The sliding-contact factor (ηsc): a novel index for slip risk definition

Abstract

The causes of slip are multiple and depend on the mechanical and aesthetic characteristics of the surfaces in contact, and on external elements related to the specific situation. The non-slip characteristics of a surface can be evaluated by measuring the dynamic friction coefficient (DCoF). Hazardous conditions generally appear and progress over time as a result of use, aging-related natural degradation, lack of or incorrect cleaning and maintenance. This study focuses on the characteristics of roughness profiles of the surfaces in contact and aims at the identification of those roughness parameters that can allow a more reliable evaluation of both the "slip risk index" and of its change over time due to alterations of surface texture. The sliding-contact factor,ηsc, is identified as a candidate for the evaluation of slip risk, and is represented by a dimensionless number that can be calculated using only the data of some roughness parameters, measured by a handheld instrument (Portable Surface Roughness Measuring Instrument), portable and easy to use. The sliding-contact factorηsc allows the evaluation of the "slip risk index" of dry and water-contaminated surfaces and can increase the accuracy of the assessment of the "slip risk index” if evaluated through the DCoF only.Article Highlights A new parameter, termed sliding-contact factor ηsc is defined and is correlated with the dynamic friction coefficient. A classification of the slip risk index can be performed by means of the introduced sliding- contact factor ηsc. The present work can represent a basis for the development of a new international standard for slip-risk assessment.