The Scaling Law for Finite Torsion of Elastic Cylinders

Abstract

The torque and forces normal to the end surfaces of cylinders of natural rubber were measured as a function of the angle of twist. The measurements were repeated on small cylinders cut from the larger cylinders to insure that the tests were on identical material. Plots of reduced torque and of reduced normal force versus reduced twist for the different sized cylinders coincide to within 1%. This result supports the simple material assumption of the classical theory of finite elastic deformations. An interesting instability was observed, and derivatives of the strain energy function were calculated.