Model of Three-Dimensional thermal stress applied in cleaning of black crusts on granite

摘要

The ability to remove the black crust from stone substrates has great research significance in Cultural Heritage. Laser cleaning has achieved good cleaning results in stone heritage in recent years. However, the extremely high light absorption and low melting point of biotite in the mineral composition of granite can easily cause damage during the cleaning process. In this study, the thermal stress generated by the laser action in the black crust was used to peel off the black crust. And a model of three-dimensional thermal stress was established under the movement of the laser heat source based on the experimental phenomenon of warping to peel off the black crust. The model agrees with the experimental results that the black crust is peeled off by tensile and shear stresses.