Simulation study on laser cladding on preplaced powder layer with a tailored laser heat source

2013 ◽  
Vol 48 ◽  
pp. 141-152 ◽  
Author(s):  
W.C. Tseng ◽  
J.N. Aoh
Keyword(s):  
Heat Source ◽  
Laser Cladding ◽  
Simulation Study ◽  
Powder Layer ◽  
Laser Heat ◽  
Laser Heat Source

scholarly journals Experimental Validation of a Laser Heat Source Model for Laser Melting and Laser Cladding Processes

2014 ◽  
Vol 8 (1) ◽  
pp. 370-381 ◽  
Author(s):  
W. C. Tseng ◽  
J. N. Aoh
Keyword(s):  
Finite Element ◽  
Heat Source ◽  
Laser Cladding ◽  
Experimental Validation ◽  
Source Model ◽  
Laser Melting ◽  
Heat Source Model ◽  
Track Width ◽  
Laser Heat ◽  
Laser Heat Source

Selective laser melting (SLM) and laser cladding are laser additive manufacturing methods that have been developed for application to the near-net-shape process and 3D printing. The temperature distributions and track profiles of SLM and clad layers require additional in-depth investigation to optimize manufacturing processes. This research involved developing a tailored laser heat source model that contains a comprehensive selection of laser beam characteristics and can be used in finite element analysis of the laser melting process. This paper presents a systematic experimental validation of the applicability of the proposed laser heat source model to single-track Nd:YAG and CO2 laser melting simulations. The evolution of the melt pool isotherms and the variation in track profiles caused by adjusting the laser power and scanning speed were numerically predicted and experimentally verified. Appropriate process parameters and the threshold power for continuous track layer formation were determined. The balling phenomenon on preplaced powder was observed at power levels below the threshold values. Nd:YAG laser melting resulted in a wide and shallow track profile, which was adequately predicted using the numerical simulation. CO2 laser melting resulted in a triangular track profile, which deviated slightly from the finite element prediction. The results indicated a high level of consistency between the experimental and the numerical results regarding track depth evolution, whereas the numerically predicted track width evolution deviated slightly from the experimentally determined track width evolution. This parametric laser melting study validated the applicability of the proposed laser heat source model in numerical analysis of laser melting processes such as SLM and laser cladding.

Development of Multi-Axis Laser-Assisted Milling Device

2017 ◽  
Author(s):  
Dong-Hyeon Kim ◽  
Wan-Sik Woo ◽  
Won-Shik Chu ◽  
Sung-Hoon Ahn ◽  
Choon-Man Lee
Keyword(s):  
Heat Source ◽  
Tool Path ◽  
Cutting Tool ◽  
Field Studies ◽  
Flat Surfaces ◽  
Laser Heat ◽  
Complex Shapes ◽  
Laser Heat Source ◽  
Removal Processes ◽  
Machining Productivity

Laser-assisted machining (LAM) process is an effective method to facilitate material removal processes for difficult-to-cut materials. In LAM process, the mechanical strength of various materials is reduced by a laser heat source focused in front of the cutting tool during machining. Since the laser heat source is located ahead of the cutting tool, the workpiece is preheated by the heat source. This enables difficult-to-cut materials to be machined more easily with low cutting energy, increasing the machining productivity and accuracy. It is difficult to apply laser-assisted milling (LAMilling) to workpieces having complex shapes, because it is not easy to control laser preheating and the cutting tool path for three-dimensionally shaped workpieces. LAMilling has only been used in limited fields such as single-direction machining of flat surfaces. To apply this process in the industrial field, studies on workpieces having various shapes are needed. This study aims to develop a laser-assisted milling device having multiple axes and to investigate the machining characteristics of several difficult-to-cut materials.

Laser Lock-In Thermography for Fatigue Crack Detection

2013 ◽  
Vol 558 ◽  
pp. 76-83 ◽  
Author(s):  
Yun Kyu An ◽  
Ji Min Kim ◽  
Hoon Sohn
Keyword(s):  
Fatigue Crack ◽  
Heat Source ◽  
High Power ◽  
Crack Detection ◽  
Laser Source ◽  
Cw Laser ◽  
Laser Heat ◽  
Laser Heat Source ◽  
Fatigue Crack Detection ◽  
Lock In

This study proposes a new nondestructive evaluation methodology named laser lock-in thermography (LLT) for fatigue crack detection. LLT utilizes a high power continuous wave (CW) laser as a heat generation source for lock-in thermography instead of commonly used flash and halogen lamps. The advantages of the proposed LLT method are that (1) the laser heat source can be positioned at an extended distance from a target structure thank to the directionality and low energy loss of the laser source, (2) thermal image degradation due to surrounding temperature disturbances can be minimized because of high temperature gradient generated by the laser source and (3) a large target surface can be inspected using a scanning laser heat source. The developed LLT system is composed of a modulated high power CW laser, galvanometer and infrared camera. Then, a holder exponent-based data processing algorithm is proposed for intuitive damage evaluation. The developed LLT is employed to detect a micro fatigue crack in a metal plate. The test result confirms that 5 μm (or smaller) fatigue crack in a dog-bone shape aluminum plate with a dimension of 400 x 140 x 3 mm3 can be detected.

Phase detection of an alternating laser heat source in infrared images using Bayesian recursive filtering

2019 ◽  
Author(s):  
Amirreza Baghbanpourasl ◽  
Gerhard Traxler ◽  
Pauline Meyer-Heye ◽  
Sriniwas Chowdhary Maddukuri ◽  
Christian Eitzinger
Keyword(s):  
Heat Source ◽  
Phase Detection ◽  
Infrared Images ◽  
Recursive Filtering ◽  
Laser Heat ◽  
Laser Heat Source

THERMAL TRANSPORT PHENOMENON IN PROCESSED MEAT HEATED BY LASER HEAT SOURCE

2008 ◽  
Vol 08 (01) ◽  
pp. 17-25
Author(s):  
SHUICHI TORII ◽  
WEN-JEI YANG
Keyword(s):  
Heat Source ◽  
Thermal Wave ◽  
Numerical Technique ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Conservation Equation ◽  
Processed Meat ◽  
Laser Heat ◽  
Short Period ◽  
Laser Heat Source

The present study deals with the effect of laser radiation on the propagation phenomenon of a thermal wave in processed meat subjected to symmetrical heating on both sides. Laser heating is modeled as an internal heat source with various time characteristics. The Cattaneo heat flux law, together with the energy conservation equation, is solved by a numerical technique based on an explicit scheme, i.e. MacCormack's predictor-corrector scheme. The study concludes that (1) if the absorption coefficient of the continuously operated laser heat source increases, then temperature overshoot occurs in processed meat within a very short period of time; (2) the overshoot and oscillation of thermal wave depend on the frequency of the heat source time characteristics; and (3) the criterion for the occurrence of thermal wave in a thin processed meat is the thickness of the order of about 1 mm.

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