Learning Forum

[Ozen26]

Hi there,

I tried to make tensile test analysis for pla specimen and ı have problem..

I couldn't find PLA (polylactic acid) so ı added PLA as a new material fig.1. After ı ran some analysis on explicit dynamic and ı couldnt't see any fracture point, even ı saw exteremly high stress for pla's ultimate and yield stress. ı know ran with very small time but with the same time ı saw fracture with standart explicit aluminum fig. 4. 

Thanks for help.

[Armin Abedini]

Hi Ozen,

I think you didn't specify any fracture criterion for your material so the source of element erosion may be due to reaching the Strain Limit (it is accessible in Erosion Controls under "Analysis Settings" in the project outline). The default value is 1.5.

[Ozen26]

ı had been tried to change Erosion Controls value right now. Like a 0.5,1, 1.5 and 3. but it didn't change. how can ı determine fracture point for PLA material?

 

 

 

 

[Ozen26]

 

After ı gave extremly high displacement (like a 50 mm) ı saw breaking.Is 0,5 geometric strain limit okay? 

 

[Armin Abedini]

I see...I believe fracture strain of materials is best to be determined experimentally. If you look it up online, you might find other researchers or labs who reported this information for your particular material.

[Ozen26]

I found article about PLA's fracture strain. It says 0,8. I will check. Thanks for helping Armin.

[Long Nguyen]

Hello, can you help me take a photo of the analysis settings? I have a project similar to yours. After declaring the PLA material, I ran an explicit test but the result was that it did not create a destructive crack in the middle, but instead it was dented at both ends. The model I used is a Short, boxy bar, not a dog bone model like yours