Non-destructive testing and mechanical testing of heat damaged of composite material

• Main Author: Zhang, Kun
• Other Authors: Wong, Brian Stephen
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Materials::Composite materials
• Online Access: http://hdl.handle.net/10356/70994
• Institution: Nanyang Technological University

Recently composite materials utilized in many industries, especially in aviation industry because of its high strength-to-weight ratio. Heat from a lightning strike, engine fire, and weapon system may cause internal delamination and epoxy degradation on the surface or through the structure. Many non-destructive test methods are not useful for the composite material. Thus, it is important to study the effective non-destructive testing (NDT) methods on composites. This project focus on the study of the capability and limitation for ultrasound A-scan, C-scan and shearography on specimens with artificial defect and heat damage defect. The specimens are fabricated using autoclave process and wet lay-up method. In total ten specimens are made using high toughness flame retardant epoxy carbon prepreg (woven). Different materials are inserted to specimens to simulate excess resin (epoxy), delamination and internal fiber damage. A 125mm by 125mm no defect specimen is fabricated using autoclave process. The specimen is cut using a slow saw machine into five specimens A1 to A5; each has the same dimensions. Specimen A2 to A5 are heated with a heat gun at 650 degrees for a different time interval. The results of Visual Inspection, Ultrasound A-scan, C-scan, Shearography and Tensile test are discussed in this report. The possible correlations between non-destructive test results and mechanical test results can be used for predicting actual mechanical properties from a non-destructive test. The objective of this project is to explore the capability of different NDT technologies to detect types of defects. And study the defects which are caused by heat on specimens and its maximum load reduction under different heat time. The specimens with artificial defects will be used to analyze what is the appropriate probe, gate mode, shear angle and shear distance for heat damaged specimens. Thus, to determine the proper equipment and setting for not only this project but also the future studies.