Question

Critical resolved shear stress is zero when slip plane is ........... degree to loading axis.

• A. 0
• B. 45
• C. 90
  s
• D. 60

Hint:

Resolved shear stress is zero when the angle between the slip plane normal and loading direction is \( 90^\circ \); this orientation prevents slip activation.

Answer 1

The Correct Option is C

According to Schmid's Law, the resolved shear stress (\( \tau \)) on a slip system depends on the orientation of the slip plane and slip direction with respect to the loading axis. The law is given by: \[ \tau = \sigma \cdot \cos \phi \cdot \cos \lambda \] where:
- \( \sigma \) is the applied normal stress,
- \( \phi \) is the angle between the loading axis and the normal to the slip plane,
- \( \lambda \) is the angle between the loading axis and the slip direction.
When the slip plane is at \( 90^\circ \) to the loading axis, \( \phi = 90^\circ ⇒ \cos \phi = 0 \), hence: \[ \tau = \sigma \cdot 0 \cdot \cos \lambda = 0 \] Thus, the resolved shear stress becomes zero when the slip plane is perpendicular to the loading axis, and no slip can occur under such an orientation.