1. 8-1 Interpretation of The stress-strain relationship at a point in an elastic material each stress component is related to each of the nine strain components by an equation of the form and can be expressed in the form of The generalized Hook’s law can be written as Alternatively, the generalized Hook’s law relating strains to stresses can be written as For a Newtonian fluid, the stress-strain relationship can be expressed where

2. 8-2 Tensor operations Where e j is the unit vector of the axis in the Cartesian coordinate

3. 8-3 When the fluid is at rest, thermal dynamic pressure p had been defined to be  kk /3. Stoke’s hypothesize [A-1] [A-2] Substituting [A-2] into [A-1], we have Derivation of the relationship between stress and strain of the fluid in motion

4. 8-4 Let i=j=x; we have Disregard thermodynamic pressure [1.1-4]