Formulation of the element matrices and vectors for elasticity problem

Boundary conditions consist of prescription of displacement and of stress. The boundary S of the body van be divided into two parts, Su and St. The boundary conditions (BC's) are described as:

Fig. 16. Boundary conditions.

	on Su	(9)
	on St	(10)

in which tx and ty are traction forces (stresses on the boundary) and the barred quantities are those with known values.