Microscopic yielding of CF/epoxy composites and the effect on the formation of thermal residual stresses
Microscopic yielding of CF/epoxy composites and the effect on the formation of thermal residual stresses
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DOI：
10.1016/j.compscitech.2005.02.003
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发表时间：
2005-08
影响因子：
9.1
通讯作者：
Thomas Hobbiebrunken;B. Fiedler;M. Hojo;Shojiro Ochiai;K. Schulte
中科院分区：
文献类型：
--
作者：
Thomas Hobbiebrunken;B. Fiedler;M. Hojo;Shojiro Ochiai;K. Schulte
采用细观有限元计算方法，研究了单向碳纤维/环氧复合材料中基体塑性和随温度变化的力学、热学性能对残余热应力形成的影响。为了研究环氧树脂纯树脂的热机械行为，对其进行了热性能和力学性能测试。将计算结果纳入数值计算，材料行为的模拟结果与实验结果吻合较好。热残余应力通过使用六角晶胞的细观力学分析来确定。将非线性计算的结果与线弹性矩阵的数值计算和分析计算的结果进行了比较。研究发现，在冷却过程中，残余应力在高剪应力处引起局部基体屈服。在发生局部屈服后，基体应力重新分布，与线弹性矩阵相比，整个基体中的残余应力减小。结果解释了局部基体屈服如何降低高残余应力的集中。
A micromechanical finite element calculation was performed in order to investigate the influence of matrix plasticity and temperature dependent mechanical and thermal properties on the formation of thermal residual stresses in unidirectional carbon fiber epoxy composites. Several thermal and mechanical experiments were carried out on epoxy neat resin specimens in order to investigate the thermomechanical behavior. The results were incorporated into a numerical calculation, and the simulation of the material behavior showed good agreement with the experiments. Thermal residual stresses were determined by a micromechanical analysis using a hexagonal unit-cell. The results of our non-linear calculation were compared with results of a numerical and analytical calculation with a linear elastic matrix. It was found that the residual stresses cause local matrix yielding at positions of high shear stresses during cooling down. The matrix stress was redistributed after local yielding occurred and leads to a reduction of residual stresses in the entire matrix compared to a linear elastic matrix. The results explain how local matrix yielding reduces concentrations of high residual stresses.