# Finding the strain

1. Nov 14, 2004

### chusifer

here's the question...the inner radius of a blood vessel with circular cylindrical cross section is distended during pressure elevation from radius a to a+∆a. assume the wall of the vessel is incompressible and the length of the vessel is constant. find the radial and circumferential infinitesimal strain, $$\epsilon_i_j$$ throughout the wall.

ok...so the circumferential strain is defined as $$\epsilon_i_j = \lambda_\theta - 1$$. and the radial strain is $$\epsilon_r = \lambda_r - 1$$. and the stress ratio, lambda is computed by the final length/initial length right? so is the radial strain just a+∆a/a - 1? and there's no value for the z axis since the vessel is imcompressible...so how would i get the stress ratio for the circumferential strain? many thanks...