dampers in transient mechanical simulation with pde toolbox

Hi all.

I would like to know if pde toolbox is able to help me in the following case.

I want to compute the transient time-response of a mechanical structure experiencing a displament at some of its boundaries.

My structure is composed of a (complex) 3D rigid-body structure, imported from STL file, and 3 identical dampers fixed beneath this structure.

Same boundary condition is applied to the bases of each one of the dampers, and it is a time-varying x translation conditon.

I know characteristics of the dampers in term of resonant frequency and damping coefficient (in 3D), and I would like to modelize them with those parameters. That is, I would like to put in my model 3 'dampers equivalent' instead of 3 'realistic' damper geometries and material properties (that I don't have).

I read in pde toolbox documentation that it is possible to apply 'TranslationalStiffness' load on surfaces or on edges. It looks appealing to me, but I don't really understand the concept of distributed stiffness on surface or edge.

Is it possible to use this 'TranslationalStiffness' on a surface to simulate a 3D damper-equivalent with a given resonant frequency and damping coefficient (in 3D)?

thanks

Answer 1

[Prathamesh]

Hi @Djabba,

I understand that you are computing the transient time-response of a mechanical structure experiencing a displacement at some of its boundaries by applying 'TranslationalStiffness' load on surfaces or on edges from the ‘PDE’ toolbox.

To accurately model the transient time-response of your structure, we need to use an approach that can account for both stiffness and damping. You can use a ‘lumped parameter model’ to do this.

Instead of trying to model the dampers as a continuous, distributed force on a surface, this method treats each damper as a separate element with its own unique properties. You would represent each of your three dampers as a spring-damper element and connect them to the specific points on your structure.

Refer below MathWorks Documentation:

Structure Mechanics: https://www.mathworks.com/help/pde/structural-mechanics.html

Lumped Elements: https://www.mathworks.com/help/simulink/ug/model-a-mechanical-system.html