Material characterization by laser speckle photometry

• Autores: Beatrice Bendjus, Ulana Cikalova, Juergen Schreiber
• Localización: SPECKLE 2012: V International Conference on Speckle Metrology : 10-12 september 2012 : Vigo, Spain / Ángel Manuel Fernández Doval (ed. lit.), María Cristina Trillo Yáñez (ed. lit.), José Carlos López Vázquez (ed. lit.), 2012, ISBN 9780819490902
• Idioma: inglés
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• Resumen

  • The damage and stress conditions of large industrial components have to be tested continuously. Especially welding processes in the field of coal production demand a nondestructive monitoring of internal stresses under an external load. In a first step, a new optical method, Laser Speckle Photometry was used during laboratory welding experiments under tensile and bending loads at high strength construction steels. Laser Speckle Photometry is a fast and contactless method for measuring spatial-temporal dynamics of speckle field with high temporal resolution after local heat excitation. The thermally induced change in the material structure causes changes in the speckle-field, which is formed by a probing laser. The shift of the speckle-field is analyzed by statistical methods, using correlation functions. The result of processing is the two-dimensional distribution of thermal diffusivity coefficient correlated to porosity, materials strain or hardness [1-3]. Here, the results of the welding experiments under load are presented. It is shown, that the Laser Speckle Photometry is a suitable technique for nondestructive monitoring and characterization of internal material stresses under external load