The general characteristics of granular soils reinforced with fibres have been reported in previous studies and have shown that fibre inclusion provides an increase in material strength and ductility and that the composite behaviour is governed by fibre content, as well as the mechanical and geometrical properties of the fibre. The present work presents a numerical procedure to incorporate fiber elements into an existing discrete element code (GeoDEM). The fiber elements are represented by linear elastic-plastic segments that connect two neighbor contacts where the fiber is located. These elements are characterized by an axial stiffness, tensile strength and length. The effect of the addition of fibers was evaluated numerically by comparing the stress-strain behavior of a pure sand with and without fibers. These simulations showed that the addition of fibers provides a significant increase in strength for the mixture in comparison with strength of the pure sand.

Photothermal beam deflection is a well-established technique for measuring thermal diffusivity. In this technique, a pump laser beam generates temperature variations on the surface of the sample to be studied. These variations transfer heat to the surrounding medium, which may be air or any other fluid. The medium in turn experiences a change in the refractive index, which will be proportional to the temperature field on the sample surface when the distance to this surface is small. A probe laser beam will suffer a deflection due to the refractive index periodical changes, which is usually monitored by means of a quadrant photodetector or a similar device aided by lock-in amplification. A linear relationship that arises in this technique is that given by the phase lag of the thermal wave as a function of the distance to a punctual heat source when unidimensional heat diffusion can be guaranteed. This relationship is useful in the calculation of the sample's thermal diffusivity, which can be obtained straightforwardly by the so-called slope method, if the pump beam modulation frequency is well-known. The measurement procedure requires the experimenter to displace the probe beam at a given distance from the heat source, measure the phase lag at that offset, and repeat this for as many points as desired. This process can be quite lengthy in dependence of the number points. In this paper, we propose a detection scheme, which overcomes this limitation and simplifies the experimental setup using a digital camera that substitutes all detection hardware utilizing motion detection techniques and software digital signal lock-in post-processing. In this work, the method is demonstrated using thin metallic filaments as samples.

An analysis of the strut‐to‐fuselage and main‐landing‐gear‐to‐fuselage joint is realized in order to evaluate the zones with a high probability of failure. The whole section is analyzed using the finite element method in order to estimate static resistance behavior, therefore it becomes necessary to create a numerical model of the section, to measure the mechanical properties of the C‐Ep composite material, and to calculate the loads applied onto the section. The section is digitized with photogrammetry. Mechanical characterization is achieved with instrumented standardized tensile tests. Results of the analysis show that the zones with higher probability of failure are found around the wing strut and the fuselage joint, with a safety factor higher than necessary even for the most critical condition, and lower in comparison with the average safety factor used on aircrafts built mostly with metals. POLYM. COMPOS., 36:1072–1083, 2015. © 2015 Society of Plastics Engineers

We compare the thermal lens (TLS) and the optical transmission (OT) spectroscopy techniques to monitor the kinetic of a photocatalytic reaction. For this, an OT measurement facility was added to a TLS set-up. The TLS was implemented in a microspatial configuration named thermal lens microscopy (TLM). Methylene blue (MB) in Water solutions were used as test samples within a concentration range in which both techniques show good sensibility. Within this range, the limit of detection obtained by TLM was about one order of magnitude lower than that achieved by OT. The methylene blue concentration evolution with photocatalytic reaction time was measured with both techniques, showing a good agreement between their results. A ZnO thin film deposited on a glass substrate by the spray pyrolysis technique was used as catalyst, and the reaction was induced by UV-violet light.

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