The state of stress at a point in an elastic material, with yield stress of 200 MPa in simple tension, and Poisson's ratio 0.3, is as shown in the figure.
The permissible value of σ by maximum principal strain theory is
σ1=1.4σ
σ2=−2σ
According to maximum principal strain theory,
∈1≤σyE
∴σ1−μσ2≤σy
1.4σ+0.3×2σ≤200
2σ≤200
∴σ=100MPa