过盈配合和预紧力的混合作用对复合材料机械连接结构的影响及其机制

为研究钉孔过盈配合情况和紧固件预紧力及二者混合作用对复合材料连接强度的影响及其机制，提出了一种基于试验验证的有限元方法，在有限元模拟结果与两组不同配合复合材料与钛合金单剪双钉连接拉伸试验吻合良好的基础上，进一步模拟6种不同螺栓预紧力和7种不同钉孔配合模式的组合，共42种不同情况的结构承载能力。通过对模拟结果的分析发现：一定的干涉配合值和预紧力虽然可能导致钉孔周围在受载较小时提前出现较小破坏，但在载荷较大时反而可以改善孔周的接触条件，从而减小孔周的纤维破坏范围，并最终提高连接结构的破坏载荷。而且钉孔配合情况和螺栓预紧力对连接结构承载能力会相互影响，即在不同钉孔配合情况下所得到的紧固件预紧力优化值会有所不同，反之亦然。因此在进行复合材料机械连接结构承载能力优化时，必须同时考虑不同参数的影响，才能获得最优的结构设计。

Combined effects and mechanism of interference fit and clamping force on composite mechanical joints

In order to investigate the combined effects of bolt-hole interference fit condition and clamping force on the strength of the bolted mechanical composite joints and their mechanism, a finite element model validated by experiments was taken out. A three dimensional nonlinear finite element model agrees well with two sets of composite-to-titanium single-lap bolted joints tensile tests. Based on the finite element model, seven interference fit conditions combined with six clamping force conditions, altogether forty two different working conditions were studied. The results show that, although certain interference fit condition and clamping force may cause some pre-failure of the joints area, they can improve the contact condition and prevent failure evolution under bigger load, making the joints strength maximize. At the same time, there is interaction between interference fit and clamping forces on the joints strength, namely the optimal clamping force will be different under different interference fit conditions, vice versa. So the two factors on the interference fit and clamping force need to be considered at the same time in order to achieve the optimal structural design.