[1] FUJINAGA S,TAKENAKA H,NARIKIYO T,et al.Direct observation of keyhole behavior during pulse modulated high power Nd:YAG laser irradiation[J].J Phys,2000,D33(5):492-497.
[2] SEMAK V V,BRAGG W D,DAMKROGER B,et al.Transient model for the keyhole duringlaser welding[J].J Phys,1999,D32(15):61-64.
[3] GONG Sh L,YAO W,LI S.Porosity formation mechanisms and controlling technique for laser penetration welding aluminum alloy[J].Transaction of the China Welding Institute,2009,30(1):59-62(in Chinese).
[4] KATAYAMA S,KOBAYASHI Y,MIZUTANI M,et al.Effect of vacuum on penetration and defects in laser welding[J].Journal of Laser Applications,2001,13(5):187-192.
[5] ZHANG X H,ZHANG X D,CHEN W Zh,et al.Prevention and mechanical analysis of porosity formation in pulsed CO2 laser welding of 30CrMnSiA[J].Laser Technology,2007,31(4):419-422(in Chinese).
[6] LI L Q,CHEN Y B,TAO W.Research on dual-beam welding characteristic of aluminum alloy[J].Chinese Journal of Lasers,2008,35(11):1783-1788(in Chinese).
[7] QIN G L,LIN Sh Y.Radial dimension of keyhole and its dynamic characteristics in laser deep penetration welding[J].Chinese Journal of Lasers,2005,32(4):557-561(in Chinese).
[8] KAPLAN A F,MIZUTANI M,KATAYAMA S,et al.On the mechanisms of pore formation during laser spot welding[J].Proc SPIE,2003,4831:186-191.
[9] KAPLAN A F,MIZUTANI M,KATAYAMA S,et al.Unbounded keyhole collapse and bubble formation during pulsed laser interaction with liquid zinc[J].J Phys,2002,D35(2):1218-1228.
[10] KAR A,ROCKSTROH T,MAZUMDER J.Two-dimensional model for laser-induced materials damage:effect of assist gas and multi-reflections inside the cavity[J].J A P,1992,71(6):2560-2569.
[11] MILEWSKI J,SKLAR E.Modeling and validation of multi-reflections for enhanced laser welding[J].Modelling and Simulation in Material Science Engineering,1996,4(3):305-332.
[12] SOLANA P,NEGRO G.A study of effect of multi-reflections on the shape of the keyhole in laser processing of materials[J].J Phys,1997,D30(23):3216-3222.
[13] FABBRO R,CHOUF K.Keyhole modeling during laser welding[J].J A P,2000,87(9):4075-4083.
[14] GANOR J,LASAGA A C,WEI P,et al.Beam focusing characteristics effect on energy reflection and absorption in a drilling or welding cavity of paraboloid of revolution[J].International Journal of Heat and Mass Transfer,1998,41(21):3299-3308.
[15] JIN X Zh,LI L J,ZHANG Y.A study on Fresnel absorption and reflections in the keyhole in deep penetration welding[J].J Phys,2002,D35(18):2304-2310.
[16] KI HYUNSON,MOHANTY P,MAZUMDER J.Multi-reflection and its influence on keyhole evolution[J].Journal of Laser Applications,2002,14(1):39-45.
[17] CHO J,NA S.Implementation of real-time multiple reflections and Fresnel absorption of laser beam in keyhole[J].J Phys,2006,D39(24):5372-5378.
[18] OSHER S,SETHIAN J A.Front propagation with curvature-dependent speed:algorithms based on Hamilton-Jacobi formulations[J].Journal of Computational Physics,1988,79(1):12-49.