Abstract
Abstract. Advanced ceramic components are frequently used in industrial applications. As a brittle material, ceramic reacts very suddenly to excessively high stresses. Existing defects lead to rapid crack growth followed by spontaneous destruction. This leads to a functional failure of the entire component. It is therefore important to develop innovative techniques to ensure a good quality condition of ceramic products. Laser speckle photometry (LSP) is an optical nondestructive testing method. It is based on the dynamic analysis of time-resolved speckle patterns that are generated by an external excitation. In this paper, we will present two investigations on ceramic components using the LSP technique. One is the nondestructive stress characterization on ceramic surfaces, and the other is the defect detection on ceramics components. The aim is to improve the quality and safety control of ceramic production in the challenging industrial field. Preliminary results have shown the potential of the LSP sensor system for the nondestructive characterization of ceramics in terms of stress monitoring and surface defect detection.
Highlights
Due to the special structural and functional properties of ceramic materials, they play an important role in many fields of industry
Since coefficient of speckles (CCoSs) assess the similarities of speckle patterns at different stress states, they will lose the correlation with the initial state if the patterns change significantly
low-temperature cofired ceramic samples (LTCCs) is opaque to 650 nm lasers, and speckle patterns generated on its surface are determined by surface scattering
Summary
Due to the special structural and functional properties of ceramic materials, they play an important role in many fields of industry. Speckle photography is a full-field optical method and, by combining it with the digital image correlation technique, can be used to measure in-plane deformations and strains in opaque materials (Blug et al, 2019; Schenuit et al, 2008; Tausendfreund et al, 2018) It records the speckle patterns before and after the deformation of the inspected workpiece. There are many common defect detection methods, such as X-ray transmission and backscattering techniques (Okuma et al, 2019; Skácel et al, 2018) and the ultrasound impulse echo method (Barth et al, 2016; Kesharaju et al, 2014; Tripathi et al, 2019), with the aim of detecting defects in both the surface and inner zones These procedures are usually complicated, and the samples are scanned individually with laboratory equipment.
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