McDesign25
Mechanical
- Feb 15, 2003
- 23
Could someone please tell me if my design methodology is correct for checking the stress and deflection of snap locks for plastic.
1) Model up the snap beam
2) Apply material (yield strength, modulus of Elast. from vendor sheets)
3) Apply constraints, loads, mesh.
4) Run FEA.
5) Check initial stress and deflection, iterate load and mesh until deflection and stress are acceptable (Just to get in the ballpark).
6) Obtain stress vs. strain curve for material from the vendor, and find the yield strain and stress, then apply a slight safety factor, i.e. 75% of the yield strain, and find the stress at that strain. Then calculate the secant modulus, and import that into the material properties. Then, iterate the load until the stress reaches the stress we calculated earlier. We continue iterating the load, snap/beam geometry, and until we are happy with the deflection. FYI, we are using Cosmos for FEA, if that helps.
Thanks.
1) Model up the snap beam
2) Apply material (yield strength, modulus of Elast. from vendor sheets)
3) Apply constraints, loads, mesh.
4) Run FEA.
5) Check initial stress and deflection, iterate load and mesh until deflection and stress are acceptable (Just to get in the ballpark).
6) Obtain stress vs. strain curve for material from the vendor, and find the yield strain and stress, then apply a slight safety factor, i.e. 75% of the yield strain, and find the stress at that strain. Then calculate the secant modulus, and import that into the material properties. Then, iterate the load until the stress reaches the stress we calculated earlier. We continue iterating the load, snap/beam geometry, and until we are happy with the deflection. FYI, we are using Cosmos for FEA, if that helps.
Thanks.