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Composite materials have been applied widely in a lot of fields because of their excellent performance. And the
composite materials may have some defects and be damaged in the process of manufacturing and usage, which will
result in the performance degradation of the composite structure and even a failure. Thus, it is necessary to detect the
defects of the composite materials. This paper introduced the thermosonics nondestructive testing technology, described
the fundamental principle of the technology, and gave some experimental results of two kinds of composite materials.
One of the two materials is carbon fiber foam sandwich composite material which has six pre-embedded debonding
defects, and the other one is carbon fiber laminated board with the impact damage caused by collisions with different
energies. And the testing results of the two materials by thermosonics are satisfactory. However, at present, the usual
thermal wave imaging nondestructive testing technique for detecting composite materials is based on flash pulse
excitation. In this paper, the carbon fiber laminated board was also detected by the pulsed method. And this paper further
compared these two kinds of thermal wave imaging nondestructive testing techniques and the corresponding results with
different excitation ways. Some differences could be found between these two methods by analyzing the results obtained
by different excitation ways. Furthermore, based on the differences and the other factors such as the principles and
devices of these two methods, we could summarize and know that these two methods have their respective advantages
and disadvantages and could be applied to different situations. In the actual testing process, which method will be
selected to detect the defects depends on the specific demands of the experiment and the characteristics of these two
methods. And these two methods can also be used together to detect defects for a comprehensive and effective result.
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