代写Project 5325 - Suppressing the cross-talk of the surface acoustic wave from ultrasonic images of b

Project 5325 - Suppressing the cross-talk of the surface acoustic wave from ultrasonic images of bulk waves in laser ultrasonic captured data

Project Type: Individual

Maximum Number of Students: 1

Project Description

Ultrasonic imaging is a powerful non-destructive evaluation tool to analyse the integrity of components. Ultrasound can be generated using a variety of modalities such as piezoelectric transducers, electromagnetic acoustic transducers (EMATs), and lasers. Piezoelectric transducers and EMATs are not designed to withstand the extreme processing environments that is typical of welding and additive manufacturing. However, laser ultrasonics (LU) offers a remote and non-contact mode of operation that makes it deployable for complex geometries, hostile environments, and places of restricted access. In LU, ultrasound is generated and detected using lasers.

One of the advantages of laser ultrasound is that it excites all ultrasonic wave modes: both bulk waves (i.e. ultrasonic waves that travel through the bulk of the material) and surface acoustic waves (i.e. ultrasonic waves that ravel at the surface) are generated. The ultrasonic data that are captured are then post processed using imaging algorithms that produce ultrasonic images of the interior of the component based on the time of the ultrasonic wave’s arrival and its velocity. Each ultrasonic wave mode has it’s own ultrasonic velocity and in many instances the wave modes from the bulk and the surface arrive at the same time, creating a cross-talk. As the surface acoustic wave is the strongest wave mode generated, a region of the ultrasonic image is saturated by its arrival and masks any features/defects within this region.

The aim of this project is to explore and implement signal processing techniques to suppress or remove the surface acoustic wave cross-talk from ultrasonic data captured using laser ultrasound for successful imaging of subsurface defects. Experimental data sets from laser ultrasound will be provided. Good Matlab knowledge is essential.

Key Objectives

Familiarise with the concept of laser ultrasound.

Understand the laser ultrasound data acquisition method.

Understand the total focusing method (TFM) imaging algorithm for laser ultrasonics.

Use TFM to produce ultrasonic images with previously recorded experimental data.

Develop several signal processing methods for suppression of the surface acoustic wave crosstalk.

Implement the developed suppression methods to image a subsurface defect within the crosstalk region from previously recorded experimental data.

Compare the advantages and disadvantages of each method.

Supervisor

Stratoudaki, Dr Theodosia (SENIOR LECTURER - EEE)

Second Supervisor

Davis, Dr Geo (RESEARCH ASSOCIATE - EEE)

Class Codes

19496 EEE Individual Project

EE900 MSc Project

EE990 MSc Project

EM401 EME Individual Project

Areas

Signal Processing

Opto Electronics

Ultrasonics

Mechanical Engineering

Topics

Optical Technologies

Image & Video Processing

Data Analysis

Non Destructive Testing

Ultrasonics

Laser Technologies

Activities

Software

Computer-based

Numerical

Measurement

Analysis

Research

Small signal

Programming