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Transverse galloping is a type of aeroelastic instability characterised by large amplitude, low frequency oscillation of a structure in the direction normal to the mean wind direction. It normally appears in bodies with small stiffness and structural damping, provided the incident flow velocity is high enough. In the simplest approach transverse galloping can be considered as a one-degree-of-freedom oscillator subjected to aerodynamic forces, which in turn can be described by using a quasi-steady description. In this frame it has been demonstrated that hysteresis phenomena in transverse galloping is related to the existence of inflection points in the curve giving the dependence with the angle of attack of the aerodynamic coefficient normal to the incident flow. Aiming at experimentally checking such a relationship between these inflection points and hysteresis, wind tunnel experiments have been conducted. Experiments have been restricted to isosceles triangular cross-section bodies, whose galloping behaviour is well documented. Experimental results show that, according to theoretical predictions, hysteresis takes place at the angles of attack where there are inflection points in the lift coefficient curve, provided that the body is prone to gallop at these angles of attack.

The main aim is to test the influence of anatomical structure (grain direction and elements size), wood hardness and machining conditions on wood surface roughness. 180 samples defect-free were obtained from beech, oak and pine and processed with different machining methods (planning, sanding with 60 grit or sanding with 180 grit). Roughness, hardness, and anatomical structure were analysed using international methodologies. An analysis of variance of the data from all the samples with the four factors in the experimental design were performed. Results showed that machining processes and species are the factors that significantly affect surface roughness, as opposed to grain direction (plane of section and stylus-grain angle), which was only shown to be significant in some subgroups. Roughness parameters of samples sanded with 180 grit were lower in contrast to samples planned or sanded with 60 grit. Hardness was found to be the property of the wood that most clearly affects its final roughness, and makes it difficult to achieve better roughness results as the hardness increases.

Surface metrology employs various measurement techniques, among which there has been an increase of noteworthy research into non-contact optical and contact stylus methods. However, some deeper considerations about their differentiation and compatibility are still lacking and necessary. This work compares the measurement characteristics of the confocal microscope with the portable stylus profilometer instrumentation, from a metrological point of view (measurement precision and accuracy, and complexity of algorithms for data processing) and an operational view (measuring ranges, measurement speed, environmental and operational requirements, and cost). Mathematical models and algorithms for roughness parameters calculation and their associated uncertainties evaluation are developed and validated. The experimental results demonstrate that the stylus profilometer presents the most reliable measurement with the highest measurement speed and the least complex algorithms, while the image confocal method takes advantage of higher vertical and horizontal resolution when compared with the employed stylus profilometer.