Assessing the influence of hand-arm posture on mechanical responses of the human hand during drilling operation

Abstract

Drilling is one of the important metal cutting processes in the industrial sectors. Though there are several research studies exclusively pertaining to drilling mechanism and the implications on materials, there are research voids that pertain to the driller’s hand-arm posture and the corresponding mechanical responses during the process. Considering the vitality of the ergonomics involved, the objective is framed to estimate the stresses acting on the hand while operating handheld drilling machine by different subjects and investigate the effects of various hand-arm postures on the stresses transmitted to the hands. Finger TPS—wireless tactile force sensor device—is employed for measuring the force exerted at the fingers while operating handheld cordless drilling machine. The nature of vibration transmitted to the human hand-arm system is affected by the contact force variation between a vibrating tool handle and the hand. The transmitted vibration will impose the stresses on the anatomical structure of the hand-arm system. In the present study, the dynamic response of a human hand to exert force during drilling task is analysed by three-dimensional finite element (FE) model of the human hand of a normal male. The model is developed from 3D reconstruction of CT scan images using the segmentation software, Mimics. The FE model contains the essential anatomical structures of a human hand. It includes both linear and nonlinear elements to represent rigid and elastic parts of the hand like the bones, tissues etc. Refined FE model is properly meshed, and analysis is carried out using finite element code ABAQUS. Preliminary results of the numerical analysis utilizing the developed model and qualitative evaluation are presented. Stress values are the highest while drilling in the extended forearm with the elbow at an angle of 180° and are followed by drilling objects located at a height above shoulder level.