New answers tagged

1

I'm not an expert, but that vertical line in the phase is usually when transitioning over a critical rotational velocity of a shaft. This happens when the excitation frequency "transverses" the critical frequency of the shaft. The displacement of the shaft can be derived for an ideal motor (no damping): $$ y = \frac{e\cdot \omega^2}{\omega_n^2 - \...


0

The load cell specification should include the frequency response. Bear in mind that the load cell itself is a dynamic system (e.g it can be modelled as a mass and spring) which may affect the dynamic response of the device under test.


0

Isn't the equation of motion more like this: \begin{align} \left( \frac{2\,ma^2}{3} + Ma^2\right)\,\, \frac{d^2 \theta}{dt^2}\, =\, - \, \frac{amg}{2} \, \cos(\theta) \, + \, \left(\frac{amg}{2} + aMg \right)\, \sin(\theta) \, - \, aK\left(2a\, \sin\Big(\frac{\theta}{2}\Big) \, - \, l_0\right) \cos\Big(\frac{\theta}{2}\Big) \end{align} The easiest way is to ...


1

If we assume a single degree of freedom vibration of the beam as a spring and mass system and substitute beam with half of its mass concentrated at its center, which is not grossly wrong and we also assume no damping, the beam will vibrate under its natural frequency and a rough estimate of its vibration amplitude can be substituted for its deflection. We ...


2

In the section "The Multiple DOF System" the Comsol document says It has been assumed that the mass matrix normalization of the eigenmodes is used and that the damping matrix can be diagonalized by the eigenmodes. Eigenvectors are assumed to be mass normalized in any mathematical derivation using them, unless somebody wants to be deliberately ...


Top 50 recent answers are included