Laser Extensometry
Laserextensometrie | A service provided by |
|---|
|
| Polymer Service GmbH Merseburg |
| Tel.: +49 3461 30889-50 E-Mail: info@psm-merseburg.de Web: https://www.psm-merseburg.de |
| Our further education offers: https://www.psm-merseburg.de/weiterbildung |
| PSM on Wikipedia: https://de.wikipedia.org/wiki/Polymer Service Merseburg |
Laser extensometry
Recording of local strain
The deformation and fracture behaviour of plastics in the tensile test is significantly influenced not only by the test conditions but also by the internal condition of the material during manufacture. The structure and morphology parameters (see: microscopic structure) of the tested specimens therefore determine not only the temporal and local deformation process, but also the area and type of upstream damage behaviour (see: micro-damage limits). The deformation process of heterogeneous and anisotropically structured plastics is basically always associated with a localization of the externally homogeneous deformation. A spatially resolved strain measurement technique such as laser extensometry is therefore required to understand these processes. Laser extensometry generally refers to scanning measurement techniques that are based on the transmission or reflection principle and use the test specimen as a radiation obstacle or reflector.
The deformation measurement is based on the determination of time, which refers to the scanning speed of a rotating mirror or prism. To record the local strain (see: laser heterogeneity of strain distribution), the test specimens must be provided with measuring marks or reflectors. The marks can be applied as a foil mask using a screen or pad printing process, or by simple light-dark contrasting using a spray or brush.
Laser extensometry – Device systems
To determine the local deformation behaviour, the following device systems are explained in detail in the Wiki-lexicon: “Polymer Testing & Diagnostics”:
- Laser double-scanner
- Laser doppler-scanner
- Laser heterogeneity of strain distribution
- Laser longitudinal–transverse scanner
- Laser multi-scanner
- Laser parallel-scanner
- Laser cross-unit
- Laser TMA-scanner
- Laser angle-scanner
- Hybrid methods, examples
References
- Bierögel, C., Grellmann, W., Fahnert, T., Lach, R.: Material Parameters for Evaluation of Polymer Welds using Laser Extensometry. Polymer Testing 25 (2006) 1024–1037; http://dx.doi.org/10.1016/j.polymertesting.2006.07.001
- Grellmann, W., Bierögel, C.: Laserextensometrie anwenden. Einsatzmöglichkeiten und Beispiele aus der Kunststoffprüfung. Materialprüfung 40 (1998) 11–12, 452−459
- Bierögel, C.: Hybrid Methods of Polymer Diagnostics. In: Grellmann, W., Seidler, S. (Eds.): Polymer Testing. Carl Hanser Verlag, Munich (2022), 3rd Edition pp. 497–513; (ISBN 978-1-56990-806-8; E-Book-ISBN 978-1-56990-807-5; see AMK-Library under A 22)
- Grellmann, W., Bierögel, C., König, S.: Evaluation of Deformation Behaviour of Polyamide using Laserextensometry. Polymer Testing 16 (1997) 225–240, DOI: https://doi.org/10.1016/S0142-9418(96)00044-X