Giusti Ruggero, Lucchetta Giovanni
Department of Industrial Engineering, University of Padua, Via Venezia 1, 35131 Padova, Italy.
Polymers (Basel). 2023 Nov 19;15(22):4459. doi: 10.3390/polym15224459.
With the increasing demand for lightweight and high-performance materials in the automotive and aerospace industries, full-thermoplastic hybrid composites have emerged as a pivotal solution, offering enhanced mechanical properties and design flexibility. This work aims to numerically model the fracture strength in full-thermoplastic hybrid composites made by forming and overmolding organosheets. The mode I fracture was investigated by modeling the behavior of T-joint specimens under a tensile test following the cohesive zone modeling (CZM) approach. The sample was designed to replicate the connection between the laminate and the overmolded part. Double cantilever beam (DCB) specimens were manufactured with organosheets and tested to mode I opening to determine the interlaminar fracture toughness. The fracture toughness out of the mode I test with DCB specimens was used to define the CZM parameters that describe the traction-separation law. Later, due to the particular geometry of the T-join specimens that under tensile load work close to pure mode I, the cohesive parameters were determined by inverse analysis, i.e., calibrating the theoretical models to match experimental results. The fracture resistance T-joint specimens appeared dependent on the fiber-bridging phenomenon during the delamination. In particular, the presence of fiber-bridging visible from the experimental results has been replicated by virtual analyses, and it is observed that it leads to a higher energy value before the interface's complete breakage. Moreover, a correspondence between the mode I fracture toughness of the DCB specimen and T-joint specimens was observed.
随着汽车和航空航天工业对轻质高性能材料的需求不断增加，全热塑性混合复合材料已成为一种关键解决方案，具有增强的机械性能和设计灵活性。这项工作旨在对通过成型和包覆成型有机片材制成的全热塑性混合复合材料的断裂强度进行数值模拟。通过采用内聚区建模（CZM）方法对T型接头试样在拉伸试验下的行为进行建模，研究了I型断裂。该样品旨在复制层压板与包覆成型部件之间的连接。用有机片材制造双悬臂梁（DCB）试样，并对其进行I型开口测试，以确定层间断裂韧性。DCB试样I型试验的断裂韧性用于定义描述牵引-分离定律的CZM参数。后来，由于T型接头试样的特殊几何形状，在拉伸载荷下其工作状态接近纯I型，因此通过反分析确定内聚参数，即校准理论模型以匹配实验结果。T型接头试样的抗断裂性能似乎取决于分层过程中的纤维桥接现象。特别是，实验结果中可见的纤维桥接现象已通过虚拟分析得到再现，并且观察到它会导致界面完全断裂前的能量值更高。此外，还观察到DCB试样和T型接头试样的I型断裂韧性之间存在对应关系。
