The Journal of the Acoustical Society of America · 1983 · 73 citations · 0 references
EngineeringMechanical EngineeringVibration MeasurementMagnetic ResonanceAcoustic SensorVibration AnalysisImproved Resonance ApparatusVibrationsPhysical AcousticAcoustic MaterialAcoustical EngineeringAcoustic AnalysisMaterials ScienceMaterials EngineeringAcoustic MethodsResonance TechniqueMaterial PropertyAcoustic PropagationMechanical VibrationSpectroscopyMaterials CharacterizationApplied PhysicsMiniature AccelerometersDouble ResonanceVibration ControlMaterials Testing
Resonant peaks in the acceleration ratio of a vibrating bar reveal the material’s Young’s modulus and loss factor. The study presents an improved resonance apparatus for characterizing material dynamic constants. The apparatus excites a bar with a noise source, records acceleration at two points with miniature accelerometers, and analyzes the signals with a dual‑channel FFT spectrum analyzer to determine propagation constants. It can measure acceleration ratios from 25 Hz to 20 kHz, accurately determining Young’s modulus and loss factor for polyurethane across −13.4 °C to 81 °C and for silicon‑carbide–aluminum and graphite–aluminum composites, proving to be a fast, reliable method.
An improved resonance apparatus for materials characterization is described. The apparatus accurately determines the propagation constants of an extensional acoustic wave by exciting a bar of material at one end with a noise source, while the other end is allowed to move freely. Miniature accelerometers measure the acceleration at two locations and their output signals are analyzed by a dual channel FFT spectrum analyzer. At certain frequencies, the acceleration ratio goes through resonant peaks whose amplitudes and frequencies are related to the Young’s moduli and loss factors of the material. The apparatus is capable of measuring the acceleration ratio over a frequency range of 25 Hz to 20 kHz. As illustrations of the technique, Young’s modulus and loss factor were determined on a viscoelastic material; polyurethane (over a temperature range −13.4° to 81 °C) and on two metal matrix composite materials: a silicon carbide–aluminum and a graphite–aluminum. The apparatus was found to be a fast and reliable method to determine dynamic constants.