Structural Stress Correction Methods for Linear Elastic Finite Element Analysis of Spot Welded Joints

2016 ◽  
Author(s):  
Hong-Tae Kang ◽  
Xiao Wu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Welded Joints ◽  
Life Prediction ◽  
Structural Stress ◽  
Test Results ◽  
Element Analysis ◽  
Linear Elastic ◽  
Spot Welded

Structural stress concepts are widely used in fatigue life prediction of spot welds and seam welds in vehicle structures. For fatigue life prediction of welded joints based on the structural stress methods, it is necessary to obtain applied force ranges versus fatigue life of the welded specimens. Then, the force ranges versus fatigue life information is converted to structural stress ranges versus fatigue life (S-N) of the joints. The structural stress ranges versus the fatigue life curve of the welded specimens becomes the material fatigue property of the welded joints to predict fatigue life of joints in vehicle structures. While converting the applied load ranges to the structural stress ranges, linear elastic finite element analysis (FEA) is used. Therefore, the applied load ranges are considered as the responses of linear elastic deformation even though the load ranges consist of the linear elastic deformation and plastic deformation. As results the structural stress ranges of the welded joints are reduced in S-N curve. This study introduces simple techniques for spot welded joints to include the plastic deformation effect on the structural stress calculation without performing elastic-plastic finite element analysis. Fatigue test results of spot welded joints for lap-shear and coach peel specimens of advanced high strength steels (AHSS) and mild steels were used. The corrected structural stress methods showed better correlation with the test results.

TTK Chitra tilting disc heart valve model TC2: An assessment of fatigue life and durability

2017 ◽  
Vol 231 (8) ◽  
pp. 758-765 ◽  
Author(s):  
NN Subhash ◽  
Adathala Rajeev ◽  
Sreedharan Sujesh ◽  
CV Muraleedharan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Heart Valve ◽  
Life Prediction ◽  
Heart Valves ◽  
Failure Modes ◽  
Fatigue Life Prediction ◽  
Element Analysis ◽  
Valve Model

Average age group of heart valve replacement in India and most of the Third World countries is below 30 years. Hence, the valve for such patients need to be designed to have a service life of 50 years or more which corresponds to 2000 million cycles of operation. The purpose of this study was to assess the structural performance of the TTK Chitra tilting disc heart valve model TC2 and thereby address its durability. The TC2 model tilting disc heart valves were assessed to evaluate the risks connected with potential structural failure modes. To be more specific, the studies covered the finite element analysis–based fatigue life prediction and accelerated durability testing of the tilting disc heart valves for nine different valve sizes. First, finite element analysis–based fatigue life prediction showed that all nine valve sizes were in the infinite life region. Second, accelerated durability test showed that all nine valve sizes remained functional for 400 million cycles under experimental conditions. The study ensures the continued function of TC2 model tilting disc heart valves over duration in excess of 50 years. The results imply that the TC2 model valve designs are structurally safe, reliable and durable.

Life Assessment of Turbine Components Through Experimental and Numerical Investigations

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Dianyin Hu ◽  
Rongqiao Wang ◽  
Guicang Hou
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Life Prediction ◽  
Life Assessment ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Creep Fatigue ◽  
Turbine Component ◽  
Good Agreement

A new lifetime criterion for withdrawal of turbine components from service is developed in this paper based on finite element (FE) analysis and experimental results. Finite element analysis is used to determine stresses in the turbine component during the imposed cyclic loads and analytically predict a fatigue life. Based on the finite element analysis, the critical section is then subjected to a creep-fatigue test, using three groups of full scale turbine components, attached to an actual turbine disc conducted at 750 °C. The experimental data and life prediction results were in good agreement. The creep-fatigue life of this type of turbine component at a 99.87% survival rate is 30 h.

Application of Two Methods for Notch Fatigue Life Prediction

2011 ◽  
Vol 488-489 ◽  
pp. 654-657
Author(s):  
Radu Negru ◽  
Liviu Marsavina ◽  
Hannelore Filipescu ◽  
Cristiana Caplescu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Reduction Factor ◽  
Volumetric Method ◽  
Life Assessment ◽  
Strength Reduction Factor ◽  
Element Analysis ◽  
Linear Elastic ◽  
Notched Specimens

The aim of this paper is the application of two methods for notch fatigue life assessment, methods which are based on finite element analysis: the theory of critical distances and the volumetric method. Firstly, un-notched and notched specimens (for three different geometries) were tested in tension under constant-amplitude loading. The use of theory of critical distances (TCD) to predict the notch fatigue life involves the determination of the material characteristic length L based on experimental results obtained for the un-notched and one type of notched specimens. For the others notched geometries, based on linear-elastic finite element analysis, the fatigue strength is predicted using the TCD. In order to apply the volumetric method, elastic-plastic stress field around notches are considered and notch strength reduction factor are determined. Finally, the predictions of the two methods were compared with experimental fatigue data for notched specimens.

Fatigue Life Prediction of Girth Gear-Pinion Assembly Used in Kilns by Finite Element Analysis

2013 ◽  
Vol 372 ◽  
pp. 292-296 ◽  
Author(s):  
K. Annamalai ◽  
S. Sathyanarayanan ◽  
C.D. Naiju ◽  
Mohammed Shejeer
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Life Expectancy ◽  
Element Analysis ◽  
Linear Elastic ◽  
Gear Design ◽  
Steel Material ◽  
Rainflow Cycle Counting ◽  
Fatigue Life Analysis

This study is focused on predicting the fatigue life expectancy of Girth gear-pinion assembly used in cement industries. Gear design and modeling was carried out using a CAD package and analysis was done using finite element analysis software, ANSYS. AISI 4135-low alloy steel material properties are considered and linear elastic finite element analysis and fatigue life analysis were carried out. The variable amplitude load is applied to simulate the real time loading of the gear-pinion assembly. Rainflow cycle counting algorithm and Minars linear damage rule is employed to predict the fatigue life. The critical stress and the corresponding deformation are discussed in the results. Finally the life expectancy of the girth gear and pinion assembly is estimated which would be useful for the periodical maintenance of the gear assembly.

scholarly journals Fatigue life assessment of welded joints in a crane boom using different structural stress approaches

2019 ◽  
Vol 13 (2) ◽  
pp. 5048-5073
Author(s):  
Brahami Riad ◽  
Hamri Okba ◽  
Sfarni Samir
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Industrial Structure ◽  
Life Assessment ◽  
Structural Stress ◽  
Element Analysis ◽  
Tubular Joints ◽  
Fatigue Life Assessment

This article presents a study of the fatigue strength of welded parts in a crane boom. First, a finite element analysis was carried out over the whole structure. Two critical welded zones were identified and a detailed analysis was carried on them, in the form of sub-models. Three different approaches for estimating the structural stress in welded zones, were presented and applied to each sub-model. Results were compared and discussed. The evaluation of fatigue resistance by the use of appropriate S-N curves for each method was also carried out and discussed. The use of these approaches on a complex industrial structure, and on tubular joints with hollow sections required to perform many adaptations and to solve several difficulties presented hereafter.

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