Resonance supported actuation of reciprocating mechanisms.

In drive lines the actuator generates a torque or a force that is required to overcome the instantaneous dynamic load. The load level depends on the mechanical resistance of the moving load and on the position of the members of the drive line. Especially when the drive mechanism includes members in reciprocating motion at relatively high frequency, the load level on the actuator may be highly variable as inertial forces are proportional to the square of frequency. The phenomenon of mechanical resonance occurs at particular frequencies, when inertial forces balance forces that are due to elastic deformation of components. In these conditions large vibration amplitudes are observed, even with small magnitudes of actuator loads and thus small input power. In classical applications, this effect is undesired. This project is a feasibility study to investigate if the resonance phenomenon can be used beneficially to support the actuator with less input power. The reference system that will be studied is a crankshaft mechanism with a variable load applied to the connecting rod. The spring that will be attached to the connecting rod, will be given a stiffness that matches the natural frequency of the entire system. The dynamics of the system will be studied, without and with spring, and appropriate metrics will be proposed to increase the efficiency of the system. In addition to other machines with reciprocating motion, the envisaged demonstrator is the Kulibrie nano air vehicle with flapping wings, on which the resonance supported drive system will enhance the efficiency. The objective of the project is to increase the energy efficiency of the drive line by at least 10 to 20%.

Keywords:Drive line, Kulibrie nano aerial vehicle, Vibrations, Resonance

Disciplines:Metallurgical engineering