应用光全反射法及图像处理技术研究真实接触面积

光全反射法是测量真实接触面积的常用手段,然而用其测得的接触图像小,接触斑点的边界模糊。作者应用波动光学的有关理论对光全反射法的基本原理进行了深入的研究,进而提出用图像处理技术识别接触区域的边界。通过钢球与平面接触的试验研究,验证了这种测量方法的准确性和可靠性,并且根据试验结果分析了赫兹接触理论的局限性。文章最后还阐述了对典型工程表面接触面积的测量与结果。

Investigation of Real Contact Area through the Application of Total Reflection Method and Image Process Technique

Total reflection method has been commonly used to detect real contact area, however the boundary of the contact spots in the contact image obtained was vague.The principle of total reflection technique was analysed thoroughly in this paper. It is found that under the condition of total reflection, there is still the energy loss of the light wave due to the absorption by the asperity surface. The functional relation between light intensity of reflection, and contact surfaces distance was derived, and accordingly, the photomicrographs of the contact spots were analysed using an image processing system to identify the contact area. The contact pair was coupled with the white synthetic sapphire and metal specimen. The Hertz' contact test was also performed so as to verify the accuracy and the reliability of this technique, in the meanwhile, the limitations of Hertz' contact theory was analysed. Finally, the contact curves of typical surfaces in engineering practice were given. The results shown that the contact of rough surfaces is discrete and the relationship between the real contact area and the load is nonlinear.