Abstract

This paper reports the experimental investigation of the modified specific energy, mechanical properties and temperature field of limestone rock that was irradiated by continuous wave fiber laser at different irradiation powers. Results show that the specific energy decreases nonlinearly from 17 kJ/cm³ to 11 kJ/cm³ and rate of perforation increases from 0.2 mm/s to 0.65 mm/s with laser power increasing from 600 W to 1000 W. The modified specific energy which is used to evaluate rock excavation efficiency is observed to decrease monotonously from 0.27 kJ/cm³ to 0.068 kJ/cm³ with increasing laser power. Higher laser power results in larger surface temperature and temperature gradient. The rate of rock surface temperature irradiated by laser with power of 1000 W reaches 14 °C/ms within 140 ms. The temperature gradient, with largest value of 1400 °C/mm near to the sample axis, decreases sharply with radius. The high solution 3D X-ray microanalyser (XRM) images show that the rock perforation is a V-shaped hole and obvious cracks penetrate the whole rock sample. The extremely rough surface and well-developed cracks for irradiated samples are observed through scanning electron microscope (SEM). X-ray diffraction (XRD) results also show that the main minerals of rock after irradiation are quite different from that of original sample. The maximum reduction rate of compressive strength of irradiated rock with laser power of 1000 W is 60%, and the maximum increasing rate of peak strain of irradiated rock with laser power of 800 W is 65%.

中文翻译：

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光纤激光对徐州石灰石改性比能，温度场和力学性能的实验研究

摘要

本文报道了在不同照射功率下，连续波光纤激光器对石灰石岩石的比能，力学性能和温度场的修正影响的实验研究。结果表明，随着激光功率从600 W增加到1000 W，比能量从17 kJ / cm ³非线性减小到11 kJ / cm ³，射孔速率从0.2 mm / s增加到0.65 mm / s。用来评估岩石开挖效率的方法单调地从0.27 kJ / cm ^3降低到0.068 kJ / cm ³随着激光功率的增加。较高的激光功率会导致较大的表面温度和温度梯度。功率为1000 W的激光照射的岩石表面温度的速率在140 ms内达到14°C / ms。温度梯度在样品轴附近的最大值为1400°C / mm，随半径急剧减小。高分辨率3D X射线显微分析仪（XRM）图像显示，岩石穿孔为V形孔，并且明显的裂纹贯穿整个岩石样品。通过扫描电子显微镜（SEM）观察到被辐照样品的极其粗糙的表面和发达的裂纹。X射线衍射（XRD）结果还表明，辐照后岩石的主要矿物与原始样品有很大不同。