漏えいラム波を用いた磁気テープ弾性率の測定

概要

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Young's moduli of VCR magnetic tapes 11 μm thick are ultrasonically measured along and transverse to the longitudinal direction. A tape sample is supported in a coupling fluid and a wide-band, line-focus PVDF transducer generates and receives the leaky Lamb wave signal (S_0 mode) together with the specular reflection. The signals are digitized and stored in the hard disc for subsequent processing. Young's modulus can be calculated from the phase velocity of the Lamb wave extrapolated to the zero-frequency limit. The influence is determined for the velocity dispersion due to the finite thickness/wavelength ratio as well as the acoustic coupling to the fluid. Three signal processing methods, i.e., direct timing, spectrum, and cepstrum methods, are compared with each other as well as with the static loading test. The VCR tapes were found to possess a large elastic anisotropy ; Young's modulus in the transverse direction was found to be 50% larger than that in the longitudinal direction.
一般社団法人日本機械学会の論文
1994-07-25