His PhD thesis was on models and computational methods for the study of dynamic behaviour of metallic bodies subjected to dry frictional contacts.

It contains (i) a detailed study of phenomenological interface constitutive laws (ii) a constitutive interface law incorporating the normal deformability of the interface and the Coulomb friction law, (iii) formulations of the dynamic and steady sliding contact problems together with proofs on existence and uniqueness of solutions, (iv) numerical techniques and algorithms for the study of the dynamic and steady sliding problems, (v) numerical finite element results and parametric studies on the stability of steady sliding and on friction induced oscillations.

Prof. João Martins was member of the general assembly of IUTAM and served as vice-president of the Portuguese Association for Theoretical, Applied and Computational Mechanics (APMTAC) in 2006 and 2007.

In 2009 the Associação Portuguesa de Mecânica Teórica, Aplicada e Computacional created the Young Researcher Award Professor João Martins.

In 2009 the Sociedade Portuguesa de Biomecânica created the Professor João Martins Award to recognize the work of young researchers in the field of biomechanics.