strange IMU sensor behaviour

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I have an IMU in my model. I have the following behaviour:

• I apply a force in z-direction bigger than g to a the model. The body is lifted and the IMU shows the correct acceleration in z-direction.
• Additionally I add a torque in x-direction to the same model after it has been lifted after some time. The body will sink since the force on the body in z-direction is split in a component, which lifts the body and a component, which accelerates the body in x-direction. Also this increasing acceleration in x-direction is being shown correctly by the IMU sensor.
• When I now remove all forces, the body falls on the floor. But now I encountered the problem, that the IMU in x-direction oszillates +/- around the last value the IMU had, before it hits the ground.

What could be the reason for this? Actually the acceleration in x-direction should be set zero by the end, since the acceleration on the body in x-direction should have been neutralized by the friction.

Kind regards andi