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Fatigue damage cumulation in brass under variable loading

Mroziński S., Dymski S.

Archives of Foundry Engineering

2009

Vol. 9, iss. 3

275-280

In the paper there was presented the course of fatigue damage cumulation in specimens made of CuZn37 brass. During the analysis the course of damage cumulation there were used parameters of hysteresis loop and microstructure changes for different levels of fatigue damage, that were registered during the tests. Basing on the analysis of three hysteresis loop parameters (stress amplitude [...], plastic strain amplitude [...] and plastic strain energy \deltaWpl) it has been found that during variable loading the smallest changes are observed for the energy \deltaWpl. Microscopic analysis of brass specimens after various fatigue levels showed that fatigue damage cumulation is also visible in changes taking place both within grains and at their boundaries. These changes include the presence of failures at boundaries of grains and slide banding systems inside of them, which are typical for plastic strain of the material.

Effective fatigue damage summation

Kolenda J.

Polish Maritime Research

2006

nr 4

11-14

The cumulative fatigue damage caused by uniaxial variable stress is considered. To facilitate the lifetime prediction at complex stress patterns, has been defined an effective stress of constant parameters, claimed to be equivalent to the sequence of original stresses in terms of fatigue life of material. The equivalence conditions are based on the theory of energy transformation systems. To the effective stress the Palmgren-Miner rule is applied. Thereby the cycle counting is not required.

FEM analyses of steel members and connections considering damage cumulation effects under cyclic loading

Shen Z. Y., Song Z. S.

International Journal of Applied Mechanics and Engineering

2004

Vol. 9, no 1

47-62

Due to the expansion of micro defects, the mechanical properties of structural steel, such as yielding strength, Young's modulus and hardening coefficient will deteriorate under cyclic loadings, and low cycles fatigue failure may take place. Based on continuum damage theory and experimental results, a cumulative damage mechanics model using effective plastic strain is suggested. A general procedure of FEM analysis considering damage cumulation effects is presented and damage crack criterion is proposed as well. Cantilever members subjected to cyclic loading are numerically simulated with FEM program which took the damage cumulation into consideration. The analytical results agree very well with the experiments, and hence, the proposed cumulative damage mechanics model is demonstrated to be accurate enough to simulate the behavior of steel structures under seismic loading. Since the model proposed in the paper can also calculate the cumulation of the damage, it means that the method can also be adopted to access the seismic behavior of steel structures under earthquakes.