This paper shows a method to compute the chord and twist distributions in wind power blades. The distributions are computed to maximize the mean expected power depending on the Weibull wind distribution at a specific site. This approach avoids assumptions about optimal attack angle related to the ratio between the lift to drag coefficients. To optimize chord and twist distributions, an efficient implementation of the Blade-Element and Momentum theory is used. In the implementation, the sophistication is dismiss to reduce computational cost. The time required to evaluate the forces in a typical turbine is in the order of milliseconds, which allows massive evaluation of trial turbines. The implementation is validated by comparing power prediction with the experimental data of the Risø test turbine. High quality in results is obtained until the stall zone, about wind speed of 13m/s proximately. Predictions are used to compute the mean power that is used as the fitness function in a genetic algorithm. An application is presented to optimize the blade of this test turbine for a specified wind distribution.

Three-dimensional (3D) printing technology has been traditionally used for the production of prototypes. Recently, developments in 3D printing using Fused Deposition Modelling (FDM) and reinforcement with continuous fibres (fiberglass and carbon fibre), have allowed the manufacture of functional prototypes, considerably improving the mechanical performance of the composite parts. In this work, we characterise the elastic tensile properties of fibre reinforced specimens, considering the variation of several parameters available during the printing process: fibre orientation, volume fraction, fill pattern, reinforcement distribution. Tensile tests were performed according to ASTM D638 to obtain Young’s modulus and ultimate strength for different material configurations available during the printing process. We also perform a fractographic analysis using Scanning Electron Microscopy (SEM) to give an insight of the failure mechanisms present in the specimens.

In this paper, we present the experimental and numerical modelling for the mechanical behaviour of woven composites reinforced with fique (furcraeaselloa) fibre, for different fique fibre woven configurations embed in an R744 epoxy matrix. The woven configurations are taken from commercial models and their mechanical properties validated by experimental data. We perform experimental tests using ASTM D3039 for the tensile response. We obtain values for Young’s modulus, ultimate strength, and deformation of unidirectional and woven reinforced composites. Scanning electron microscopy (SEM) is used for the fractographic analysis of the reinforced specimens. For the numerical model of the woven composite, we use the Texgen software to define the finite element voxel model and to estimate orthotropic mechanical parameters. Then, we determine the equivalent elastic properties of the composite, according to the materials and the fibre-matrix relations. We compare and validate the numerical results with the experimental data. We obtain stress and strain fields for the yarns and the matrix. The objective of this work is to establish a baseline of the mechanical behaviour of these natural reinforced composites to propose applications for structural engineering.

The present research proposes a methodology to determine the strength of a spinal bone in patients who suffer from prostate cancer using diagnostic imaging, with the purpose of verifying if metastasis has occurred, and critical conditions have been reached. Advanced numerical methods allow the modelling of anisotropic materials for different applications in biomedical engineering. The computed tomography images (CAT) provide the information to create a 3D model of the bone, in this case, the lumbar vertebra L5. Using segmentation software, it is possible to identify the mechanical properties of the materials that form the bone and define anisotropic conditions. The 3D anisotropic model is evaluated using finite element analysis (FEA), considering the appropriate boundary conditions and its respective material properties, and compared with the reference case of a healthy bone in an initial stage to assess the damage. Indicators based on the changes in stiffness of the vertebra could provide evidence of the need for chirurgical intervention.

In this paper, the stress influence in the guided wave velocity of the fundamentaltorsional mode is presented. Two analytical models, based on the Acoustoelasticity effect, tocompute the fundamental torsional mode velocity propagating in a specimen subject to anaxial stress are studied. These models are obtained due to the relation between the T(0, 1)guided wave velocity and the bulk shear velocity. The analytical models to calculate the guidedwave velocity are functions of the stress, second and third order elastic constants. A series ofaxial stress levels applied to a cylindrical waveguide is investigated with numerical simulations(Finite Elements) to estimate variations of the T(0, 1) guided wave velocity. This analysisprovides a criterion to evaluate the practical implementation of a stress monitoring schemebased on velocity variations of the fundamental torsional mode.