Laser short-pulse heating with time-varying intensity and thermal stress development in the lattice subsystem

2005 ◽  
Vol 219 (1) ◽  
pp. 73-81 ◽  
Author(s):  
B S Yilbas ◽  
A F M Arif
Keyword(s):  
Thermal Stress ◽  
Lattice Site ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
High Stress ◽  
Surface Region ◽  
Substrate Material ◽  
Temperature Gradients ◽  
Stress Levels

Laser short-pulse heating of solid surfaces results in non-equilibrium energy transport in the region irradiated by the laser beam. Owing to the large temperature gradients in the lattice subsystem, high stress levels develop in the surface region of the substrate material. In the present study, temperature and stress fields in the substrate material are presented for the case of the laser short-pulse heating of gold. Electron kinetic theory and a two-equation heating model are introduced to account for non-equilibrium energy transport during the laser heating pulse. Laser pulses exponentially decaying with time are accommodated in the simulations. It is found that lattice site temperature gradients attain high values inspite of the low magnitude of the lattice site temperature. This, in turn, results in high stress levels in the surface region of the substrate material. Thermal stress is compressive owing to high thermal strain development and low displacement of the surface.

Laser shortpulse heating of a gold-chromium-gold multilayer assembly

2003 ◽  
Vol 217 (7) ◽  
pp. 797-809
Author(s):  
B S Yilbas ◽  
A F M Arif
Keyword(s):  
Thermal Stresses ◽  
Energy Transport ◽  
Thermal Strain ◽  
High Stress ◽  
Surface Region ◽  
Coupling Factor ◽  
Substrate Material ◽  
High Electron ◽  
Stress Levels ◽  
Non Equilibrium

Laser shortpulse heating of metallic substrates results in non-equilibrium energy transport in the region irradiated by a laser beam. Although the heating duration is short, thermal strain developed due to high-temperature gradients results in high stress levels in this region. In the present study, laser shortpulse heating of a gold-chromium-gold (Au-Cr-Au) multilayer assembly is considered. An electron kinetic theory is introduced when modelling the non-equilibrium energy transport while elastoplastic analysis is carried out to obtain thermal stresses inside the multilayer assembly. A numerical scheme is introduced to discretize the governing equations while the finite element method is employed for the solution of the stress field. It is found that temperature in the Cr layer is higher than the Au layer in the surface region. This is because of a high electron-phonon coupling factor of Cr. The stress levels below the elastic limit of the substrate material are obtained. The displacement of the surface at the irradiated spot centre is in the order of 10−9-10−7m.

Entropy Production During Laser Picosecond Heating of Copper

2002 ◽  
Vol 124 (3) ◽  
pp. 204-213 ◽  
Author(s):  
Bekir Sami Yilbas
Keyword(s):  
Entropy Production ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Surface Region ◽  
Irreversible Processes ◽  
Heating Process ◽  
Theory Approach ◽  
Lattice Systems ◽  
Nonequilibrium Energy

Nonequilibrium energy transport taking place in the surface region of the metallic substrate due to laser short-pulse heating results in entropy production in electron and lattice systems. The entropy analysis gives insight into the irreversible processes taking place in this region during the laser short-pulse heating process. In the present study, entropy production during laser shortpulse heating of copper is considered. Equations governing the nonequilibrium energy transport are derived using an electron kinetic theory approach. The entropy equations due to electron and lattice systems and coupling of these systems are formulated. The governing equations of energy transport and entropy production are solved numerically. Two pulse shapes, namely step input intensity and exponential intensity, are employed in the analysis. It is found that entropy production due to coupling process attains higher values than those produced due to electron and lattice systems. The effect of pulse shape on the entropy production inside the substrate material is significant.

Analytical solution for thermal stresses during the laser pulse heating process

2001 ◽  
Vol 215 (12) ◽  
pp. 1429-1445 ◽  
Author(s):  
M Kalyon ◽  
B S Yilbas
Keyword(s):  
Free Surface ◽  
Thermal Stress ◽  
Laser Pulse ◽  
Thermal Stresses ◽  
Pulse Heating ◽  
Stress Gradient ◽  
Substrate Material ◽  
Stress Generation ◽  
Stress Levels ◽  
Laser Pulse Heating

Laser pulse heating of surfaces initiates thermal stress generation in the region irradiated by a laser beam. Depending on the level of thermal stresses, structural changes occur inside the substrate material. In the present study, laser step input pulse heating and thermal stress generation are considered. The governing equations of heat conduction and momentum are solved analytically. In the analysis, two cases are considered, namely a stress-free surface (σx = 0 at x = 0) and a zero stress gradient at the surface (ϑσx/ϑx = 0 at x = 0). The temperature and stress fields are computed using the closed-form solution, which is derived using a Laplace transformation method. It is found that considerably high stress levels developed at some depth below the surface. The stress-free surface condition suppresses a rise in thermal stress in the surface vicinity of the substrate material, while the zero stress gradient condition at the surface results in compressive stress levels in the surface vicinity.

Entropy analysis in relation to laser shortpulse heating of silver

2003 ◽  
Vol 217 (9) ◽  
pp. 1049-1065 ◽  
Author(s):  
B S Yilbas
Keyword(s):  
Entropy Generation ◽  
Lattice Site ◽  
Energy Transport ◽  
Surface Region ◽  
Substrate Material ◽  
Metallic Substrate ◽  
Thermomechanical Coupling ◽  
Theory Approach ◽  
Lattice Coupling ◽  
Non Equilibrium

Laser shortpulse heating triggers non-equilibrium energy transport in the surface region of the metallic substrate. In this case, volumetric entropy generation is governed by the non-equilibrium energy transport due to coupling of electron and lattice subsystems as well as thermomechanical coupling in the lattice system. In the present study, non-equilibrium energy transport inside the metallic substrate is modelled using an electron kinetic theory approach. Volumetric entropy generation inside the substrate material during non-equilibrium energy transport is formulated. The effect of thermomechanical coupling on the energy transport is included in the analysis. Temperature and volumetric entropy profiles are computed for silver. It is found that an electron temperature well in excess of lattice site temperatures occurs in the surface vicinity of the substrate material. Volumetric entropy generation due to electron-lattice coupling dominates the other sources of entropy generation. Thermomechanical coupling has no significant effect on the volumetric entropy generation due to a small thermal displacement of the irradiated surface, which is in the order of 10-10 m at the centre of the irradiated spot.

Study into laser short-pulse heating of a layered structure

2009 ◽  
Vol 224 (5) ◽  
pp. 1099-1111
Author(s):  
B S Yilbas
Keyword(s):  
Seebeck Coefficient ◽  
Temperature Rise ◽  
Layered Structure ◽  
Lattice Site ◽  
Pulse Heating ◽  
Short Pulse ◽  
Silicon Layer ◽  
Theory Approach ◽  
Seebeck Coefficients ◽  
Lead Layer

Laser short-pulse heating of a lead—silicon—gold-layered structure is considered and non-equilibrium equation in the lattice and electron subsystems is formulated using the electron kinetic theory approach. The Seebeck coefficient in the metallic and silicon layers is also formulated. Electron and lattice site temperature rise in the subsystems and the Seebeck coefficients are computed for time exponentially decaying pulse. The study is extended to include the influence of the first layer (lead layer) thickness on temperature rise and the Seebeck coefficients. It is found that the lattice site temperature across the interface of the lead and silicon layers increases sharply. The Seebeck coefficient predicted in the silicon layer is higher than in the metallic layers in the structure.

Thermal stress analysis and entropy generation rate due to laser short pulse heating of a metallic surface

2014 ◽  
Vol 92 (12) ◽  
pp. 1681-1687 ◽  
Author(s):  
Bekir Sami Yilbas ◽  
Haider Ali ◽  
Ahmad Yousef Al-Dweik
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Stress Field ◽  
Entropy Generation ◽  
Pulse Heating ◽  
Short Pulse ◽  
Entropy Generation Rate ◽  
Metallic Surface ◽  
Thermodynamic Irreversibility ◽  
Thermal Stress Field

An analytical solution is developed for thermal stress in exponentially time decaying laser short-pulse heating of a metallic surface. Because the heating duration is short, a nonequilibrium heating model incorporating the electron kinetic theory approach is used to formulate the temperature distribution during the laser heating pulse. Thermomechanical coupling is introduced in the analysis to formulate the thermal stress field. Thermodynamic irreversibility is considered and the entropy generation rate due to heat transfer and thermal stress field is formulated during the heating process. It is found that temperature decays gradually in the surface region and becomes sharp as the distance increases towards the solid bulk. Thermal stress is compressive in the irradiated region. Thermodynamic irreversibility due to heat transfer dominates thermodynamic irreversibility because of the thermal stress field.

Analytical solution for electron and lattice site temperatures due to laser-induced non-equilibrium energy transport in metals

2010 ◽  
Vol 88 (7) ◽  
pp. 479-491 ◽  
Author(s):  
Hind M. Al-Theeb ◽  
Bekir S. Yilbas
Keyword(s):  
Experimental Data ◽  
Analytical Solutions ◽  
Energy Transport ◽  
Short Pulse ◽  
Substrate Material ◽  
Theory Approach ◽  
Short Pulse Laser ◽  
Numerical Predictions ◽  
Temperature Distributions ◽  
Pulse Laser Heating

The present study describes the modeling of short-pulse laser heating of gold and copper materials. The energy transport due to a laser short pulse is formulated using the electron kinetic theory approach. Electron and lattice temperature distributions inside the substrate material during the laser short pulse are formulated analytically. In the analysis, the Laplace transformation technique is used. The results obtained from the analytical solutions are compared with numerical predictions and experimental data. It is found that the results obtained from the numerical and analytical solutions for temperature distributions are in good agreement with the experimental data.

Analytical solution for laser short-pulse heating of two-dimensional solids: volumetric and surface heat source considerations

2013 ◽  
Vol 91 (7) ◽  
pp. 522-529
Author(s):  
B.S. Yilbas ◽  
A.Y. Al-Dweik
Keyword(s):  
Analytical Solution ◽  
Heat Source ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Thermal Response ◽  
Solid Substrate ◽  
Surface Heat ◽  
Heat Sources ◽  
Power Intensity

An analytical solution for lattice temperature distribution in a metallic solid subjected to laser short-pulse heating is presented. The method of similarity solution is adopted for the solution of the diffusive–ballistic energy equation. Volumetric and surface heat sources are each incorporated separately in the analysis. The material thermal response due to both heat sources during the short heating period is analyzed. It is found that a volumetric heat source resulted in smaller temperature increase in the irradiated material than a surface heat source, despite the same laser power intensity being used in both cases. This is attributed to energy transport mechanisms taking place in the solid substrate due to volumetric and surface heat sources.

Non-equilibrium energy transport and entropy production due to laser short-pulse irradiation

2016 ◽  
Vol 94 (1) ◽  
pp. 130-138 ◽  
Author(s):  
H. Ali ◽  
B.S. Yilbas ◽  
A.Y. Al-Dweik
Keyword(s):  
Laser Pulse ◽  
Entropy Generation ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Pulse Intensity ◽  
Laser Pulse Intensity ◽  
Nano Size

Laser short-pulse heating of a nano-size wire is considered and entropy generation rate is predicted during the heating pulse. The analytical solution of the heat equation is obtained using the Lie point symmetry for the laser short-pulse heating. The nano-size wire is assumed to be symmetric along its y-axis. Laser pulse intensity is considered to be Gaussian at the irradiated surface while the exponential decay of the laser pulse is incorporated in the time domain. It is found that surface temperature variation in the lattice subsystem almost follows the laser pulse intensity distribution at the surface. Entropy generation rate attains low values along the symmetry axis and it increases considerably in the region of the nano-size wire edges. This behavior is associated with the temperature gradient, which attains high values in the region close to the nano-size wire edge.

Laser short-pulse heating: Three-dimensional consideration

2001 ◽  
Vol 215 (9) ◽  
pp. 1123-1138 ◽  
Author(s):  
B. S. Yilbas
Keyword(s):  
Kinetic Theory ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Three Dimensional ◽  
Gold Surface ◽  
Equation Model ◽  
Three Dimensions ◽  
Theory Approach ◽  
Energy Transfer Mechanism

Non-equilibrium energy transport takes place in solids once the laser pulse duration reduces to picoseconds or less. It is this energy transfer mechanism that defines the laser interaction process and therefore the rate at which the material is heated through the collisional process. In the present study, laser short-pulse heating of a gold surface is considered. An electron kinetic theory approach is introduced to model the energy transport process in three dimensions. The governing equation of energy transport is solved numerically, and the electron and lattice site temperatures are predicted. In order to validate the electron kinetic theory predictions, a two-equation model is employed to compute the temperature field in the substrate material. It is found that energy transport due to the diffusional process is unlikely during the heating period considered at present. The predictions of electron kinetic theory agree well with the results obtained from the two-equation model.

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