This paper is an experimental and theoretical study of changes in a laser-induced photoacoustic signal near a hole in metal plates of D16 aluminum alloy. The process of photoacoustic signal generation from metals is analyzed within the classical thermoelasticity framework, with account for only the thermal effect of laser irradiation on metal lattice deformation. A comparison is made of photoacoustic experimental and theoretical results obtained for a mechanically stressed aluminum alloy plate with a hole. The effect of external mechanical stresses on the behavior of laser photoacoustic signals near the hole is studied experimentally and theoretically. It is found that the classical theory of thermoelasticity is not enough to correctly describe the stress dependence of the photoacoustic signal near a hole in aluminum alloy plates. In order for the obtained experimental and theoretical results to agree, along with the thermal effect of laser irradiation on the lattice, it is necessary to account for the additional effect of the electron gas. A calibration procedure of the laser photoacoustic signal with respect to stress is described. It is shown that internal stresses in metals can be estimated by the photoacoustic method in combination with the hole drilling method.

中文翻译：

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内应力金属板孔洞附近激光诱导光声效应的理论和实验研究

本文是对 D16 铝合金金属板孔附近激光诱导光声信号变化的实验和理论研究。在经典热弹性框架内分析了从金属产生光声信号的过程，仅考虑了激光照射对金属晶格变形的热效应。对带有孔的机械应力铝合金板的光声实验和理论结果进行了比较。从实验和理论上研究了外部机械应力对孔附近激光光声信号行为的影响。发现经典的热弹性理论不足以正确描述铝合金板孔附近光声信号的应力依赖性。为了使获得的实验和理论结果一致，以及激光照射对晶格的热效应，有必要考虑电子气的附加效应。描述了激光光声信号相对于应力的校准过程。结果表明，金属中的内应力可以通过光声法与钻孔法相结合来估计。