本研究主要探討長脈衝雷射於金屬薄板引發應力與變形現象，分析水膜覆蓋層及不同雷射加工參數所引發應力之影響，分別以實驗及數值模擬進行探討。實驗中使用Nd-YAG脈衝雷射(波長1064 nm)分別加熱具水膜覆蓋的銅片與不鏽鋼片，並使用陶瓷壓電感測器與白光干涉儀量測脈衝雷射作用產生之應力與板件變形，且分別針對不同水膜厚度、試件厚度以及不同雷射加工條件進行討論。在數值分析部分，考慮材料之彈塑性行為，採用單純力學模式以有限元素軟體計算雷射引發應力造成板件變形與殘留應力，並與實驗結果比較。

結果顯示當雷射能量不足使試件表面產生熔融或汽化反應時，雷射引發之應力主要為雷射作用過程中所產生之熱應力與輻射壓力效應；當試件表面產生熔融或汽化，在水膜覆蓋下，剝蝕效應與電漿產生之回彈壓力將使應力顯著增加，且應力與變形會隨著雷射功率、脈衝作用時間、水膜厚度的增加而增加，但隨板件厚度增加而減少。

The aim of this study is to analyze the phenomena of the laser induced stress and deformation on the metallic plate with a long pulse laser, and investigate the effects of the water film on the substrate experimentally and numerically. In the experiment, an Nd-YAG laser was used as a pulse energy source to heat the copper and 304 stainless steel plates respectively. The stress and plate deformation have been measured with ceramic piezoelectric transducers and white light interferometer respectively. With various thicknesses of the water film and substrate, the effects of the process parameters were investigated in the experiment. Furthermore a finite element software was adopted to calculate plate deformation, residual stress and strain in the numerical analysis.

It was shown that the main sources of the stress terms at low intensity radiations are the thermal stress and radiation pressure produced directly by the laser interaction. However, at the focus of the laser beam, a strong stress response due to the recoil pressure produced by the ablation and plasma mechanisms on the stainless steel substrate might occur. The stress could be enlarged by covering the water film on the substrate. It can be found that the stress and deformation increases with the laser power, pulse duration time, and thickness of water film in the present study.

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