Probabilistic modeling of the size effect and scatter in High Cycle Fatigue using a Monte-Carlo approach: Role of the defect population in cast aluminum alloys. (June 2021)

• Record Type: Journal Article
• Authors: El Khoukhi, Driss; Morel, Franck; Saintier, Nicolas; Bellett, Daniel; Osmond, Pierre; Le, Viet-Duc
• Is Part Of: International journal of fatigue. Volume 147(2021)
• Publication Date: 2021-06
• Subjects: High cycle fatigue -- Cast aluminum alloys -- Probabilistic model -- Representative Volume Element (RVE) -- Size effect in fatigue -- Highly stressed volume -- Scatter in fatigue strength -- Casting defect population; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2021.106177
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: Probabilistic modeling based on Monte-Carlo theory is used to predict the fatigue behavior of cast aluminium alloys. Magnitude of size effect and scatter are linked to the characteristics of defects population. Two alloys with different degrees of porosity are used to validate the probabilistic approach. The model is capable to predict the average fatigue strength with a relative error <5%. High density and/or large size defects lead to minor size effect and less scatter. Low density and/or small size defects induce large size effect and high scatter. Abstract: In this study, a probabilistic model based on Monte-Carlo theory is applied to predict the fatigue behavior of cast aluminum alloys. The objective of the proposed approach is to investigate the effect of porosity (i.e. the defect size distribution and spatial density) on the fatigue strength and its associated scatter for uniaxial fatigue loads with the load ratio R = 0.1. The proposed model is applied to two cast aluminum alloys with very different defect characteristics. The results for these two alloys confirm that the model can be used to predict the average fatigue strength with a relative error <5%. It also accurately reproduces the experimentally observed trends concerning the scatter in fatigue strength. The scatter is underestimated but is of the same order of magnitude as the experimental values. It is believed that this is because the proposed model considers that the porosity is the only source of scatter. It is demonstrated that the model is well adapted for the prediction of the volume or scale effect in fatigue. This approach can also be used to estimate the Representative Volume Element in Fatigue for cast aluminum alloys.