Using the information in Problem P1.8, design a composite torque tube that is 30% lighter than the..

Using the information in Problem P1.8, design a composite
torque tube that is 30% lighter than the steel tube but has the same torsional
stiffness. Will the axial stiffnesses of these two tubes be the same?

Problem P1.8

The shear modulus (G) of steel and a quasi-isotropic carbon
fiber– epoxy is 78 and 17 GPa, respectively. The mean diameter (D) of a
thin-walled steel torque tube is 25 mm and its wall thickness (t) is 3 mm.
Knowing that the torsional stiffness of a thin-walled tube is proportional to
D3 tG, calculate:

1. Mean diameter of a composite tube that has the same
torsional
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Using the information in Problem P1.8, design a composite
torque tube that is 30% lighter than the steel tube but has the same torsional
stiffness. Will the axial stiffnesses of these two tubes be the same?

Problem P1.8

The shear modulus (G) of steel and a quasi-isotropic carbon
fiber– epoxy is 78 and 17 GPa, respectively. The mean diameter (D) of a
thin-walled steel torque tube is 25 mm and its wall thickness (t) is 3 mm.
Knowing that the torsional stiffness of a thin-walled tube is proportional to
D3 tG, calculate:

1. Mean diameter of a composite tube that has the same
torsional stiffness and wall thickness as the steel tube

2. Wall thickness of a composite tube that has the same
torsional stiffness and mean diameter as the steel tube

3. Difference in weight (in percentage) between the steel
tube and the composite tube in each of the previous cases, assuming equal
length for both tubes

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