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在体胞模型的基础之上应用解析方法分析了颗粒或短纤维增强复合材料的本构行为,结合数值计算给出了表征材料本构关系的解析表达式,提出了一种新的正交椭球坐标变换以简化推导过程,在计算中,将真实位移场分为两部分:基本场的扰动场,然后通过摄动方法将原来的非线性问题转化为一组线性方程组的求解,计算了当基体材料和夹杂的特征参数取不同值时的应力应变曲线,并与已有的实验和分析结果进行了比较,符合得较好,通过对数值计算结果的拟合,提出了一个颗粒或短纤维增强复合材料的弹塑性本构关系的解析表达式。 相似文献
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The mode I plane strain crack tip field with strain gradient effects is presented in this paper based on a simplified strain
gradient theory within the framework proposed by Acharya and Bassani. The theory retains the essential structure of the incremental
version of the conventionalJ
2 deformation theory. No higher-order stress is introduced and no extra boundary value conditions beyond the conventional ones
are required. The strain gradient effects are considered in the constitutive relation only through the instantaneous tangent
modulus. The strain gradient measures are included into the tangent modulus as internal parameters. Therefore the boundary
value problem is the same as that in the conventional theory. Two typical crack problems are studied: (a) the crack tip field
under the small scale yielding condition induced by a linear elastic mode-IK-field and (b) the complete field for a compact tension specimen. The calculated results clearly show that the stress level
near the crack tip with strain gradient effects is considerable higher than that in the classical theory. The singularity
of the strain field near the crack tip is nearly equal to the square-root singularity and the singularity of the stress field
is slightly greater than it. Consequently, theJ-integral is no longer path independent and increases monotonically as the radius of the calculated circular contour decreases.
The project supported by the National Natural Science Foundation of China (19704100 and 10202023) and the Natural Science
Foundation of Chinese Academy of Sciences (KJ951-1-20) 相似文献
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