Scopul nostru este sprijinirea şi promovarea cercetării ştiinţifice şi facilitarea comunicării între cercetătorii români din întreaga lume.
This paper presents some experimental results concerning the acoustic emission (AE) of different structures under stretches, in order to predict their behaviour at maximum extent efforts. Acoustic emission signals are prevailed by sensitive AE sensor, fixed on the material surface by an electroacoustic material. The AE piezoelectric sensor realizes the mechanical to electrical energy conversion, and the output signal is displayed on the memory digitalRead more
This paper presents some experimental results concerning the acoustic emission (AE) of metallic materials, submissive at mechanical tests. In experimental work we utilized a piezoelectric sensor which output signal is displayed on the memory digital oscilloscope. As results, the signal analysis in time and frequency can be used to determine the attenuation coefficients, delaminating, voids, defects, etc. The receiver transducer (sensor) on the oppositeRead more
This paper presents the experimental researches concerning the design and the manufacture of an ultrasonic piezoceramic transducer, for mechanical vibration, with application in the surface processing of the fragile and hard materials. The measurements of the main parameters and characteristics were made with the HP 4194 Impedance/Gain-Phase Analyzer Hewlett Packard, USA. The piezoceramic transducer was made like a sandwich of PZT tores and metallicRead more
PbTiO3 (PT) ceramics were prepared by sol-gel method. The crystallisation and morphology properties were investigated by XRD, DSC and SEM microscopy. To study the influence of ultrasounds in the preparation process and properties of PbTiO3 ceramics, the gel phase was submitted on ultrasonic field of 35 kHz frequency and time about 40 minutes. Thermal hysteresis curves were determined by DSC 92 Differential Scanning Calorimeter, SETARAM, France inRead more