Material characterization of SS 316 in low-cycle fatigue loading

This study deals with simulation of low-cycle fatigue (LCF), followed by evaluation of fatigue parameters, which would be suitable for estimating fatigue lives under uniaxial loading. The cyclic elastic–plastic stress–strain responses were analyzed using the incremental plasticity procedures. Finite-element (FE) simulation in elastic–plastic regime was carried out in FE package ABAQUS. Emphasis has been laid on calibration of SS 316 stainless steel for LCF behavior. For experimental verifications, a series of low-cycle fatigue tests were conducted using smooth, cylindrical specimens under strain-controlled, fully reversed condition in INSTRON UTM (Universal Testing Machine) with 8,800 controller at room temperature. The comparisons between numerical simulations and experimental observations reveal the matching to be satisfactory in engineering sense. Based on the cyclic elastic–plastic stress–strain response, both from experiments and simulation, loop areas, computed for various strain amplitude, have been identified as fatigue damage parameter. Fatigue strain life curves are generated for fatigue life prediction using Coffin–Manson relation, Smith–Watson–Topper model, and plastic energy dissipated per cycle (loop area). Life prediction for LCF has been found out to be almost identical for all these three criteria and correlations between predicted and experimental results are shown. It is concluded that the improvement of fatigue life prediction depends not only on the fatigue damage models, but also on the accurate evaluations of the cyclic elastic–plastic stress/strain responses.     

Influence of the length of the loading cycle on the low-cycle fatigue of ZhS6F alloy under nonisothermal conditions

Kiev Institute of Civil Aviation Engineers. Kuibyshev. Translated from Problemy Prochnosti, No. 1, pp. 76–79, January, 1989.     

High-temperature strength and creep of weld seams of molybdenum alloys in low-cycle loading

We present the cyclic creep and low-cycle fatigue characteristics of the cast weld metal in a weld seam of low-alloy molybdenum alloys TsM6 of the system Mo-Zr-B and TsM10 of the system Mo-Al-B under conditions of high-temperature mild cyclic tension compared with analogous indices for the base metal. We show that the experimental results may be satisfactorily described analytically starting from the concept of equivalent stresses and experimental data on static creep and long-term strength of a material under the corresponding temperature conditions. We have obtained analytical experiments for determination of the equivalent stresses for a trapezoidal load variation cycle based on time and energy criteria for equivalent damage to the material.Translated from Problemy Prochnosti, No. 11, pp. 32–44, November, 1994.     

Predicting the rate of fatigue crack growth in biaxial low-cycle loading

The authors propose a new criterion of predicting the rate of crack growth in biaxial loading based on analysis of the local stress-strain state of the crack tip, the size of the plastic zone, and the plasticity margin of cyclic failure. The derived calculation dependences are compared with the experimental data obtained by the authors and other investigators. The results are in satisfactory agreement as a result of taking into account the effect of the load level, the properties of the material, and the biaxial loading.Translated from Problemy Prochnosti, No. 5, pp. 18–23, May, 1991.     

Study of the low-cycle fatigue of steel ÉI415 after prior creep

Experimental studies have been carried out on the effect of prior creep on the resistance of steel ÉI415 to low-cycle fatigue. It has been shown that partial exhaustion of the stress-rupture strength life at high stresses does not reduce the low-cycle strength and deformation properties of the material in question.Moscow Energy Institute. Translated from Problemy Prochnosti, No. 10, pp. 23–26, October, 1989.     

A method for low-cycle fatigue life assessment of metallic materials under multiaxial loading

A new method of fatigue life assessment under multiaxial low-cycle regular and irregular loading is proposed, which is based on the modified Pisarenko-Lebedev criterion, the linear damage accumulation hypothesis, and the nonlinear Manson approach. The results of low-cycle fatigue tests of titanium alloy VT9 under irregular proportional and non-proportional biaxial loading are given. The tests were carried out at three Mises strain levels (0.6, 0.8, and 1.0%) with various combinations of proportional and non-proportional strain paths. All the tests were carried out at room temperature. The proposed method turned out to be effective and to allow for such factors as strain state type, strain path type and loading irregularity. __________ Translated from Problemy Prochnosti, No. 1, pp. 56–59, January–February, 2008.