UNIVERSITY of PLYMOUTH

 

MECH115: Engineering Science 1

 

Tutorial examples: - Weight & Life Cycle                           

 

 

  1. In a previous tutorial question the shafts shown below were found to have the same polar moment of inertia (J) of 982 cm4. If the maximum allowable shear stress in the material is 70MN/m2 find the torque which can be transmitted by each shaft. If the material density is 9.8 g/cc, find the weight for a 1 meter length of each shaft and hence compare the strength to weight ratio of each. [13750 & 11460 Nm, 76.97 & 31.07 kg, 178.6 Nm/kg & 368.8 Nm/kg]

 

 

 

 

 

 

 

 

 

 

 

 


  1. For the hollow shaft in Question 1 find the inner diameter which gives it the same strength as the solid shaft. Find the percentage reduction in weight.  [9.667 cm, 49.5% reduction]

 

  1. Compare the maximum bending moment each of the sections below can sustain if the maximum allowable stress is 90 MN/m2. [937.5 Nm, 390.8 Nm]

 

 

 

 

 

 

 

 

 

 

 

 

 

 


  1. What height is needed to make the RHS shown in Question 3 the same strength as the solid section. Compare the weight of a 1 m length of each of the equal strength sections. [ 8.7 cm, 12.25 kg & 5.24 kg]

 

  1. Investigate and report on the material used for making a final drive shaft on a typical motor vehicle, and the factor of safety to which to is designed.

 

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