The electrodynamic shaker shown in Figure P18.49 is commonly used as a vibration tester. A constant current is used to generate a magnetic field in which the armature coil of length l is immersed. The shaker platform with mass m is mounted in the fixed structure by way of a spring with stiffness k. The platform is rigidly attached to the armature coil, which slides on the fixed structure thanks to frictionless bearings.
a. Neglecting iron reluctance, determine the reluctance of the fixed structure, and hence compute the strength of the magnetic flux density B in which the armature coil is immersed.
b. Knowing B, determine the dynamic equations of motion of the shaker, assuming that the moving coil has resistance R and inductance L. c. Derive the transfer function and frequency response function of the shaker mass velocity in response to the input voltage VS .
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What will be an ideal response?
Searching for ways to cut costs and increase profit, one of the industrial engineers at Home Comfort Furniture Manufacturers, Inc. determined that the equivalent annual worth of an existing machine over its remaining useful life of 2 years is $70,000 per year. The IE also determined that used machines like the one currently in use are not available any longer, but the defender can be replaced with a challenger that is more advanced. It will have an AW of $80,000 if it is kept for 2 years or less, $75,000 if it is kept between 3 and 4 years, and $65,000 if it is kept for 5 to 10 years. If the company uses a specified 3-year planning horizon and an interest rate of 15% per year, determine (a) when the company should replace the machine, and (b) the AW for the next 3 years.
What will be an ideal response?
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A) Wheel bearing (chassis) grease B) Silicone grease C) Anti-seize compound D) Synthetic grease
Who showed that two parallel wires carrying currents experience the force of attraction or repulsion depending on the current direction?
A. Georg Ohm B. Hans Christian Oersted C. Joseph Henry D. Andre Marie Ampere