Reliability assessment of multiaxial creep and multiaxial fatigue using stochastic modeling

Abstract

In the present study, a new stochastic model using Markov chain is developed in order to perform statistical reliability assessment of material life under various loading conditions. Multiaxial fatigue life and variable multiaxial fatigue prediction methods are surveyed. The proposed stochastic model is applied for the low cycle fatigue life prediction and reliability assessment of 316L stainless steel under variable multiaxial loading. In the proposed model, fatigue phenomenon is considered as a Markov process, and damage vector and the reliability are defined on every plane. Any low cycle fatigue damage evaluating method can be implemented in the proposed model. The propose model enables calculation of statistical reliability and crack initiation direction under variable multiaxial loading, which are generally not available. In the present study, a critical plane method proposed by Kandil et al., maximum tensile strain range, and von Mises equivalent strain range are used to calculate fatigue damage. When the critical plane method is chosen, the effect of multiple critical planes is also included in the proposed model by employing the global reliability. Maximum tensile strain and von Mises strain methods are used for the demonstration of the generality of the proposed model. The material properties and the stochastic model parameters are obtained from uniaxial tests only. The stochastic model made of the parameters obtained from the uniaxial tests is applied to the life prediction and reliability assessment of 316L stainless steel under variable multiaxial loading. The predicted results show good accordance with experimental results. The stochastic modeling of high temperature low cycle fatigue is developed using a new energy based high temperature low cycle fatigue life prediction method by Hong and LeeE1? which can take consideration of temperature and strain rate effect. In this case the stochastic modeling is identical to the room temperature uniaxial fa...