内聚力模型的形状对胶接结构断裂过程的影响

内聚力模型被广泛应用于粘接结构的断裂数值模拟过程中,为深入分析不同形状内聚力模型与胶黏剂性质和粘接结构断裂之间的关系,本文分别采用脆性和延展性两种类型胶黏剂,对其粘接的对接试件进行了单轴拉伸、剪切实验,以及其粘接的双臂梁试件进行了断裂实验.3种类型的内聚力模型(抛物线型、双线型和三线型)分别模拟了以上粘接结构的断裂过程,并与实验结果进行对比.结果发现:双线型的内聚力模型适用计算脆性胶黏剂的拉伸与剪切的断裂过程;指数型内聚力模型较适合计算延展性胶黏剂的拉伸和剪切的断裂过程,临界应力、断裂能和模型的形状参数是分析拉伸和剪切的重要参数;双臂梁试件的断裂过程模拟结果发现,断裂曲线与胶黏剂性质有关,内聚力模型形状参数也有影响.通过实验与计算结果分析,双线型内聚力模型更适合脆性胶黏剂粘接的双臂梁断裂计算,而三线型更适合计算延展性胶黏剂粘接的双臂梁断裂过程,此研究结果对胶黏剂的使用和粘接结构的断裂分析有很重要意义.

INFLUENCE OF COHESIVE ZONE MODELS SHAPE ON ADHESIVELY BONDED JOINTS 1)

Cohesive zone models have been increasingly used to simulate fracture of adhesively bonded joint. In order to understand the relation between the delamination of the different types of adhesives and the shape of cohesive zone models (CZMs), the uniaxial tension and shear experiments were conducted using two distinct adhesives, an epoxy-based adhesive in a brittle manner and VHBTM tape adhesive in a ductile manner. Three types of CZMs shapes are adopted, including exponential, bilinear, and trapezoidal models. The results demonstrate that the bilinear CZM more suitably simulate the tension and shear failure of the brittle adhesive, while the exponential CZM suitably describes the ductile adhesive. The cohesive strength, work of separation and the shape parameters are the significant effect factors on the simulation results of the uniaxial tension and shear debonding procedures. Nevertheless, the shape of CZM has certain influences on the simulation of the double cantilever beam fracture. The comparison between the numerical and the experiment results demonstrate that the bilinear CZM more suitably simulate the double cantilever beam fracture of the brittle adhesive, while the trapezoidal CZM suitably describes the ductile adhesive. The investigation results are significant to use CZMs to precisely analyze adhesively bonded joints fracture.