Internal Code: MAS5707
You have been contracted by the Minister of Defence to tender for the contract to oversee the installation of a new RADAR system The Radar system is modelled as a single degree of freedom with mass 20kg and spring stiffness 75000 N/m. Ignore the effect of damping. The
rotating part of the RADAR imparts a force of 1000sin(?t) and is designed to rotate at three different speeds: 5Hz, 10Hz and 15 Hz.
The tender is by open competition, which will be judged not only on the amount of vibration reduction in the radar system but also on the minimum increase in mass and the cost of the device. The cost of each extra kg is $1 and the cost of each 1000N/m is $1. In order not to interfere with the supporting structure the minimum resulting natural frequency allowed is 2Hz.
• Explanation of the theory used
• The design of the absorber where only the reduction in vibration level is considered
• The design of an absorber where vibration level increases in mass and cost are considered.