Development of a Generation Mechanism of Synchronous Vibration Suitable for Hand-Held Vibrating Tools: Investigation of an Impact Model with Two Oscillators

The hand-arm vibration syndrome characterized by Raynaud's disease is caused by long-term use of hand-held vibrating tools. The purpose of the present research is to develop a new vibrating tool using self-synchronization phenomena in order to reduce hand-arm vibration. In the present paper, an elementary model with a generation mechanism of synchronous vibration suitable for a tamping rammer used to compact cohesive soils on the ground is developed. This model consists of upper and lower blocks coupled by coil-springs, and two rotor-type oscillators are mounted individually on the lower blocks. The nonlinearity due to the impact behavior between the lower block and the ground is approximated by piecewise linear characteristics. The synchronized solutions and the stability are analyzed by applying the improved shooting method for impact vibration analysis. Analytical and experimental results confirm that stable synchronized solutions which are able to achieve a good balance between vibration control and excitation exist. In addition, it is proven that the existence region of the stable solutions can be expanded by setting the system parameters appropriately.