Units
The metric S.I. system is used throughout. The basic unit of stress, and hence, modulus of elasticity and stiffness, is the Pascal (Pa) which is 1 N/m2. Multiples of this are used for convenience viz.: 1 MPa = 1 x 106 N/m2, 1 GPa = 1 x 109 N/m2. All strains are quoted in micro-strain, 1 micro-strain = 1 x 10-6 µm/m. In all cases, logarithmic terms are to base 10.
