Iso-Spectral Rotating and Non-Rotating Beams
Ananth Kumar
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Abstract
It is shown that centrifugal stiffening effects in rotating beams can be countered by spanwise stiffness variation for a given mode. Smart materials such as magnetorheological elastomer can be used to vary the stiffness in a manner such that a given mode is destiffened. The flexural stiffness functions are demonstrated using a p-version finite element rotating beam code and represent a multifunctional rotating structure concept which can be used for active stiffness control.
Key takeaways
- Rotating beams are useful mathematical models for a number of structure such as helicopter rotor blades, wind turbine blades, gas turbine blade etc [1].
- In such rotating beams, the effect of rotation in increasing the frequency of the jth mode is countered by a characteristic variation of flexural stiffness along their length to give natural frequencies corresponding to a non-rotating beam.
- At these limits it can be observed that the fundamental frequencies of the equivalent rotating beams approach 0.
- But the FSFs give a basis for construction of beams that are nearly equivalent to non-rotating beams.
- The centrifugal stiffening effect of rotating beam can be overcome by designing the beam with special flexural stiffness variations which are obtained in this paper.
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