Research On Vibration Energy Harvesting Technology For Building Self-powering Magneto-rheological Damper

Comparing with normal hydraulic damper, magneto-rheological (MR) damper, which is a structural vibration control device and uses controllable magneto-rheological fluid as the working liquid, has a lot of merits, such as simple structure, adjustable damping force output, wide dynamic range, fast response, easily to combine with computer, etc. Because it combines the advantages of both active vibration control device, i.e. real-time adjustable damping force and passive vibration control device, i.e. the ability of fail-safe protection, MR damper system has been widely used in the vibration control areas, such as transportation, building, aerospace, automatic weapons, and has achieved good control results for mitigating the effect of undesired vibrations and protecting the structures from damage. To practically construct vibration and shock mitigation systems using MR dampers, either external power supply or current-control equipment is inevitably necessary for activating electromagnetic coils inside MR dampers for provision of magnetic field to the MR fluid. However, the external power supply and current control system will inevitably increase the complexity of the MR damper system and reduce the reliability of the vibration control system, in particular for some applications such as large-scale bridge and other outdoor structural vibration control applications, which inconvenience provide or cannot guarantee a reliable apply of electricity for MR dampers.This dissertation will study the state-of-the-art technology of harvesting electrical power from external vibrations, which exist in the working environment of the MR damper, and using the harvested electrical power to energize the magneto-rheological damper. Because of not requiring the external power and control equipments, great merits such as size and weight reduction, less maintenance and lower cost could be achieved for the current MR damper systems. And it’s possible to improve its reliability and promote the use of MR dampers to control the vibration of outdoor structures. In addition, the self-powered (power generation) technology is energy saving and environmentally friendly, and in line with the world development trend.First of all, this paper systematically studied the magneto-rheological properties of MR fluids and the mechanical proterties of the MR damper in order to obtain the mathematical model of the output damping force and the external input current. An experimental prototype of the single-rod and single-cylinder MR damper was designed and manufactured with the aim of experimental study. Based on the theoretical and test research results, it can be seen that the normal electrical power for MR damper is about2W10W and this will be an evulation criteria for success of the vibration energy harvesting research.In order to convert vibration energy into electrical energy, a PZT disc-stack vibration harvester, which is fit for the MR damper use, was designed. The electromechanical model for the PZT harvester, considering the coupled relation between the mechanical and electrical part, was built to investigate the relationship between the output electrical and external vibration, structural parameters and external resistance. An experimental prototype of the PZT disc-stack harvester was manufactured in order to experimentally investigate the harvested electrical power. The test results show that the designed PZT harvester can generate enough electrical power for the MR damper under high-frequency vibration condition, and partially meet the electricity needs of the MR damper under low-frequency vibration conditions.Another vibration energy harvesting method, the electromagnetic vibration energy harvesting technology, is analyzed to harvest sufficient electrical power to power the MR damper. A novel two-phase tubular linear electromagnetic vibration energy harvester was designed and evaluated to harvest electrical power. The magnetic circuit model and the output power model of this novel electromagnetic harvester were investigated. Firstly, an experimental prototype of the electromagnetic harvester was designed and manufactured. A series of test were done to evaluate the ability of the electromagnetic vibration energy harvester. The results show that the electromagnetic harvester can generate enough electrical power for the MR damper under low-frequency vibration conditions and the output electrical power is proportional to the strength of the structural vibration. So, it indicates that the proposed two-phase tubular linear electromagnetic vibration energy harvester can be used to construct self-powering MR damper system and give an adaptive control to the environmental vibrations.Finally, the works of this dissertation was concluded. The innovations and contributions of this dissertation were evaluated. The potential research issues as the continuation of this research were pointed out.