A part has been designed for kinematic function and its dime

A part has been designed for kinematic function and its dimensions cannot be changed. To minimize deflections under the same loading in all directions irrespective of stress levels, which of these materials would you choose: polyethylene polymer, silicon nitride ceramic, aluminium metal, titanium metal, stainless steel metal, carbon-fibre reinforced expoxy composite. Why?

Solution

To minimize deflections irrespective of stress levels one has to choose the material haing the largest value of youngs modulus, because deflection is inversely proportional to youngs modulus

Titanium Modulus = 113.8 GPa

Steel Modulus = 200 GPa

carbon-fibre reinforced expoxy composite = 70 to 80 GPa

Aluminium = 70 GPa

Silicon Nitride Ceramic = 170 GPa

Polyethylene polymer = 0.7 GPa

Therefore stainless steel is the best material to minimize deflection