Altair RISE

A program to recognize and reward our most engaged community members

Nominate Yourself Now!

Experiment Setting when Reproduce Example Guide - RD-E: 0800 Hopkinson Bar

Hi all, I am reproducing RD-E: 0800 Hopkinson Bar from the Example Guide. It's a tensile Hopkinson Bar Test.

I want to know the experiment setting of this test. Does the transmission bar be hold fixed during the test, or it moves freely with the whole system. This matters because it will affect how much stress and strain will be created in the specimen.

RD-E: 0800 Hopkinson Bar Guide: https://help.altair.com/hwsolvers/rad/topics/solvers/rad/hopkinson_bar_example_r.htm

Find more posts tagged with

Radioss

Accepted answers

HarishT

Hi Steve

Yes you are correct transmission bar need to fixed and velocity applied to the incident bar.

Regards

Harish

HarishT

Hi gauge length is 8 mm, and the specimen length is 16mm

RegardsHarish

All comments

HarishT

Hi Steve

Yes you are correct transmission bar need to fixed and velocity applied to the incident bar.

Regards

Harish

Steve_zz

Also, it seems that the Johnson-Cook Model given in https://help.altair.com/hwsolvers/rad/topics/solvers/rad/hopkinson_bar_example_r.htm might use a weird reference strain rate.

Here, in the second equation, the denominator of the logarithmic term should be 80 if I understand it correctly.

HarishT

Hi Steve,

In Radioss Johnson-Cook Model use the below equations to calculate the stress as shown on below picture.

As you said let me cross check the documenation its its a 80 or 0.08

Regards

Harish

HarishT

Hi Steve,

In documetaion there is slight mistake as shown in below picture.

Units used should be g mm ms MPa

Steve_zz

Thank you for confirming that. Would the documentation be updated with the correct value?

Steve_zz

Also, the https://help.altair.com/hwsolvers/rad/topics/solvers/rad/hopkinson_bar_example_r.htm does not specify the dimension of the specimen, but does provide a figure (Figure 4. Specimen geometry and cross-section (dimensions in mm)), showing that the Gauge length is 8mm.

However, by loading the project file, it seems that the gauge length is 4 mm, and the specimen length is 8 mm. I want to confirm this detail.

HarishT

Hi gauge length is 8 mm, and the specimen length is 16mm

RegardsHarish