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Mehdi Salehi,Saeed Ziaei-Rad,Mostafa Ghayour,Mohammad Ali Vaziri-Zanjani 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3
Vibration-based structural damage detection has been the focus of attention by many researchers over the last few decades. However, most methods proposed for this purpose utilize extracted modal parameters or some indices constructed on the basis these parameters. Our literature review revealed that few papers have employed frequency response functions (FRFs) for detecting structural damage. In this paper, a technique is presented for damage detection which is based on measured FRFs. Independent component analysis (ICA) has been implemented on the spatiotemporal responses in each frequency in order to reduce the dimension of the data. This is based on the concept that the forced harmonic response of a linear vibrating system can be fully captured utilizing a single ICA mode. A different approach is also presented in which ICA is applied to the frequency domain data. Operational deflection shapes (ODSs) have been decomposed using ICA to localize the damage. The efficiency of both methods is demonstrated through some numerical and experimental case studies.
Bird strike analysis on a typical helicopter windshield with different lay-ups
Reza Hedayati,Saeed Ziaei-Rad,Arameh Eyvazian,Abdel Magid Hamouda 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.4
In the current paper, bird strike to a typical helicopter windshield is investigated using smoothed particles hydrodynamic (SPH) finiteelement method. Five types of lay-ups in a windshield (single layer stretch acrylic, single layer glass, two-wall cast acrylic, acrylic withPolyvinyl butyral (PVB) interlayer and glass with PVB interlayer) is considered and in each case the thickness which prevents the birdfrom perforating the windshield is calculated. Since helicopters can have lateral movement in addition to their longitudinal movement,the effect of incident angle on the integrity of windshield is also investigated. Simulations showed that among the five cases presented,glass with PVB interlayer can be the best choice for being used in windshield against bird strike. Another conclusion is that for the sameinitial velocity, the angled impact can cause more damage in the windshield than the direct impact.