基于弹-塑-断裂理论的镐型截齿截割机理研究与实验验证

为研究镐型截齿在截割煤岩过程中的截割机理,建立镐型截齿外轮廓的数学模型,基于弹性力学、塑性力学和断裂力学等理论,提出了煤岩截齿截割力作用下发生弹-塑-断裂失稳理论模型,以此来描述截齿截割煤岩机理,并依据理论模型分别推导出煤岩在弹性变形、塑性变形和断裂失稳状态下截齿截割力以及煤岩应力表达式。最后采用自主搭建实验设备进行不同截割倾角的镐型截齿截割煤岩实验,实验结果表明:煤岩在截齿截割力作用过程中,随着截齿截割深度的增加,截齿与煤岩的接触面积逐步增大,煤岩存在弹性变形阶段、塑性变形阶段以及断裂失稳阶段并与理论模型相符;截割倾角为90°、75°、60°时,截齿截割阻力理论值与实验值的均方根误差分别为0.082 kN、0.199 kN、0.204 kN,理论值与实验值相差较小,验证理论模型的正确性。

Cutting mechanism of conical pick based on elastic-plastic-fracture theory and test verification

To study the cutting mechanism of conical pick in process of cutting coal,a mathematical model of external contour of conical pick was established.Based on theories of elastic mechanics,plastic mechanics and fracture mechanics,the theoretical model for elastic-plastic-fracture instability to happen under action of cutting force of pick cutting coal rock was proposed to describe the mechanism of pick cutting coal rock.According to the model,expressions for pick cutting force and coal rock stress under coal rock’s elastic deformation,plastic deformation and fracture instability were derived.Finally,the self-built test equipment was used to perform pick cutting coal rock tests with different cutting angles.The test results showed that during pick cutting force being exerted on coal rock,the contact area between pick and coal rock gradually increases with increase in pick cutting depth,coal rock has elastic deformation stage,plastic deformation one and fracture instability one,and these facts are consistent with what the theoretical model describes;when cutting angle is 90°,75°,60°,RMS errors between the theoretical value and the test one of pick cutting resistance are 0.082 kN,0.199 kN and 0.204 kN,respectively,the difference between the theoretical value and the test one is small to verify the correctness of the theoretical model.