This article describes a method for modeling the propagation of cracks on any 3D surface. Taking a previous cellular automata model as basis, this method allows any type of cracks on any type of triangulated 3D object. Our model's main advantage is that it proposes a semi-physical solution, making it at the same time user controllable and easily extensible. After summarizing works in the literature, we make a brief and simple description of what physically are cracks and how they are generated. Based on this idea, we detail our model of crack propagation. We first introduce the general development of cracks. We then propose our original model of spectrum stress. This is followed by the description of the mutual interaction between cracks and stresses. Finally, a set of graphical examples, with their respective parameters, concludes this paper