Structural characteristics of spinning pretwisted orthotropic beams

Abstract This study investigates the structural characteristics of spinning pretwisted orthotropic beams by the finite element method. This structural element can be used to model fluted cutting tools such as the twist drill bit and the end milling cutter, etc. The objectives of present study are as follows: (1) to derive the equations of motion which govern the lateral vibration of spinning pretwisted orthotropic beams by the Hamilton's principle. The beam is assumed to follow the Euler and Timoshenko beam theories, respectively. The rotary inertia and axial force are also included. Then the Galerkin method is applied to obtain the finite element models. (2) To investigate the structural stability of the spinning pretwisted orthotropic beam from the eigenvalue analyses of the finite element models obtained above. Plotting the figures of natural frequency vs rotational speed and rotational speed vs axial force, respectively, to find the instability regions and types. The effect of pretwist angle on the elastic stability is also studied.

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