Studies of bolted joints of dissimilar materials in fatigue: a numerical and finite element approach to connection modelling

为了估计机械接头和胶接接头在准静态载荷作用下的应力分布和破坏过程，已建立了许多有限元和数学模型。特别是，研究的重点是建立准静态载荷下螺栓连接的准确模型，但对这些连接的疲劳模拟重视不够。本研究课题旨在研究碳纤维/环氧与钢的异种复合材料接头在疲劳过程中的应力分布和失效情况。对各种常规连接技术进行有限元分析和数学模型。为了验证和改进这些，随后将制造一些接头并进行疲劳测试，然后再进行实验测试。还将考虑以下疲劳现象：热降解、腐蚀(主要由盐水引起)、装配/制造变异性的影响(例如，螺栓预应力变化)。然后，测试结果将为修改初始FEA/MATLAB应力模型提供进一步的基础，使其与实验结果相似。总体而言，该项目旨在确定不同疲劳机制对关节强度的影响，并随后对这些变化进行计算建模。该提案旨在为航空航天、风能和波浪发电应用中常见的疲劳机制建模提供新的见解。

A number of finite element and mathematical models have been produced to estimate the stress distribution and failure processes of mechanical and adhesive joints under quasi-static loading. In particular, studies have focused on producing accurate models of bolted joints in quasi-static loading, but insufficient emphasis has been placed on modelling fatigue of these joints. This research topic looks to investigate the stress distribution and failure of dissimilar composite joints in fatigue (e.g. carbon fibre/epoxy to steel).Finite element analysis and mathematical models will be produced for a variety of conventional joining techniques. For validation and refinement of these, a number of joints will then be manufactured and fatigue-tested before being experimentally tested. The following fatigue phenomena will also be considered: thermal degradation, corrosion (primarily by salt water), effect of assembly/manufacturing variability (e.g., varying bolt pre-stress). Test results will then provide a further basis for altering initial FEA/matlab stress models such that they are analogous with experimental results. Overall, the project aims to identify the effects of different fatigue mechanisms on joint strength and subsequently model these variations computationally. The proposal looks to provide novel insight into the modelling of fatigue mechanisms commonly encountered in aerospace, wind and wave power applications.