The influence of both preload and the presence of shim types on the mechanical properties of composite-aluminium single-bolt, single-lap joints were studied in this paper. The load-displacement curve and surface strain field of joints in different shim types and preloads were obtained through tensile experiments. A progressive damage model was established using the UMAT subroutine in ABAQUS. A hybrid failure criterion and a linear continuous degradation model were used to describe the progressive damage of composite laminates. The results show that for joints with no shim and for those with various types of shims, the tensile stiffness, peak load and initial damage load could be reduced when the preload is insufficient or too large. Compared with joints with no shims or with peelable fibreglass shims, joints with liquid shims required a larger preload to achieve the best mechanical properties. As the proportion of peelable fibreglass shim increased, the tensile stiffness and peak load continued to increase in joints with a mixed shim of liquid and peelable fiberglass shim. Shims can serve as tension bearings, but have little effect on the initiation and development of bearing failure.

本文研究了预紧力和垫片类型对复合铝单螺栓单搭接接头力学性能的影响。通过拉伸试验得到了不同垫片类型和预紧力下接头的载荷-位移曲线和表面应变场。使用 ABAQUS 中的 UMAT 子程序建立渐进式损伤模型。使用混合失效准则和线性连续退化模型来描述复合材料层压板的渐进损伤。结果表明，对于无垫片接头和各种垫片接头，当预紧力不足或过大时，其抗拉刚度、峰值载荷和初始损伤载荷均会降低。与无垫片或可剥离玻璃纤维垫片的接头相比，带有液体垫片的接头需要更大的预紧力才能达到最佳的机械性能。随着可剥离玻璃纤维垫片比例的增加，液体和可剥离玻璃纤维垫片混合垫片的接头的拉伸刚度和峰值载荷继续增加。垫片可以用作拉力轴承，但对轴承失效的发生和发展几乎没有影响。