Vibration of Rubber Cord

Abstract

Experimentally, a rubber cord seems to have characteristics of a string on one hand, and of a beam on the other. Equation of motion with a term of damping was introduced as for a rubber cord. Then the solution was compared with the results of experiments, and the dynamical characteristics of rubber obtained as rubber vibration isolators were taken into account. 1) Vibration of rubber cord with a concentrated mass. Linear vibration with one degree of freedom was assumed. Elastic modulus E calculated from this experiment was compared with static modulus. Values of E are thought to be adequate when the ratio between dynamic and static moduli is taken into consideration. 2) Torsional vibration of rubber cord. Shear modulus G^^- calculated in the same way was compared with the static shear modulus. 3) Free damped vibration of rubber cord. A term of damping was added to an ordinary equation of string. Results of experiments could be explained by an equation ∂²y/∂t²=a²(∂²y/∂x²)-2c(∂/∂t)(∂²y/∂x²), when an effective value of tension was taken into account.