> 10 \pJava Excel API v2.6 Ba==h\:#8X@"1Arial1Arial1Arial1Arial + ) , * `<DC, title[*]contributor[author]contributor[advisor]keywords[*]date[issued] publisher citationsidentifier[uri]identifier[doi]abstractrelation[journal]relation[volume]relation[no]relation[page]MMultiphysical Analysis of Thermo-Elastic Effect in Laser-Material Interaction\18ǽ2015-02\ՑYPxhttps://repository.hanyang.ac.kr/handle/20.500.11754/128930;
http://hanyang.dcollection.net/common/orgView/200000425824;YThermo-elastic effect in laser-material interaction is of great interest for current industries because of its advantage of producing mechanical effect non-contactually. Phenomena induced by the thermo-elastic effect are cracking and thermo-elastic wave generation. Cracking can occur when the thermal stress is greater than the yield stress. A thermo-elastic wave can be generated by the fast variation of thermal stress when the irradiation time is very short (generally less than a microsecond).
However, the thermo-elastic effect has not been sufficiently analyzed yet. In particular, laser-induced slipping, which is a kind of cracking phenomenon in non-metallic materials of crystal structure such as silicon, has been seldom studied. Furthermore, numerical model for laser-induced slipping has not yet been developed.
Therefore, in this thesis, the multiphysical model to simulate laser-induced slipping was developed. In this model, volume absorption and temperature-dependent properties were considered. Directional shear stress and temperature-dependent yield stress were calculated to predict the slip occurrence with initiation time. In order to verify the model, the slip occurrence as a function of initiation time was experimentally measured using a laser scattering technique. In the experiments, a silicon wafer was irradiated by a continuous near infrared laser.
In terms of thermo-elastic wave generation, the previous models are limited to the conditions of Gaussian spatial beam profile and constant material properties. However, when a slit mask is used to produce a line laser beam, the spatial beam profile irradiated on the surface is not Gaussian but almost square-like. Thus, it is necessary to consider a square-like spatial beam profile in this case. In addition, consideration of temperature-dependent material properties is required in order to match with real situations.
Therefore, in this thesis, the multiphysical model was developed to simulate the thermo-elastic wave generation to take into account the square-like spatial beam profile and temperature-dependent material properties also. By using this model the thermo-elastic surface wave was simulated. In order to verify the model, the thermo-elastic surface wave was theoretically analyzed and experimentally measured. In the experiments, an aluminum alloy specimen was irradiated by a Nd:YAG pulsed laser and the thermo-elastic surface wave was detected using a piezoelectric transducer.
Consequently, the multiphysical models were suitable for the analysis of laser-induced slipping and thermo-elastic wave generation induced by thermo-elastic effect in laser-material interaction. It is expected that the models can be used for laser-induced slipping prediction and thermo-elastic wave prediction and visualization.|t@ < 8֑ǩX 1 D <\ 0Ĭ | ¬ ǔ t Ǵ ֬ | ȩD . 1 Xt XՔ @ lИ 1 <\, lИ@ Q%t m Q% X, 1Ӕ Ӥ t pȬ X\ Q%X `x T Xt \. 췘 1 \ l D D\ <\, ҈ lЬ lpX D < XՔ lИX |ǅx ¬Q t pX l JX \ t xĳ JX.
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