Improvement in Accuracy of a Multi-Joint Robotic Ultrasonic Inspection System for the Integrity of Composite Structures

Jea Seang Lim,Ik Keun Park,Tae Sung Park,Yu Min Choi

doi:10.3390/app10196967

Abstract

Composite materials have attracted significant attention with regard to the manufacturing of structures that require weight reduction, such as automobiles and aircraft, because they are more resistant to corrosion and fatigue than conventional metal materials. However, such materials exhibit a reliability degradation problem, i.e., their mechanical and physical properties deteriorate due to the occurrence of delamination and voids. Ultrasonic inspection methods have been widely applied for nondestructive detection of such defects in structures; however, the application of these approaches has been impeded due to high anisotropy and acoustic attenuation. In addition, the existing ultrasonic inspection methods require considerable time and cost for the inspection of large materials or structures. These problems were addressed in this study by developing an automatic ultrasonic inspection system; this was achieved by adopting a squirter-type water injection device, which uses a multi-joint robot and the through-transmission ultrasonic method. In addition, a software program to correct axis misalignment was developed and verified to solve the deterioration in defect detectability and accuracy that was caused by axis misalignment, which may occur during the use of the developed system. This development was accomplished after measuring the coordinates of the deformed mechanical part using a three-dimensional laser measuring instrument.

Highlights

Composite materials are artificially manufactured from two or more materials that complement their most attractive properties while maintaining their macroscopic characteristics, which is in contrast to the metal alloys that have been widely used in the past as raw materials for various structures.Representative composite materials include carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), and epoxy resin materials [1,2]
In the through-transmission ultrasonic (TTU) method, ultrasound is generated by one sensor and received by the other sensor while water is injected through the squirters on both sides, as shown in Figure 1; the water is used as a couplant and it must be continuously injected
An algorithm for correcting the deformation and misalignment of the bogie part developed to solve the deterioration in the accuracy and reliability of inspection to ensure the integrity was developed to solve the deterioration in the accuracy and reliability of inspection to ensure the of composite material structures

Summary

Introduction

Composite materials are artificially manufactured from two or more materials that complement their most attractive properties while maintaining their macroscopic characteristics, which is in contrast to the metal alloys that have been widely used in the past as raw materials for various structures.Representative composite materials include carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), and epoxy resin materials [1,2]. Composite materials are artificially manufactured from two or more materials that complement their most attractive properties while maintaining their macroscopic characteristics, which is in contrast to the metal alloys that have been widely used in the past as raw materials for various structures. Lighter, and more resistant to corrosion and fatigue than conventional metal materials [3]; they have attracted significant attention as materials for structures that require weight reduction, such as automobiles, aircraft, and structures for defense and aerospace industries. The initial production costs of these composite materials are higher than those of metal materials. This cost encompasses all the expenditures incurred from the sourcing of raw materials to the manufacturing process.

Methods

Results

Conclusion