Mechanics is defined as the relationship between force applied to an object and the resultant deformation

Mechanics is defined as the relationship between force applied to an object and the resultant deformation, translation and rotation. Mechanical stress describes the intensity of the load (mechanical force, denoted by ?) and mechanical strain describes the degree of the corresponding deformation. Strain, or stretch ratio, is denoted by the symbol ? and is the ratio of the length of a deformed line segment to its unstretched length. In the context of 3D cardiac biomechanics, stresses and strains necessarily reported as square tensors comprised of nine components. Stresses are given in terms of the Cauchy stress, the force acting over an area in the deformed configuration.
Mechanical properties of the tissues discussed in the review will henceforth described by the single-valued strain energy density function, W(F). Materials whose stress-strain relationship can be described by this function are termed hyperelastic.