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SDOF (mechanical simple oscillator)

Posted Dec 17, 2019, 3:09 p.m. EST Structural & Acoustics, Studies & Solvers, Structural Mechanics Version 5.3a 1 Reply

Enrico Borellini
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Hi, I've a problem with the mechanical simple oscillator. I do the system with node pinned, spring and mass, then I launch the calculation. I wait the sinousoidal graph, but the result is a sinousoidal graph tending to zero. I don't set a damper. Why ? Where am i wrong ?

P.s. I've attached the graph

1 Reply Last Post Dec 18, 2019, 7:03 a.m. EST
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago Dec 18, 2019, 7:03 a.m. EST

Hi,

It can be caused by numerical damping in the time-integration algorithm, even though the damping seems surprisinly strong here. If you are using BDF, try Generalized alpha instead. Solver settings, as wel as things like tolerances and time steps can affect the outcome.

Regards,
Henrik

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Henrik Sönnerlind
COMSOL
Hi, It can be caused by numerical damping in the time-integration algorithm, even though the damping seems surprisinly strong here. If you are using BDF, try Generalized alpha instead. Solver settings, as wel as things like tolerances and time steps can affect the outcome. Regards, Henrik

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