross-section was modeled due to geometry symmetry. The dim ensions and boundary conditions of numerical model were shown in Fig.2. The symm etric boundary conditions were applied along the left edge of the model, and the left bottom corner was additional constrained in vertical direction to prevent body motion. The finite element meshes of overall and local numerical model was shown as Fig.3. In this study, two cases of material model were used to describe the material behavior of the underfill: the case1 was linear elastic model that assumed Young’s Modulus (E) and thermal expansion coefficient (CTE) were consta nt during thermal cycling; the case2 was MKIN model (in ANSYS) that had nonlinea r temperature-dependent stress-strain relationship and temperature-dependent CTE. The material model applied to the solder bump was ANAND model (in ANSYS) th at described time-dependent plasticity phenomenon of viscoplastic material. Bot h the FR-4 substrate and silicon chip were assumed as temperature-independent elastic material; moreover, FR-4 substrate is orthotropic while silicon chip is isotropic. From the comparison between numerical results of linear and nonlinear material a ssumption of underfill, (i.e. case1 and case2), the quantities of plastic strain around the interconnection from case1 are higher than that in case2. Thus, the linear
文摘In this paper, the stress-strain curve of material is fitted by polygonal line composed of three lines. According to the theory of proportional loading in elastoplasticity, we simplify the complete stress-strain relations, which are given by the increment theory of elastoplasticity. Thus, the finite element equation with the solution of displacement is derived. The assemblage elastoplastic stiffness matrix can be obtained by adding something to the elastic matrix, hence it will shorten the computing time. The determination of every loading increment follows the von Mises yield criteria. The iterative method is used in computation. It omits the redecomposition of the assemblage stiffness matrix and it will step further to shorten the computing time. Illustrations are given to the high-order element application departure from proportional loading, the computation of unloading fitting to the curve and the problem of load estimation.
基金The authors would like to extend their sincere appreciation to the Deanship of Scientific Research at King Saud University for its funding of this research through Research Group Project No.RG-1440-011.
文摘The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret the relationship between the different lithologies and the tectonic setting,in order to elucidate the nature of kinematic analysis in the Halaban region.The kinematic analyses were applied to feldspar porphyroclasts,quartz and hornblende for twenty-six samples.The kinematic vorticity number(Wm)for deformed rocks in the study area ranged from~0.6 to 0.9.The direction of the long axes for finite strain data(X axes)revealed a WNW trend with shallow dipping.The direction of the short axes for finite strain data(Z axes)were represented by vertical with associated horizontal foliation.The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region.Furthermore,our finite strain data shows no significant volume change during deformation.The subhorizontal foliation was synchronized with thrusting and deformation.Furthermore,throughout the overlying nappes,the same attitudes of tectonic contacts are observable,the nappes in the orogens being formed from simple shear deformation.
文摘In order to study contemporary crustal movement of Antarctic,China has not only constructed the deformation monitoring network in West Antarctic Fildes strait region,but also monitored the network by using DI-20 Geodimeter and GPS instruments,and participated the Antarctic GPS Campaign Observation organized by SCAR as well.During mathematics processing of crustal horizontal deformation observations,a method to bring deformation parameters into the error equations of observations is discussed in this paper.Several classical deformation models,such as rigid body displacement and strain,are introduced in detail.By analyzing the reference datum of statistical geodetic network,a conclusion is drawn that it is unfit to use rank-defected reference datum for the crustal deformation analysis,and another method is developed to set up different additional weight matrix for every different kind of parameter,the classical adjustment and rank-defected adjustment are well unified.Two methods of considering or non-considering the relation between point parameters and deformation parameters are compared,and the former is more appropriate than the latter.A series of programs are developed to implementing the method mentioned above and the analysis of West Antarctic Fileds deformation monitoring network.It is also involved GPS data processing and analysis of deformation results in the paper.The research results indicate that it seems exacting displacement in Fildes rift region,but the displacement is not large,just a little rift shear movement.
文摘In order to research contemporary crustal movement of Antarctica, China has constructed the deformation monitoring network in the Fildes Strait region,West Antarctica, monitored the network by using DI 20 geodimeter and GPS instruments, and participated the Antarctic GPS Campaign Observation organized by SCAR as well. During mathematics processing of crustal horizontal deformation observations,a method to bring deformation parameters into the error equations of observations is discussed in this paper. Several classical deformation models,such as rigid body displacement and strain,are introduced. By analyzing the reference datum of static and dynamic geodetic network,the method is developed to set up different additional weight matrix for every different kind of parameter. A series of programs are developed to implementing the method mentioned above and the analysis of West Antarctic Fildes Strait deformation monitoring network. Discussion is also made of GPS monitoring data by using the principle of monitoring network strain analysis in the paper. The research results indicate that the displacement did occur in Fildes rift region,but the displacement was not large,just a slight rift shear movement.
文摘The cyclic stress-strain responses (CSSR), Neuber's rule (NR) and cyclic strain-life relation (CSLR) are treated as probabilistic curves in local stress and strain method of low cycle fatigue analysis. The randomness of loading and the theory of fatigue damage accumulation (TOFDA) are considered. The probabilistic analysis of local stress, local strain and fatigue life are constructed based on the first-order Taylor's series expansions. Through this method proposed fatigue reliability analysis can be accomplished.
基金supported by the Special Fund for Earthquake Research in the Public Interest(No.201108009)
文摘At a sampling rate of 100 samples per second,the YRY-4 four-gauge borehole strainmeters（FGBS） are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a high sampling rate, data from the YRY-4 strainmeters demonstrate fairly satisfactory self-consistency. The strain tensor seismograms demonstrate the senses of motion of P waves, that is, the type of seismic wave travels in the direction of the maximum normal strain change. The observed strain patterns of S waves significantly differ from those of P waves and should contain information about the source mechanism. Spectrum analysis shows that the strain seismograms are consistent with conventional broadband seismograms from the same site.
基金Sponsored by National Natural Science Foundation of China(51074052,50734002)
文摘With mean yield（MY）criterion,an analytical solution of the collapse load for a defect-free pipe elbow under internal pressure is first obtained.It is a function of ratio of thickness to radius t0/r0,strain hardening exponent n,curvature influence factor mand ultimate tensile strength.The collapse load increases with the increase of m,and it is the same as the burst pressure of straight pipe if m=1is assumed.The MY-based solution is compared with those based on Tresca,Mises and twin shear stress（TSS）yield criteria,and the comparison indicates that Tresca and twin shear stress yield criteria predict a lower bound and an upper bound to the collapse load respectively.However,the MY-based solution lies just between the TSS and Tresca solutions,and almost has the same precision with the Mises solution.
文摘In order to understand failure mechanisms of the tunnel excavated in the stratified rock masses in deep mine, the physical modeling experiment by using the large-scale model was carried out. The field case simulated in the experiment is a main connection tunnel located at depth of 1000 m in Qishan coal mine,Xuzhou mining district. Tunnel deformation was monitored by using strain gauges and a video camera simultaneously. Crack initiation and propagation process during the test were analyzed based on image analysis of the captured video photographs. At the same time, deformation process of the key monitoring points around the tunnel section is given by the monitored strain plots. Under the increasing external loads, crack initiation occurs firstly on the left wall of the tunnel, then on the immediate roof.Complete failure of the tunnel occurs as a result of the slippage of the rock layers along the interfaces.
文摘Nano domain Al substituted Zinc ferrite was prepared by chemical route using Ethylene Diamine as ligand.High purity precursors nitrate salts of Zinc,Fe(3+),Al(3+)were utilized along with citric acid which acts as both fuel and complexing agent.Two different molar ratios of Zn(2+):(Fe3+):Al(3+)is 1:1.5:0.5 and 1:1.25:0.75.After ensuring proper mix of the solution Ethylene diamine was added dropwise to form a gel like mass with proper pH control.Before annealing,thermal analysis was carried to determine the crystallization/phase transition zone.Drying was carried in several stages.Initially,gel like mass was obtained after drying at 40°C while pH was about 7.Drying of gel was carried in oil bath at about 90°C and powdered mass obtained was grinded followed by auto combustion at 150°C for 60 minutes before annealing at 150°C,350°C,650°C,950°C for 2 hours to ensure the phase formation.Crystallite size,lattice strain and lattice parameters were studied from XRD analysis.
文摘The experiment regarding material determination of a vehicle part was conducted. The experiment on stamping production of a part using the steels A, B and C was made. The strain data on the deformed parts were measured. The forming limit diagrams for the steels were examined and evaluated. The results show that three steels are unsuitable for this stamping part. The desired material properties with an optimal strain hardening exponent value were determined using experimental and analytical methods. The steel D was chosen as a desired material. The results show that the steel D is appropriate for mass production. In addition, the feasibility of the application of thinner material to this part was studied. The validity of the material selection was verified theoretically and experimentally.
基金the Italian Minister for Education,Research,and University(Grant No.2017KL4EF3)“Sapienza”Universiti di Roma(Grant No.RM120172A77FB346)。
文摘We present a computational framework for the study of cardiac motion.The bio-mechanical model captures the passive and active properties of the cardiac tissue as well as the fiber architecture.We focus on the analysis of deformations of a beating left ventricle(LV),comparing numerical simulations with real data acquired by echocardiography.The goal is to determine the clinical relevance of the LV strains pattern and to investigate the relationships between that pattern and the arrangement of myocardial fibers.The proposed framework could in principle be used for a wide range of clinical applications.
基金Project supported by the Micro/Nano Science and Technology Center Science Founation of Jiangsu Province (Nos.BK2002147 and 02KJA460001) the Excellent Young Teachers Program of MOE of China and the National Natural ScienceFoundation of China (No. 50135040).
文摘The bending strength of microfabricated polysilicon beams was measured by beam bending using a nanoindenter. Also, the tensile strength of microfabricated polysilicon thin ?lms was measured by tensile testing with a new microtensile test device. It was found that the bending strength and tensile strength of polysilicon microstructures exerts size e?ect on the size of the specimens. In such cases, the size e?ect can be traced back to the ratio of surface area to volume as the governing parameter. A statistical analysis of the bending strength for various specimen sizes shows that the average bending strength of polysilicon microcantilever beams is 2.885 ± 0.408 GPa. The measured average value of Young’s modulus, 164 ± 1.2 GPa, falls within the theoretical bounds. The average fracture tensile strength is 1.36 GPa with a standard deviation of 0.14 GPa, and the Weibull modulus is 10.4 -11.7, respectively. The tensile testing of 40 specimens on failure results in a recommendation for design that the nominal strain be maintained below 0.0057.
