CW laser machining of hard ceramics—I. Effects of three-dimensional conduction, variable properties and various laser parameters

Roy, Subhransu; Modest, Michael F.

doi:10.1016/0017-9310(93)90169-7

Cited by 73 publications

(22 citation statements)

References 9 publications

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“…After substituting equations (16) into (17), the equations are transformed from physical coordinates (r z t ) to computational coordinates ( ), followed by finite differencing [24]. This results in extremely long and tedious relations, which will not be reproduced here.…”

Section: Thermal Stressesmentioning

confidence: 99%

Transient Elastic and Viscoelastic Thermal Stresses During Laser Drilling of Ceramics

Modest

1998

Journal of Heat Transfer

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Lasers appear to be particularly well suited to drill and shape hard and brittle ceramics, which are almost impossible to netshape to tight tolerances, and can presently only be machined by diamond grinding. Unfortunately, the large, focussed heat flux rates that allow the ready melting and ablation of material, also result in large localized thermal stresses within the narrow heat-affected zone, which can lead to micro-cracks, significant decrease in bending strength, and even catastrophic failure. In order to assess the where, when and what stresses occur during laser drilling, that are responsible for cracks and decrease in strength, elastic and viscoelastic stress models have been incorporated into our two-dimensional drilling code. The code is able to predict temporal temperature fields as well as the receding solid surface during CW or pulsed laser drilling. Using the resulting drill geometry and temperature field, elastic stresses as well as viscoelastic stresses are calculated as they develop and decay during the drilling process. The viscosity of the ceramic is treated as temperature-dependent, limiting viscoelastic effects to a thin layer near the ablation front where the ceramic has softened.

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Section: Thermal Stressesmentioning

confidence: 99%

Transient Elastic and Viscoelastic Thermal Stresses During Laser Drilling of Ceramics

Modest

1998

Journal of Heat Transfer

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“…To meet the accuracy requirement and reduce computing time, the gradient mesh generation was used. That is, the laser heating region size is 7u0.05u0.35 mm 3 and the mesh size is 0.01u0.01u0.035 mm 3 . The intermediate part region size is 7u0.1u0.35 mm 3 and the mesh size is 0.01u0.05u 0.035 mm 3 .…”

Section: Mathematical Modelmentioning

confidence: 99%

“…That is, the laser heating region size is 7u0.05u0.35 mm 3 and the mesh size is 0.01u0.01u0.035 mm 3 . The intermediate part region size is 7u0.1u0.35 mm 3 and the mesh size is 0.01u0.05u 0.035 mm 3 . The outermost region size is 7u0.6u0.35 mm 3 (sample A) or 7u4.85u0.35 mm 3 (sample B) and the mesh size is 0.01u0.2u0.035 mm 3 .…”

Section: Mathematical Modelmentioning

confidence: 99%

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Effect of Specimen Size on Laser Scribing Width and Depth of Al₂O₃Ceramics: Experiment and Numerical Simulation

2016

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Abstract. To obtain high precision and quality of laser ceramic scribing , people should consider the laser scribing parameters and the geometries of specimen size. In this paper, the effect of specimen size on laser scribing width and depth of Al 2 O 3 ceramics was simulated and verified by using ANSYS software and Diode Pumped Solid State (DPSS) laser scribing, respectively. The calculated results and the experimental results all proved that the specimen size had important effect on laser scribing width and depth due to the heat accumulation effect during laser scribing.

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“…The resulting non-dimensional set of non-linear movingboundary problem is solved using boundary-fitted coordinates together with a structured grid. Details of the heat transfer model can be found in Roy and Modest [8] and, to a lesser extent in Modest [6]. Relevant non-dimensional parameters governing the heat transfer are…”

Section: Heat Transfermentioning

confidence: 99%

Minimization of elastic thermal stresses during laser machining of ceramics using a dual-beam arrangement

Modest

2001

Journal of Laser Applications

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Lasers are emerging as a valuable tool for shaping and cutting hard and brittle ceramics. Unfortunately, the large, concentrated heat flux rates that allow the laser to efficiently cut and shape the ceramic also result in large localized thermal stresses in a small heat-affected zone. These notable thermal stresses can lead to micro-cracks, a decrease in strength and fatigue life, and possibly catastrophic failure. In order to assess where, when, and what stresses occur during laser scribing, an elastic stress model has been incorporated into a two-dimensional drilling as well as a three-dimensional scribing and cutting code. The results of the analysis for a single Gaussian laser source show that substantial tensile stresses develop over a thick layer below and parallel to the surface, which may be the cause of experimentally observed subsurface cracks. In this work the effect of splitting the beam into two parts is discussed: a highly-focussed beam that does the actual drilling or scribing, and a partially defocussed beam, used to heat the material ahead of, around, or behind the laser beam. Different secondary beam scenarios are investigated, and their effect on reducing the damaging tensile stresses is evaluated.

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CW laser machining of hard ceramics—I. Effects of three-dimensional conduction, variable properties and various laser parameters

Cited by 73 publications

References 9 publications

Transient Elastic and Viscoelastic Thermal Stresses During Laser Drilling of Ceramics

Transient Elastic and Viscoelastic Thermal Stresses During Laser Drilling of Ceramics

Effect of Specimen Size on Laser Scribing Width and Depth of Al₂O₃Ceramics: Experiment and Numerical Simulation

Minimization of elastic thermal stresses during laser machining of ceramics using a dual-beam arrangement

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CW laser machining of hard ceramics—I. Effects of three-dimensional conduction, variable properties and various laser parameters

Cited by 73 publications

References 9 publications

Transient Elastic and Viscoelastic Thermal Stresses During Laser Drilling of Ceramics

Transient Elastic and Viscoelastic Thermal Stresses During Laser Drilling of Ceramics

Effect of Specimen Size on Laser Scribing Width and Depth of Al2O3Ceramics: Experiment and Numerical Simulation

Minimization of elastic thermal stresses during laser machining of ceramics using a dual-beam arrangement

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Product

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Effect of Specimen Size on Laser Scribing Width and Depth of Al₂O₃Ceramics: Experiment and Numerical Simulation