纤维复合材料的形变功密度断裂准则

 通过单边缺口、中心裂纹和中心圆孔碳/环氧和玻璃/环氧复合材料层合板试样的试验证实,在考虑了材料的各向异性后,把各向同性材料的J积分分析结果用于确定复合材料层合板的断裂过程区特征长度d₀是适宜的。 根据碳/环氧复合材料层合板的有限元分析结果和试验观察,提出了一个新的断裂准则 σ_y（d0,0）ε_y（d0,0）=ασ_Fε_F 称为形变功密度断裂准则。这个准则已得到试验验证。使用本文方法可以得出不随试样几何形状和应力分布而变化的特征长度。

DEFORMATION WORK DENSITY FRACTURE CRITERION FOR COMPOSITE MATERIALS

A method for predicting the fracture strength of composite laminates with notches is an important research topic and very useful for engineering application.An experimental research on C/EP and G/EP composite laminates specimens with a single notch, a centric circular hole or a sharp tipped crack was accomplished. It is proved that the results of J-integral analysis for isotropic materials are applicable to determining the characteristic length d0 of the fracturing zone in composite materials but with taking their anisotropy into account.Based on the finite element analysis of notched composite laminates and experimental observation, a new fracture criterion for composite laminates under an uniaxial tensile load is proposed as followsThis criterion is called deformation work density fracture criterion for composite laminates as the deformation work density within a distance do from the notch is taken as a main parameter.In order to verify this model the tests for C/EP （02°/±45°/02°/± 45°/90° ）s and woven glass fibre/epoxy（0° /90°） composite laminates with a centric hole or a crack of different sizes have been completed. The fracture strength can be predited by using this criterion and the charateristic length d0 obtained from eq. （11）. Tables 3 and 4 show good agreement between the analytical results and the experimental data.