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Previous studies into the use of high-power diode lasers (HPDLs) for the removal of unwanted grout between tiles revealed the dominant cause of the material removal to be thermally induced chemical reactions occurring within the material during the process. In this work a simple, easily programmable, three-dimensional, finite difference numerical model for the laser-based grout removal process is presented. The primary aim of the analysis is to calculate the temperature profile inside the grout, and thus to predict the material phase and the resultant geometry of the volume removed as a result of continuous-wave HPDL treatment. The effects of varying laser power and speed using different laser beam shapes are examined over the entire range of the heating cycle. The calculated results are compared with experimental results, showing reasonable agreement between removal depths obtained experimentally and those predicted by the model. [ABSTRACT FROM AUTHOR]

Optimization of the geometry (curvature of the vitrified enamel layer) of a laser-generated single-stage ceramic tile grout seal has been carried out using a finite element (FE) model. The overall load-bearing capacities and load–displacement plots of three selected geometries were determined experimentally by the indentation technique. Simultaneously, an FE model was developed utilizing the commercial ANSYS package to simulate the indentation. Although the load– displacement plots generated by the FE model consistently displayed stiffer identities than the experimentally obtained results, there was reasonably close agreement between the two sets of results. Stress distribution profiles of the three FE models at failure loads were analysed and correlated so as to draw an implication on the prediction of a catastrophic failure through an analysis of FE-generated stress distribution profiles. It was observed that although increased curvatures of the vitrified enamel layer do enhance the overall load-bearing capacity of the singlestage ceramic tile grout seal and bring about a lower nominal stress, there is a higher build-up in stress concentration at the apex that would inevitably reduce the load-bearing capacity of the enamel glaze. Consequently, the optimum geometry of the vitrified enamel layer was determined to be flat. [ABSTRACT FROM AUTHOR]

A finite element (FE) model has been developed utilizing the commercial ABAQUS package to determine the temperature distribution generated during the high-power diode laser (HPDL) processing of a novel ceramic tile grout seal, known as an amalgamated oxide compound grout (AOCG). The model was developed specifically to find the temperatures reached at the base of the ceramic tile grout seal, since temperatures in excess of 100°C must be attained so as to ensure certain chemical changes (the complete irreversibility of the water-glass reaction required by the process). Fourier's law and Laplace's equation were employed to build the temperature field equations under appropriate boundary conditions in two-dimensional coordinates, while the ABAQUS FE model was used to calculate the temperature field and model the thermal profile in the ceramic tile grout seal. Both the FE-generated thermal profiles and the resultant operating maps predicted temperatures and vitrification depths which were consistently higher than those obtained experimentally. Notwithstanding this, a comparison of the results revealed that the predicted depths of vitrification were in very close agreement with those observed on AOCG samples treated with the HPDL. [ABSTRACT FROM AUTHOR]