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

复合材料作为技术领域的先进材料，其变形和断裂行为与常规材料有很大的不同。变形和断裂行为的主要机制与不同材料之间界面的存在密切相关。因此，阐明界面附近的变形机理，建立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。在这个项目中，重点研究了以下几点。为了明确复合材料的变形和断裂机理，从复合材料中提取了一个由纤维和基体组成的单元，采用有限元方法对复合材料在不同应力系统下的精确变形行为进行了全面研究。阐明了增强材料的尺寸和形状对增强材料变形行为的影响。在动载荷作用下，观察到非常特殊的变形行为，这与材料特性、形状、尺寸和施加的变形速率密切相关。利用轻载万能试验机，对复合材料的组成材料进行了综合试验。利用所得数据建立了适合上述研究的本构方程。在本构方程中考虑了应变速率和温度敏感性，以及应变速率历史相关的流变应力。考虑到单元复合材料的相互作用，建立了描述复合材料整体变形和断裂行为的非局部连续体模型。数值模拟验证了所提模型的正确性。通过对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，由足够数量的单元复合材料组成的复合材料的施工是非常困难的。应要求对复合材料进行直接模拟。获得的部分结果已作为原创论文和贡献论文发表在下一页。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