PSI - Issue 71

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 71 (2025) 42–49

5 th International Structural IntegrityConference & Exhibition (SICE 2024)

Keywords: Lug joint, Stress concentration factor, Stress intensity factor, Fatigue crack growth estimation. 1. Introduction Lug joints play a crucial role in various engineering fields by effectively supporting loads through a pin connection. Lug-bush-pin joints come in several configurations, each designed for specific functional requirements and applications. These configurations can include standalone male lugs — plate-like structures with either straight or rounded edges — connected by a pin. Alternatively, they may feature a combination of male and female lugs, which resemble fork-like structures linked by a single pin as shown in Fig. 1. These joints not only offer increased flexibility but also make installation and disassembly easier. However, they need to withstand a wide range of vibratory and fatigue loads, which can make them vulnerable to fatigue failures. Research has shown that using an interference fit between the lug and the bushing significantly improves fatigue life, making this design choice essential for enhancing both performance and durability. Abstract Lug-Bush-Pin joints are extensively used in almost all the disciplines of mechanical engineering design as structural members. Due to their simplicity and highly efficient load-bearing characteristics, lug joints are extensively used in aircraft for the attachments of flaps, ailerons, and engine pylons. These joints are sensitive to fatigue and hence their fatigue strength dictates the life of the entire structure. In the current study, a typical lug and bush are joined through an interference fit and the pin is considered to be snugly fit initially in the assembly. Interference level varying from 0.1 to 0.5% of bush diameter was considered for the lug-bush interface. Wear of pin is generally allowed by design resulting in pin-bush clearance, which in turn can affect the stress distribution of the joint. Typical clearances ranging from 0.1 to 0.5% of pin diameter were considered. The joint was analyzed for static and fatigue performance using a nonlinear elastic-plastic finite element analysis. A total of 56 geometric cases, involving clearance of bush with the lug in combination with snug fit pin and varying levels of clearance fit at the pin were examined. The fatigue life is estimated for each of the bush-pin fit combinations. Unstructured Mesh Method (UMM) and Separating, Morphing, Adaptive, and Re-meshing Technology (SMART) are employed to ascertain Fatigue Crack Growth analysis. The results suggest a good correlation with analytical solutions within the 2.5% variation of accuracy. Fatigue crack growth rate response was also studied for the bush and Pin joint at the locations of high-stress. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SICE 2024 organizers Study of Geometric Interference Parameters on the Stress Distribution and Fatigue Crack Growth in Pin Loaded Lug Joint Abdul Khader Jilani Shaik, Raghu V Prakash * a Department of Mechanical Engineering, Indian Institute of Technology (IIT), MADRAS,Chennai-600 036,India

*Corresponding author. Tel.:+91 44 2257 4694 ; fax: +91-44-2257 4652. E-mail address: raghuprakash@iitm.ac.in

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SICE 2024 organizers 10.1016/j.prostr.2025.08.007