Na Jin Seo1, Thomas J Armstrong. 1. Department of Industrial and Operations Engineering, University of Michigan, Ann Arbor, MI 48109, USA. najins@umich.edu
Abstract
OBJECTIVE: To investigate relationships among grip forces, normal forces, contact area for cylindrical handles, handle diameter, hand size, and volar hand area. BACKGROUND: Data describing those relationships are needed to predict thrust forces and torque capability. METHOD: Additional analyses were performed retrospectively on data collected in two previous studies in which participants performed maximum grip exertions on cylinders (diameter 38-83 mm) while grip force, normal force, and contact area were recorded. The length, width, and volar area of the hand were measured. RESULTS: Average total normal force on cylinders was 2.3 times greater than grip force measured using a split cylinder (R2 = 65%), regardless of the handle diameter examined. The ratio of handle diameter to hand length explained 62%, 57%, and 71% of the variances in grip force, normal force, and contact area, respectively. Estimated hand area (hand length x width) had a linear relationship with measured hand area (using photographs; R2 = 91%), although it was 8% less than the measured area. CONCLUSION: This work describes the relationship between normal force and grip force independent of handle size (for handle diameters from 38 to 83 mm). Normal force and contact area can be explained by the interaction between handle size and hand size. Hand area can be estimated by hand length times width. APPLICATION: The quantitative relationships described in this paper can be used in the design of objects and hand tools to determine optimal handle sizes for maximizing grip force, total normal force, or contact area.
OBJECTIVE: To investigate relationships among grip forces, normal forces, contact area for cylindrical handles, handle diameter, hand size, and volar hand area. BACKGROUND: Data describing those relationships are needed to predict thrust forces and torque capability. METHOD: Additional analyses were performed retrospectively on data collected in two previous studies in which participants performed maximum grip exertions on cylinders (diameter 38-83 mm) while grip force, normal force, and contact area were recorded. The length, width, and volar area of the hand were measured. RESULTS: Average total normal force on cylinders was 2.3 times greater than grip force measured using a split cylinder (R2 = 65%), regardless of the handle diameter examined. The ratio of handle diameter to hand length explained 62%, 57%, and 71% of the variances in grip force, normal force, and contact area, respectively. Estimated hand area (hand length x width) had a linear relationship with measured hand area (using photographs; R2 = 91%), although it was 8% less than the measured area. CONCLUSION: This work describes the relationship between normal force and grip force independent of handle size (for handle diameters from 38 to 83 mm). Normal force and contact area can be explained by the interaction between handle size and hand size. Hand area can be estimated by hand length times width. APPLICATION: The quantitative relationships described in this paper can be used in the design of objects and hand tools to determine optimal handle sizes for maximizing grip force, total normal force, or contact area.
Authors: Erik W Sinsel; Daniel S Gloekler; Bryan M Wimer; Christopher M Warren; John Z Wu; Frank L Buczek Journal: Med Eng Phys Date: 2015-12-18 Impact factor: 2.242
Authors: Alice Wichelhaus; Christoph Harms; Julia Neumann; Steffen Ziegler; Günther Kundt; Karl Josef Prommersberger; Thomas Mittlmeier; Marion Mühldorfer-Fodor Journal: BMC Musculoskelet Disord Date: 2018-02-14 Impact factor: 2.362