Bolt failure analysis

Vibhor Rajput
Vibhor Rajput New Altair Community Member
edited June 2021 in Community Q&A

Hello Folks,

 

I am working on the bolt strength problem. I am using M10, 10.9 grade bolts. In the first step pretension is applied and 2nd step actual(external) load is applied which should cause the shear. But when I am checking results- Max shear is nearly same in both steps (Pretension- 352 Mpa and Actual load- 358 Mpa). Considering the shear criteria which is 0.5 UTS (10.9 bolt 1000 Mpa), how should I validate the bolt design? Most of shear stress is due to pretension. Using linear superposition in Hyperview and eliminating pretension from the step, Max shear is 53 Mpa. I am using optistruct as solver.

The bolts are actually failing in the testing.

 

Can someone please help me in validating the bolt design?

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Answers

  • Adriano A. Koga
    Adriano A. Koga
    Altair Employee
    edited June 2021

    Just a sanity check: Without pretension, applying only the external load, how much of stress you get? Is it comparable?

    As they're non-linear loadcases, due to contacts, linear superposition wouldn't apply well.

     

    The other point: for pretension are you using in the 2nd loadcase BOTH STATSUB(PRETENS) and CNTNLSUB to carry over the state from the 1st loadcase?

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