Meaning
Minimum internal pressure required to trigger permanent deformation on a specific atomic plane provides a fundamental measurement of material strength. Use of the critical resolved shear stress allows engineers to predict when a single crystal will begin to permanently deform under load. It represents a capability limit rather than a capacity metric.
Calculation of this value depends on the Schmid factor, which relates the applied force to the orientation of the lattice.
Plasticity Threshold
Yielding begins when the internal shear reaches this specific magnitude. The critical resolved shear stress remains constant for a given material and temperature regardless of the total load direction. Measuring this property requires high precision mechanical testing on oriented samples.
Dislocation Movement
Atomic planes slide past each other once the threshold is crossed. For a critical resolved shear stress to be accurately measured, the sample must be free of pre-existing defects that would pin dislocations. This movement leads to macroscopic strain that is irreversible once the stress is removed.
Yield Prediction
Engineers apply this value to determine the safety margins for structural components. While a pilot result might show high strength, the critical resolved shear stress indicates the true boundary of mechanical stability in a production environment. Calling the yield point early results in premature failure of the assembly.
The value varies with temperature and impurity levels.
