Answer Happy

Part C Only Please
1. A motor is mounted on a beam as shown below and runs at a constant speed of 3500 rpm. At this speed, the beam oscillates. The motor has a mass of 8 kg, the unbalanced part of the motor has a mass of 4kg and an eccentricity of 0.3mm. The steel beam is 15cm long, 10cm wide and lcm thick. 177 1. (a) Determine the equivalent mass and stiffness of combined system. (4 marks) (b) Find the mass and stiffness of a suitable vibration absorber if the available clearance for the absorbers motion is 2.5 cm. (4 marks) (c) The motor is now run at a speed equivalent to the natural frequency of the system. (i) Find the mass and stiffness of a suitable vibration absorber if the frequencies of the 2DOF system are to be at 25% away from the resonant frequency. (6 marks) (ii) What are the two running speeds (rpm) that are best avoided for the new system. (3 marks) (ii) Confirm that this new absorber does not exceed the clearance available. (3 marks)