Microscopic deformation mechanism and its application to the evaluation of macroscopic deformation behavior of fiber reinforced composite materials

复合材料作为一种先进材料，其变形和断裂行为与传统材料有很大的不同。不同材料之间存在的界面是影响材料变形和破裂的主要机制。因此，研究复合材料界面附近的变形机制，发展基于材料微观响应的复合材料强度评价方法具有重要意义。在本项目中，重点研究了以下几点.为了阐明复合材料的变形和断裂机理，本文将复合材料抽象为一个由纤维和基体组成的单元，利用有限元方法对复合材料在不同应力体系下的变形行为进行了详细的研究.研究了钢筋尺寸和形状对钢筋抗弯强度的影响 ...更多信息 行为已经被澄清。在动态载荷下观察到非常特殊的变形行为，这些行为与材料的特性、形状、尺寸以及所施加的变形速率有着深刻的关系.利用万能轻载试验机，对复合材料的组成材料进行了综合试验。所得数据用于建立适合于上述研究的本构方程。本构方程考虑了应变率和温度敏感性，以及应变率历史相关的流变应力.通过考虑单元复合材料之间的相互作用，建立了描述复合材料整体变形和断裂行为的非局部连续介质模型。通过数值模拟验证了模型的正确性.通过对复合材料动态变形行为的研究，阐明了由于变形行为的绝对时间依赖性，由足够多的单元复合材料组成的复合材料的构造是非常困难的。应要求对复合材料进行直接模拟，所得部分结果已作为原创论文和投稿论文发表，详见下页。少

The deformation and fracturing behaviors of composite materials which are extensively employed as the advanced materials in the field of technology are substantially different from those of conventional materials. The main mechanism of deformation and fracturing behaviors is deeply related to the existence of the interface between the different materials. Consequently, it is very important to clarify the deformation mechanisms near the interface and to develop the evaluation procedure of the strength of the composite materials based on microscopical response of the materials. In this project, following points are intensively investigated.1. In order to clarify the deformation and fracturing machanisms of the composite materials, a unit consist of a fiber and matrix is extracted from the composite material and precise deformation behaviors under different stress system is fully investigated by means of finite element method.2. The effect of size and shape of the reinforcement on the def … More ormation behavior has been clarified. The very peculiar deformatin behaviors are observed under dynamic loading, which are deeply related to the material characteristics, shape, size and deformation rate applied.3. By means of universal testing machine for light load, the comprehensive experiments have been done for the component materials of composite. The obtained data is emloyed to the establishment of the constitutive equation suitable for the introduction of the above mentioned investigation. The strain rate and temperature sensitivities, and the strain rate history dependent flow stress are accomodated in the constitutive equation.4. The non-local continuum model which describes the global deformation and fracturing behaviors of the composite materials has been developed by acounting for the interaction of the unit composites. The appropriateness of the proposed model has been checked by the numerical simulation.5. By the present investigation, the dynamic deformation behavior is concerned, it has been clarified that the construction of the composite materials consist of sufficiently large number of unit composite is very difficult because of the absolute time dependence of deformation behavior. The direct simulation of the composite materials should be required.The part of the results obtained have been published as original papers and contributed papers shown in the next page. Less