Measurement of contact stiffness of steel plates with various machined surfaces
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The purpose of my thesis is to measure and analyze the contact stiffness of the interface between steel materials with different roughnesses and a polished steel block. An apparatus with measurements based on contact resonance and with simple dynamics was developed by Serpe (1999) and used in my experiment. Such measurements have not been previously made with steel materials of different roughness. A particular challenge of my research is to introduce wavy surface texture into analysis of contact stiffness of rough surfaces. The measured results are compared with the prediction based on the Greenwood and Williamson (G-W) model for surface with a Gaussian distribution or exponential distribution of asperity heights and with periodically wavy surfaces. We find that a uniformly wavy surface model overpredicts the stiffness by one to three orders of magnitude, compared with measurements. Very strict control and characterization of sample geometry and three-dimensional surface roughness will be needed to eventually obtain good agreement between theory and experiment.