I am performing direct cyclic analysis in Abaqus, on a metal plate subjected to tension in order to study the crack growth. Outputs of strain and stress seem to be reliable (in their qualitative behaviour) except for one problem. At the beginning of every cycles there are discontinuities or gaps. These discontinuities increases with the plastic deformation along the test. Moreover, even if the cyclic step is the first, strain/stress are not zero at the beginning. Do you have suggestions?
Many thanks.
Yes, you have includes the influence of heat transfer mechanism in the phisical propierties
Dear Yusdel, thanks for your answer. Can you specify better what the problem can eb and how to fix this?
I am not a user of ABAQUS and am not in a position to answer you in detail, even though I was working on FEM program construction in the 1970"s and was fairly good at abacus when I was an elementary school pupil.
When the materials are subjected to cyclic loading, they typically have residual strains and/or residual stresses after some cycling under no loading conditions. This may cause a certain level of discontinuity at the end of each cycle, depending on its materials property. Therefore, you may need to conduct cycling materials testing to obtain the fundamental stress-strain curves and temperature data under given loading and surrounding temperature conditions, among others, thereby gaining necessary materials property data for ABAQUS. In the case of low cycle fatigue, residual stress/strain values will typically increase, as the materials property is changed with repeated loading cycles. Check what kind of data are required in ABAQUS analysis and apply the materials data you obtained with your own experiment. You will understand the reasons why the discontinuity is occurring in your analysis in a concrete manner. If you can make these clear, you can write a new paper by yourself. I hope this will help you and/or answer your question.
Hiroshi Honda, Ph. D., P. E.
Dear Dr. Honda, many thanks for your very interesting answer.
Unfortunately, at this point I have no possibility to perform experimental testing (I am wating for an answer about a research funding grant), but I will search in literature about the problem you pointed out. Do you think that the mechanical phenomena you indicated can be related to the pinching behaviour (more typical for RC) under cyclic testing?
Furthermore, I found in Abaqus Manual something very interesting which could explain partially the problem (http://130.149.89.49:2080/v6.8/books/usb/default.htm?startat=pt03ch06s02at06.html). I thank you again.
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