The increasing application of composites in the aviation and automobile industry demands a better understanding of composite material behavior under high loading rate. This shall provide a better insight of actual loads on occupants while preserving livable crashworthy structure. In this study, a high stroke rate MTS servo-hydraulic testing machine is used to characterize the behavior of composite materials at high strain rates. At higher stroke rates, the output of the load detection system acquired by the load cell deviates from the true load-time wave form of the specimen. This is due to the convolution of the structural response of the detection system with the true characteristic of the specimen. To identify the true nature of the specimen load-time behavior, the de-convolution of the detection system response is necessary to restore the specimen characteristic wave form closer to its true behavior. The convolution of data set in the time domain is a time consuming process which explains the benefit of using the frequency domain; as the convolution in time domain corresponds to multiplication in the frequency domain. This process requires the transformation of the time domain data to frequency domain data via Fast Fourier Transform (FFT). In the frequency domain the complex division of the Fourier transfer of the detection system output with frequency response function of the detection system shall provide the true complex input characteristic. This paper elaborates the methodology utilized for obtaining the Frequency Response Function (FRF) of the load detection system using digital Fourier analysis with a single input/output data set. This also emphasizes precautions and guidelines for improving results with FFT to obtain true FRF measurements of the load detection system. The FRF obtained is successfully used to identify the actual specimen wave form characteristic. This is achieved by extracting the structural response of the load detection system from the load cell output.
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ASME 2009 International Mechanical Engineering Congress and Exposition
November 13–19, 2009
Lake Buena Vista, Florida, USA
Conference Sponsors:
- ASME
ISBN:
978-0-7918-4388-8
PROCEEDINGS PAPER
Investigation and Modification of Frequency Response Function Using Digital Fourier Analysis for High Speed Dynamic Testing Facility
Chandrashekhar K. Thorbole,
Chandrashekhar K. Thorbole
The Engineering Institute, Farmington, AR
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Keshavanarayana S. Raju
Keshavanarayana S. Raju
Wichita State University, Wichita, KS
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Chandrashekhar K. Thorbole
The Engineering Institute, Farmington, AR
Keshavanarayana S. Raju
Wichita State University, Wichita, KS
Paper No:
IMECE2009-12172, pp. 407-421; 15 pages
Published Online:
July 8, 2010
Citation
Thorbole, CK, & Raju, KS. "Investigation and Modification of Frequency Response Function Using Digital Fourier Analysis for High Speed Dynamic Testing Facility." Proceedings of the ASME 2009 International Mechanical Engineering Congress and Exposition. Volume 15: Sound, Vibration and Design. Lake Buena Vista, Florida, USA. November 13–19, 2009. pp. 407-421. ASME. https://doi.org/10.1115/IMECE2009-12172
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