Composite materials have been increasingly used in aircraft structures. However, these composite structures are susceptible to damage from external low-velocity impacts. In this paper, an impact identification algorithm is proposed to estimate the impact location and force time history simultaneously. A localisation method based on basis vectors is proposed, and the impact force time history is reconstructed by simplified transfer functions. The basis vector stands for the relationship between the impact location and the sensor signals, and the transfer function shows the relationship of the sensor signal and the force time history. An experiment is conducted on a flat glass fibre-epoxy matrix composite plate to verify the developed algorithm using only four sensors. The soft impactor and hard impactor are two typical impactors for impact events; therefore, the impact experiment is performed by the rubber and the steel impactors, respectively. The experimental results indicate that the proposed algorithm is feasible for the identification of impact events on plate-like composite structures.

In this study, an impact energy identification method based on basis vectors is proposed to estimate the impact location and impact energy using piezoceramic sensors. A large number of parameterized impact experiments have been conducted on a composite plate to illustrate the linear relationship between signal energy and impact energy, which is also revealed by a theoretical analysis. The signal features of stress waves caused by different impactors are analyzed in the frequency domain to obtain a feature vector. A location basis vector including signal power and arrival time has been presented to determine the impact position without the need for the velocity of the stress wave. Furthermore, the energy basis vector has been defined to estimate the impact energy based on the relationship between the impact energy and signal energy. The results of this study show that the proposed method is able to effectively estimate the location and impact energy of the impact source on the composite plate.

Abstract.n this paper we present the evaluation results of solar thermal cooling performance of PDMS/glass composite lamination in which the microfluidic flowpaths have been fabricated on the interface between PDMS and glass. The microfluidic flowpaths was designed into pinnate-like and its pattern was transferred onto the surface of PDMS piece through UV flatbed-printer and soft molding, then plasma bonded onto glass, forming PDMS/glass compound window with an area of 10×8 cm 2 . The temperature distribution of thus-made device was monitored with IR imager and thermal-couple when DI water with different flow-rates was forced flowing into and out. The results show that this pinnate-like PDMS/glass microfluidic device could significantly realize good heat-transfer, when it was exposed to environmental temperature higher up to 38ºC, the outlet temperature of the flowing water at 5 mL/min could be reduced by 8~10ºC when the inlet flowing water was given at room temperature.