Example b31 - coupled electromechanics. This example solves a coupled electromechanics problem on a 2d square made up from 4*4 elements. There are 9*9 grid points in each element and an ischemic VanCapelle Durer ionic current equation is used. All boundaries are fixed to have zero displacements and a pole-zero constitutive law is used. The explicit grid solver is used to solve the monodomain equation.