复合材料螺栓连接松弛的弹-黏塑性分析方法

预紧力松弛是影响复合材料螺栓连接结构耐久性的主要原因之一。本文重点讨论导致预紧力松弛的材料蠕变与粗糙表面接触蠕变的相互影响。内容包括建立了以弹-黏塑性理论为基础的复合材料蠕变本构模型,并结合考虑粗糙表面的分形接触理论,将其推广到与时间相关的弹-黏塑性接触问题。数值结果与实验结果对比表明,考虑粗糙表面接触效应时,计算误差从2.87%~4.37%降至0.04%~0.5%,预测准确性有显著提高。表面分形参数D和G的讨论结果表明,接触表面越粗糙,预紧力越容易松弛。这对工程上通过控制表面形貌参数来改善表面接触性质具有指导意义。

An elastic-viscoplastic approach for modelling preload relaxation of bolted composite joints

Preload relaxation is one of the main causes affecting the durability of bolted composite joints. This paper focuses on the interaction between material creep and contact creep of rough surface which induces the preload relaxation. The content includes:A creep constitutive model of composites based on the elastic-viscoplastic theory was established and extended to the elastic-viscoplastic contact problem with time-dependent combined with the fractal contact theory of rough surface. The comparison between numerical results and experimental results shows that the calculation error decreases from 2.87%-4.37% to 0.04%-0.5% when considering the rough surface contact effect, whose accuracy is significantly improved. The discussion results of the surface fractal parameters D and G show that the rougher the contact surface is, the easier the preload will be to relax, which will be of guiding significance to improve the surface contact properties by controlling surface topography parameters.