PSI - Issue 71

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

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Table 3 Results of Mesh Convergence Study. No. of Elements No. of Nodes

Equivalent Peak Stress (in MPa)

Equivalent Elastic Strain

129692 147750

190120 216190

1229

0.006368 0.006349

1248.3

234130

337850

1242.9

0.006327

416630 0.006311 The selected mesh reduces computational time by 60% compared to the finest mesh. Consequently, this mesh size is appropriate for the analysis and is expected to produce promising results. 3 Stress Analysis The static and fatigue analyses explored interference fits ranging from 0.5% to 0.1% of the lug hole diameter, along with pin clearance tolerances of -0.1% to -0.5% of the bush's inner diameter. The clearance between the bush and the lug varied from -0.1% to 0.5%, depending on the type of pin used, resulting in 56 geometric fit combinations for the lug joint. Using strain-life parameters, the numerical analysis was extended to predict fatigue life characteristics, considering various factors in both the static and fatigue assessments. • Maximum Equivalent (Von-Mises) Stress or peak stress and its location and zone (Refer to Fig. 4) • Equivalent (Von Mises) Strain (Refer to Fig. 5) • Maximum Equivalent (Von Mises) Stress or peak stress and its location and zone 590290 1247.1

• Equivalent (Von Mises) Strain & Maximum deformation • Variation of Stress Concentration Factor (SCF) with distance • Verification of the SCF with theoretical or analytical equations • Estimation of Fatigue life of Bush and Lug

As part of the stress analysis, the bottom end of the lug was fixed, and a gradually increasing load ranging from 9.5 kN to 28 kN was applied during each load reversal cycle on the pin. The contact definitions between the lug and the bush, and between the bush and the pin, were carefully calibrated to accurately capture the interference and snug/clearance fit types, respectively. The contact formulation is based on the Augmented Lagrange Element (ALE) method, which accounts for asymmetric behaviour.

Fig. 4 Peak Equivalent Stress (in MPa).

Fig. 5 Peak Equivalent Strain.

4 Study of Stress Concentration Factor (SCF) The Stress Concentration Factor (SCF) using net section stress, K tn = (1) Based on research findings, it has been established that the Stress Concentration Factor (SCF) exhibits an increase in proportion to the increase in pin clearance. Furthermore, the SCF demonstrates a decline as the interference of the bush increases up to a specific threshold. However, any increase in the interference of the bush beyond 0.4% of the lug hole interference does not yield noteworthy advantages. The SCF for a standard Lug Bush Pin combination, subject to varying clearance, has been meticulously examined using analytical SCF as per Peterson (2007). A comparison of the SCF derived from Finite Element Analysis (FEA) and analytical techniques is detailed in Table 4, within an error margin of 2.3%. This comprehensive analysis was undertaken to validate the precision of the numerical simulation model developed for the present study.