vibrations

Fontanela instability in non-linear oscillators with cyclic symmetry

I wanted to bring attention to the very important Fontanela et al recent results in vibrations of cyclic structures like in turbine engines.

A ``small'' but interesting riddle from the theory of vibrations

A ``small'' but interesting riddle from the basic theory of vibrations. Haven't run into it in any physics/classical mechanics text/reference.

How to recover eigenvector components for specified displacements ?

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I have a problem visualising specified displacements from a modal/buckling analysis.

When solving the algebraic system of equations [K]{u}={f} resulting from FEA discretization, the vector {u} does not have components for the specified displacements, zero or not zero, because the corresponding degrees of freedon (dof) have been eliminated. To visualize all the displacements, even the ones that are specified, we recover them from the input data to create a longer vector {u|u*} where {u} are the active dof and {u*} are the specified dof, zero or not zero.

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Hi,

I´m analizing the modes of a structure but I don´t know how to plot the different modes (I only see the first one). I´m using  Adina 8.7.3.

Thank you very much!

gap of von mises stress between Ansys and Abqus

Hello ,

I am doing the correlation between Ansys and Abaqud for a shroud of cooling module (solid 92-C3D10) .I find the coorelation is perfect in frequency , but when i do the powerspectral density analysis, i noticed a gap of 10-20% on the peak value of nodal von mises stress ,  i'd like to know the reason of the diffrence .

Thank You .

Free Vibrations of Nonuniform Timoshenko Beams II

This post contains the equations of nonuniform Timoshenko beam theory, a seconf order finite difference method for the solution of the free vibrations thereof and a Scilab computer program implementation. The implementation also allows for the calculation of static deflection for a user specified load distribution that can also contain point loads. A number of static and free vibration examples are given.

I hope this can be useful to students and others.

Rotor dynamics

“Project of automatic balancing system for rigid
rotors”

ABSTRACT

The paper presents the
conceptual design for the automatic system for balancing rigid rotors.

Lord Rayleigh 