PSI - Issue 71

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

43

Nomenclature σ ns Net Section stress, MPa

σ peak Peak Equivalent Stress, MPa K t Stress Concentration Factor K I Stress Intensity Factor, MPa √ ΔK Stress Intensity Factor Range, MPa √ E Young's Modulus, MPa ϵ f ' Ductility coefficient c Ductility exponent K' Strength Coefficient, MPa n' Strain Hardening exponent

.

Fig. 1 Male and Female Lug Configurations.

The exploration of how geometric parameters influence stress distribution in lug joints due to fit tolerance relaxation is a vital area of research. Numerous studies have demonstrated the effectiveness of interference fits and cold working processes in enhancing the fatigue life of these joints. For example, Laghzale et al. (2016) developed an analytical model that incorporates elastic-plastic behavior to assess stresses in interference fit assemblies with varying levels of interference, yielding valuable insights for the current study. Similarly, Li et al. (2022) investigated contact pressure distribution at the interfaces of pins and lugs, providing essential data for evaluating the pressure distribution among lug, bush, and pin combinations. Additionally, Hui et al. (2022) offered critical insights into the fracture failure of different lug joints, significantly contributing to the development of the numerical simulation model. Grant et al. (1994) also presented important findings regarding high stress resulting from geometric variations. Furthermore, Antoni and Gaisne (2011) derived analytical expressions for stress field distributions in a bush-lug joint system under varying conditions. This body of research has laid the groundwork for the numerical simulation model, which encompasses a range of fit combinations. The study continues to examine the estimated fatigue life of lug joints, focusing on the combined effect of varying geometric fit dimensions and fatigue loading. 2. Numerical Simulation Study In order to conduct a comprehensive analysis of the impact of geometric parameters, a detailed model of a typical Lug-Bush-Pin joint was crafted using the dimensions depicted in Fig. 2 with the assistance of PTC Creo Parametric 9.0.0, an advanced solid modeling tool. The Lug component was specified to be made from Aluminum Alloy 2024 T4 for its specific material properties. Both the Bush and the Pin were designated to be composed of AISI 4340 steel selected for their robustness and durability. Our investigation involved subjecting the Lug-Bush Pin assembly to a uniaxial tensile load specifically applied to the Pin. This facilitated in-depth analysis of its mechanical response and behavior under this loading condition.

Table 1 Bush - Pin fit combinations. Designation of Fit combination

Description

BI1-PC1 to C5

Bush 0.1% interference with Lug and Pin 0.1% to 0.5% clearance with Bush and so on Bush 0.1% Clearance with Lug and Pin 0.1% to 0.5% clearance with Bush and so on

BC1-PC1 to C5

BS-PS

Bush and Pin are snugly fitted