Incidence of Predisposing Factors on the Human Hand-arm Response with Flexed and Extended Elbow Positions of Workers Subject to Different Sources of Vibrations

Abstract

Purpose This paper analyses the predisposing factors that affect the time response of the hand–arm system. Predisposing factors are the method of tool use, tool type, source of power, the mass of tool, workpiece held in hand, dimensions of the handle, grip force and push force, and dynamic and thermal properties of handgrips. Methods This research considers the variability of the time response of the hand–arm system with respect to predisposing factors evaluated in 5 working conditions. The mathematical model consists of a distributed parameter representation in the form of a beam characterized by a continuous distribution of the mass, damping, and elasticity of the physical properties of the human and–arm system. The mathematical model considers the action of the extensor muscles of the elbow. The experimental investigations evaluate the forced vibrations of the human hand–arm system in work conditions. Novelty in research The analysis of predisposing factors on the human hand–arm response with flexed and extended elbow positions of workers subject to different sources of vibrations represents the novelty in this research. Operators assume different human hand–arm postures when using manual power tools. The human hand–arm with flexed and extended elbow positions are the postures of workers evaluated in this research. The research on postures of workers aims to provide an evidence base for prevention. Another important objective is to provide a better overview of the extent of the occupational burden of workers. Work-related diseases include musculoskeletal disorders. Results Posture factors of the human hand–arm system and predisposing of occupational hand–transmitted vibration exposures are considered to estimate the response of human hand–arm positions in the time domain. Conclusions Mathematical model and experimental investigations provide a better evaluation of health risks and muscle actions associated with exposure to hand–transmitted vibration from power tools in work conditions.