The self-tapping screw connectors are widely used in Cold-formed Steel (CFS) construction due to their rapid fastening with automatic power driving and ease of installation via a self-drilling process. However, there is a lack of a robust numerical method for the modelling of behaviours of screw fasteners bearing against steel sheets, where the connections can undergo different failure modes including fracture, bearing, tilting, pull-out and shear failure, particularly for CFS thin plates. A nonlinear explicit dynamic finite element (FE) model is developed in this paper to address this issue by validating the modelled load-deformation relationships and failure modes with available tests in literature. The proposed numerical model is improved in two aspects comparing to available research: firstly, a ductile fracture criterion was proposed that could address the fracture of ply metals subjected to complex stress state with less trial-and-error process. Secondly, the threads in the screw fasteners and ply sheets were carefully modelled where the inter-locking capacity between the screws and steel sheets were better taken into account, eliminating the need for an artificial friction factor. The FE modelled results were compared against the test results and showed good agreement in terms of connection strength and failure modes, including fracture, bearing, tilting, pull-out and shear failure. Finally, parametric studies were carried out to investigate the influence of steel sheet thickness and the screw outer diameter on the force–displacement relationships of the steel lap joints.

自攻螺钉连接器由于具有快速的紧固和自动动力驱动能力，并且易于通过自钻过程进行安装，因此广泛用于冷弯型钢（CFS）结构中。但是，缺少一种可靠的数值方法来建模承压钢板的紧固件的行为，在这种情况下，连接会经历不同的破坏模式，包括断裂，轴承，倾斜，拉出和剪切破坏，尤其是对于CFS薄的情况板。本文开发了一种非线性显式动态有限元（FE）模型，以通过利用文献中的可用测试验证建模的载荷-变形关系和破坏模式来解决此问题。与现有研究相比，所提出的数值模型在两个方面进行了改进：首先，提出了一种延性断裂准则，该准则可以解决层板金属在复杂应力状态下的断裂，而试验和错误过程较少。其次，仔细模拟了紧固件和帘布层中的螺纹，从而更好地考虑了螺钉和钢板之间的互锁能力，从而消除了人工摩擦因数。有限元模型的结果与测试结果进行了比较，并在连接强度和破坏模式（包括断裂，轴承，倾斜，拉出和剪切破坏）方面表现出良好的一致性。最后，进行了参数研究，以研究钢板厚度和螺钉外径对搭接接头力-位移关系的影响。