Recent MSCE Theses
2013
Dynamic Response Assessment and Modeling of a Small Wind Turbine Structure
Molly Pruess, Degree Candidate
Abstract: Demand for energy is continually increasing worldwide and new sources of energy must be tapped. Small wind turbine (SWT) energy production output will have an important role in the energy future of rural homes and farming operations. SWTs are often located on sites with less than ideal wind conditions, resulting in more turbulent wind loading and a larger dynamic input. A better understanding of the dynamic frequencies of small wind turbines could lead to more efficient structural and foundation designs. By analyzing raw dynamic measurements from three types of measurement transducers (pressure cells, tiltmeters, and strain gages) using a fast Fourier transform, the natural frequencies of vibrations of an 80 ft. SWT were found and compared to three analytical, linear elastic, finite element models. From the data collected, it was concluded that using the upper bound of subgrade modulus design recommendations for spring constant calculations over estimated the first and second measured modal frequencies by approximately 1.5%. Using the lower bound design recommendations underestimated the same measured frequencies by approximately 9%. Verifying the structural design using dynamic analysis is achievable if the structural geometry and a reasonable range of engineering soil properties for the soil type are well understood.