Finite element analysis of riveted / bolted joints : effect of clearance

• Main Author: Chin, Zhi Kai
• Other Authors: Sellakkutti Rajendran
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Aeronautical engineering
• Online Access: https://hdl.handle.net/10356/141197
• Institution: Nanyang Technological University

Rivets and bolts are mechanical fasteners used to join two or more pieces of materials together. One very commonly used method on aircrafts to connect skin panels together is called the lap joint. Traditional formulas assume that load carried by a lap joint is equally shared between all fasteners in the connection. It is important to check various real-world factors that could lead the above assumptions to be invalid. The project utilizes a finite element software, ANSYS, to model and study the effects of clearance on riveted and bolted joints. A single row, 5-fastener lap joint is used for this study. An ANSYS code has been written to facilitate the automatic modelling and data collection process. This helps to improve accuracy and consistency throughout the entire modelling process, saving time and reducing human error. The lap joint is placed under a tensile load and factors such as load distribution and stress distribution are closely observed as the clearance increases. The results of the study show that load distribution of a riveted lap joint is not affected by clearance, but stress distribution is greatly affected due to the reduced contact area when the rivet tilts. The effects mentioned above can be reduced greatly if a bolted lap joint is used instead. It was also observed that when one hole has much larger clearance than the rest, the load initially carried by the fastener is now distributed to the other 4 fasteners, with the nearest fastener carrying the most and the furthest fastener carrying the least. This uneven load distribution can contribute to the failure of lap joints. Lastly, in an overloaded lap joint, the fasteners are predicted to fail starting from the outermost, to the innermost.