The internal stresses generated during quenching can produce warping and even cracking of a steel body and, therefore, the prediction of such stresses is an important task. Phenomenological aspects of quenching involve couplings between different physical processes occurring in the phenomena. The present contribution is concerned with modelling and simulation of quenching, presenting an anisothermal model formulated within the framework of continuum mechanics and the thermodynamics of irreversible processes. A numerical procedure is developed based on an operator split technique associated with an iterative numerical scheme in order to deal with non-linearities in the formulation. With this assumption, the coupled governing equations are solved involving four uncoupled problems: thermal, phase transformation, thermoelastic and elastoplastic behaviours. The proposed general formulation is applied to analyse progressive induction hardening of steel cylinders. Numerical results suggest that the proposed model is capable of capturing the main behaviour observed in experimental data.

The aim of this work is to evaluate the applicability of the Wheeler and Willenborg models to predicting fatigue crack growth retardation in a flash welded structural steel subjected to a single overload during constant amplitude (CA) fatigue crack propagation test. Compact tension specimens, in different microstructural conditions, were subjected to a single overload at a given crack length during CA fatigue loading and crack growth rate da/dN vs. the stress intensity factor range deltaK was monitored, evidencing the retardation in crack propagation over an interval of crack length. The size of the delay zone as well as the number of the delay cycles were predicted by both the Wheeler and Willenborg models and then compared with the experimental data. Finally, the results are presented and discussed focusing on the comparison between the predictions made by the two models in the light of the experimental data

The use of intra-radicular posts for rebuilding of damaged teeth is a normal practice in contemporary dentistry. However, dental roots restored with posts are subjected to the risk of failure under occlusal loads, particularly in cases of small dentin thickness. This study adopted the finite element analysis to compare the elastic stress distribution in simulated endodontically treated maxillary central incisor restored with two different esthetic posts, a ceramic post and a prefabricated fiber glass post. Under masticatory load, the shear stress and von Mises equivalent stress were determined for the different regions of the two models. The results demonstrated that stress concentrations occurred mainly in the cervical dentin in the prefabricated fiber glass post model. The ceramic post model presented stress concentration in a region limited to the proper post adjacent to its apical end, thus preserving the root dentin.

A 2D fi nite element analysis was applied to calculate shear and von Mises equivalent stresses developed, under masticatory loading, in an upper central incisor restored with cast gold post and carbon fi ber reinforced epoxy resin post. Based on the predicted shear stress levels, it is concluded that the gold post model is more prone to shear failure along the post-dentin interface. Whereas shear stress concentration also occurs in both models at the core-crown interface, the stress level predicted there is higher for the carbon fi ber post model which would be more susceptible to crown displacement. Finally, the prediction of von Mises equivalent stress indicates a nonuniform distribution, with the stress preferentially concentrated in the gold post along its interface with the tooth dentin. For the carbon fi ber post restored model, on the other hand, the von Mises stresses are more uniformly distributed achieving its maximum level in the tooth dentin.

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