Femtosecond filamentation dynamics of synthesized coronary profile laser beam in air: numerical simulations

2021 ◽  
Author(s):  
Yuri E. Geints ◽  
Alexander Zemlyanov
Keyword(s):  
Laser Beam ◽  
Numerical Simulations ◽  
Femtosecond Filamentation

scholarly journals Consideration of Absorption Coefficient Changes in Numerical Simulations of Laser Forming

2019 ◽  
Vol 44 (1) ◽  
pp. 1-5
Author(s):  
Helge Kügler ◽  
Frank Vollertsen
Keyword(s):  
Absorption Coefficient ◽  
Laser Beam ◽  
Numerical Simulations ◽  
Surface Oxidation ◽  
Laser Beams ◽  
Laser Forming ◽  
Beam Forming ◽  
Work Piece ◽  
Solid State Lasers ◽  
Co2 Lasers

Material processing with laser beams is well-known in nowadays production. Compared to CO2 lasers, modern solid state lasers are, amongst others, popular because of higher energy efficiency and higher absorption when metals like steel and aluminum are irradiated. However, the absorption of metals is not only dependent on the chemical composition of the work piece metal and the laser beam wavelength. Previous investigations determined the oxidation of the surface as an influence on laser beam absorption changes due to multiple irradiation. In this study, a method is presented for considering the absorption coefficient changes caused by surface oxidation in numerical simulations. Reproductions of single trajectories were assigned with appropriate absorption coefficients calculated from a function generated by reference tryouts. With the described approach, benefits are gained for numerical simulations of laser beam forming (like bending) and other processes with an iterative heat input.

scholarly journals Simulation and Experimental Comparison of Laser Impact Welding with a Plasma Pressure Model

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1196 ◽  
Author(s):  
Sepehr Sadeh ◽  
Glenn H. Gleason ◽  
Mohammad I. Hatamleh ◽  
Sumair F. Sunny ◽  
Haoliang Yu ◽  
...  
Keyword(s):  
Laser Beam ◽  
Numerical Simulations ◽  
Pressure Pulse ◽  
Weld Strength ◽  
Experimental Comparison ◽  
Lap Shear ◽  
Impact Welding ◽  
Laser Impact ◽  
Temporal Profiles ◽  
Laser Impact Welding

In this study, spatial and temporal profiles of an Nd-YAG laser beam pressure pulse are experimentally characterized and fully captured for use in numerical simulations of laser impact welding (LIW). Both axisymmetric, Arbitrary Lagrangian-Eulerian (ALE) and Eulerian dynamic explicit numerical simulations of the collision and deformation of the flyer and target foils are created. The effect of the standoff distance between the foils on impact angle, velocity distribution, springback, the overall shape of the deformed foils, and the weld strength in lap shear tests are investigated. In addition, the jetting phenomenon (separation and ejection of particles at very high velocities due to high-impact collision) and interlocking of the foils along the weld interface are simulated. Simulation results are compared to experiments, which exhibit very similar deformation and impact behaviors. In contrast to previous numerical studies that assume a pre-defined deformed flyer foil shape with uniform initial velocity, the research in this work shows that incorporation of the actual spatial and temporal profiles of the laser beam and modeling of the corresponding pressure pulse based on a laser shock peening approach provides a more realistic prediction of the LIW process mechanism.

scholarly journals Forming of thin-walled elements using laser heating and mechanical load

Mechanik ◽  
2018 ◽  
Vol 91 (2) ◽  
pp. 148-151
Author(s):  
Piotr Kurp ◽  
Jacek Widłaszewski ◽  
Zygmunt Mucha
Keyword(s):  
Numerical Analysis ◽  
Laser Beam ◽  
Numerical Simulations ◽  
Laser Heating ◽  
Mechanical Load ◽  
Experimental Investigations ◽  
Aircraft Engines ◽  
Preliminary Results ◽  
Experimental Stand ◽  
Thin Walled

The paper presents assumptions and preliminary results of experimental investigations and numerical simulations of forming thin-walled elements using laser beam and mechanical load. An experimental stand, dedicated for bending thin-walled tubes and conical diffusers, which are used in aircraft engines, has been designed and built. The method and stand, which were tested in laboratory conditions, together with numerical analysis results show new possibilities of forming thin-walled elements.

Femtosecond filamentation in air at low pressures: Part I: Theory and numerical simulations

2006 ◽  
Vol 259 (1) ◽  
pp. 265-273 ◽  
Author(s):  
A. Couairon ◽  
M. Franco ◽  
G. Méchain ◽  
T. Olivier ◽  
B. Prade ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Femtosecond Filamentation ◽  
Low Pressures

Energy Efficient Laser Beam Welding of Metals with a Ultra-High Brightness Direct-Diode Laser System

2015 ◽  
Vol 805 ◽  
pp. 162-170 ◽  
Author(s):  
Artur Laukart ◽  
Michael Dobler ◽  
Stefanie Kohl ◽  
Haro Fritsche ◽  
Andreas Grohe ◽  
...  
Keyword(s):  
Power Consumption ◽  
Laser Beam ◽  
Numerical Simulations ◽  
Diode Laser ◽  
Laser Beam Welding ◽  
Laser Wavelength ◽  
Efficient Production ◽  
High Brightness ◽  
Laser Systems ◽  
Conventional Laser

The rising level of automation in the automotive industry also involves the use of more and more machines and with that an increase in power consumption. This requires the employment of more efficient production processes with higher efficiency. Laser beam welding offers the opportunity to substitute conventional laser sources like solid state lasers with ultra-high brightness direct-diode laser systems which have the advantage of less power consumption at a comparable beam quality. However, the absorption of laser radiation on metallic surfaces depends on the wavelength, thus the effect of the direct-diode laser wavelength on the welding process has to be investigated. In our research the effect of the laser wavelength on energy efficiency was studied by means of numerical simulations. Furthermore, experimental investigations were carried out to validate the numerical solutions. Different aluminum alloys and steel materials which are used in the automotive environment were investigated within the experiments. Due to the current lack of direct-diode laser systems with a laser power comparable to conventional laser systems, numerical simulations were also used to analyze these future systems. Thus we were able to assess the increase of efficiency in laser beam welding which will be achievable with future high-power direct-diode laser systems.

Numerical Simulations on the Formation of Speckles in Nanofluids Illuminated by a TEM 00 Laser Beam

2009 ◽  
Vol 26 (4) ◽  
pp. 044201 ◽  
Author(s):  
Yan Qin ◽  
Qian Ming ◽  
Ni Xiao-Wu ◽  
Lu Jian ◽  
Li Qiang ◽  
...  
Keyword(s):  
Laser Beam ◽  
Numerical Simulations

Two-photon excitation microscopy in cellular biophysics

1995 ◽  
Vol 53 ◽  
pp. 62-63
Author(s):  
David W. Piston ◽  
Brian D. Bennett ◽  
Robert G. Summers
Keyword(s):  
Confocal Microscopy ◽  
Laser Beam ◽  
Duty Cycle ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10-5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

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