Development of a Biomechanical Model for Torque and Thrust Strength on Cylindrical Handles

Research Trainee: Na Jin Seo, MS, PhD Student, Dept. of Industrial and Operations Engineering at the University of Michigan

Faculty Researcher: Thomas J. Armstrong, PhD, Professor of Industrial and Operations Engineering at the University of Michigan

The aim of this work is to develop models for predicting the capacity of the hand to apply torque and thrust force about and along the long axis of cylindrical handles. More specifically, this work will develop a biomechanical model of isometric or “quasi isometric” torque and thrust force that can be exerted on cylindrical handles of a given diameter and surface friction when gripped at a given angle.

Our proposed biomechanical model and preliminary research show that torque strength about the long axis of a cylindrical handle is greater when torque is applied in the direction of the fingers than in the direction of the thumb.

The proposed study will 1) validate the biomechanical model for various handle materials. It will also examine 2) the effect of torque on pushing and pulling along the long axis of the handle and 3) the effect of grip force on wrist flexion and extension strength. In addition, the coefficient of friction will be measured for different parts of the hand with different normal force levels and handle materials.

The models developed in this study can be used to establish force design limits for work tasks that will accommodate desired percentiles of the male and female population. They also can be used to design equipment that minimizes force requirements, localized fatigue and the risk of work-related musculoskeletal disorders.


Research trainee’s current position:
Na Jin Seo completed her PhD in 2007 and is currently an Associate Professor in the Division of Occupational Therapy at the Medical University of South Carolina.