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Applying constant strain as loading condition in Abaqus
Tue, 2013-03-26 13:40 - nibalog
Hello All:
I am running a simple thermal tension coupon test with two steps.
Step 1: Apply a 10 lbs load on the coupon at certain temp.
Step 2: Keep the strain constant and reduce temp ( the material would
try to contract but I must keep the strain constant by increasing load)
Is there a way for me to do step 2 in abaqus and have it predict the load or stress required to maintain constant strain?
I would appreciate your comments? Thanks
Forums:
Not possible
In abaqus, displacement based elements are used, and therefore displacements and forces are primary variables. Since strain is material point response, therefore there is no way it can be maintained constant. In reality also, the strain is measured at a point where it assumed that the strain/stress field is uniform. What is measured is displacement between two ponints, and strain is derived from it using appropriate equations. So, in experiments also, strain can not be maintained constant unless feedback control loop is employed in which the current displacement reading is fed to the controller that actuates the next force/displacement increment in order to keep strain constant.
If this can be done in abaqus, you can maintain constant strain. But the force/displacement history is already predefined before the start of analysis. This means, in order to achieve what you want, you must know how the force will vary beforehand (which implies you already know the material point solution, which is exactly what you're trying to solve for).
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