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Static simulation and real-life tests do not match

Question asked by Yari Wesseling on Jan 7, 2021
Latest reply on Jan 8, 2021 by Tadas D.

Hi,

 

I'm currently studying mechanical engineering and some classmates and I are doing an assignment where the objective is to hand-calculate, simulate, and test a certain object for deformation and stresses. For this object, we chose crossbow limbs, these ones to be specific: Link. (website is in Dutch)

 

While we're not sure which specific steel type the crossbow is made of, we ran the simulations with S235JR.

We exactly modeled the limbs in Solidworks and ran a bunch of static simulations on it after doing the tests. Our tests told us that the limbs would begin to show plastic deformation between around 175N to 210N (on each limb). Solidworks however tells us that at 30N on each limb, the edges of the limbs far exceed the 235 yield strength (in Von Mises stress):

 

We do not understand why this stress is so high yet during our tests the crossbow was not even near plastic deformation at 30N. We checked the displacement in Solidworks against the displacement we measured in the tests and they differ by no more than 5% (keeping in mind measurement errors during the tests).

Is there something we're missing or is this an error we made in the simulation?

 

Thanks in advance for any help, if something is not clear I will elaborate in the comments.

Also, English is not my native language so If there are any errors I apologize.

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