Answer Happy

PROBLEM STATEMENT AND DESIGN CRITERIA: Design a driveshaft for an automobile. Specifically, there are five design criteria that must be met: (1) The shape constraint is that the materials must be able to be fabricated into the length and diameter requirements of the driveshaft, which are variable, depending on the size of the vehicle (see Table 1). (2) The static torque, critical rotational speed, and twist rate of a typical driveshaft must be met, which are variable, depending on the size of the vehicle (see Table 1). (3) The material must meet the maximum and minimum service temperatures of the driveshaft, which are typically -40 to 130°C. (4) The driveshaft must resist environmental degradation - for example, humidity, engine oil, road salt. (5) The driveshaft must be resistant to impact. The specifications for criteria (1) – (3) are summarized in Table 1.
Compact Medium-Sized Cars Cars Light Trucks Medium-Sized Heavy-Duty Trucks Trucks 1.14 70 1.70 1.40 75 2.83 1.91 95 3.39 1.91 100 8.14 2.54 114 10.85 12000 7200 6000 3000 5400 Length (m) Diameter (mm) Static torque (kNm) Critical speed (r min!) Twist rate (ºkNm-'m-') Maximum service temperature (°C) Minimum service temperature (°C) 7.5 5.0 3.0 2.0 0.8 120 120 130 110 90 -40 -40 -40 -40 -40 Source: G. Lewis, Selection of Engineering Materials. Copyright © 1990 by Prentice-Hill, Inc. Table 1: Design Specifications for a Typical Automotive Driveshaft.