Issue 52

A. Ahmadi et alii, Frattura ed Integrità Strutturale, 52 (2020) 67-81; DOI: 10.3221/IGF-ESIS.52.06 67 A comparative study on the fatigue life of the vehicle body spot welds using different numerical techniques: Inertia relief and Modal dynamic analyses A. Ahmadi, G.H. Farrahi * School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran a.ahmadi@mech.sharif.edu , farrahi@sharif.edu K. Reza Kashyzadeh School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran Department of Mechanical and Instrumental Engineering, Academy of Engineering, Peoples’ Friendship University of Russia (RUDN), Moscow, Russia kazem.kashyzadeh@gmail.com Sh. Azadi Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran Saipa Automotive Research and Innovation Center, Tehran, Iran azadi@kntu.ac.ir K. Jahani Saipa Automotive Research and Innovation Center, Tehran, Iran jahani.kambiz@airic-ir.com A BSTRACT . Owing to the expensive and time-consuming nature of durability experiments, finite element based durability analysis is quite prevalent in the automotive industry. Numerical fatigue life analyses are typically divided into two different categories, the quasi-static methods which are faster and the dynamic methods which are more accurate. The aim of this paper is to compare the inertia relief and modal dynamic approaches in terms of formulation, accuracy and computation time. The chosen case study is the fatigue life of the vehicle body which is considered the main load-bearing component in a vehicle. By utilizing multi-body dynamics model and driving the vehicle on different standardized roads and by different velocities, the loadings, which act on the body are calculated and later used for the stress analysis. Then, by using the structural stress method, the fatigue life of the vehicle spot welds is calculated and the results are compared for both approaches. The findings reveal that the modal dynamic method is almost 37 times more time-consuming than the inertia relief approach, but if accuracy is desired, it can be up to 96% more accurate. Also Citation: Ahmadi, A., Farrahi, G.H., Reza Kashyzadeh, K., Azad, Sh., Jahani, K., A comparative study on the fatigue life of the vehicle body spot welds using different numerical techniques: Inertia relief and Modal dynamic analyses, Frattura ed Integrità Strutturale, 52 (2020) 67-81. Received: 31.10.2019 Accepted: 09.01.2020 Published: 01.04.2020 Copyright: © 2020 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.