Grant: Discovery Grants Program - Individual

It is desirable to use the same device for simultaneous vibration suppression (VS) and energy harvesting (EH). A linear device has a narrow frequency bandwidth. The applicant's last DG program aimed to develop effective broadband devices for the dual-purpose. In particular, the concept of the nonlinear energy sink (NES) was explored. As shown in Most Significant Contributions, several contributions have been made. This proposal seeks a funding renewal to further the studies and extend them into new directions. The short-term objectives are as follows: 1. Develop 2 multi-stable NESs (MSNESs) that can be manually tuned to assume mono-, bi-, or tri-stable state. MSNES A will be formed by adding a tunable magnetic spring to a previously developed non-traditional NES. MSNES B will be formed by placing a previously developed tunable multi-stable piezoelectric energy harvester between the primary mass and the ground. The performances of both combined systems will be investigated numerically and experimentally. To maximize VS and EH under a given excitation, a 2-objective optimization will be conducted to find the optimum tuning parameters and the load resistance. 2. Apply MSNESs to multiple-degree-of-freedom (MDOF) systems and metastructures. Three configurations will be considered: a 2DOF periodic-type primary system with 1 MSNES, a 3DOF periodic-type primary system with 2 MSNES, and a 3DOF periodic-type primary system with 3 MSNESs. The study will focus on VS and EH performances of the systems under transient responses and forced responses. A 2-objective optimization will be conducted to maximize EH and VS. The results will be validated experimentally. The results will be generalized for application in metastructures. 3. Apply MSNESs to structural health monitoring (SHM) and machine condition monitoring (MCM). For SHM, a four-floor shear structure will be chosen as a target. Proper sensors will be selected to monitor its structural integrity. A set of suitable sensor nodes and receivers will be chosen. An autonomous power unit will be built by combining MSNES B with a suitable energy harvesting circuit. The power unit will be integrated with the sensor node. By attaching the integrated unit to the structure, its performances will be evaluated. For MCM applications, the focus will be on the modification of MSNESs A and B for the purpose of the frequency up-conversion to harvest energy from low-frequency ambient vibration. The device to be developed is a 2DOF system consisting of a low-frequency linear oscillator (LFLO) and a high-frequency nonlinear oscillator (HFNO). The studies will focus on maximizing power output of the device in a wide frequency band around the natural frequency of the linearized HFNO. The research will result in novel devices with a great potential in VS and EH applications. The research will contribute to the knowledges and techniques in the relevant areas, and provide an interdisciplinary training environment to HQPs.