Fatigue Durability Analysis for Welded Bogie Frame of AALRT
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Date
2016-06
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Addis Ababa University
Abstract
This research paper presents the fatigue durability analysis for the welded bogie frame of AALRT. The purpose of this research is to observe the fatigue life of the welded bogie frame and to protect it from failure. In the analysis of the research a three-dimensional finite element model of the bogie frame has been used to investigate the effect of the applied loading force at the frame surface area and observing the effects on the welded joints. The specimen S/N-curve is locally modified by different influence parameters as stress-gradient to take into account notch effects, mean-stress influence which is quantified by means of a Haigh-diagram, surface roughness and treatments, temperature, technological size, etc. This paper discusses some applications of the outstanding fatigue simulation program FEMFAT supporting the assessment of the applied loads and welding seams.
On the bases of the model analysis the following results have been achieved. Output results without Sensitivity Factor: – maximum and minimum log10 damage values are 30 and -7.09 respectively, maximum and minimum log10 endurance safety factors are 1 and -5.11 respectively, maximum and minimum fatigue limits are 282 N/mm2 and 255 N/mm2 respectively, and fatigue life is 2e^6. Output results with small weld seam sensitivity Factor: – maximum and minimum log10 damage values are 30 and -20 respectively, maximum and minimum log10 endurance safety factors are 1 and -5.11 respectively, maximum and minimum fatigue limits are 282 N/mm2 and 0 N/mm2 respectively, and fatigue life is 2e^6. Hence it is possible to conclude that the maximum damage result, which is 30 in number is much exaggerated result, it is because the weld quality that I have taken is poor. Whereas the fatigue limit at each analytical outputs has been proved to be the recommended value. The endurance safety factor is below the anticipated value. There for a special attention should be given to the welded joints. Based on sensitivity seam thickness results, it is possible to conclude that welded connections are almost nearer to failure because they are highly exposed to residual stress. The study is significant and applicable because it introduces new knowledge on fatigue life analysis of welded bogie frame in the minds of the beneficiaries of the study particularly to those who are working in Railway Corporation.
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Keywords
AALRT, welded bogie frame, Fatigue, durability