In this work, we extend the simulation method for deformable objects proposed by Muller et al. (2005) so as to be able to simulate fracturing. In Muller et al., the object surface vertices are handled such as particles in a particle system: moved by external forces and by internal restitution forces, which try to restore the original object form using a shape matching technique. This method allow us to simulate stretching and twisting effects in a stable manner, and, because it is geometrically motivated, it is ideal to situations which does not demand physical realism, as in games and animation. Muller et al. propose in their work a composed simulation mode, in which deformable objects work like a composition of clusters of its surface vertices: these clusters behave like deformable objects on their own. Our contributions focus on a variation of this model. We propose the hierarchical vertex surface segmentation method from Attene et al. (2006) as an automatic way of determining clusters which are natural parts of the object. We also created a technique to smoothly calculate the influence of the clusters in each vertex, considering global and local aspects of the object. Finally, we established an algorithm which detects fractures between vertex clusters and which breaks the object surface accordingly. We employed a set of 3D objects to demonstrate that our method is capable of naturally simulating fractures, for systems which demand simpler, real-time results, as well as for systems which need richer and more detailed fractures.