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The authors present the characterization of the behavior of a Carbon Fiber Reinforced Polymer (CFRP) under dynamic loading. The study deals with thin shields representative of the shields employed for satellite protection. The process was divided into two steps. First, experiments over a wide scale of strain rates were performed, including planar plate impacts, electron beam shots, and laser-induced shocks. The loads generated by these experiments can be unidirectional or two-dimensional with durations from a tenth of nanoseconds up to several microseconds. Rear surface velocities were recorded by Doppler Laser Interferometry, and damaged target was recovered when possible. Analysis of these results provides data about equation of state, elasto-plasticity behavior, and the damage process. In a second part, those data were used to develop an isotropic numerical model for the CFRP composite. This model is assessed in simulations with the hydrocode HESIONE (CEA) for all the previous experiments. Although slight differences were highlighted for laser-induced shocks, the model provides relevant results for simulating dynamic behavior of the CFRP composite. [ABSTRACT FROM AUTHOR]

We present a series of shock-wave measurements on aluminum based on the use of a simultaneous Photon Doppler Velocimetry (PDV) and triature velocity interferometer system for any reflector. Our dual setup can accurately measure shock velocities, especially in the low-speed range (<100 m s−1) and fast dynamics (<10 ns) where measurements are critical in terms of resolution and unfolding techniques. Especially, the direct comparison of both techniques at the same measurement point helps the physicist in determining coherent settings for the short time Fourier transform analysis of the PDV, providing increased reliability of the velocity measurement with a global resolution of few m s−1 in velocity and few ns FWHM in time. The advantages of such coupled velocimetry measurements are discussed, as well as new opportunities in dynamic materials science and applications. [ABSTRACT FROM AUTHOR]

The velocity interferometer system for any reflectors measurements on laser shock-loaded samples of sintered steels with 10%-28% porosity was used to investigate the effects of porosity on shock wave propagation in porous media. The model could be useful to simulate shock wave propagation in multilayered material including porous components such as plasma sprayed coatings and also lead to a better estimation of the stress history causing the debonding in adhesion testing methods based on laser induced spallation.

The energy content of finishing diets offered to feedlot cattle may vary across countries. We assumed that the lower is the energy content of the finishing diet, the shorter can be the adaptation period to high-concentrate diets without negatively impacting rumen health while still improving feedlot performance. This study was designed to determine the effects of adaptation periods of 6, 9, 14 and 21 days on feedlot performance, feeding behaviour, blood gas profile, carcass characteristics and rumen morphometrics of Nellore cattle. The experiment was designed as a completely randomised block, replicated 6 times, in which 96 20-month-old yearling Nellore bulls (391.1 ± 30.9 kg) were fed in 24 pens (4 animals/pen) according to the adaptation period adopted: 6, 9, 14 or 21 days. The adaptation diets contained 70%, 75% and 80.5% concentrate, and the finishing diet contained 86% concentrate. After adaptation, one animal per pen was slaughtered (n = 24) for rumen morphometric evaluations and the remaining 72 animals were harvested after 88 days on feed. Orthogonal contrasts were used to assess linear, quadratic and cubic relationships between days of adaptation and the dependent variable. Overall, as days of adaptation increased, final BW (P = 0.06), average daily gain (ADG) (P = 0.07), hot carcass weight (P = 0.04) and gain to feed ratio (G : F) (P = 0.07) were affected quadratically, in which yearling bulls adapted by 14 days presented greater final BW, ADG, hot carcass weight and improved G : F. No significant (P > 0.10) days of adaptation effect was observed for any of feeding behaviour variables. As days of adaptation increased, the absorptive surface area of the rumen was affected cubically, where yearling bulls adapted by 14 days presented greater absorptive surface area (P = 0.03). Thus, Nellore yearling bulls should be adapted by 14 days because it led to improved feedlot performance and greater development of rumen epithelium without increasing rumenitis scores. [ABSTRACT FROM AUTHOR]

Coatings processed by thermal deposition techniques involve porosity. The Laser adhesion test developed for testing bond strength of a coating on its substrate requires a good knowledge of shock wave propagation in such media. Experiments carried out on plasma sprayed copper samples, about 14% porous, with velocity interferometer system for any reflector measurements display the discrepancy of previously used models. Hence, a one-dimensional formulation of the compaction process, based on a simple P-α model, is proposed to improve the correlation between experimental and computed data signals obtained on a plasma sprayed copper under dynamic loading. Besides, this improvement allows the estimation of the bond strength of a plasma sprayed copper on aluminum substrate. [ABSTRACT FROM AUTHOR]