FEA Tensile Test of Dog Bone Specimen

[Anonymous]

Dear People,

This is a Dog Bone Model. I would like to do Tensile test in FEA Simulation. So, I would like to know where to apply boundary conditions. Let say if the left side is the load side and right side is the displacement constraint side. I have marked 5 places. I would like to know where to apply load and constraints on the marked 5 sections. Please let me know. Thanks in advance.

FYI

Please see the attached hand sketched model for your reference.

[John_Holtz]

Hi @Anonymous

Since you are trying to duplicate a physical test, you should use loads and constraints that best duplicate the physical test.

For example, I can imagine that the test apparatus uses clamps to hold the dog bone over the area between 1 and 5. If this is how it works, then you should constrain those faces on one end (the right side) with fixed constraints. Chances are the apparatus clamp moves a known distance on the other end, so use Constraints > Prescribed Displacements (on the left end) to apply the load. Just like the apparatus measures the applied force, you will measure the calculated applied force for the input displacement by looking at the reaction force results.

[Anonymous]

Okay, but how do I give the load. Since it is an uniaxial tensile test, the load was 100mm/min.So, how do I describe the load?  Should the load condition be displacement or velocity since the load is 100mm/min?

Will it converge until it breaks or how it works? Please let me know.

[Anonymous]

What are you trying to learn from this simulation?

I'm not sure that you need to worry about all 5 of those places if this is just a tensile test.

Fix one end and pull on the other if you just care about your typical elongation and approximate failure point. It needs to be non-linear and you will want a nice quality mesh.

[Anonymous]

I have the tensile test experiment data and I want to simulate and compare it with the experiment. The load in the uniaxial experiment is 100mm/min, Could you please explain me about the type of load that should be applied? If it is displacement, should I give the increment till required time (let say till 60 sec)?

Thanks in advance

[John_Holtz · Accepted solution]

Hi @Anonymous

Do you have your results yet? Just run it and see what happens!

There are only two options for a large displacement, nonlinear analysis:

1. Nonlinear Static. Since a static analysis is independent of time, there is no velocity associated with the analysis. You are going to guess what the maximum displacement is that you want to simulation, and apply that displacement as I described previously. In theory, the analysis will be able to stretch the model to infinite distance, infinite stress because nonlinear static does not model parts breaking. From the calculated stress results, you can judge when the part will fail. (In reality, the analysis will fail to converge at some load just because it is a model that is limited by math.)
2. Event Simulation. This is a time-dependent analysis, so in theory you could apply a displacement of 100 mm over 60 seconds of time. However, Event Simulation is for dynamic events like impacts that occur over time spans of milliseconds. You will not be able to use Event Simulation to model something that occurs over seconds or minutes of time.

[Anonymous · Accepted solution]

Here's a video I made that is very close to what you're trying to do.

https://youtu.be/6Nh4gHGHHZ4

[Anonymous]

To add to what @John_Holtz said, strain will also be critical to determining actual catastrophic failure because it is common for a stress strain curve to flatten or even dip down below ultimate strength.

[Anonymous]

Thank you very much for your help.

[Anonymous]

This video is a good example and resembles my test. Thank you