Acoustic methods for regionalizing an impact force acting on a helmet structure

dc.contributorWilliams, Keith A.
dc.contributorHubner, James Paul
dc.contributor.advisorShepard, W. Steve
dc.contributor.authorDavis, Jacob
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractIt is often desired to know the location and magnitude of a force acting on a structure. Unfortunately, it is not always possible or desirable to install a sensor at the force location, such as when the force location is unknown or when the application of a force sensor would change the force transmission characteristics. A structure subjected to an impact has many different vibrational modes that are excited to different levels based on the excitation location. These vibrations decay with time depending on their different rates of modal damping and the associated acoustic radiation characteristics. This response of the structure can be measured and used to inversely reconstruct the input force. It is theoretically possible to use acoustic measurements for force reconstruction, but the method involved would be extremely difficult. In this study, approaches that are much simpler and easier to implement were considered. Acoustic signatures for several structure impact locations were measured, normalized relative to the force magnitude, and processed to examine the ability to correlate the acoustic signal to the force impact location. Various processing techniques, such as the Short Time Fourier Transform, were considered. A primary interest focused on the ability of using single-number metrics that describe features of the acoustic signature to aid in identifying the force location. For the experiments, a football helmet structure was used and multiple impact locations on the helmet were tested. The ability of these acoustic signatures, including those processed into single-number metrics, to aid in identifying the impact location was assessed.en_US
dc.format.extent81 p.
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.titleAcoustic methods for regionalizing an impact force acting on a helmet structureen_US
dc.typetext of Alabama. Department of Mechanical Engineering Engineering University of Alabama's
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