Yanzhen Wang¹, Xuefeng Yan^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.121, No.1, pp. 123-144, 2019, DOI:10.32604/cmes.2019.07052

Abstract A single model cannot satisfy the high-precision prediction requirements given the high nonlinearity between variables. By contrast, ensemble models can effectively solve this problem. Three key factors for improving the accuracy of ensemble models are namely the high accuracy of a submodel, the diversity between subsample sets and the optimal ensemble method. This study presents an improved ensemble modeling method to improve the prediction precision and generalization capability of the model. Our proposed method first uses a bagging algorithm to generate multiple subsample sets. Second, an indicator vector is defined to describe these subsample sets. Third, subsample sets are selected… More >

H. C. Cheng¹, C. Y. Yu², W. H. Chen³

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 1-18, 2005, DOI:10.3970/cmes.2005.007.001

Abstract In this study, a simple but effective solution methodology that integrates a modified global/local finite element (GLFE) modeling technique and a two-staged constitutive modeling strategy is presented for the thermal-mechanical modeling of solder joints in an area array typed electronic package for characterizing the associated solder joint fatigue life under the JEDEC temperature cycling specification. The effectiveness and applicability of the proposed technique are demonstrated through two case studies, each of which is associated with an area array typed test vehicle. The geometry profile of solder joints in the test vehicle is determined by the Surface Evolver [Brakke (1996)]. For… More >

Trenton M. Ricks¹, Thomas E. Lacy, Jr.^1,2, Brett A. Bednarcyk³, Steven M.Arnold³, John W. Hutchins¹

CMC-Computers, Materials & Continua, Vol.40, No.2, pp. 99-130, 2014, DOI:10.3970/cmc.2014.040.099

Abstract A multiscale modeling methodology was developed for continuous fiber composites that incorporates a statistical distribution of fiber strengths into coupled multiscale micromechanics/ finite element (FE) analyses. A modified twoparameter Weibull cumulative distribution function, which accounts for the effect of fiber length on the probability of failure, was used to characterize the statistical distribution of fiber strengths. A parametric study using the NASA Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) was performed to assess the effect of variable fiber strengths on local composite failure within a repeating unit cell (RUC) and subsequent global failure. The NASA code FEAMAC… More >