Find load at fracture for beam
Find load at fracture for beam
(OP)
Is it possible to predict the load at fracture for a simple FEA beam with some certainty using linear FEA package? For example, I am interested in finding the bracketed range of forces that could produce a failure of a cantilevered beam that is fixed on one end and a concentrated force on the other end. However, I only have use of a linear static FEA package, and was wondering if this was adequate to determine the force at failure based on the von mises stresses and looking at the material properities, stress v. strain curve. If I could achieve this with a simple cantilevered model, could the same results be applied to a more complex FEA model. The material is a plastic polymer with a 70% elongation at failure, 6% at yield and has a limited linear range up to 1% elongation, before it becomes non-linear. Is there any technical papers or rules of thumb for estimating the breaking force assuming the loading is applied slowly, i.e. the same rate as the material property data? Thanks.





RE: Find load at fracture for beam
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RE: Find load at fracture for beam
Another approach would be to use you linear FEM with iterations. Apply a small load, output the deformation, now use this as a starting point for the next run. Be sure to apply the new material stiffness for each run. Examine the extreme fiber stress compared to the rupture allowable of the material. (von mises is for yield as Fk mentioned).
Now, depending on the shape of your beam, the failure may be stability of the compression side of the beam. Even a square shape would probably fail in block compression well before material rupture.
If this is a usual analysis that you perform, a nonlinear FEM program with physical testing would be helpful. A testing program would be the best way to verify your eventual method.
RE: Find load at fracture for beam
I would have agreed with your initial thoughts.
Garland