GATE 2017 ME (ME2) – Question 43
A helical compression spring of circular wire has maximum shear stress 24 MPa under a compressive load. With the same load, both wire diameter and mean coil diameter are doubled. The maximum shear stress is ______ MPa.
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Correct answer: 6 to 6
Explanation
For fixed load, torsional spring shear is proportional to D/d³, with the curvature factor unchanged because D/d is unchanged. Doubling both dimensions multiplies stress by2/2³=1/4. Direct shear also scales as1/d². Thus maximum shear stress becomes24/4=**6MPa**.