Question

1. There are three types of harmonic excitation: direct excitation, bottom excitation, and rotational imbalance. Compare and analyze the similarities and differences in the response characteristics of the three harmonic excitation and integrate these three problems to describe the characteristics of the general harmonic response.

2. Measurement equipment applied with rotational unbalanced harmonized excitation, and there is a wheel-balance machine used to change tires of a car. Investigate and explain the necessity and operation of this machine and how it works.

3. Accelerometers are constructed using the principles of bottom excitation. Obtain the damping ratio to increase the amplitude accuracy of this accelerometer.

Answer 1

A vehicle runs smmothly when there is negligible unbalance . But when there is consdierable unbalance in wheel due to asymmetrical mass distribution lead to periodic forces acting on axle that further affect steering wheel that starts oscillating and vibrating . Consequently , disturbances are produced and riding becomes difficult. So in order to overcome this problem wheel balance machine is required.

Working of wheel balance machine:

1.It equalizes the weight of combined tire and wheel assembly so that it can rotate or spin smoothly at very high speed. In this machine, whole wheel assembly is put on a balancer whose centre coincides with the centre of wheel and spins it to determine the location where weight should be put to balance the unbalanced mass.