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Statics analysis of Multi-body dynamics

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Hello,

I made a mass, spring, damping system with multibody dynamics component. I already fished analysis of time depent motion with my system. but, it has a lot of errors when I solve this system with stationary solver. include symetric matrix error, singular matrix error, division by zero, etc ...

I want to know how can I do static analysis with my multibody dynamics system.

Thank you


1 Reply Last Post 14.05.2019, 01:57 GMT-4
Pawan Soami COMSOL Employee

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Posted: 6 years ago 14.05.2019, 01:57 GMT-4

Hello Park,

It is difficult to say anything without seeing the model file however a fundamental difference between a time dependent analysis and stationary analysis is the presence of inertia and damping forces (or resistances) which are included in the former but not in latter. For a simple system of mass-spring-damper, in stationary analysis, it is just a balance of all spring forces to all applied loads.

So when you have a system, with rigid body dofs (degrees of freedom) present, it is possible to solve in time dependent analysis or frequency domain analysis but not in stationary analysis. Basically in order to find a stationary (static or steady-state) solution, you need to constrain all your bodies (or dofs) either directly or indirectly using constraints or springs.

Regarding the error messages like singular matrix, they will be automatically resolved once there is no rigid body dof in your system. Feel free to get back to me here or write us on support@comsol.com in case of further doubts.

Best regards, Pawan Soami

Hello Park, It is difficult to say anything without seeing the model file however a fundamental difference between a time dependent analysis and stationary analysis is the presence of inertia and damping forces (or resistances) which are included in the former but not in latter. For a simple system of mass-spring-damper, in stationary analysis, it is just a balance of all spring forces to all applied loads. So when you have a system, with rigid body dofs (degrees of freedom) present, it is possible to solve in time dependent analysis or frequency domain analysis but not in stationary analysis. Basically in order to find a stationary (static or steady-state) solution, you need to constrain all your bodies (or dofs) either directly or indirectly using constraints or springs. Regarding the error messages like singular matrix, they will be automatically resolved once there is no rigid body dof in your system. Feel free to get back to me here or write us on support@comsol.com in case of further doubts. Best regards, Pawan Soami

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