Detecting and monitoring defects and damages on a pipeline using self-develop guided lamb wave system

Abstract

This project was done as a first step to develop applied technology for Lamb wave Structural Health Monitoring (SHM) system. First part was to self-develop the system, where we concentrate on the actuator and sensor using piezoelectric buzzer (PB) that can be easily obtained in the market. In determining its feasibility; we investigate its natural frequency, electrical to mechanical conversion and vice versa, its performance against different frequency and its circuit configuration in relation to the systems. From there, we configure the system to create the simplest system to generate and detect the Lamb wave. From this system, we experimenting the symmetrical and asymmetrical wave on a mild steel plate with a thickness of 1mm for frequency between 0-2000Hz to find its velocity and used it to compare to the theoretical calculation. Second part was using the self-develop SHM system, we introduce defects or asymmetrical obstacle to the plate. The asymmetrical obstacle parameter was manipulated where we change the distance of the defect from the actuator, the mass of the defect and the area of contact. It was discovered that the Lamb wave velocity changes with the distance and with the surface area of contact of the obstacle but do not change with mass. The wave amplitude ratio changes with distance and surface area of contact but do not change with mass. Although it was still a crude design but some obstacle could be detected by this self-developed Lamb wave SHM system.