94 F. Magi et al. 8.4 Conclusions This paper has presented a testing strategy based on SLDV technology for monitoring the fatigue behaviour of composites components under vibratory tests. It is important to say that these tests are executed at large vibration amplitudes, sometimes in the order of 80 mm peak to peak. Due to such amplitudes, the SLDV seemed the only measurement technology capable of tackling these levels and, thanks to its contactless feature; SLDV has enabled several different measurement techniques. MONTEVERDI software was designed around such a technology with the intent of fully automating lengthy vibration fatigue tests. Some of the tests results obtained during an ongoing research programme are presented and discussed in the paper. The composite fatigue behaviour is complex and several parameters are required for understanding the evolution of damage. In this paper, the temperature was shown to be a useful indicator for identifying the damage initiation. Tracing of resonant frequency alongside the acquisition of deflection shapes helps to understand how the damage tends to propagate. Similar signs are given by the mapping of additional nonlinear spectral harmonics, which are caused by the increasing level of damage, from the LDV output signal. Additional information regarding the failure criteria for composites from vibratory conditions are discussed in more details in dedicated composites journals. Acknowledgements The authors would like to acknowledge the support of Rolls-Royce plc for the support of this research through the Composites University Technology Centre (UTC) at the University of Bristol, UK. References 1. Lazan, B., Gannett, A., Kirmser, P., Klumpp, J., Brown, J.: Dynamic testing of materials and structures with a new resonance-vibration exciter and controller. Ohio (1952) 2. Lazan, B.: Fatigue Failure Under Resonant Vibration Conditions (1954) 3. Wozney, G.: Resonant-vibration fatigue testing. Exp. Mech. 2(1), 1–8 (1962) 4. Bertini, L., Santus, C., Boulet, J., Leclerc, P., Desmazures, C.: Resonant bench for fatigue testing of steel drill pipe connections. In: AIAS 41ı CONVEGNO NAZIONALE, pp. 5–8 (2012)
RkJQdWJsaXNoZXIy MTMzNzEzMQ==