Strength of Materials
Stress & Strain
GATE 2022
Medium
A structural member under loading has a uniform state of plane stress which in usual notations is given by σx=3P, σy=−2P and τxy=√2 P, where P>0. The yield strength of the material is 350 MPa. If the member is designed using the maximum distortion energy theory, then the value of P at which yielding starts (according to the maximum distortion energy theory) is
- 70 MPa
- B90 MPa
- C120 MPa
- D75 MPa
Explanation
Von Mises equivalent stress: σe=√(σx²−σxσy+σy²+3τxy²) = √(9P²−(3P)(−2P)+4P²+3(2P²)) = √(9P²+6P²+4P²+6P²) = √(25P²) = 5P. Setting σe equal to yield strength: 5P=350, so P=70 MPa.
Source: GATE ME 2022 Session 2 (ME-2) (2022)
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