# Frequency step with loads to keep contacts preloaded **URL:** \ **Category:** General Questions\ **Created:** [December 5, 2023, 10:38pm UTC](https://prepomax.discourse.group/t/frequency-step-with-loads-to-keep-contacts-preloaded/1320 "2023-12-05T22:38:04Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![imgprojts](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@imgprojts](https://prepomax.discourse.group/u/imgprojts)\ **Post date:** [December 5, 2023, 10:38pm UTC](https://prepomax.discourse.group/t/frequency-step-with-loads-to-keep-contacts-preloaded/1320/1 "2023-12-05T22:38:04Z")
I have two plates that are bolted to each other and I want to do a frequency sweep step to find the modes of vibration. So I want to see what sort of simplification I can use to not have to model the screws. One idea was to have a friction contact and then apply a preload clamping force but it seems that the frequency step doesn’t allow loads to be added. So how could I simulate two plates bonded together that allow some slip while running a frequency step? ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [December 5, 2023, 10:44pm UTC](https://prepomax.discourse.group/t/frequency-step-with-loads-to-keep-contacts-preloaded/1320/2 "2023-12-05T22:44:35Z")
Check this recent discussion about the influence of contact on frequency and ssd results: [Steady State Dynamics Step with Contact stiffness](https://prepomax.discourse.group/t/steady-state-dynamics-step-with-contact-stiffness/1313) ---
**Author:** ![imgprojts](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@imgprojts](https://prepomax.discourse.group/u/imgprojts)\ **Post date:** [December 5, 2023, 10:47pm UTC](https://prepomax.discourse.group/t/frequency-step-with-loads-to-keep-contacts-preloaded/1320/3 "2023-12-05T22:47:20Z")
ha ha! I was just there skimming over to see if it related.