Difficulty: Medium
Correct Answer: All of the above
Explanation:
Introduction / Context:Mohr’s circle is a powerful graphical tool for 2D stress transformation. It provides principal stresses, maximum shear stress, and normal and shear stresses on any oblique plane from a single diagram, unifying different combined-stress scenarios.
Given Data / Assumptions:
Concept / Approach:Mohr’s circle plots normal stress on the abscissa and shear stress on the ordinate. For any given 2D state, the center C is at ( (sigma_x + sigma_y)/2, 0 ) and the radius R = sqrt( ((sigma_x − sigma_y)/2)^2 + tau_xy^2 ). Rotating 2 * theta around the circle yields the transformed stresses on a plane at angle theta.
Step-by-Step Solution:
Construct circle with center and radius from the given sigma_x, sigma_y, tau_xy.A pure uniaxial case with shear (option a) maps to a circle offset from zero with nonzero tau.Two perpendicular direct stresses without shear (option b) map to a circle with tau_xy = 0.The most general 2D case (option c) is directly represented and solved.Verification / Alternative check:The analytical transformation equations sigma_theta = (sigma_x + sigma_y)/2 + ((sigma_x − sigma_y)/2) * cos(2theta) + tau_xy * sin(2theta) and tau_theta = −((sigma_x − sigma_y)/2) * sin(2theta) + tau_xy * cos(2theta) yield identical results to the circle construction, confirming its universality in plane stress.
Why Other Options Are Wrong:
Common Pitfalls:Misinterpreting the 2*theta rotation rule; forgetting sign conventions for shear; or applying plane-stress Mohr’s circle to 3D states without modification.
Final Answer:All of the above
Discussion & Comments