modeling a constant strain rate test

[dpollack]

Hello,

I am trying to model a constant strain rate test. My model is very simple block with the bottom area held constant and a load placed on the top area. I tried a constant displacement load but it changes the strain rate considerably over the loading time- which is understandable- but unwanted in my modeling.

Does anyone have a simple constant strain rate test procedure they can share?

Thank you

 

[juzz]

Hello, dpollack!

This is my advice:

For constant strain analysis I use an uniform temperature loading.
Please see:

eps=alfa*deltaT

where:
eps is the constant strain that I need
alfa is the thermal expansion coefficient
deltaT is the uniform temperature

so if I know eps I could put

deltaT=eps/alfa

and I will obtain a constant strain eps in my model

For constant strain rate you need to apply not a constant temperature but a linear one (depending on time). So you need a transient analysis and put a linear temperature:

T = T0 + Trate*time

where:
T0 = 0 (I have no initial deformation)

time = will vary from 0 to endtime (the time at the end of your loadstep in transient analysis)

Trate = epsrate/alfa

epsrate = constant strain rate

The strain will be linear too and of course the strain rate will be constant.

Good luck,

Juzz
---------------------------------
Justin Onisoru
Researcher
Romanian Academy - Institute of Solid Mechanics
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