Development of a Dynamic Biomechanical Model for Load Carriage: Phase III Part C1: Pressure and Force Distribution Measurement for the Design of Waist Belts in Personal Load Carriage Systems
Abstract
In previous studies, two biomechanical models were developed that used pack and person geometry as well as pack mass to determine the reaction forces on the body. One problem has been determining the pack-person interface forces using Tekscan(TM) pressure sensors on rounded surfaces such as the shoulder and waist. The goal of this study was to determine design factors that affect force distribution of the backpack waist belt. A human-sized symmetrical lower torso (SLT) was created. A method of calculating the directional coordinates of applied forces was developed in order to understand the reactions between pack and person. Tekscan(TM) Sensors were used to measure the surface pressures between the torso and the waist belt. These were converted to normal force measures based on the mathematical coordinates of each sensel. Calibration factors, a factor of effective sensel area and a frictional coefficient for the in situ orientation of each sensor were calculated and used for the calculation of the directional forces. Then, using sites on the waist belt, known forces were applied and the resulting directional forces correlated moderately well with the known applied forces (19%). The pressure distributions of three waist belts were compared and the design features were examined to account for differences in distribution. The distributions were compared to results of the previous biomechanical models and determined to be too complex to be resolved with the simplified hoop stress theory. The study determined the importance of waist belt design, frictional force from belt tightening, and influence of load in understanding the force distribution of a waist belt. It is recommended that each pack and load condition be tested using this approach if one wishes to use the waist strap force gauge to determine compressive forces on the lumbar spine and on the hips.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2005
- Accession Number
- ADA480768
Entities
People
- L. J. Hadcock
Organizations
- Queen's University