Drop Test Simulation in ANSYS 1

[Talos]

Hello All, Hope somebody can help

We want to simulate the dropping of an object from a certain height onto a floor. The acceleration will be standard earth gravity and the part in question will have a point mass applied to the centre of gravity of the part. We want to simulate the stress and total deformation of the part upon impact.

I understand that you can use a system under classical ansys, but can we perform this under workbench if we assume the part will fall perfectly onto its bottom face


Thanks

Dave

 

[cbrn]

Hi,
I don't agree with the assumption "...will fall perfectly onto its bottom face".
In WB, as well as in Classical however, you need a transient analysis. Then, in order to simulate the crash against a rigid surface, you have two ways IMO:
1- build a plate of adequate length / width in order to make sure that the object won't "miss" the plate. Mesh it coarse, and assign it a very high stiffness (if you want to consider it rigid. In v.11.0, you can define the body as "rigid" directly)
2- add a Commands snippet and insert the APDL needed to define a rigid region, as you would do in Classical.

Then, you set up a contact pair between the target "rigid surface" (this will be the TARGET) and the surface(s) of the dropped body which can possibly hit the "ground" (these will be the CONTACT).
If in the previous step you used commands, you need to setup the contact pair via APDL as well.

Hope this helps or give some idea in some way...

Regards

 

[Talos]

Thanks cbrn

I don't know a great deal about APDL. I understand the concept of the TARGET and the CONTACT, but how do I simulate the movement of the one part towards the 'ground'. (ie if the part is falling from 10in its velocity won't be a high as if it were dropped from 10ft at the point of contact)
I probably havent described that very well

 

[cbrn]

Hi,
if you aren't familiar with APDL then disregard option 2 in my previous post.
You will have to define a TRANSient analysis, with a certain duration (pre-calculate by hand the time needed for the body to hit the "ground", and specify a duration somewhat longer than this, so you can see deformation / rebound / etc effects) and a certain number of steps. Specify global acceleration (e.g. 9810 mm/s, constant over all the analysis steps), fix-restrain the "ground" (also this restraint must be constantly applied over the steps).
Read the documentation for Transient analyses, it's very useful.
As "contact" settings, use preferably an Augmented Lagrange formulation, and carefully read the Contact Technology Guide about the settings to use for "normal stiffness" and "penetration tolerance", as these will highly influence your analysis (because most probably you will have a highly "unplanar" contact ).

Regards

 

[Talos]

Thats great, thanks for your help. Now know where i am looking

Thanks again