PSI - Issue 71

Abdul Khader Jilani Shaik et al. / Procedia Structural Integrity 71 (2025) 42–49

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It is essential to underscore the following observations: The data identifies a critical crack length of 4.246 mm for a single left-hand (LH) crack, beyond which there is a marked acceleration in the crack growth rate. In the scenario involving two pre-cracks, the critical crack lengths are determined to be 4.3 mm for the right-hand (RH) crack and 2.8 mm for the LH crack. The developed fatigue crack model is illustrated in Fig. 11, and the numerical simulation model for the twin-cracked lug is presented in Fig. 12. The phenomenon of fatigue crack growth is evidenced in both figures for their respective configurations.

Fig. 11 Fatigue Crack growth model with single through crack.

Fig. 12 Fatigue crack growth of a Twin cracked Lug model.

10 Conclusions ➢ The study emphasizes the importance of maintaining bush interference within the range of 0.3% to 0.4% for achieving maximum joint life. ➢ The impact of bush clearance on joint fatigue life is significant, with a 59.5% reduction observed when transitioning from a snug fit to a 0.5% clearance fit. ➢ The present work emphasizes the value of using the numerical simulation model to develop a comprehensive digital twin model of the lug joint, accounting for different operational conditions. Further research should focus on the effects of loading and operational conditions, like temperature and creep, on lug joint performance and reliability. Utilizing numerical simulation models to develop digital twin representations can help optimize these factors, ultimately enhancing the fatigue life and overall performance of the lug joint. Acknowledgements The first author acknowledges the support received from ADA, DRDO and IIT Madras to pursue this study as part of the Master’s degree dissertation project. References ASTM E 1820 – 08a Standard Test Method for Measurement of Fracture Toughness, approved Dec.1, 2008. Published Jan 2009. Grant RJ, Smart J, Stanley P. A parametric study of the elastic stress distribution in pin-loaded lugs. The Journal of Strain Analysis for Engineering Design. 1994;29(4):299-307. Hui L, Wang H, Huang Y, Yang W, Zhou S. Effects of different structural parameters on the 7075-T651 aluminium alloy lug structure fatigue life.2022. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; 236(15):3304-3312. Li Y, Huang R, Zhao S, Wang J. Contact pressure analysis of pin-loaded lug with clearance. 2022. Advances in Mechanical Engineering. 2022;14(6) N. Antoni, F. Gaisne, Analytical modelling for static stress analysis of pin-loaded lugs with bush fitting, 2011. Applied Mathematical Modelling 35 (1), 1-21 N. Laghzale, A. Bouzid, Analytical Modelling of Elastic-Plastic Interference Fit Joints 2016, International Review on Modelling and Simulations 9, ISSN 1974-9821 Peterson's Stress Concentration Factors 2007, second edition. Walter D. Pilkey, DOI: 10.1002/9780470172674.ch1 S. Boljanović et alii 2016, Frattura ed Integrità Strutturale, 35, 313-321 Zhongping Zhang, Yanjiang Qiao, Qiang Sun, Chunwang Li, and Jing Li, 2009. Theoretical Estimation to the Cyclic Strength Coefficient and the Cyclic Strain-Hardening Exponent for Metallic Materials: Preliminary Study. JMEPEG 18, 245 – 254 ASM International DOI: 10.1007/s11665-008-9286-5& https://www.astmsteel.com/product/4340-steel-aisi/