Probability Analysis in Determining the Behaviour of Variable Amplitude Strain Signal Based on Extraction Segments

Abstract

This paper focuses on analysis in determining the behaviour of variable amplitude strain signals based on extraction of segments. The constant Amplitude loading (CAL), that was used in the laboratory tests, was designed according to the variable amplitude loading (VAL) from Society of Automotive Engineers (SAE). The SAE strain signal was then edited to obtain those segments that cause fatigue damage to components. The segments were then sorted according to their amplitude and were used as a reference in the design of the CAL loading for the laboratory tests. The strain signals that were obtained from the laboratory tests were then analysed using fatigue life prediction approach and statistics, i.e. Weibull distribution analysis. Based on the plots of the Probability Density Function (PDF), Cumulative Distribution Function (CDF) and the probability of failure in the Weibull distribution analysis, it was shown that more than 70% failure occurred when the number of cycles approached 1.0 x 10 11 . Therefore, the Weibull distribution analysis can be used as an alternative to predict the failure probability.

Fatigue Failure of a Pressing Machine

“…The detailed case study presented in this paper finally led to an employment of the local stress-strain approach using a statistical assessment. An analysis of fatigue lifetime and the causes of an early fatigue fracture may be carried out by several known methods: using local stress-strain approaches [1,2], statistical approaches [3,4], deterministic fatigue analysis (experimental) [2], spectral fatigue analysis [5,6], time-domain fatigue analysis, fracture-mechanics-based assessment of fatigue damage [1,7], etc. The detailed case study presented in this paper finally led to an employment of the local stress-strain approach using a statistical assessment.…”