An investigation on the relationship between grip, push, and contact forces applied to a tool handle.
Welcome-D; Rakheja-S; Dong-R; Wu-JZ; Schopper-AW
Int J Ind Ergon 2004 Dec; 34(6):507-518
Owing to the strong dependence of the health risks associated with vibration exposure of the human hand and arm on hand force, a laboratory study was conducted to develop a methodology for measurement of the contact force at the tool handle-hand interface, and to identify the relationship between the contact force and the hand grip and push forces. A simulated tool handle fixture was realized in the laboratory to measure the grip and push forces using compression/extension force sensors integrated within the handle and a force plate, respectively. The contact force was derived through integration of the interface pressure over the contact area. These were measured using a capacitive pressure-sensing grid. The measurements were performed with 10 male subjects and three circular cross-section handles of different sizes under different combinations of grip and push forces. The hand-handle interface pressure data were analyzed to derive the contact force, as functions of the constant magnitudes of the grip and push forces, and the handle size. The results suggest that the hand-handle contact force is strongly dependent upon not only the grip and push forces but also the handle diameter. The contact force for a given handle size can be expressed as a linear combination of grip and push forces, where the contribution of the grip force is considerably larger than that of the push force. The results further suggest that a linear relation can characterize the dependence of the contact force on the handle diameter. The validity of the proposed relationship is demonstrated by evaluating the magnitudes of errors between the estimated contact forces with the measured data for the range of handle diameters, and grip and push forces considered in the study.
Hand-injuries; Hand-protection; Hand-tools; Risk-factors; Risk-analysis; Vibration-exposure; Laboratory-testing; Demographic-characteristics; Sex-factors
Engineering & Control Technology Branch, NIOSH, 1095 Willowdale Road, MS 2201, Morgantown, WV 26505, USA
Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
International Journal of Industrial Ergonomics