'Spring mount - modal dynamic analysis' simulation project by ahmedhussain18


#1

I created a new simulation project called 'Spring mount - modal dynamic analysis':

This project demonstrates the benefit of using modal dynamic analysis case over a simple linear dynamic analysis case.


More of my public projects can be found here.


#2

Spring mounts are commonly used to isolate broad range of low disturbing frequencies produced by the equipment operating in wide vibration sensitive spans such as upper level of buildings. A generator operating at 4th floor of a building can be a good example. In this project the dynamic damped response of the spring mount was observed by applying a pressure on the top plate and releasing it immediately.The generator geometry used for thumbnail was provided by ievgen whereas the geometry of spring mount was created on Onshape and than uploaded to SimScale platform. Due to symmetry, only quarter of the model was taken in to account. The geometry used is shown in the figure below.

It was than meshed using Parametrized tetrahedralization tool on platform. the mesh is shown in the figure below.

The purpose of this analysis is to show how doing the modal dynamic analysis for the linear dynamic case can help in attaining nearly the same results in less computation time. Therefore first simple linear dynamic analysis was performed. The base of the spring was restricted and symmetry was applied. Than a pressure of 0.1 MPa was applied on the red highlighted face for a short interval and than released immediately. This causes the plate to oscillate and than the displacement and vonMises stress values were computed on node_1 and node_2 respectively.

Same case was performed using modal analysis solver. Compared to the general dynamic solver, modal dynamic solver computes the results based on the eigenmodes of the system which is much faster. The analysis was run for first 5 modes and took 13 min. to complete compared to 16 min. in case of simple dynamic analysis case. The difference wasn’t that much considering the mesh was small and the analysis didn’t run for longer duration. One can also see that the applied load actually corresponds to the very first eigenmode of the system, therefore 5 modes were enough to get the right results. If it would have been a different mode e.g. 10th eigenmode than one have to consider running analysis on 15 mode since than running on only 5 modes would have given wrong results.

Below is the comparison of displacement and vonMises stress results on node_1 and node_2 respectively. One can see a good comparison between the two cases.

Comparison of displacement on node_1

Comparison of vonMises stress on node_2