Investigations on the influence of handle shape and size to overcome the vibration discomfort

Abstract

Non automated tool handles transmit a large magnitude of vibration to the hand which causes discomfort and pain Therefore the need for a better handle design is a matter of prime concern to overcome musculoskeletal disorders This study was aimed to examine the influence of handle shapes on vibration reduction with an increased contact area and to overcome the contact pressure which causes discomfort and pain Six different prototype handles handle B to G were designed by considering the anatomical shape of the hand and fabricated using 3D printing technology A traditional cylindrical shape handle reference handle A was developed for evaluation of the vibration and comfort perception of the new prototype handles The effect of handle shapes was evaluated with objective and subjective measurements using twelve subjects The Root Mean Square RMS values of the vibration levels were recorded at the wrist elbow and shoulder of each subject The total vibration value ahv of each of six novel prototype handles was compared to the reference 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% The results showed a significant level of vibration reduction in the acceleration of the new prototype handles which were rated to be more comfortable than the traditional cylindrical handle The hybrid middle finger FE model was developed using ABAQUS software to simulate the contact interaction between the finger and the handle. The hybrid finger model is used to grip various diameter handles 30mm 40mm 44mm and 50mm with 10N grip force The static and dynamic behavior of the finger model is evaluated as a result in terms of contact pressure CPRESS and finger deformations newline