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Unknown expression in Random Vibration example model

Posted 06.11.2025, 06:40 GMT-5 Modeling Tools & Definitions, Studies & Solvers, Structural Mechanics Version 6.1 0 Replies

Marco Norambuena

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I'm trying to replicate one of COMSOL's example models, called "Random Vibration Test of a Motherboard". I'm following this example to learn how to apply this study in another simple mode. The the motherboard example there is an expression that I have been unable to identify its origin or definition.

In Component1>Definitions>Variables1 there are three variables called a_absX, a_absY and a_absZ, they are defined by an average function aveop1() and an expression solid.a_abs_rvX, solid.a_abs_rvY and solid.a_abs_rvZ. Where each is described as an Acceleration in each direction.

I have been unable to find/identify where solid.a_absX(YZ) is defined. If I use it in my own model, when I try to evaluate the 'Global Evaluation Sweep' that contains this variable as rvib1.psd(a_absZ) I get an error saying thet solid.a_abs_rvZ is an undefined variable.

Could someone please explain where/how the solid.a_abs_rvZ(XY) expression is defined? Best regards.

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