RESUMO
Resonant ultrasound spectroscopy was utilized to determine the mechanical properties of a planar interface between a cold-sprayed iron deposit and an aluminum alloy substrate. The measurements were done at room temperature and with a thermal cycle from room temperature to 500 °C. The properties of the interface were assessed by analyzing the resonant frequencies of a sandwich-like sample by means of a numerical model. While the as-sprayed deposit at the room temperature exhibited a perfect adhesion to the substrate, the thermal cycle led to deterioration of the properties due to precipitation of FeAl3 along the interface and subsequent cracking. The modal analysis enabled localization of the damage zone along the interfaces and simulating its temperature evolution during the cooling run.
RESUMO
Objective To investigate the mechanical properties of human enamel based on resonant ultrasound spectroscopy (RUS).Methods The rectangular parallelepiped specimens of human enamel were processed.The theoretical resonant frequencies of specimens were estimated and paired with the experimental resonant fre quencies measured from RUS experiments.An iterative procedure was used to adjust elastic constants of enamel until the theoretical frequencies corresponded to the experimental frequencies based on minimum mean-squared error criterion.In addition,elastic modulus,shear modulus and Poisson's ratio were calculated respectively.Results The elastic modulus,shear modulus and Poisson's ratio ranged from 61.52 to 80.46 GPa,21.51 to 51.86 GPa and 0.18 to 0.43,respectively.Eliminating the effect of large specimen variances,the average of elastic modulus,shear modulus and Poisson's ratio was 72.84 GPa,31.94 GPa and 0.27,respectively.Conclu sions RUS performs a feasibility of measuring the mechanical properties of human enamel with repeatable and nondestructive advantages.All the elastic constants and mechanical parameters can be estimated through a sig nal experiment.The results provide references for the development of biomimetic dental restoration materials.
RESUMO
Objective To investigate the mechanical properties of human enamel based on resonant ultrasound spectroscopy (RUS). Methods The rectangular parallelepiped specimens of human enamel were processed. The theoretical resonant frequencies of specimens were estimated and paired with the experimental resonant frequencies measured from RUS experiments. An iterative procedure was used to adjust elastic constants of enamel until the theoretical frequencies corresponded to the experimental frequencies based on minimum mean-squared error criterion. In addition, elastic modulus, shear modulus and Poisson’s ratio were calculated respectively. Results The elastic modulus, shear modulus and Poisson’s ratio ranged from 61.52 to 80.46 GPa, 21.51 to 51.86 GPa and 0.18 to 0.43, respectively. Eliminating the effect of large specimen variances, the average of elastic modulus, shear modulus and Poisson’s ratio was 72.84 GPa, 31.94 GPa and 0.27, respectively. Conclusions RUS performs a feasibility of measuring the mechanical properties of human enamel with repeatable and nondestructive advantages. All the elastic constants and mechanical parameters can be estimated through a signal experiment. The results provide references for the development of biomimetic dental restoration materials.
RESUMO
The cross-section eigenmodes of micrometric cylinders were measured in the range of several tens of MHz to about 0.5 GHz. The vibrations were excited using subnanosecond laser pulses. The cross-section eigenmodes were simulated using finite element modeling in a 2D geometry. Using the method of resonant ultrasound spectroscopy, the vibration spectrum of an aluminum wire of diameter 33 µm served to determine Young's modulus and Poisson's ratio with a precision of 0.7% and 0.3%, respectively. The calculated and measured frequencies of cross-section eigenmodes were fitted with a precision better than 0.5% in the 50-500 MHz range.
