12-09-2017, 12:14 PM
The harvester is composed of an ME transducer, a cantilever beam, a cylindrical magnet and a circular magnet. The cylindrical magnet is attached to the free end of the beam. The ME transducer is placed in the bore of the circular magnet which can produce an optimized bias magnetic field through the transducer, resulting in an improved ME voltage coefficient. During vibration, the cylindrical magnet moves relative to the transducer which generates electric energy due to the variation of the magnetic field. The resonant frequency of the mower can be adjusted by taking advantage of the repulsive magnetic force between the magnets. A prototype is manufactured and tested. A tunable resonant frequency range of 4.4 Hz is reached and the maximum power generated is 68.8μW under an acceleration of 0.2g at a resonant frequency of 25.4Hz.
Conventionally, to functionalize a mechanical part of composite material, the piezoelectric transducers are glued onto the surface of the structure and the power and control electronics are remote. To protect the transducer elements and their connections and to develop some industrial products in plug and play mode, it is necessary to develop a wide distributed network of piezo-ceramic and integrate them into the heart of the composite during the manufacturing process of composite structures. However, if the material parameters and structural performance could be influenced by the location of the piezoelectric elements along the thickness of the composite material, there is no experimental research on this influence until now. It is therefore absolutely necessary to investigate this point. In this work a set of bundles (about 50 mm wide and 500 mm long) of composite glass fiber with six layers (about 1.6-1.8 mm thick) are fabricated with three integrated piezoelectric elements in a specific thickness. This parameter is modified for each beam. At first, the material parameters of each beam are measured, a set of experiments is performed for the beams. Piezoelectric disks are used as sensors, a beam-specific offset is applied as the initial value, and the output voltage of the piezoelectric element versus time is measured.
Conventionally, to functionalize a mechanical part of composite material, the piezoelectric transducers are glued onto the surface of the structure and the power and control electronics are remote. To protect the transducer elements and their connections and to develop some industrial products in plug and play mode, it is necessary to develop a wide distributed network of piezo-ceramic and integrate them into the heart of the composite during the manufacturing process of composite structures. However, if the material parameters and structural performance could be influenced by the location of the piezoelectric elements along the thickness of the composite material, there is no experimental research on this influence until now. It is therefore absolutely necessary to investigate this point. In this work a set of bundles (about 50 mm wide and 500 mm long) of composite glass fiber with six layers (about 1.6-1.8 mm thick) are fabricated with three integrated piezoelectric elements in a specific thickness. This parameter is modified for each beam. At first, the material parameters of each beam are measured, a set of experiments is performed for the beams. Piezoelectric disks are used as sensors, a beam-specific offset is applied as the initial value, and the output voltage of the piezoelectric element versus time is measured.