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Prüfung von Elastomeren mit Hilfe neuer zerstörungsfreier Prüfverfahren

 
: Netzelmann, U.; Walle, G.; Wolter, B.; Sklarczyk, C.; Maisl, M.

Deutsche Kautschuk-Tagung 2000. Kurzfassungen
Nürnberg, 2000
S.247-249
Deutsche Kautschuk-Tagung <2000, Nürnberg>
Deutsch, Englisch
Konferenzbeitrag
Fraunhofer IZFP ()
Elastomer; zerstörungsfreie Prüfung; NMR

Abstract
For quality assurance of elastomers, non-destructive techniques are an impotant tool. This contribution will show some applications of modern testing techniques based on different physical mechanisms.
Ultrasound techniques are sensitive to interface properties and can be used for detection of small voids or poor adhesion at joining interfaces. Testing is usually performed under water, although air-coupled techniques are being developed. Different imaging modes allow a comprehensive representation of the structure of the test object. Non-linear elastic properties can be used for determination of early damage states in materials.
Optical testing techniques are contact-free and fast. Shearography is a holographic technique that can be used in rough industrial enviroment and is well suited to test defect in comparably soft materials like elastomers.
In a similar way fast and contact-free works active thermography. Heat is deposited in the sample surface by a strong flash lamp. The thermal response is then measured by an infrared camera and stored in a frame buffer. Sub-surface defects are detected as small temperature contrasts occurring after the heating pulse.
Microwave measurement are being used to determine the density of foams or the thickness of coatings. For non-imaging applications and process control, this technique can be very fast.
Cross-sections and volume properties of test objekts with complicated shape are best analysed by X-ray techniques. Depending on the task to be solved, a set of variants including 3D tompgraphy is available to the industrial user.
An attractive new technique ist the nuclear magnetic resonance (NMR) technique in one-side access mode. In contrast to conventional NMR equipment, it is not necessary to bring a test object into a magnet bore. Objects of arbitrary size can be analysed up to a depth of a few centimeterc. The new instruments allow laterally and depth resolved characterisation of moisture, heterogenities, cross-link density and the state of the material.

: http://publica.fraunhofer.de/dokumente/N-2035.html