Fillet weld design – Nature of loading for parallel fillet welds Evaluate the statement: “Parallel fillet welds are designed for bending strength.” Select the correct response.
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AAgree
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BDisagree
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CAgree only for intermittent welds
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DAgree only for dynamic loads
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EDisagree unless weld throat is doubled
Answer
Correct Answer: Disagree
Explanation
Introduction / Context:Fillet welds are commonly classified by orientation relative to the applied load: parallel or transverse. Correctly identifying the governing stress (shear vs. normal) is essential for safe welding design.
Given Data / Assumptions:
- Parallel fillet weld: weld axis is parallel to the applied force.
- Design per elementary weld mechanics (throat area concept).
Concept / Approach:When the load is parallel to the weld axis, the weld primarily resists by shear along its throat area. Conversely, a transverse fillet weld (load perpendicular to weld axis) is governed by normal (tensile/compressive) stress—sometimes loosely termed “bending” in plates.
Step-by-Step Reasoning:Identify orientation: parallel fillet weld → shear on throat.Design equation: τ_allow ≥ P / (Σ throat areas).Bending checks are associated with eccentricities or transverse fillet welds, not the basic parallel case.
Verification / Alternative check:Standard weld design references classify stresses by orientation; parallel fillet welds are sized on allowable shear stress of the weld metal and throat area.
Why Other Options Are Wrong:“Agree” statements misidentify the governing stress; adding conditions (intermittent/dynamic) does not change the fundamental shear nature.
Common Pitfalls:Confusing fillet weld orientation; neglecting eccentric loads that can introduce additional moments, which is a separate check.
Final Answer:Disagree