Finite element analysis simulations for ultrasonic array NDE inspections

Abstract

Abstract. Advances in manufacturing techniques and materials have led to an increase in the demand for reliable and robust inspection techniques to maintain safety critical features. The application of modelling methods to develop and evaluate inspections is becoming an essential tool for the NDE community. Current analytical methods are inadequate for simulation of arbitrary components and heterogeneous materials, such as anisotropic welds or composite structures. Finite element analysis software (FEA), such as PZFlex, can provide the ability to simulate the inspection of these arrangements, providing the ability to economically prototype and evaluate improved NDE methods. FEA is often seen as computationally expensive for ultrasound problems however, advances in computing power have made it a more viable tool. This paper aims to illustrate the capability of appropriate FEA to produce accurate simulations of ultrasonic array inspectionsminimizing the requirement for expensive test-piece fabrication. Validation is afforded via corroboration of the FE derived and experimentally generated data sets for a test-block comprising 1D and 2D defects. The modelling approach is extended to consider the more troublesome aspects of heterogeneous materials where defect dimensions can be of the same length scale as the grain structure. The model is used to facilitate the implementation of new ultrasonic array inspection methods for such materials. This is exemplified by considering the simulation of ultrasonic NDE in a weld structure in order to assess new approaches to imaging such structures.

Effective grain orientation mapping of complex and locally anisotropic media for improved imaging in ultrasonic non-destructive testing

“…Thirty-two sources were placed on the top boundary of the domain and a pressure wave (with centre frequency 1.5 MHz) was sent into the material from each source in turn. The average time-variant, normal stress was then measured at 32 points along the bottom edge of the domain to simulate our receiving array [33]. These received waveforms were processed to extract the first times of arrival of the wave front (measured as the time at which the receiver is first subjected to a stress greater than 10 −6 Pa).…”

“…Thus, given the incident wave angle, the speed that the wave travels through that cell can be calculated from where the wave vector bisects the rotated slowness curve. The longitudinal group slowness curve (the reciprocal of the group velocity) for a transversely isotropic cubic austenitic weld is obtained by solving the Christoffel equation [12] with a cubic stiffness tensor where c 11 = 203.6GPa, c 12 = 133.5GPa and c 44 = 129.8GPa and the density is ρ = 7874kg/m 3 (these are taken from the weld properties used in [32,33]). Note that the method is not restricted to the examination of cubic materials and a straightforward extension could be realized to consider hexagonal materials.…”

“…The arrays had a pitch (element spacing) of 2 mm and the depth of the component was 40 mm. It is important to note that the Onscale software models many of the physical phenomena present in the ultrasonic phased array inspection, for example mode conversion and diffraction, and it has previously been validated against experimental data [33]. We treat these aspects of the data as system noise.…”

A Novel Versatile Approach for Underwater Conformal Volumetric Array Design

“…Finite element analysis (FEA) has been described as the best way to obtain quantitative data for an acoustic array design [ 52 ]. Its reliability to evaluate the integrity of theoretical designs in academic and commercial applications has been emphasized [ 57 , 58 ]. Consequently, a commercial FEA software, Pzflex ® (version 1.21.7.0), is employed to validate the design as well as evaluate the TVR level of the conformal array with respect to the target minimum of 147 dB.…”

Design-for-testing for improved remanufacturability

“…This is a fair representation of the physical scenario as ultrasonic trandsucers are usually placed in a single plane so that we effectively inspect a slice of the component. However, it can be noted that PZFlex has the capability to read in computer aided design (CAD) files of 3D components [7] and so the framework developed can easily be extended to more complex inspection scenarios in the future if necessary.…”