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Difficulty: MediumStructural Shapes and Profiles

A mechanical design requires a structural component to act as a drive shaft, meaning it will primarily experience twisting forces (torque) along its longitudinal axis. Evaluate this statement: A closed hollow circular tube provides greater torsional stiffness and resistance to twisting than an open structural shape, such as an I-beam or C-channel, of equal weight and material.

Answer: Answer

Answer

True
The statement is accurate. For a given weight of material, a closed hollow circular profile is the most efficient cross-sectional shape for resisting torsional (twisting) loads because it distributes material in a continuous loop along the outer edge. Open profiles like I-beams or C-channels are designed specifically for bending moments and are highly susceptible to warping under torsion.

Step-by-Step Solution

1
Identify the primary force acting on the structural component based on the given scenario.
The component acts as a drive shaft, which means it experiences twisting forces, known as torsion or torque.
Different structural shapes are optimized to resist specific types of mechanical forces (e.g., bending, compression, torsion).
2
Analyze how different cross-sectional profiles handle torsional loads.
Closed profiles (like circular tubes) resist torsion efficiently, while open profiles (like I-beams or C-channels) have low torsional stiffness.
Torsional stress is best resisted when the material forms a continuous, unbroken loop far from the central axis, maximizing the polar moment of inertia.
3
Evaluate the accuracy of the statement based on the mechanical analysis.
The statement correctly claims that the closed hollow circular tube provides greater torsional stiffness than an open shape of equal weight.
This aligns with the fundamental mechanical principles governing structural profiles under torsion.

Key Concept

Torsional strength of closed versus open structural profiles
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Topics

Structural Shapes and Profiles

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