Innovative Structural Materials: Reducing Weight of Transportation Equipment by Teruo Kishi

Author:Teruo Kishi
Language: eng
Format: epub
ISBN: 9789819935222
Publisher: Springer Nature Singapore

Fig. 4.74 Endurance limit curve (mean stress-shear stress amplitude relationship)

4.4.3.3 Inspection Technologies

When conducting inspections with the aim of ensuring the soundness of adhesive bonding, it is necessary to conduct a surface inspection to check the properties of the adherend surface before bonding and a non-destructive inspection to check for existence of defects after bonding.

As a pre-bonding surface inspection, wettability tests such as contact angle measurement are generally performed. However, this involves problems, e.g., it is not possible to perform bonding work until the liquid used in the measurement has dried. Thus, it is not realistic to apply this method to 100% inspections such as those in the automobile manufacturing process, since shortening of the process time is always required. In this theme, an inspection technology using the LIBS (Laser-Induced Breakdown Spectroscopy) method was developed as a high-speed, non-contact inspection technology. This equipment performs elemental analysis by laser beam irradiation of the adherend surface and detection by a spectrometer of the emitted light of plasma from the measurement point, and thus enables rapid, non-contact inspection of large surface areas. Figure 4.75 shows the LIBS inspection method, and Fig. 4.76 shows the rate of decrease in adhesive strength and the signal intensity of Si detected by LIBS when a small amount of silicone oil was applied as a contaminant to the aluminum alloy (adherend). As this method is capable of detecting contaminants on the adherend that reduce adhesive strength by about 5%, its sensitivity may be sufficient for practical purposes [67, 68].

Fig. 4.75 Overview of LIBS system

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