When setting restraint conditions in structural analysis, if there is a bolt mounting hole, the inside diameter of the hole in contact with the bolt or the surface in contact with the bolt head may be fixed to determine the restraint conditions.
In this case, a contact condition is given between the fixing bolt and the inside diameter of the hole.
The bolt is often metal, and if it is considered as a rigid body, the surface in contact with the contact condition will also behave as a rigid body. In other words, deformation around the fixing hole is not taken into account.
Here are the analysis results. You can see that the deformation near the fixing hole is almost zero.
Then, what kind of results can be obtained by conducting tests on actual equipment under the assumed analytical conditions?
It can be seen that the deformation shape and deformation of the hole do not match the analytical values.
To solve this problem, it is necessary to perform calculations that take into account the change in the contact state between the bolt and the hole at each time step.
LS-DYNA, which is widely used in automobile collision analysis, is good at this calculation.
LS-DYNA enables calculations that take into account the contact state at each time step.
When the same conditions were analyzed using LS-DYNA, the deformation of the hole can be taken into account, so the amount of deformation can be close to the value of the actual test.
However, the larger the change in contact conditions, the longer the calculation time and the higher the risk of errors occurring. It is a good use of LS-DYNA to determine approximate design values by general structural analysis and verify detailed analysis using LS-DYNA.
~Related Articles~.
▶ Weld Lines and Their Effects
▶ Mechanisms of gas burning
Comments