The model is illustrated in Fig. 2.1 and refer to Anongba (2020a). The medium is elastic and infinitely extended, to which is attached a Cartesian system \(x_{i}\) . It consists of a crack in \(Ox_{1} x_{3}\) of finite extension along \(x_{1}\) with a straight front parallel to \(x_{3}\) . The crack is under load; initially, it is static and extends from \(x_{1} = - a\) to a. At a given time taken as t = 0 and load \(\sigma_{ij}^{a}\) , it starts moving at constant velocity v. Its extension after time interval t is given by \(\left| {x_{1} } \right| \le c = a + vt\) . Uniform tension \(\sigma_{22}^{a}\) (mode I) and shear \(\sigma_{21}^{a}\) (mode II) applied at infinity are considered separately.