Experimental analysis of interface contact behavior using a novel image processing method*

Abstract

The spatial and temporal evolution of real contact area of contact interface with loads is a challenge. It is generally believed that there is a positive linear correlation between real contact area and normal load. However, with the development of measuring instruments and methods, some scholars have found that the growth rate of real contact area will slow down with the increase of normal load under certain conditions, such as large-scale interface contact with small roughness surface, which is called the nonlinear phenomenon of real contact area. At present, there is no unified conclusion on the explanation of this phenomenon. We set up an experimental apparatus based on the total reflection principle to verify this phenomenon and analyze its mechanism. An image processing method is proposed, which can be used to quantitative analysis micro contact behaviors on macro contact phenomenon. The weighted superposition method is used to identify micro contact spots, to calculate the real contact area, and the color superimposed image is used to identify micro contact behaviors. Based on this method, the spatiotemporal evolution mechanism of real contact area nonlinear phenomena is quantitatively analyzed. Furthermore, the influence of nonlinear phenomenon of real contact area on the whole loading and unloading process is analyzed experimentally. It is found that the effects of fluid between contact interface, normal load amplitude and initial contact state on contact behavior cannot be ignored in large-scale interface contact with small roughness surface.

Mechanism analysis and improved model for stick-slip friction behavior considering stress distribution variation of interface

“…In our previous research, [46] an identification and quantitative analysis method of interface micro contact behavior is proposed. In this section, this method is used for analyzing the interface micro contact behavior in the stick-slip process.…”

“…8(a). [46] When the graphs of three kinds of tangential forces are superimposed together, different colors indicate different contact behaviors in the process of tangential force growth. Blue indicates that the initial contact point disappears, green indicates that the new contact point disappears with the increase of tangential force, sky blue indicates that the initial contact point grows and then disappears, and purple, yellow and black indicate that the contact area growth.…”

Optimization of image processing methods based on wavelet transform and adaptive thresholding

“…The effectiveness of denoising directly affects the subsequent processing done on the image [4][5]. However, some traditional image-denoising algorithms, such as the Wiener filter, are not ideal for removing image noise while blurring some important details of the image [6][7][8]. Since wavelet transform has good localization properties, it has been widely used as a signal and image processing tool [9][10][11].…”