Laser non-conduction limited heating and prediction of surface recession velocity in relation to drilling

Yilbaş, Bekir Sami; Shuja, S.Z.

doi:10.1243/095440603322407290

Cited by 12 publications

(10 citation statements)

References 18 publications

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“…This is because of the amount of energy absorbed in the surface region, which is considerably higher than at some depth below the surface where melting takes place. Comparison of recession velocity obtained from present predictions along the symmetry axis and one-dimensional analytical solution [17]. Figure 11 shows the quality in the liquid-solid mushy zone for different laser power intensities at three depths below the surface.…”

Section: Resultsmentioning

confidence: 96%

“…Moreover, increasing power intensity does not alter the magnitude of recession velocity significantly, particularly in the early heating period. Moreover, Figure 9 shows the recession velocity of the surface obtained from the previous analytical solution [17] and present predictions. It can be observed that both results are reasonably in agreement.…”

Section: Resultsmentioning

confidence: 96%

“…This occurs because of the threshold power intensity required for the evaporation process. As the power intensity increases beyond the threshold, the rate of evaporation accelerates significantly [17]. Figure 5 shows a three-dimensional view of the cavities formed after the evaporation process for different laser power intensities at 8 ns heating duration.…”

Section: Resultsmentioning

confidence: 99%

“…They considered a twodimensional model and explosively propagating molten layers in the analysis. Yilbas and Shuja [17] examined the mass removal from the laser irradiated surface. They formulated the recession velocity of the solid surface as well as the evaporation front velocity.…”

Section: Introductionmentioning

confidence: 99%

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Laser Evaporative Heating: Influence of Laser Pulse Intensity on the Cavity Formation

Mansoor

Yilbaş

Shuja

2008

Heat Transfer Engineering

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The influence of laser pulse intensity on the recession velocities of vapor-liquid and liquid-solid interfaces is examinednumerically. In order to determine the location of interfaces, the energy method is used. The mushy zone formation is considered across the zones where the phase change occurs. The energy method enables one to determine the quality of vapor and liquid qualities in the vapor-liquid and liquid-solid mushy zones. It is found that laser power intensity has a significant effect on the cavity size, particularly on the depth of the cavity. The recession velocity of the vapor-liquid and liquid-solid interfaces is high in the early heating period due to high rate of evaporation. INTRODUCTIONIn material processing, laser machining is demanding for the operations requiring precision, low cost, and a small heat affected zone. When a laser beam with sufficient power intensity interacts with the solid substrate, heating of the irradiated surface and consequent melting and evaporation processes take place. Initially, a cavity is formed, and the mass removal from the cavity takes place either by the evaporation alone or by the evaporation with the liquid ejection processes. The evaporation-only process occurs for laser short-pulses (∼10 −9 s), and liquid ejection takes place for pulses with milliseconds. The mass removal from the solid substrate through evaporation process forms the basis for the shape required in laser machining, such as a drilled hole or a cut edge. The model studies associated with laser solid substrate interactions give insight into the physical phenomenon that is involved in the process. Consequently, understanding the physical phenomenon in mass removal during laser irradiation enables us to set the appropriate controlling parameters to obtain improved end product quality, which is drilled hole or cut edges. Therefore, investigation into model studies in relation to laser machining is fruitful.Considerable research studies were carried out to examine the laser machining process. High intensity laser-induced vaporization and explosion of solid material were investigated by Dabby and Peak [1]. They formulated the heating situation analytically and obtained a temperature distribution in the vapor front with the assumption of initial temperature distribution. Steady-state and transient laser melting of solid surfaces were examined by Basu and Date [2] during laser cutting process. They indicated that the steady-state solution yielded two counter rotating circulation cells in the laser melt pool. Energy transfers and penetration velocity during a high-energy drilling process were investigated by Wei and Ho [3]. They used the enthalpy method and avoided the mushy zone in between phases through introducing temperature-correction parameters. A theoretical and an experimental study of the physical processes in relation to laser drilling were carried out by Liu et al. [4]. They discussed the hydrodynamic behavior of the vapor/plasma generated during ablation and computed the vapor expansion. The ...

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Laser Evaporative Heating: Influence of Laser Pulse Intensity on the Cavity Formation

Mansoor

Yilbaş

Shuja

2008

Heat Transfer Engineering

View full text Add to dashboard Cite

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“…They indicated that liquid ejection from the laser produced cavity should be considered for laser power intensities close to the threshold intensity for evaporation. Yilbas et al [8] investigated laser induced phase change processes in relation to drilling. However, the studies were limited to vapor front formation and vapor front expansion into its ambient was omitted.…”

Section: Introductionmentioning

confidence: 99%