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Surface-applied fibre optic strain sensors were investigated using a unique validation facility equipped with application-independent optical reference systems. First, different adhesives for the sensor's application were analysed regarding their material properties. Measurements resulting from conventional measurement techniques, such as thermo-mechanical analysis and dynamic mechanical analysis, were compared with measurements resulting from digital image correlation, which has the advantage of being a non-contact technique. Second, fibre optic strain sensors were applied to test specimens with the selected adhesives. Their strain-transfer mechanism was analysed in comparison with conventional strain gauges. Relative movements between the applied sensor and the test specimen were visualized easily using optical reference methods, digital image correlation and electronic speckle pattern interferometry. Conventional strain gauges showed limited opportunities for an objective strain-transfer analysis because they are also affected by application conditions.

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The performance of shock absorbers has been tested in specific regulatory drop tests onto an unyielding target at the BAM drop test facility. Optical surface digitisation methods have been used to measure, analyse and evaluate permanent deformations of shock absorbers more systematically. The measurement principle of the used fringe projection technique and its technical application to shock absorber investigations is explained in detail. Furthermore, examples of shock absorber testing results as well as final data visualisation are given in the present paper.

High-sensitivity moir é interferometry with the in situ deformed grating replication technique is adopted to investigate the deformations of a nickel-based polycrystal superalloy under uniaxial tensile loading. By multiple replication of several desired loading levels and observing them in moir é interferometry, nearly real time deformation measurements can be conducted flexibly even when the testing machine is far away from the optical set-up. As an alternative to deformed specimen grating replication caused by mechanical loading, a thermally induced deformed specimen grating can also be replicated at an elevated temperature and deformation fields can be obtained by observing the replicated pieces in moir é interferometry at room temperature. Thermally induced deformations of a microelectronic assembly are given as an example.