A CTOD test is performed on a three point bend specimen. Figure below shows the deformed specimen after it has been unloaded. That is, the displacements shown are the plastic components. P (a) Derive an expression for plastic CTOD (8) in terms of A, and specimen dimensions (consider 4W as the span of the specimen before loading). (b) Suppose that and Aare measured on the same specimen, but that the plastic P rotational factor, r, is unknown. Derive an expression for rp in terms of Ap, Vp and specimen dimensions, assuming the angle of rotation is small. www. W 2W V 8p Wp(W-a)