Study Of Low Cycle Fatigue Behavior Research Articles

Experimental Study of Low-Cycle Fatigue Behavior of a Welded Flange-Bolted Web Connection in Steel Moment-Resisting Frames

This paper describes an experimental investigation of the low-cycle fatigue (LCF) behavior of welded flange-bolted web (WFBW) connections, which are commonly employed in high-rise steel moment-resisting frames (MRFs) in Japan. The main parameters investigated in this study were (1) bolt configuration of the web connection and (2) steel grade. According to test results, LCF capacity depends on the slip behavior of different bolt configurations, even at relatively minor inelastic rotations. Slip behavior effects can be evaluated by the yield strength of the shear plate or the slip-critical strength; for specimens whose shear plate yield strength was designed to be higher than the slip-critical strength, LCF capacity showed that the upper limit can neglect slip behavior. Furthermore, it was shown that LCF behavior can be evaluated by the same fatigue curve in the relationship of fatigue capacity and beam rotation amplitude, regardless of steel yield stress.

Computational study of low-cycle fatigue behaviour of lotus-type porous material

A computational study of low-cycle fatigue behaviour of lotus-type porous material subjected to uniaxial/biaxial tension and compressive loading cycles is presented in this paper. The considered computational models have different pore topology patterns. The low-cycle fatigue analysis is performed using a damage initiation and evolution law, based on the inelastic hysteresis energy for stabilized loading cycle. The direct cyclic analysis is used to obtain the stabilized response of a model subjected to periodic loading. The present study clarifies the influences of pore topology on the low-cycle fatigue behaviour under different type of transversal loading conditions with respect to the pore orientations.

Neutron Diffraction Study of Low-Cycle Fatigue Behavior in an Austenitic–Ferritic Stainless Steel

By performing in situ neutron diffraction experiments on an austenitic–ferritic stainless steel subjected to low-cycle fatigue loading, the deformation heterogeneity of the material at microscopic level has been revealed. Based on the in situ neutron diffraction data collected from a single specimen together with the mechanical properties learned from the ex situ micro-hardness, a correlation has been found. The performance versus diffraction-profile correlation agrees with the cyclic-deformation-induced dislocation evolution characterized by ex situ TEM observation. Moreover, based on the refined neutron diffraction-profile data, evident strain anisotropy is found in the austenite. The high anisotropy in this phase is induced by the increase in dislocation density and hence contributes to the hardening of the steel at the first 10 cycles. Beyond 10 fatigue cycles, the annihilation and the rearrangement of the dislocations in both austenitic and ferritic phases softens the plastically deformed specimen. The study suggests that the evolution of strain anisotropy among the differently oriented grains and micro-strain induced by lattice distortion in the respective phases mostly affect the cyclic-deformation-induced mechanical behavior of the steel at different stages of fatigue cycles. The stress discrepancy between phases is not the dominant mechanism for the deformation of the steel.

Characterization of cyclic plastic bending of austenitic AISI 304 stainless steel

Steels used in chemical, nuclear and power industries are usually subjected to repeated loads that may induce significant inelastic deformations. Successful assessment of a component life places a great demand on understanding of material behaviour under strain histories involving cyclic plasticity under bending conditions.This work is concerned with an experimental study of low-cycle fatigue behaviour under both load and deflection controlled conditions. The tests were conducted on AISI 304 stainless steels with the objective of determining strain cycling properties under cyclic plastic bending. These properties are characterized by the cyclic stress-strain hysteresis responses obtained.The cyclic bending plasticity behaviour is investigated for beams with circular cross-section at two conditions of the material, under constant strain and under constant stress. Hysteresis loops for five different strain ranges of ±0.4%, ±0.82%, ±1.1%, ±1.33% and ±1.55% were obtained and also for different stress ranges of 730, 800, 870 and 940 MPa. The material exhibits cyclic hardening in its virgin state, the rate of hardening is very rapid at first but diminishes quickly as the stabilized condition is approached. The cyclic hardening for the constant strain condition is higher than the constant load condition.The results also confirm the applicability of the reference stress method for predicting the cyclic moment-curvature curve for beams with circular cross-sections. The observed strain values are higher in the lower strain range and lower in the higher strain. However, the correlation obtained is considered quite satisfactory in view of the nonlinearity of the problem.