The displacement function u(x) for a tensile specimen of uniform cross section and length, L, fixed at one end and subjected to a displacement d at the other, is just the linear relation u(x)=(x/L)d.
(a) Find the Lagrangian strain in the direction of the longitudinal axis of the specimen (x).
(b) What is the error between large d =10^30 mm and small d =10^-6 µm, and discuss the result. Assume L=22 mm.