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Measuring friction on the human body is challenging on areas where the surface of the skin is curved. Handheld devices for measuring friction may make it easier to rapidly measure from hard-to-reach areas, however, the orientation of the probe relative to the surface is often sub-optimal to reliably measure the normal force. Here, the friction on the surfaces of a mannequin and a human body are measured and corrected using a curvature correction technique. This is accomplished by accounting for the shape of the measurement surface and the orientation of the measurement device relative to that surface. Two strategies for constructing the surface shape of the measurement surface are compared. [Display omitted] • Implement a curved surface correction method in 3D with a linear sliding handheld tribometer. • Test methods for capturing the 3D curved surface shape for the surface correction method. • Measure sliding friction on a human body. [ABSTRACT FROM AUTHOR]

In situ measurement of frictional properties, particularly of human skin, is challenging. A major challenge is that the measured surface may be curved and oriented arbitrarily relative to the measurement device, making it difficult to obtain accurate and reliable friction estimates. Here we propose a method to simultaneously estimate the orientation of the surface during friction measurements, using a custom-made hand-held tribometer. The method accounts for the position and orientation of the tribometer relative to the shape of the measured surface. Our simple calibration method allows lightweight tribometers to be built with cheaper materials like plastic, without sacrificing accuracy. [Display omitted] • Propose a general method to measure force data on curved surfaces for sliding contacts and friction analysis. • Implement this curve correction method with a linear sliding handheld tribometer. • Describe the importance of carefully testing and calibrating the outputs of lightweight devices that may have low flexural rigidity. [ABSTRACT FROM AUTHOR]

Abstract: The developers of innovative automotive active systems have recently stimulated new interest toward the analysis of the frictional behaviour of brake and clutch facings. This paper presents the experimental results acquired with a laboratory setup on brake and clutch facing samples in sliding motion for different operating conditions. An artificial neural network has been used to obtain a comprehensive view of the influence of the main sliding parameters. The study has also taken into account the not weak influence of the sliding acceleration to improve the friction coefficient prediction during transient operations of these dry friction based devices. [Copyright &y& Elsevier]

Experiments were performed to investigate the effect of micropitting on friction coefficient. Two twin-disc machines were used: one to develop micropitting on a disc pair, the other one to measure the friction coefficient. Fatigue was endured on one disc pair; another was used as a reference to dissociate the impact of micropitting from other factors. The study shows that friction coefficient was impacted by the development of micropitting. It also underlines a clear correlation between micropitting magnitude and friction coefficient. The influence on friction of classical parameters, such as roughness and oil, was also discussed in order to validate that only micropitting growth influenced friction measurements. • The impact of micropitting on the friction coefficient of two lubricated surfaces is investigated. • Two twin disc machines are used: one to generate micropitting, one to measure friction coefficient. • A correlation between micropitting magnitude and friction coefficient increase is underlined. [ABSTRACT FROM AUTHOR]