Sioutis Ioannis, Tserpes Konstantinos
Laboratory of Technology & Strength of Materials, Department of Mechanical Engineering & Aeronautics, University of Patras, 26500 Patras, Greece.
Materials (Basel). 2022 Jul 22;15(15):5108. doi: 10.3390/ma15155108.
In the present work, a numerical model based on the cohesive zone modeling (CZM) approach has been developed to simulate mixed-mode fracture of co-consolidated low melt polyaryletherketone thermoplastic laminates by considering fiber bridging. A modified traction separation law of a tri-linear form has been developed by superimposing the bi-linear behaviors of the matrix and fibers. Initially, the data from mode I (DCB) and mode II (ENF) fracture toughness tests were used to construct the R-curves of the joints in the opening and sliding directions. The constructed curves were incorporated into the numerical models employing a user-defined material subroutine developed in the LS-Dyna finite element (FE) code. A numerical method was used to extract the fiber bridging law directly from the simulation results, thus eliminating the need for the continuous monitoring of crack opening displacement during testing. The final cohesive model was implemented via two identical FE models to simulate the fracture of a Single-Lap-Shear specimen, in which a considerable amount of fiber bridging was observed on the fracture area. The numerical results showed that the developed model presented improved accuracy in comparison to the CZM with the bi-linear traction-separation law (T-SL) in terms of the predicted strength of the joint.
在本研究中，基于内聚区模型（CZM）方法开发了一个数值模型，通过考虑纤维桥接来模拟共固化低熔点聚芳醚酮热塑性层压板的混合模式断裂。通过叠加基体和纤维的双线性行为，开发了一种改进的三线性形式的牵引分离定律。最初，使用I型（DCB）和II型（ENF）断裂韧性试验的数据来构建接头在张开和滑动方向上的R曲线。将构建的曲线纳入使用在LS-Dyna有限元（FE）代码中开发的用户定义材料子程序的数值模型中。采用一种数值方法直接从模拟结果中提取纤维桥接定律，从而无需在测试过程中持续监测裂纹张开位移。通过两个相同的有限元模型实现了最终的内聚模型，以模拟单搭接剪切试样的断裂，在该试样的断裂区域观察到了大量的纤维桥接。数值结果表明，与具有双线性牵引分离定律（T-SL）的CZM相比，所开发的模型在接头预测强度方面具有更高的精度。
