Numerical Simulation of Pulsed Laser Bending

2002 ◽  
Vol 69 (3) ◽  
pp. 254-260 ◽  
Author(s):  
X. R. Zhang ◽  
G. Chen ◽  
X. Xu
Keyword(s):  
Steel Plate ◽  
Pulsed Laser ◽  
Computation Time ◽  
Domain Size ◽  
Laser Pulses ◽  
New Method ◽  
Laser Bending ◽  
Computational Capability ◽  
Thermomechanical Effect ◽  
Good Agreement

The aim of this work is to develop an efficient method for computing pulsed laser bending. During pulsed laser bending, thousands of laser pulses are irradiated onto the target. Simulations of the thermomechanical effect and bending resulted from all the laser pulses would exceed the current computational capability. The method developed in this work requires only several laser pulses to be calculated. Therefore, the computation time is greatly reduced. Using the new method, it is also possible to increase the domain size of calculation and to choose dense meshes to obtain more accurate results. The new method is used to calculate pulsed laser bending of a thin stainless-steel plate. Results calculated for a domain with a reduced size are in good agreement with those obtained by computing all the laser pulses. In addition, experiments of pulsed laser bending are performed. It is found that experimental data and computational results are consistent.

Influence of Temperature on the Removal Rates of CH2(ã1A1 ) by Inert Gases and Hydrocarbons

1990 ◽  
Vol 45 (5) ◽  
pp. 649-656 ◽  
Author(s):  
R. Wagener
Keyword(s):  
Rate Constants ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Inert Gases ◽  
Probe Laser ◽  
Gas Cell ◽  
Reaction Conditions ◽  
Removal Rates ◽  
Influence Of Temperature On ◽  
Good Agreement

Abstract The reactions of CH2(ã1A1) with the inert gases He, Ar, N2 , with H2 and with the hydrocarbon reactants CH4 , C2H6 , C2H4 and C6H6 have been investigated at 210, 295 and 475 K. CH2(ã1A1) was generated by pulsed laser photolysis in a quasistatic thermostated gas cell and detected by pulsed laser induced fluorescence. Concentration profiles of CH2(ã1A1) were recorded under first order reaction conditions by varying the time delay between the photolysis and the probe laser pulses. The second order rate constants determined at room temperature are in good agreement with those of earlier work. No differences between the removal rates of ortho-and para-methylene nuclear spin states by the inert gases were observed. The experimental rate constants were fitted to an expression k = A -(77295 K)n. The results are given in the form {A ± AΔA} {n ± Δn) with A in units of 1013 cm3/mol • s:

EFFECTS OF PLASMA SHIELDING ON PULSED LASER ABLATION

2006 ◽  
Vol 20 (15) ◽  
pp. 899-909 ◽  
Author(s):  
DUANMING ZHANG ◽  
DAN LIU ◽  
ZHIHUA LI ◽  
SIPU HOU ◽  
BOMING YU ◽  
...  
Keyword(s):  
Pulsed Laser ◽  
Laser Pulses ◽  
Ablation Depth ◽  
Plasma Radiation ◽  
Ablation Process ◽  
Laser Plasma Interaction ◽  
Relevant Role ◽  
Plasma Shielding ◽  
Good Agreement ◽  
Pulsed Laser Irradiation

We have developed a theoretical model which studies the characteristics of laser-plasma interaction, the effect of plasma shielding and plasma radiation in the ablation process. The model is used to simulate 25 ns square pulsed laser irradiation on YBa 2 Cu 3 O 7 targets, and pulsed laser with the pulse width of 25 ns (FWHM) irradiation on Ni targets. The evolution of the plasma length and the transmitted intensity are performed. The model shows the variation of ablation depth with energy density. Moreover, we obtain the dependence of the ablation depth on the number of laser pulses. The satisfactorily good agreement between our results and experimental results confirms that plasma shielding plays a relevant role in the ablation process.

Picosecond Single-Photon and Femtosecond Two-Photon Pulsed Laser Stimulation for IC Characterization and Failure Analysis

2009 ◽  
Author(s):  
V. Pouget ◽  
E. Faraud ◽  
K. Shao ◽  
S. Jonathas ◽  
D. Horain ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Single Photon ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Laser Stimulation ◽  
Two Photon ◽  
Resolution Improvement ◽  
Ultrashort Laser

Abstract This paper presents the use of pulsed laser stimulation with picosecond and femtosecond laser pulses. We first discuss the resolution improvement that can be expected when using ultrashort laser pulses. Two case studies are then presented to illustrate the possibilities of the pulsed laser photoelectric stimulation in picosecond single-photon and femtosecond two-photon modes.

Boundary Friction for a Line Contact Model: An Empirical Approach

2015 ◽  
Vol 642 ◽  
pp. 8-12
Author(s):  
William W.F. Chong ◽  
Miguel de La Cruz
Keyword(s):  
Steel Plate ◽  
Friction Model ◽  
Boundary Friction ◽  
Slider Bearing ◽  
Base Oil ◽  
Atomic Force ◽  
Alternative Approach ◽  
Nanoscale Friction ◽  
Friction Measurements ◽  
Good Agreement

The paper introduces an alternative approach to predict boundary friction for rough surfaces at micros-scale through the empirical integration of asperity-like nanoscale friction measurements. The nanoscale friction is measured using an atomic force microscope (AFM) tip sliding on a steel plate, confining the test lubricant, i.e. base oil for the fully formulated SAE grade 10w40. The approach, based on the Greenwood and Tripp’s friction model, is combined with the modified Elrod’s cavitation algorithm in order to predict the friction generated by a slider-bearing test rig. The numerical simulation results, using an improved boundary friction model, showed good agreement with the measured friction data.

Prediction of Cutting Forces in Milling Stainless Steels using Chamfered Main Cutting Edge Tool

2005 ◽  
Vol 21 (3) ◽  
pp. 145-155 ◽  
Author(s):  
C.-S. Chang
Keyword(s):  
Stainless Steel ◽  
Cutting Forces ◽  
Steel Plate ◽  
Cutting Edge ◽  
304 Stainless Steel ◽  
Workpiece Material ◽  
Material Force ◽  
Force Data ◽  
Edge Tool ◽  
Good Agreement

AbstractTo study the cutting forces, the carbide tip's surface temperature, and the mechanism of secondary chip and main chip formation of face milling stainless steel with a chamfered main cutting edge has been investigated. Theoretical values of cutting forces were calculated and compared to the experimental results with SUS 304 stainless steel plate as a workpiece material. Force data from these tests were used to estimate the empirical constants of the mechanical model and to verify its prediction capabilities. A comparison of the predicted and measured forces shows good agreement. A preliminary discussion is also made for the design of special tool holders and their geometrical configurations. Next, the tips mounted in the tool holders are ground to a chamfered width and the tool dimensions are measured by using a toolmaker microscope.

Development of an Instantaneous Velocity-Vector-Profile Method Using Conventional Ultrasonic Transducers

2021 ◽  
Author(s):  
Dongik Yoon ◽  
Hyun Jin Park ◽  
Tomonori Ihara
Keyword(s):  
Velocity Vector ◽  
Ultrasound Velocity ◽  
Ultrasonic Transducers ◽  
New Method ◽  
Ultrasound Transducers ◽  
Accuracy And Precision ◽  
Conventional Ultrasound ◽  
Measurable Distance ◽  
Profile Technique ◽  
Good Agreement

Abstract The velocity vector profile technique based on an ultrasound pulsed Doppler method can enrich the information of a flow field, however, it has shown a low availability because a new design of special transducers is required for each measurement case. This study proposes a new method of profiling the velocity vectors using conventional ultrasound transducers that are widely supplied to UVP (Ultrasound velocity profile) users. We constructed a configuration of the transducers to minimize the uncertainty of the detection points at the receivers, and a measurable distance was theoretically determined by the configuration. Two feasibility tests were carried out. One was a test for the assessment of the measurable distance, which agreed well with the theoretical distance. The other was the evaluation of the measurement of two-dimensional velocity vectors by the new method and it was performed in a towing tank facility without the velocity fluctuation. From the evaluation, it was confirmed that the measured vectors showed good agreement to the reference values, and their accuracy and precision were competitive compared to previous studies. The developed method was applied to two unsteady flows for demonstrations. The results clarified that the proposed method guarantees high availability and accuracy for the velocity vector profiles.

Emission of molecular nitrogen at tight focusing of femtosecond laser pulses in air

2021 ◽  
pp. 42-48
Author(s):  
A.A. Ilyin ◽  
◽  
K.A. Shmirko ◽  
S.S. Golik ◽  
D.Yu. Proschenko ◽  
...  
Keyword(s):  
Particle Density ◽  
Molecular Nitrogen ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Plasma Particle ◽  
Sharp Drop ◽  
Radiation Level ◽  
Femtosecond Radiation ◽  
Tight Focusing ◽  
Good Agreement

A numerical model describing the dynamics of plasma particle density upon filamentation of femtosecond radiation in the air is presented. The simulation results are in good agreement with the experimental data. The pumping processes of the N2 and N2+ radiative levels are investigated. The model predicts a sharp drop in electron temperature and density within 1 ns. For the first positive nitrogen system, an excess of the population of the upper radiation level over the population of the lower one is observed for 550 ps.

MOLECULAR DYNAMICS SIMULATION OF PULSED LASER ABLATION

2011 ◽  
Vol 25 (04) ◽  
pp. 543-550 ◽  
Author(s):  
XIU-FANG GONG ◽  
GONG-XIAN YANG ◽  
PENG LI ◽  
YIN WANG ◽  
XI-JING NING
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Laser Pulses ◽  
Solid Surfaces ◽  
Dynamics Simulation ◽  
Angular Distributions ◽  
Adiabatic Expansion ◽  
Expansion Model

We have developed a simplified molecular-dynamical model for simulating ablation of solid surfaces by laser pulses, and specifically investigated expansion of Cu cloud in vacuum vaporized on the surface, showing that the angular distributions of the plume depend on the shape of the laser spot on the surface. In particular, experimentally observed flipover effects have been obtained, and an adiabatic constant determined from our simulations via an adiabatic expansion model agrees well with previous measurements.

Pulsed Laser Treatment of Virgin, Self and Europium Implanted Nickel: Evidence of Defect Impurity Interaction

1981 ◽  
Vol 7 ◽  
Author(s):  
G. Battaglin ◽  
A. Carnera ◽  
G. Della Mea ◽  
P. Mazzoldi ◽  
Animesh K. Jain ◽  
...  
Keyword(s):  
Solid Solution ◽  
Liquid Phase ◽  
Laser Treatment ◽  
Ruby Laser ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Metastable Solid Solution ◽  
Ion Channeling ◽  
Impurity Interaction ◽  
The Eu

ABSTRACTWe present a comparative study (by 1.8 MeV 4He+ ion channeling) of virgin, self and Eu implanted single crystals of nickel, under irradiation with single ruby laser pulses. The as implanted Eu is nearly non-substitutional and remains so, even after laser treatment. The comparative defect dechanneling behaviour provides explicit evidence of defect-impurity interaction which may be suppressing the formation of an expected metastable solid solution in the Eu-Ni system, which possesses miscibility in the liquid phase. A clear surface Eu peak appears at 2.1 J/cm2.

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