Hello Software: SolidWorks 2023 sp3; Simulation Premium license I performed a random vibration simulation of a "complex" mechanical system.
All the simulation parameters seem to me to be well configured;
After the frequency analysis, I obtain a mass participation > 80% for the three directions.
When analyzing the results "Resulting displacements" I obtain a result that is inconsistent with respect to the fixation system (the excitation base) i.e. the whole system moves in the direction of excitation and this even at the level of the fixations.
You will find an image explaining the problem. PS: the 4 crosses represent the anchor points.
Do you have any advice on how to fix this problem? Does this type of problem require a specific setting that I missed?
First of all, welcome to the forum where you will meet a lot of top Pros in all the features and trades covered by SW, including PDM, macros, etc...
For your problem, for what I understand, can you confirm that 1°) you have done a static analysis 2°) that you have done the frequency analysis 3° ) Have you also done the dynamic study since you don't mention it in your message.
I ask this last question because what you say about "resulting displacements" catches my attention.
1- No 2- Yes 2- Yes. I don't really understand the question there. I have created a new linear dynamic random vibration study. After the configuration, I have the possibility to see the constraints of VonsMises and the Displacements
If I may, it seems to me that you are making an incorrect deduction.
Why do I ask if you did a static analysis first? ==> is that it allows you to check if your contacts and especially if your ASM is fixed somewhere.
==> frequency analysis can only be used to calculate frequencies and associated eigenmodes (frequency Hz). But be careful , this does not calculate either the constraints or the displacements. This shows a distortion but you should not take into account the table on the right URES or other.
==> the dynamic study is based on frequency analysis, which is therefore a prerequisite. Indeed, these use frequencies and eigenmodes to indicate the response of the structure to one or more dynamic loads. What adds time is since the efforts vary according to the weather. Also be careful, the results are given for each step, so the beginning and the end do not necessarily correspond to the result of the static study at the beginning. You have to set up the maximum constraint on each time step
These are the main points I can make because I no longer have the PRO version because I no longer use it (I can only do static with my 2022 version)
Thank you for your remarks. Indeed, frequency analysis makes it possible to determine the natural frequencies of the system and vibration analysis is based on frequency analysis.
Concerning the static analysis: indeed it can allow an evaluation of the assembly.
It turns out that I redid the simulation with a single piece. The room I took is the room where the anchors are. I find the same phenomenon of displacement of the part with the same displacement value (1.4m)
It's a question of degrees of freedom, if you allow your component to move in one direction, it will not deprive itself of it. Restart your static study with new displacement limitations until you obtain coherent values (deformation, stresses, etc.) and then use these settings for your vibration study.
If I may say so, and if I myself have understood correctly, you have to start from a static analysis to do the frequency since it does not calculate either the constraints or the displacements.
In other words, if your static analysis is not well configured, the other analyses cannot be correct, since we recover the contacts, forces etc... It also makes it possible to realize that the static study forces are less important than in dynamics. Kind regards
It is therefore written that: The following types of imposed displacements are not supported for the excitation of the selected base: Symmetry, Pivot, On a cylindrical face, and On a spherical face.
So in my case I had used excitation of the selected base on cylinders.
I used the uniform excitation of the base which is applied to all the imposed displacements so I have a single imposed displacement which is an embedding that takes into account the excitation. As a result, I no longer have to move the system. CQFD.
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