The Tensile modulus, principle direction results indicate how much stress is needed to cause a unit of movement.
This help topic covers the following Fiber orientation Pack analysis results:
The Tensile modulus in first and second principal direction results are recorded for each laminate in the model over the duration of the analysis. Therefore, each laminate in the model will have different results. You can check the tensile modulus in each laminate by animating the default contour plot, which will animate the result over the Normalized thickness.
The first principal direction coincides with the fiber orientation first principal direction, and is determined by the Fiber orientation analysis. The second principal direction is perpendicular to the first principal direction.
The thermo-mechanical property calculation for fiber-filled composites are based on the orthotropic assumption, that fiber-filled material properties are different in three orthogonal principal directions. Under this assumption, there are 9 independent mechanical constants and three independent thermal expansion coefficients. In Midplane/Dual Domain models, because of the plain stress assumption in the shell structure analysis in warpage, only 4 mechanical constants (Tensile modulus in first/second principal directions, Poisson ratio v12, Shear modulus G12) are necessary.