Fatigue Life Analysis of an Automotive Tensioner Through Strain-Life Approach

2015 ◽  
Author(s):  
Maryam Talimi ◽  
Jean W. Zu
Keyword(s):  
Fatigue Life ◽  
Stress Analysis ◽  
Drive System ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Fatigue Life Assessment ◽  
Front End ◽  
Life Analysis ◽  
Fatigue Life Analysis ◽  
Prediction Approach

In this paper, fatigue life assessment of a tensioner is studied through dynamic load analysis, stress analysis, and stress-life fatigue analysis approach. Tensioner is a critical part of an automotive front end accessory drive system, providing pre-tension to the belt. The front end accessory drive systems are responsible for transmitting power from the crankshaft to the accessory components. Due to the engine pulsation, components of the accessory drive including the tensioner are subjected to dynamic loads leading to fatigue failure. The fatigue life assessment of a mechanical component highly depends on loading, geometry, and material properties. In addition, the dynamic behavior of the front end accessory drive is complicated due to coupling between several modes of vibrations in belt, pulleys, and the tensioner arm. Duo to the complexity of the parameters involved and complicated dynamics, the fatigue life analysis of FEAD components is a challenging task. This paper includes three main parts, namely stress analysis, fatigue properties prediction, and life estimation. The dynamic analysis of a generic front end accessory drive system is performed in order to obtain effective loads on the tensioner. Stress state for the tensioner in case of different applied loading conditions is performed via a series of Finite Element (FE) analyses, and the critical region of the part is determined. Finally, fatigue life is estimated through strain-life approach. Modest work has been found in this area providing a comprehensive solution to the fatigue life investigation of power train components. The present study offers a comprehensive modeling approach which predicts the automative tensioner lifetime. The lifetime of any FEAD system components can be determined using the developed fatigue life prediction approach.

Fatigue Life Analysis of Polyurethane Bending Stiffeners

2005 ◽  
Author(s):  
Fre´de´ric Demanze ◽  
Didier Hanonge ◽  
Alain Chalumeau ◽  
Olivier Leclerc
Keyword(s):  
Fatigue Life ◽  
Effective Strain ◽  
Fatigue Behaviour ◽  
Life Assessment ◽  
Test Results ◽  
Critical Areas ◽  
Fatigue Life Assessment ◽  
Fatigue Data ◽  
Life Analysis ◽  
Fatigue Life Analysis

Following some experiences of bending stiffeners fatigue failures during full scale tests performed at Flexi France on flexible pipe and stiffener assemblies, Technip decided to launch in 1999 a major research program on fatigue life analysis of bending stiffeners made of Polyurethane material. This fatigue life assessment is now systematically performed by Technip for all new design of flexible riser bending stiffeners. This totally innovative method comprises a number of features as follows: Firstly fatigue behaviour of polyurethane material is described. The theoretical background, based on effective strain intensity factor, is detailed, together with experimental results on laboratory notched samples, solicited under strain control for various strain ratios, to obtain fatigue data. These fatigue data are well fitted by a power law defining the total number of cycles at break as a function of the effective strain intensity factor. The notion of fatigue threshold, below which no propagation is observed, is also demonstrated. Secondly the design used by Technip for its bending stiffeners, and most of all the critical areas regarding fatigue for these massive polyurethane structures are presented. Thirdly the methodology for fatigue life assessment of bending stiffeners in the critical areas defined above is discussed. Calibration of the strain calculation principle is presented versus finite element analysis. Based on all fatigue test results, the size of the equivalent notch to be considered at design stage, in the same critical areas, is discussed. Finally, a comprehensive calibration of the methodology according to full and middle scale test results is presented. The present paper is therefore a step forward in the knowledge of fatigue behaviour of massive polyurethane bending stiffener structures, which are critical items for flexible risers integrity, and widely used in the offshore industry. The confidence in bending stiffeners reliability is greatly enhanced by the introduction of this innovative methodology developed by Technip.

Fatigue Life Analysis of Al 8090 Helicopter Fuselage Panels

2007 ◽  
Vol 348-349 ◽  
pp. 637-640
Author(s):  
Marco Giglio ◽  
Andrea Manes ◽  
Massimo Fossati
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
High Stress ◽  
Experimental Tests ◽  
Life Assessment ◽  
Fatigue Crack Growth Resistance ◽  
Anisotropic Mechanical Properties ◽  
High Crack ◽  
Life Analysis ◽  
Fatigue Life Analysis

Considering the aerospace structures, the advantages of Al-Li alloys in comparison with conventional aluminium alloys comprise relatively low densities, high elastic modulus, excellent fatigue and toughness properties, and superior fatigue crack growth resistance. Unfortunately, these alloys have some disadvantages due to highly anisotropic mechanical properties and due to a very high crack growth rate for microstructurally short cracks. This could mean relatively early cracking in high stress regions such as rivet holes in helicopter fuselage panels. Consequently a more accurate approach in fatigue life analysis is requested. Considering that the 8090 T81 aluminium alloy has been widely used in an helicopter structure, in particular in the bolted connection between the stringers and the modular joint frame in the rear of the fuselage, it is extremely important to found a reliable procedure for the fatigue life assessment of the component. Thus, using the results of experimental tests made on panel specimens, a FE general model and two submodels of the critical zone (involved in fatigue damage during the tests) have been modelled in order to investigate the complex state of stress near the rivets holes. These stress values obtained have been elaborated for a fatigue assessment.

Estimation and Analysis for the Fatigue Life of Rail Joint Bolt

2013 ◽  
Vol 683 ◽  
pp. 783-786
Author(s):  
Xiao Peng Li ◽  
Xing Ju ◽  
Guang Hui Zhao ◽  
Ya Min Liang
Keyword(s):  
Numerical Simulation ◽  
Fatigue Life ◽  
Traffic Accidents ◽  
Theoretical Calculations ◽  
Practical Significance ◽  
Fatigue Properties ◽  
Tightening Torque ◽  
Railway Traffic ◽  
Life Analysis ◽  
Fatigue Life Analysis

One of the most important reasons for railway traffic accidents is the fatigue failure of the rail joint bolt. Therefore, the research on the fatigue properties of rail joint bolt has important practical significance. This paper analyzed the influence of different pre-tightening torque on the fatigue life of the rail joint bolt. Besides, the best pre-tightening torque of the bolt was acquired through theoretical calculations. Finally, the fatigue life of the rail joint bolt was predicted according to the relevant basic theory and methods of fatigue life analysis, which applied numerical simulation technology.

Stress Analysis and Fatigue Life Assessment of a Piston in an Upgraded Engine

2019 ◽  
Vol 19 (2) ◽  
pp. 402-411
Author(s):  
Mohsen Najafi ◽  
Hadi Dastani ◽  
Mostafa Abedini ◽  
Salim Pirani
Keyword(s):  
Fatigue Life ◽  
Stress Analysis ◽  
Life Assessment ◽  
Fatigue Life Assessment
Sign in / Sign up

Export Citation Format

Share Document