Influence of handle shape and size to reduce the hand-arm vibration discomfort

Non-automated tool handles transmit a large magnitude of vibration to operators' hands, causing discomfort and pain. Therefore, the need for a better handle design is a matter of prime concern to overcome musculoskeletal disorders such as hand-arm vibration syndrome.

This study aimed to examine the influence of handle shapes in reducing the transmission of hand-arm vibration.

Seven different handles were designed and fabricated using 3D printing technology at the SSN College of Engineering, with consideration for the anatomical shape of the hand. The frequency-weighted Root Mean Square (RMS) values of the vibration levels transmitted were recorded at the wrist of twelve subjects, unaffected by musculoskeletal disorders. Subjective ratings of vibration and comfort perception were measured using the Borg Scale of Perceived Exertion.

The total vibration value (ahv) of each of the six novel prototype handles (B-G) was compared to that of the reference handle denoted handle-A. The vibration reductions for handles B to G respectively were 0.542 m/s2 (14.59%), 0.481 m/s2 (12.95%), 0.351 m/s2 (9.45%), 0.270 m/s2 (7.27%), 0.407 m/s2 (10.96%) and 0.192 m/s2 (5.17%).

A significant level of vibration reduction was achieved by the prototype handles. Qualitative feedback from the study subjects suggests that they were not aware of the levels of vibration being transmitted to the hand with each handle.