Mechanical Properties of a Crab Shell

l. The mechanical behaviour of crab shell is similar to that of prawn solid cuticle, especially in the occurrence of a low strain discontinuity in their bulk tensile stress-strain curves. 2. Although isolated crab chitin breaks in tension by the progressive failure of individual lamellae and exhibits post-fracture delamination, whole crab cuticle fails in an entirely brittle manner. 3. The mechanical properties of isolated crab chitin are highly susceptible to the effects of hydration as is typical of other animal chitins. 4. It is suggested that crab solid cuticle is a composite material, the properties of which are closely analogous to those of pre-stressed concrete.