Y-axis

The axis in the plane of a laminate perpendicular to the x-axis.


Yarn

A continuous, ordered assembly of essentially parallel, collimated filaments, usually with a twist.


Yield point

The first stress in a material, less than the maximum rate attainable stress, at which the strain increases at a higher rate than the stress. The point at which permanent deformation of a stressed specimen begins to take place. (Also see stress and strain.)


Young's modulus

Ratio of normal stress to the corresponding strain for tensile or compressive stresses less than a material's proportional limit.