基于计算机视觉和声学的小粒咖啡破裂机理特性的研究

Study on Mechanism of Coffea Arabica Break Based on Computer Vision and Acoustics

为提高小粒咖啡加工效果,从多角度分析其破裂机理。通过制备小粒咖啡样本,利用电子试验机发现小粒咖啡样本在不同阶段下的裂纹数目(宽度大于0.1 mm)与裂纹最大宽度的变化情况,并获得有无钻孔处理的小粒咖啡样本在裂纹压密阶段、增长阶段、平稳阶段、非平稳阶段的变化情况,以及两者的能量、应力变化趋势。由COMSOL分析有无钻孔处理的小粒咖啡样本裂纹声源位置以及数目。分析有无孔洞的小粒咖啡样本内应力波的损失系数以及小粒咖啡样本表面光点的损失系数,将应力波的损失系数、光点的损失系数所得理论小粒咖啡样本内应力结果与试验所得应力结果进行比较。结果显示:有无钻孔处理的小粒咖啡样本的裂纹声源数目,两者分别为1573、876,有钻孔处理的小粒咖啡样本要比无钻孔处理的小粒咖啡样本破裂程度更为明显。由应力波的损失系数、光点的损失系数所得理论小粒咖啡样本内应力结果与试验所得结果总体变化大致相同。通过SPSS求得有无孔洞的小粒咖啡样本情况下,应力波的损失系数所得应力波峰前后两者的相关系数分别为0.976、0.912;0.932、0.824。光点的损失系数所得应力波峰前后两者的相关系数分别为0.993、0.967;0.973、0.864。

In order to improve the processing effect of coffea arabica,the cracking mechanism was analyzed from many aspects.Through the preparation of coffea arabica samples,the changes of crack number(width greater than 0.1 mm)and maximum crack width in different stages of coffea arabica samples were found by using electronic testing machine,and the changes of crack densification stage,growth stage,stationary stage and non-stationary stage of coffea arabica samples with or without drilling treatment were obtained,as well as the change trend of energy and stress potential.COMSOL was used to analyze the location and number of crack sources of coffea arabica samples with or without drilling.The loss coefficient of internal stress wave and light spot on the surface of coffea arabica samples with or without holes were analyzed.The theoretical results of internal stress of coffea arabica samples were compared with the experimental results.The results showed that the number of crack sources of coffea arabica samples with or without drilling treatment was 1573 and 876 respectively,and the crack degree of coffea arabica samples with drilling treatment was more obvious than that of coffea arabica samples without drilling treatment.According to the loss coefficient of stress wave and the loss coefficient of light spot,the internal stress results of theoretical coffea arabica samples were almost the same as the experimental results.The loss coefficient of stress wave was obtained by SPSS,and the correlation coefficients before and after the stress peak were 0.976,0.912,0.932,0.824,respectively.The correlation coefficients before and after the stress peak were 0.993,0.967,0.973,0.864,respectively.