Hi Qinghai Jin,
Your Simulation study seems very interesting.
Random vibrations are a bit tricky. Can you please attach the model so we can have a closer look at your results.
Please use the pack and go to gather all related files.
Sorry, Mohamed EI Orche,
The design is in Patent pending, I don't think it is applicable to release it here now.
The problem is found just right now. it needs some treatment the connections in between the top cover and the bottom lid.
in other words, the Transmissibility in between parts is very very low if the connections is not setup right.
Indeed, The contacts/connections are very critical for accurate results.
make sure you have a good quality mesh as well.
Are you getting reasonable stress values now ?