I performed one random vibration analysis for one lights chassis after modal analysis( it shows 140HZ for the whole chassis natural freq. ),

Its structure is pretty close to LED street lights,  I got the bottom lid/cover is overstressed rms over dozens of times. the lid looks similar to power box lid.

I double checked the connections in between lid and chassis bodies. I tried its bond, rigid connections or treat the lid as remote mass.

the stress plot results are still too big as common sense.

The following plot doesn't include lid

the following plot has lid

the following plot is lid only

Please advise, thanks first.

Happy weekend to everybody.