Material Selection for AC Motor: A Material Engineer's Perspective

You work as amaterialengineer in an electrical company and your managerhas asked you to perform certain tasks:Task I:AnAC motoris anelectric motordriven by analternating current(AC). The AC motor shown in figure 1 commonly consists of two basic parts, an outsidestatorhaving coils supplied with alternating current to produce arotating magnetic field, and an insiderotorattached to the output shaft producing a second rotating magnetic field. The rotor magnetic field may be produced by permanent magnets, reluctance saliency, or DC or AC electrical windings.Figure 1: AC motorAs amaterial engineer, your role is to select the best materials for the motors and other machines. Your manager asked you to do the following base on these two requirements: A-Reasonable quality.B-Reasonable cost.1-You were asked to design and manufacture the frame of the motor. Which material (cast iron,aluminium,or polyethylene) will you choose to manufacture the outer frameof the motorto obtain the highest hardness? Give reason for your choice.2-Based on the electrical material properties. What you will choose to manufacture the stator coils. (Aluminium, Copper or Plastic). Give reasons for your choice. Page 4of 743-To insulate the coils in the stator what will you use (Zinc, Steel or fiberglass). Give reasons for your choice.4-Youhavefounda failure in functionality of the motor andthat most of motors fail due to excessive heat of their winding. You were asked to design and manufacture anElectric Engine Motor Cooling Fin.Finsattached to the shaft help in heat transfer from the inside of the motor housing to the outer environment. Which material (Aluminium, concrete,or polyester) will you choose to manufacture the finsof the AC motorto obtain the highest heat transfer? Give reason for your choice.5-Will the fins be lighter in weight if it is made of Aluminium, concrete, or polyester? Explain your answer.6-Explain three types of metal corrosion that can be occurred in electrical motors, then suggest different scenarios to prevent the occurrence of these types. (Support your answers by drawings).7-Mention two corrosion types thatthe insulating materialin coilscan experience and how to solve such issues.Task II:1)Define the terms soft and hard magnetism by comparing the shape with their respective hysteresis curves. Give two examplesof a technological application for them.2) Figure 2 shows B-versus-H curve for nickel-iron alloy.a) What is thevalue of thesaturation flux density?b) According to this loop, describe how the losses can be found?c) What is the coercivity. Find its value from the curve?d) What is the remanence. Find its valuefrom the curve?