Difficulty: Easy
Correct Answer: at the fixed end
Explanation:
Introduction:Bending failure typically initiates where bending moment is maximum. For a cantilever with an end load, recognizing the bending moment distribution is key.Given Data / Assumptions:
Concept / Approach:Maximum bending moment occurs at the fixed support for a cantilever with end load. Extreme fiber stress is largest there, so yielding/crack initiation starts at the fixed end section.Step-by-Step Solution:
Shear diagram: constant along span; bending moment varies linearly from 0 at free end to Pl at fixed endMaximum σ_bending at fixed end: σ = Mc/ITherefore, failure initiates at the fixed endVerification / Alternative check:Comparative check of stress magnitudes along the beam confirms the fixed section is critical.Why Other Options Are Wrong:
Common Pitfalls:Confusing maximum deflection (free end) with maximum bending stress (fixed end).Final Answer:
at the fixed end
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