Modeling laser drilling in percussion regime using constraint natural element method

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Abstract The laser drilling process is the main process used in machining procedures on aeronautic engines, especially in the cooling parts. The industrial problematic is to reduce geometrical deviations of the holes and defects during manufacturing. The interaction between a laser beam and an absorbent metallic matter in the laser drilling regime involves thermal and hydrodynamical phenomenon. Their role on the drilling is not yet completely understood and a realistic simulation of the process could contribute to a better understanding of these phenomenon. The simulation of such process induces strong numerical difficulties. This work presents a physical model combined with the use of the original Constraint Natural Element Method to simulate the laser drilling. The physical model includes solid/liquid and liquid/vapor phase transformations, the liquid ejection and the convective and conductive thermal exchanges. It is the first time that all these phenomena are included in a modelling and numerically solved in a 2D axisymmmetric problem. Simulations results predict most of measurements (hole geometry, velocity of the liquid ejection and laser drilling velocity) without adjusting any parameters.

Multiphysics simulation of single pulse laser powder bed fusion: comparison of front capturing and front tracking methods

“…However, we also find that the steady melt pool thickness h mp in forced conduction regime increases with laser power. This result contradicts the well-known "piston" model (Semak and Matsunawa, 1997) (which gives accurate physical description of melt pools driven by recoil pressure) and experimental observations (Girardot et al, 2017), both showing the inverse trend. Such a result is supposed to be due to the simplified expression of the recoil pressure implemented here.…”

Laser-induced plume investigated by finite element modelling and scaling of particle entrainment in laser powder bed fusion

“…At intermediate vaporisation intensities (T > T V ), vaporized matter is more or less confined by the ambient gas and β R , ṁ and P s evolve with the temperature and with the local Mach number. However, Hertz-Langmuir equation is not valid anymore, so the authors apply Pang's method [20]-also proposed by Girardot et al [12]-which consists in bridging the two evaporation regimes by a smoothed third-order polynomial:…”

“…Transient mass (11) and momentum (12) conservation laws are solved in both the metal and gas domains:…”

“…A conservation equation of metal vapour concentration is coupled to the equation of momentum conservation (12):…”

“…In the same prospect, gas kinetics results and empirical laws are extensively used in numerical computations of laser ablation [10,11], laser drilling [12], laser (spot [13][14][15][16][17]) welding [18][19][20][21][22][23], LPBF [24][25][26][27] and electron beam melting (EBM) [28]. To date, one of the most self-consistent numerical model has probably been proposed by Pang and co-workers [20][21][22].…”