Tensile Test on composite panel (Ply Failure)

FahadShafiFahadShafi Member Posts: 2

I am trying to figure out the tensile strength of the composite panel and how does fiber misalignment influences it. The panel here is 2mm thick consisting of 0/4/4/0 degree plies each of 0.5mm. Using ACP PrePost, I applied multiple failure criterias to observe where exactly the ply fractures. For the standard displacement i.e. 2mm, I am getting the following failure contour for the top ply:

I don't know what does th, e1t and e2t stands for. I think from the legend it is safe to conclude that the entire red region has fractured. To find the localised region of failure, Should I reduce the applied displacement ?

Lastly, I wanted inquire about the stresses I am getting. In my opinion, these values are much higher.

Is the stress contour alright? Or have I messed up the boundary conditions ? (I applied fixed support on one tab, applied displacement along x on the other, and constrained the panel displacement in z and y directions)

Best Answer

  • sharveysharvey San Diego, CAPosts: 91Member
    Accepted Answer

    Hello @FahadShafi

    So, the e1t and e2t are max strain failure in the 1 direction (fiber) in tension, and correspondingly the e2t is max strain tension in the 2 direction. The th is Tsai Hill criteria. From the plot, it does show that failure is occurring. The legend shows the max to be 3.49 and from that plot I can not tell where. You should reduce the load or displacement to bring the failure closer to 1.0 Now 1.0 does not mean the part will fracture. It means the laminate will start to be damaged (which you typically wish to avoid). The residual load capability will depend on the laminate. Of course if you had all 0 plies, then failure can happy suddenly as there are no cross plies for the load to redistribute and even hold the matrix together, etc. I would reduce the loading yes. For the stress plot, you typically look at stress components (3 normals and 3 shear) that are in the fiber or matrix orientation. Looking at scalar equivalents like Max Principal or Von Mises is less common since there is not often an allowable to compare to. The strengths of the material are measured in the fiber/matrix orientations. The stress contour looks reasonable, albeit high. The layup while symmetric is not balanced and when you pull you will get some coupling behavior. If you were to free up the y and z constraints on the end you pull on you will see the end tab will deflect and not extend just in x. Let us know if this helps. Thank you.

    Sean Harvey


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