Ultrasonic attenuation and phase velocity of high-density polyethylene pipe material

Abstract

Knowledge of acoustic properties is crucial for ultrasonic or sonic imaging and signal detection in nondestructive evaluation (NDE), medical imaging, and seismology. Accurately and reliably obtaining these is particularly challenging for the NDE of high-density polyethylene (HDPE), such as is used in many water or gas pipes, because the properties vary greatly with frequency, temperature, direction and spatial location. Therefore the work reported here was undertaken in order to establish a basis for such a multiparameter description. The approach is general but the study specifically addresses HDPE and includes measured data values. Applicable to any such multiparameter acoustic properties dataset is a devised regression method that uses a neural network algorithm. This algorithm includes constraints to respect the Kramers-Kronig causality relationship between speed and attenuation of waves in a viscoelastic medium. These constrained acoustic properties are fully described in a multidimensional parameter space to vary with frequency, depth, temperature, and direction. The resulting uncertainties in acoustic properties dependence on the above variables are better than 4% and 2%, respectively, for attenuation and phase velocity and therefore can prevent major defect imaging errors.

A multiband approach for accurate numerical simulation of frequency dependent ultrasonic wave propagation in the time domain

“…6 shows close agreement with the desired empirical solution, obtained in our acoustic properties study, 5 over the frequency range covered by the bands. The bands are defined such that equal frequency content of the initial pulse exists in each band.…”

“…Describing the general frequency dependence of wave acoustic properties in HDPE using power law viscoelastic dispersion is highly accurate, as shown in Ref. 5. Conversely, it is inaccurate to reduce these acoustic properties to a fixed frequency description.…”

“…In our preceding study of the ultrasonic viscoelastic acoustic properties of HDPE pipe material, 5 we provide a unique, accurate, and reliable description of the viscoelastic properties of HDPE, covering the range of frequencies and temperatures needed for practical ultrasound NDE of this material. The properties are presented there in the desired manner as spectra of attenuation and phase velocity.…”

“…In our preceding HDPE pipe acoustic properties study 5 we presented a description of ultrasonic viscoelastic bulk wave dispersion that conforms to theoretical viscoelastic constraints and that is necessarily causal, using the KramersKronig relation. The variation in properties with frequency is the modelling challenge which we aim to address here; while this will take the specific example of HDPE properties, the approach is general and can be used for any dispersive medium.…”

Laboratory Study on Non-Destructive Evaluation of Polyethylene Liquid Storage Tanks by Thermographic and Ultrasonic Methods

“…Since the probe's focus is "swept," even defects that are stacked can be detected, which would not be possible by conventional pulse-echo methods [33]. PAUT has shown great capabilities to detect the embedded defects in HDPE pipes and joints [34][35][36][37][38][39][40][41][42].…”