Implicit and Explicit Integration Schemes of a Double Structure Hydro-Mechanical Coupling Model for Unsaturated Expansive Clays

Author(s):  
Jian Li ◽  
Pengyue Wang ◽  
Lu Hai ◽  
Yanhua Zhu ◽  
Yan Liu
2018 ◽  
Vol 9 (4) ◽  
pp. 465-474 ◽  
Author(s):  
Evangelos Gavalas ◽  
Ioannis Pressas ◽  
Spyros Papaefthymiou

Purpose The purpose of this paper is to compare the performance of implicit and explicit integration schemes for simulating the metal rolling process using commercial software packages ANSYS™ and LS-DYNA™. Design/methodology/approach For the industrial application of finite element method, the time discretization is one of the most important factors that determine the stability and efficiency of the analysis. An iterative approach, which is unconditionally stable in linear analyses, is the obvious choice for a quasi-static problem such as metal rolling. However, this approach may be challenging in achieving convergence with non-linear material behavior and complicated contact conditions. Therefore, a non-iterative method is usually adopted, in order to achieve computational accuracy through very small time steps. Models using both methods were constructed and compared for computational efficiency. Findings The results indicate that the explicit method yields higher levels of efficiency compared to the implicit method as model complexity increases. Furthermore, the implicit method displayed instabilities and numerical difficulties in certain load conditions further disfavoring the solver’s performance. Originality/value Comparison of the implicit and explicit procedures for time stepping was applied in 3D finite element analysis of the plate rolling process in order to evaluate and quantify the computational efficiency.


2013 ◽  
Vol 05 (04) ◽  
pp. 1350040 ◽  
Author(s):  
WENBIN ZHOU ◽  
FENG HAO ◽  
DAINING FANG

Poor cyclic performance of lithium-ion batteries is calling for efforts to study its capacity attenuation mechanism. The internal stress field produced in the lithium-ion battery during its charging and discharging process is a major factor for its capacity attenuation, research on it appears especially important. We established an electrochemical –mechanical coupling model with the consideration of the influence of elastic stiffening on diffusion for graphite anode materials. The results show that the inner stress field strongly depends on the lithium-ion concentration field, greater concentration gradients lead to greater stresses. The evolution of the stress field is similar to that of the concentration gradient but lags behind it, which shows hysteresis phenomenon. Elastic stiffening can lower the concentration gradient and increase elastic modulus, which are two major factors influencing the inner stress field. We conclude that the latter is more dominant compared to the former, and elastic stiffening acts to increasing the internal stress.


2014 ◽  
Vol 986-987 ◽  
pp. 823-827
Author(s):  
Qing Yuan Zheng ◽  
Min You Chen ◽  
Bing Gao ◽  
Nan Jiang

Reliability of IGBT power module is one of the biggest concerns regarding wind power system, which generates the non-uniform distribution of temperature and thermal stress. The effects of non-uniform distribution will cause failure of IGBT module. Therefore, analysis of thermal mechanical stress distribution is crucially important for investigation of IGBT failure mechanism. This paper uses FEM method to establish an electrical-thermal mechanical coupling model of IGBT power module. Firstly, thermal stress distribution of solder layer is studied under power cycling. Then, the effects of initial failure of solder layer on the characteristic of IGBT module is investigated. Experimental results indicate that the strain energy density and inelastic strain are higher which will reduce reliability and lifetime of power modules.


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