Acoustic Imaging of Microstructures of Carbon Fiber-Reinforced Composite Laminates
- PDF / 910,732 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 67 Downloads / 252 Views
Acoustic Imaging of Microstructures of Carbon Fiber-Reinforced Composite Laminates Songping Liu, Vadim M. Levin1 and Enming Guo The NDT&E Center for Composites, Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024, China. 1 Lab. of Acoustic Microscopy, Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygin St, Moscow 117977, Russia. ABSTRACT The properties and homogeneity of a composite laminate are strongly dependent on structures and microstructures in it. The investigations have shown that the microstructures of carbon fiber-reinforced polymer composite laminates can be visualized by means of acoustic imaging techniques. The frequency of ultrasonic wave to be used is up to 50MHz. The composite laminates to be investigated include unidirectional carbon fiber-reinforced polymer composite laminates, bi-directional carbon fiber-reinforced polymer composite laminates and carbon fiber woven composite laminates. Very useful quantitative information about inside structures of the composites can be visualized in plan-section of the laminates in the depth directions by ultrasonic T-scan imaging technique. Typical results have been represented in this article. INTRODUCTION Microstructures of carbon fiber-reinforced composites are becoming more and more important for the applications of composites in industry and investigations of new composite materials because of their affects on the properties of composites. In addition, some important information, such as homogeneity of constituents, distributed defects in a composite lamination, can be obtained by means of investigating the microstructure. Up to date, the destructive visual methods, for examples, optical microscopy, is the common method used to visualize the microstructure of a material, but only local structural information in cross-section or limited zone can be observed. Therefore, there are a lot of investigations in the world have been focused on the fields of evaluation of micro-structural information and the distributions of constituents in composites [1-8]. Quantitative information about microstructures and the distributed defects in carbon fiber-reinforced composite laminates can observed by means of ultrasonic T-scan imaging techniques, which is based on time of flight of ultrasonic wave in composites.
U10.3.1
BASIC CONSIDERATION OF IMAGING BY ULTRASONIC T-SCAN Microstructure models for bi-directional composite laminates Figure 1 is typical microstructures of two bi-directional carbon fiber-reinforced composite laminates in across-section, which is obtained by optical microscope. Figure 1(a) is a part of microstructure of a bi-directional laminate, which is made of 32 carbon fiber prepreg plies of [0º 2s/+45º2s /90º2s /-45º2s /0º2s…]16s. Each layer is composed by two plies with same directions of fiber bundles. There is a visible interface between them. Figure 1(b) is another part view of
Interfaces
-45º2s 0º2s
Interplies
+45º2s
-45º2s (a) Without distributed defects (No.#A-1, X100)
Defect
Defect
(b) Wit
Data Loading...
