Contact area

About: Contact area is a research topic. Over the lifetime, 12358 publications have been published within this topic receiving 256401 citations. The topic is also known as: contact patch & contact region.

Characterization of machining of AISI 1045 steel over a wide range of cutting speeds. Part 1: Investigation of contact phenomena

Abstract: Friction conditions at the tool-chip interface are one of the most important inputs for modelling and simulation of the machining process. However, the nature of the tool-chip contact is often assumed in developing finite element models, thereby seriously affecting their reliability. In this paper, results of an investigation into the tool-chip contact interface using uncoated tungsten-based cemented carbide tools in dry high-speed turning of AISI 1045 steel are presented. The tests were conducted at cutting speeds ranging between 198 and 879m/min with a feed rate of 0.1mm/rev and a constant depth of cut of 2.5 mm. The effects of cutting speed on tool rake face contact length, contact area, friction, element mapping, and surface roughness are studied and discussed. It is shown that the quantitative methods, used here to characterize the tool-chip contact region, can provide valuable data for accurate and reliable modelling of the metal machining process over a wide range of cutting speeds.

Scaling Normal Adhesion Force Capacity with a Generalized Parameter

Abstract: The adhesive response of a rigid flat cylindrical indenter in contact with a compliant elastic layer of varying confinement is investigated experimentally and described analytically. Using a soft elastic gel with substrate thickness, t, and indenter radius, a, 28 unique combinations of the confinement parameter, a/t, are examined over a range of 0.016 < a/t < 7.2. Continuous force capacity predictions as a function of a/t and material properties are provided through a scaling theory and are found to agree well with the experimental data. We further collapse all of the data over orders of magnitude in adhesive force capacity onto a single line described by a generalized reversible adhesion scaling parameter, A/C, where A is the contact area and C is the compliance. As the scaling analysis does not assume a specific separation mechanism the adhesive force capacity is well described during both axisymmetric edge separation and during interfacial fingering and cavitation instabilities. We discuss how the geom...

Contact Mechanics of Laser-Textured Surfaces

Abstract: We study numerically the contact mechanics of a flat and a curved solid. Each solid bears laser-induced, periodic grooves on its rubbing surface. Our surface topographies produce a similar load and resolution dependence of the true contact area as nominally flat, but randomly rough, self-affine surfaces. However, the contact area of laser-textured solids depends on their relative orientation. The estimated true contact areas correlate with kinetic friction measurements.

Numerical study of the hydromechanical behavior of two rough fracture surfaces in contact

Abstract: Flow in fractures is traditionally modeled by characterizing the aperture distribution with some deterministic function or set of stochastic parameters. Other models generate the aperture distribution by the closure of two stochastic surfaces. The objective of this research is to develop a model where the aperture distribution is determined during the closure of two random elastic surfaces with complete hydromechanical interaction. Because stress and strain conditions required to generate a given aperture distribution are calculated during closure, the model is used to couple the mechanical and hydraulic characteristics of the fracture. Stochastic realizations of clay fracture surfaces are generated by measuring one-dimensional profiles of a fracture surface. Next, the spectral representation of the profile is related to the fractal dimension of the fracture. Using the fractal dimension determined from one-dimensional clay profiles, an equivalent two-dimensional fractal surface is generated. Conceptually, each surface consists of linear elastic rectangular asperities resting upon a linear elastic half-space. During closure, asperities that come into contact deform and punch into the half space creating mechanical interaction between all the asperities on the grid. Once we determine the aperture distribution at an applied stress level, a hydraulic gradient is applied across the fracture and fluid flow is determined. Nodal pressures created by flow deform the aperture distribution coupling hydraulic to mechanical behavior. Stress versus relative closure results indicate that stress increases nonlinearly with relative closure. Fluid pressures in the aperture distribution exert a significant influence on the mechanical characteristics of a fracture. Fluid discharge through the fracture decreases exponentially with an increase in relative closure. Flow calculated in the rough walled aperture distribution deviates increasingly from the parallel plate model with the geometric mean aperture as the percent contact area increases. The deviation results from an increase in tortuosity and channelling of the flow field in the aperture distribution. We can use this model to develop stress and flow versus relative closure constitutive relationships for a single fracture as a function of fracture surface geometry.