Force Distribution at Hand/Handle Coupling: The Effect of Handle Type

Handle location and geometry play an important role in container design and effectiveness. An ideal handle position and angle should minimize stress at L5/S1 and minimize average grip pressure on the two hands with force distributed evenly on both hands. Handles in such a position will be most comfortable for performing a MMH task and reduce the likelihood of compressive injuries on the lumbar spine. Most of the published research on container handles have used the psychophysical, biomechanical, and/or physiological methods to determine handle effectiveness. The force distribution at the exact point of energy transfer, namely the hand/handle interface has rarely been addressed by the scientific community. The intent of this study was to determine the force distribution at the hand/handle interface and use the same to compare the effectiveness of various handle types, positions, and angles. Six factors were tested in this experiment using a fractional factorial design. The pressure at the interface was measured using a number of force sensing resistors (FSRs) in each hand. The results indicate handle positions 2/2, 8/8, and 3/7 to be far superior to position 6/8. The average pressure at the FSR sites appear to be the least at handle angles of 0 degree. Further, the force distribution for the cut-out handle appears to be more uniform than that for the cylindrical handle (circular cross-section). Based on these findings recommendations are made for container designer.