As linear equations, the transformed stresses are given by
main.mechmat.89y for TI-89 (by Chris Vincent)
main.stress01.89y for TI-89 (by David McKinnon)
main.strain01.89y for TI-89 (by David McKinnon)
These programs run on the TI-89 titanium. TICellSheets is required. Mechmat requires you to input the original stress values and gives the rotated stress values.
Stress01 requires you to input the original stress values, gives the rotated stress values, and converts stress to strain for both the original and rotated axes. It also calculates the principal and max. shear angles.
Strain01 requires you to input the original strain values, gives the rotated strain values, and converts strain to stress for both the original and rotated axes. It also calculates the principal and max. shear angles.
Note that the modulus of elasticity and Poisson's ratio must be input, as well, for the stress/strain conversions to work. Also note that these calculations work only for plane stress/strain.
Or in matrix notation,
