Fatigue Analysis of Automative Tensioner in Front End Accessory Drive Systems

摘要

Tensioners, as critical parts of automotive Front End Accessory Drive (FEAD) systems, are subjected to a significant range of dynamic loads due to engine pulsations which can lead to fatigue and operational failure. It is challenging to analytically investigate the fatigue life for powertrain components given the parameters involved. In this paper, the fatigue life assessment of a tensioner is studied through three main steps, namely stress analysis, fatigue properties estimation, and fatigue life prediction. Series of finite element analyses are carried out to investigate stress distribution in the tensioner spindle and pinpoint the critical areas. In addition, the fatigue properties of the tensioner are estimated using the experimental data. The tensioner fatigue behavior is analyzed through strain-life approach. The predicted fatigue parameters was then used to generate the cyclic stress-strain curve for the material of the selected tensioner based on Morrow theory. Finally, the fatigue estimation method was modified based on Neuber's rule and using the generated cyclic stress-strain curve for the die cast A380 tensioner. This model presents the Neuber parameter life data to account for plasticity correction.;The possibility of using the newly developed HPDC magnesium alloys, MRI 153M and MRI 230D as alternative materials for tensioner casting parts is investigated in this study. Wohler curves for these different alloys AZ91D, MRI153M, and MRI230D are presented and then compared to current material for casting parts of the tensioner, A380 aluminum alloy. Effects of possible design variables were also investigated in the study using the response surface method. A methodology to achieve an optimal design shape for the tensioner based on the application and loading was proposed when considering life of the part. This research work presents an in-depth quantitative modeling approach to estimate the fatigue life of the automotive tensioner under real working condition by developing the stress histories. The developed modeling approach is applicable for evaluating any cases involving power train mechanical components.