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Monitoring techniques for special alloys from some medical prostheses.
Savin, A. ; Vizureanu, P. ; Převorovský, Zdeněk ; Steigmann, R. ; Chlada, Milan ; Krofta, Josef ; Baltatu, M.S. ; Craus, M. L. ; Nový, F.
The paper presents complementary methods for noninvasive evaluation of an exotic class of alloys possible to be used in medical prosthetics. The interest in this study is the analysis of Ti alloys with different concentration of Mo and Si, in order to make the elastic modulus and Poisson ratio reach values appropriate with human bones. The both methods, acoustic emission and resonant ultrasound spectroscopy are proposed as complementary methods for nondestructive evaluation of entire sample volume.
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Comparison of the dynamic and static elasticity modules in damaged wood
Kloiber, Michal ; Kotlínová, M.
This work deals with evaluation of wood properties, that are obtained on the base of ultrasound testing with defectoscopic Arborsonic Decay Detector. Ultrasound waves expand with speed, that depends on wood quality. From time of stress wave propagation and wood density dynamic modulus of elasticity was calculated. The same test specimens were statically loaded afterwards, and dynamic and static modulus of elasticity were compared. These characteristics of wood according to damage by biotic factors change rapidly. This work proofs possibility of non-destructive wood properties by constructive-technical research of wood constructions.
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Ultrazvukové časově-reversní zrcadlo-numerická simulace v desce s defektem
Krofta, Josef ; Převorovský, Zdeněk
The time reversal mirror (TRM) is a method which can be effective in NDE of defects in materials. In this case an input ultrasonic wave is transmitted into the examined sample, then recorded by receiving transducers, time reversed and sent back by the same transducers. A simple numerical model of a solid plate was developed. Using this model, a simulation of TRM was performed. The propagation of ultrasonic waves used in time reversal method is studied. A number of tests with various configurations of transducers and defects and different methodology of the TRM procedure is simulated.
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