Impact of thermal loads on interfacial debonding in FRP strengthened beams

AbstractThe effect of thermal loads on the debonding mechanisms in beams strengthened with externally bonded composite materials is analytically investigated. The analytical approach adopts a high-order stress analysis model and a fracture mechanics model that uses the concept of the energy release rate through the thermo-mechanical form of the J-integral. The two models are combined to synthesize the relation between the energy release rate, the mechanical loads, the thermal loads, and the interfacial crack length simulating the thermo-mechanical debonding process. The model is supported through comparison with experimental results taken from the literature. The comparison quantifies and explains various phenomena observed in the experiments and mainly the non-monotonic dependency of the debonding failure load on the temperature. The impact of the temperature on the interfacial stresses and on the stability of the debonding process is also studied. Finally, the effect of an uniform thermal load on the debonding behavior of a strengthened beam is studied revealing the impact of the thermal load on the debonding stability and strength characteristics

ESDA2008-59393 ADVANCED FERROELECTRIC MFC ACTUATORS: THE EFFECT OF FERRO- ELASTIC DOMAIN SWITCHING

ABSTRACT Macro Fiber Composite (MFC) actuators, which are commonly integrated in modern smart structures, may be subjected to high levels of mechanical loads. Opposed to the electrical actuation, these loads are not always controlled or anticipated by the user. Thus, they may yield a response that is beyond the linear range due to a stress induced ferro-elastic domain switching. In this paper, the phenomenon of domain switching and mechanical depolarization in the MFC actuator and the resulting degradation of the actuation capabilities are investigated. As an illustrative numerical example, the response of MFC layers in an active beam element is analyzed. Emphasis is placed on the location of the fiber segment along the active beam with a distinction between the compressed and the tensed layers. The results highlight the range of effects associated with the potential nonlinear response of the active structure under high levels of mechanical load

écriture et action dans les vies d’Antoine Arnauld et Blaise Pascal (1696) : pour un pont historiographique

Depuis les années 1960, l’histoire de la France moderne profite d’un dialogue intense et productif entre l’histoire anglophone américaine et l’histoire française écrite dans l’hexagone. Mais ce dialogue, toujours fructueux, semble perdre en intensité ces dernières années. Des historiens soucieux de le faire vivre essaient de le revigorer par la publication de traductions dans des numéros spéciaux des revues, ce qui offre autant d’occasions de réfléchir aux rapports historiens outre-Atlantique..