A comprehensive study of the delay vector variance method for quantification of nonlinearity in dynamical systems

• Main Authors: V. Jaksic, D. P. Mandic, K. Ryan, B. Basu, V. Pakrashi
• Format: Article
• Language: English
• Published: The Royal Society 2016-01-01
• Series: Royal Society Open Science
• Subjects: delay vector variance; signal nonlinearity; structural dynamics; benchmarking; wind turbine blade
• Online Access: https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.150493

Although vibration monitoring is a popular method to monitor and assess dynamic structures, quantification of linearity or nonlinearity of the dynamic responses remains a challenging problem. We investigate the delay vector variance (DVV) method in this regard in a comprehensive manner to establish the degree to which a change in signal nonlinearity can be related to system nonlinearity and how a change in system parameters affects the nonlinearity in the dynamic response of the system. A wide range of theoretical situations are considered in this regard using a single degree of freedom (SDOF) system to obtain numerical benchmarks. A number of experiments are then carried out using a physical SDOF model in the laboratory. Finally, a composite wind turbine blade is tested for different excitations and the dynamic responses are measured at a number of points to extend the investigation to continuum structures. The dynamic responses were measured using accelerometers, strain gauges and a Laser Doppler vibrometer. This comprehensive study creates a numerical and experimental benchmark for structurally dynamical systems where output-only information is typically available, especially in the context of DVV. The study also allows for comparative analysis between different systems driven by the similar input.