A modified model for simulating the effect of temperature on ultrasonic attenuation in 7050 aluminum alloy

摘要

Knowing propagating properties of an ultrasonic wave can enhance the non-destructive testing techniques in alloy materials field, such as the electromagnetic acoustic transducer techniques, and the piezoelectric ultrasonic transducer techniques. When temperature is taken into consideration, the ultrasonic propagating attenuation become very complex process. In this paper, a loss factor coefficient function with change in temperatures is established and the loss factor damping model with temperature term is coupled into the equations of elastic wave motion. A modified frequency domain model for calculating the ultrasonic attenuation due to temperature changes in 7050 Aluminum alloy is then developed. The model is validated experimentally using a high power pulse transmitter/receiver RPR-4000, a resistant high temperature electromagnetic acoustic transducer set-up and a 7050 Aluminum alloy sample. The simulation and the experimental results are determined to be in good agreement. The numerical model is used to calculate the ultrasonic-waves field, the ultrasonic attenuation, and the ultrasonic propagation directivity considering the temperature effect. The modeling results indicate that the ultrasonic energy attenuation is significantly affected by temperature. When the temperature increases from 20°C up to 480°C, the ultrasonic energy attenuates by 32.31%. It is also found that the length of near acoustic field increases with the increase in temperature. There is a common basic mode for the attenuation of ultrasonic waves, in which the attenuated mode cannot be affected by other factors. Increasing the temperature or the frequency, the ultrasonic propagation can obtain an excellent directivity. Results obtained from the present model will provide a comprehensive understanding of design parameter effects and consequently improve the design/performance in the non-destructive testing techniques.