Yield surface of transversely isotropic foams under axisymmetric loadings
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摘要: 利用二维有效应力和平均应力的描述方法,推导出三维横观各向同性泡沫材料在轴对称载荷下的特征平均应力、特征应力以及特征应变的表达式,得到用特征平均应力和特征应力描述的屈服面模型;并通过对面心立方单胞模型进行有限元分析,研究了横观各向同性泡沫材料的泡孔长径比对弹性性能和屈服面的影响.结果表明:随泡孔长径比的增加,泡孔伸长方向对应的泡沫模量增加,而与其垂直方向的泡沫模量则减小,且屈服面发生了逆时针转动;得到的屈服面模型与Gurson修正模型基本一致,且同有限元结果相符,为横观各向同性泡沫提供了一种新的屈服面描述.Abstract: The effective stress and mean stress description method for two-dimension (2D) materials was applied to obtain the formulae of characteristic mean stress, characteristic stress, and characteristic strain of three-dimension (3D) transversely isotropic materials under proportional axisymmetric loadings. Then the yield surface model expressed by characteristic mean stress and characteristic stress was established. Through the analysis of transversely isotropic face-centered cubic unit cell model by using finite-element method (FEM), the impact of cell aspect ratio on the elastic properties and the yield surface for transversely isotropic foams was also investigated. The results show that the increase of cell aspect ratio leads to the augment of longitudinal modulus, the decrease of transverse modulus and the anticlockwise rotation of yield surface. The model corresponds well with the modified Gurson-s model and the FEM results, and thus provides a new description for 3D transversely isotropic foams- yield surface.
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Key words:
- foams /
- yield /
- finite element method
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