Problems that are considered in this book model various mechanical phenomena, especially from rod theory and viscoelasticity. Differential equations that arise have coefficients which are not smooth, can be even distributions (Dirac delta and Heaviside functions), and some equations are coupled with fractional differential equations. This is why one has to go beyond classical spaces and look for solutions within generalized function spaces such as spaces of distributions, Sobolev spaces and Colombeau's generalized functions. Different kinds of techniques are presented and afterwards are...