If the industry generally considers composite materials as potentially interesting, the lack of durability makes their often limited employment. Indeed, the design of composite structures often requires taking account of the long-term behaviour under various types of complex solicitations. This study is based on the development of a methodology for modeling the long term behavior under constant load for multilayer composite structures subjected to complex solicitations. This study is on the evaluation of the long-term behaviour of tri-layers glass/polyesterwood composite material. The objective is the evaluation of the long term strength of this material by the Goldenblat-Kopnov criterion. The studied model is an orthotropic tri layer plate of sandwich type with upper and lower flanges (skins) are in composite material glass/polyester KACT-B and the intermediate layer (soul) is pine wood. The character of loading of the plate is reflected in the model by the functions σ ik (ξ), σ mn (ξ) which can be of different natures. For example, to load in the long term by constant constraints in time (the weight own element for example), we will have: σ ik = const, σ mn = const. The results of the calculations show that, for this type of material, the conditions of strength to the dangerous points of the plate are met.

This study focuses on the characterization of train brake blocks. The brake blocks are an essential organ of train speed control system to ensure comfort and safety to passengers and crew. However, poor quality soles can cause a premature wear of the wheels whose consequences are on the one hand, a damaged brake function, and also high repair costs. Samples were carried out on 3 different batches of brake blocks. Their metallurgical characterization consisted of a study of the hardness and microstructural analysis (microstructures and chemical analyzes) of the different samples. The results show that the hardness of some soles is greater than that of the wheel, mainly associated with a cementite microstructure. This can lead to a premature wear of the wheels at the expense of brake blocks.

The aim of this study is to characterize thermal insulating local material, kapok, from a study in 3 dimensions in Cartesian coordinate and in dynamic frequency regime. From a study a 3 dimensional the heat transfer through a material made of wool kapok (thermal conductivity: λ = 0.035 W/m/K; density: ρ = 12.35 kg/m 3 ; thermal diffusivity: α = 17, 1.10-7 m 2 /s) is presented. The evolution curves of temperature versus convective heat transfer coefficient have helped highlight the importance of pulse excitation and the depth in the material. The thermal impedance is studied from representations of Nyquist and Bode diagrams allowing characterizing the thermal behavior from thermistors. The evolution of the thermal impedance with the thermal capacity of the material is presented.

One of the major problems encountered in the prediction of the hereditary viscoelastic behavior of polymeric composites, is the determination of the heredity kernels. This issue comes down to the identification of the model characterizing the viscoelastic properties of these materials. The purpose of this work is to propose a model for prediction of viscoelastic nonlinear behavior of a composite laminate matrix polyester KACT-B by the study and analysis of the heredity kernels and their influence on the life time of this material. The identification of this model required the experimental determination at room temperature, of the viscoelastic parameters of the heredity kernels by a macroscopic approach. These data provide predictive tools for the establishment of the life time under static complex solicitation and yield strength in the long term for this type of material. Sufficiently interesting in terms of concept and methodology, experimental tests in this study, performed on polymeric fiberglass composite, are still few but develop at a pace that we can look in the near future access suitable for purposes of design data.

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