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The paper presents the interdisciplinary approach of two fields - the artistic (musical) and technical (forestry engineering, wood processing engineering, mechanical and physical engineering) apparently opposite but which can be happily exploited for both parties. Thus, we can speak of a new paradigm of education through which art can combine with the technical sciences for the benefit of all. The aim of the paper is to present experimental methods in mechanical and acoustic evaluation of violins from engineering and artistic perspectives. The presented results are part of a larger study carried out within an experimental demonstration research project.

Methods to predict the fracture of thin carbon fibre-reinforced polymers (CFRPs) under load are of great interest in the automotive industry. The manufacturing of composites involves a high risk of defect occurrence, and the identification of those that lead to failure increases the functional reliability and decreases costs. The performance of CFRPs can be significantly reduced in assembled structures containing stress concentrators. This paper presents a hybrid experimental–numerical method based on the Tsai–Hill criterion for behavior of thin CFRPs at complex loadings that can emphasize the threshold of stress by tracing the σ-τ envelope. Modified butterfly samples were made for shearing, traction, or shearing-with-traction tests in the weakened section by changing the angle of force application α. ANSYS simulations were used to determine the zones of maximum stress concentration. For thin CFRP samples tested with stacking sequences [0]8 and [(45/0)2]s, the main mechanical characteristics have been determined using a Dynamic Mechanical Analyzer (DMA) and ultrasound tests. A modified Arcan device (AD) was used to generate data in a biaxial stress state, leading to the characterization of the material as a whole. The generated failure envelope allows for the prediction of failure for other combinations of normal and shear stress, depending on the thickness of the laminations, the stacking order, the pretension of the fasteners, and the method used to produce the laminations. The experimental data using AD and the application of the Tsai–Hill criterion serve to the increase the safety of CFRP components.

This paper deals with the acoustic and elastic properties of resonant wood, classified into four classes, according to the classification of wood quality by the manufacturers of musical instruments. Traditionally, the quality grades of resonant wood are determined on the basis of the visual inspections of the macroscopic characteristics of the wood (annual ring width, regularity, proportion of early and late wood, absence of defects, etc.). Therefore, in this research, we studied whether there are correlations between the acoustic and elastic properties and the anatomical characteristics of wood used for the construction of violins. The results regarding the identification of the anatomical properties of resonant spruce, the wood color, and the acoustic/elastic properties, determined by ultrasonic measurements, were statistically analyzed to highlight the connection between the determined properties. From the statistical analysis, it can be seen that the only variables with the power to separate the quality classes are (in descending order of importance) the speed of sound propagation in the radial direction, Poisson’s ratio in the longitudinal–radial direction, and the speed of propagation of sounds in the longitudinal direction.

TiMoZrTaSi alloys appertain to a new generation of metallic biomaterials, labeled high-entropy alloys, that assure both biocompatibility as well as improved mechanical properties required by further medical applications. This paper presents the use of nondestructive evaluation techniques for new type of alloys, TiMo20Zr7Ta15Six, with x = 0; 0.5; 0.75; 1.0, which were obtained by vacuum melting. In Ti alloys, the addition of Mo improves tensile creep strength, Si improves both the creep and oxidation properties, Zr leads to an α crystalline structure, which increases the mechanical strength and assures a good electrochemical behavior, and Ta is a β stabilizer sustaining the formation of solid β-phases and contributes to tensile strength improvement and Young modulus decreasing. The effects of Si content on the mechanical properties of the studied alloys and the effect of the addition of Ta and Zr under the presence of Si on the evolution of crystallographic structure was studied. The influence of composition on fracture behavior and strength was evaluated using X-ray diffraction, resonant ultrasound spectroscopy (RUS) analyses, SEM with energy dispersive X-ray spectroscopy, and acoustic emission (AE) within compression tests. The β-type TiMo20Zr7Ta15Six alloys had a good compression strength of over 800 MPa, lower Young modulus (69.11–89.03 GPa) and shear modulus (24.70–31.87 GPa), all offering advantages for use in medical applications.

An integral part of our environment in addition to the surface of the Earth is the adjacent part of the atmosphere, the lower layer of the troposphere. This part of the troposphere has essential influence on weather evolution and information on its condition is an important part of the weather forecasting models. Standard methods of the data acquisition such as radars, satellites and weather stations do not provide information with sufficiently high temporal and spatial resolution. The subject of the article is a method of monitoring the condition of lower layers of the troposphere by passive monitoring and evaluation the parameters of cellular network signals. The elementary theory of an virtual sensor for the atmospheric radio refractive index monitoring and the preliminary results of experimental monitoring of the selected meteorological situation are presented.

TiMoZrTaSi alloys appertain to a new generation of metallic biomaterials, labeled high-entropy alloys, that assure both biocompatibility as well as improved mechanical properties required by further medical applications. This paper presents the use of nondestructive evaluation techniques for new type of alloys, TiMo20Zr7Ta15Six, with x = 0; 0.5; 0.75; 1.0, which were obtained by vacuum melting. In Ti alloys, the addition of Mo improves tensile creep strength, Si improves both the creep and oxidation properties, Zr leads to an α crystalline structure, which increases the mechanical strength and assures a good electrochemical behavior, and Ta is a β stabilizer sustaining the formation of solid β-phases and contributes to tensile strength improvement and Young modulus decreasing. The effects of Si content on the mechanical properties of the studied alloys and the effect of the addition of Ta and Zr under the presence of Si on the evolution of crystallographic structure was studied. The influence of composition on fracture behavior and strength was evaluated using X-ray diffraction, resonant ultrasound spectroscopy (RUS) analyses, SEM with energy dispersive X-ray spectroscopy, and acoustic emission (AE) within compression tests. The β-type TiMo20Zr7Ta15Six alloys had a good compression strength of over 800 MPa, lower Young modulus (69.11–89.03 GPa) and shear modulus (24.70–31.87 GPa), all offering advantages for use in medical applications.

Biocompatibility of medical implants is a long-sought goal of the physical sciences and medical research communities. This concept refers to a material’s capacity to induce a response adequate to a bone host. However, identifying materials which are fulfilling this requirement for a wide range of different applications is still an unresolved issue. In this paper, are analyzed the properties of TiMo20SixZr7Ta15 alloys with different ratios of Si (x=0; 0.5; 0.75;1.0) with possibilities of use for medical applications, using a set of complementary testing methods based on X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and resonant ultrasound spectroscopy (RUS). Across the compositions, the methods emphasize the mechanical properties of the sample, their microstructural characteristics, hardness and mechano-elastic properties, in order to establish a correlation between the structural parameters and mechanical properties of the sample, which are crucial in the understanding the feasibility of incorporating these alloys into prosthetics.

Mg0.5Ca alloys are potentially biocompatible, osteoconductive, biodegradable metallic materials that can be used in bone repair due to their in situ degradation in the body. Adding rare earth elements such as gadolinium, the degradation rate of Mg-0.5Ca-xGd [x = 0, 0.5, 1, 1.5 wt%] alloy taken into study is reduced. SEM, EDS were used for morphological characterization and also noninvasive testing (Resonant Ultrasound Spectroscopy and ultrasound method) were used to determine the mechanical characteristics. The influence of gadolinium over the properties and structure of this alloy is studied, to choose the optimal percent of alloying elements added for compatibility with human bones.

Because of the uneven colour of black locust wood, different technologies are used to change the colour, the bestknown being chemical and thermal treatments. Some of them affect the mechanical properties of wood, such as elasticity modulus, strength, durability. This study aims to compare the physical and mechanical properties of black locust wood control samples and treated wood samples with ammonia hydroxide, in terms of density profile, colour values (CIE L*, a*, b*), mechanical properties of samples subjected to static bending, viscous-elastic properties (storage modulus (E&rsquo, ), loss modulus (E&rdquo, ) and damping (tan)).Two types of ammonia-fuming treatment were applied on samples: first treatment T1-5% concentration of ammonia hydroxide for 30 days, second treatment T2-10% concentration for 60 days. The results highlighted the following aspects: the overall colour change in the case of the second treatment is 27% in comparison with 7% recorded for the control samples, the lightness and yellowness values are the most affected by the second ammonia treatment of black locust wood. The density increased with almost 20% due to ammonium fuming (10% concentration/60 days), in case of static bending, the elastic modulus (MOE) tends to decrease with increasing the exposure time to ammonium, but the modulus of rupture (MOR) increases with almost 17% and the breaking force increases too, with almost 41%. In the case of dynamic mechanical analysis, the temperature leads to different viscous-elastic behaviour of each type of samples.

Biodegradable materials are a further development of new medical applications, such as orthopedic implants and vascular stents, or the tissue scaffold. The variety of alloying elements introduced into magnesium alloys lead to superior corrosion resistance and mechanical properties similar to the biological bone. From a mechanical point of view, increasing the percentage of calcium leads to decreased strength and elongation resistance, and Yttrium addition greatly improves tensile strength and favors a slower degradation process. Three different Mg-0.5Ca-xY alloys were obtained, varying the concentration of the Y-element. The Mg-0.5Ca-xY system was tested from the point of view of micro-scratch and micro-indentation with three determinations each, obtaining results for Young's mode, micro-hardness, COF and stiffness. These alloys possess mechanical properties for use as orthopaedic applications. As future studies, mechanical properties can be improved by performing heat treatments.

The magnitude of improvement of mechanical properties of laminates using expensive technologies is important to justify the investment in new equipment. The objective of this research is to evaluate the mechanical properties of a cross-ply and quasi-isotropic symmetrical plain weave carbon-epoxy laminate produced with a vacuum bagging method and an autoclave processing method for a given set of epoxy/carbon fabric types. Autoclave-processed laminates exhibit higher static strengths, higher moduli in tension, compression and bending but lower Charpy impact toughness. New findings about materials properties were deduced from dynamic multi-frequency tests between 1 Hz and 50 Hz where it was found that the activation energy was 1.8 times higher in autoclave-processed specimens. Autoclave laminates had, on an average, 1.7-times lower damping ratio in the glassy plateau region and a 3-times lower peak damping ratio in the glass transition region than wet lay-up specimens.

The aim of this paper is to use dynamic mechanical analysis to examine the modifications of the elasto-dynamical properties of a composite made of small waste oak particles of various sizes (0.04 and 1 mm) and a polyester resin (440-M888 POLYLITE), subjected to photo-degradation by UV radiation and thermal degradations induced by temperature variations between 30 and 120 °C. Oak (Quercus robur) waste particles used in this study were the unmerchantable by-product left after converting logs into lumber. The size of the waste oak particles significantly modifies the morphological and mechanical properties of lignocellulosic composites. On the other hand, UV radiation and thermal degradation are recognized as factors causing structural modification observed at the interface between the particles and the matrix. The rheological parameters (storage modulus E′, loss modulus E″ and damping tan δ) and the glass transition temperature were determined both before and after UV treatment with the DMA242 C Netzsch instrument. Structural morphological modifications related to the impact of photo-degradation on fibres and the matrix were observed with an atomic force microscope. A strong nonlinear effect of particle size on the mechanical and rheological properties of the composites was observed.

Zirconium oxide doped with rare earth elements (Y, Ce, etc.) is an important candidate material for incorporation in medical implants and prosthetics. Due to their mechanical properties, the doped compounds hold a unique place among the oxide ceramics since they can undergo phase transformations allowing a toughening mechanism. We aim to determine the influence of different types of thermal treatments for Zr1-xCexO2 (x=0.1; 0.15; 0.20) as well as the structural and mechanical properties of these materials using X-ray and Neutron Diffraction (ND) as well as high resolution of SEM imaging combined with Electron Backscattered Diffraction (EBSD). Our analyses have shown that, following the doping mechanism, the samples exhibit stable crystallographic structures but also improved material strengths, which can make these compounds suitable for a wide range of promising clinical applications.

Ti-based alloys are accessible for use in the human body due to their good mechanical properties, corrosion resistance, and biocompatibilities. These main properties of alloys are important criteria for choosing biomedical implants for human bones or for other kinds of applications in general medicine. This paper presents a comparison of four new Ti-based alloys desired to satisfy various requirements for biomedical implants. The materials were prepared with recipes for two new system alloys, TiMoZrTa (TMZT) and TiMoSi (TMS), alloys with nontoxic elements. The presented research contains microstructure images, indentation tests, Vickers hardness, XRD, and corrosion resistance, showing better characteristics than most commercial products used as implants (Young&rsquo, s modulus closer to the human bone).

Composites reinforced with carbon fibers are widely used in automotive, aviation, nautical, in the blades structure of the wind turbines. Composite structures shows outstanding mechanical properties at static and cyclic behavior but the impact damage represents a problem extensively studied because during and after impact local damage and interlaminar fissures occur which cannot be detected easy. As a result, the experimental and theoretical approach to impact behavior of composites is a method of diagnosis and prognosis of phenomena that develop as a result of shock stresses. The paper focuses on the finite element modeling of the composite plate made of twelve layers which are arranged at an angle of 45° to each other, thus obtaining a quasi-isotropic material. The impact of the plate with low energy was simulated, resulting the equivalent stresses von Mises, shear stresses and deformations of each layer. It was found that the variation of stresses von Mises on the thickness of plate is linear and the shape and magnitude of the delamination developed in each layer depend on the difference between stiffness of the successive layers and rigidity of the interface between layers. The FEM results were confirmed experimentally. The novelty of the paper consists of the plate modeling as a multilayers structure and the simulation of impact with low energy. It were analyzed the shapes of strains from each layer and compared with experimental results.

The hydraulic turbine blades are made from stainless steels having a hard layer for the improvement of the hydro abrasive wear, corrosion resistance, and resistance to mechanical impacts in order to increase the reliability of the turbine. The thin films from stellite and tungsten carbide were obtained by the method: electrospark deposition because it has relatively low costs, are easy to obtain, the layers have a good adherence to support and the thickness can be variable in function of the established conditions. In this paper, the physical, chemical and mechanical properties of the samples will be determined using Scanning Electron Microscope (SEM), in order to emphasize the structure film-substrate and repartition of the deposition elements on the surface and in transversal section. Also, the samples were nondestructively tested using the electromagnetic sensor with metamaterials in order to establish the adherence of the thin films to the steel, proving the potential of this NDT techniques. The complex signal delivered by the sensor has been stored while scanning a 6x6 mm area. The processing algorithm involve the use of the bidimensional Fourier transform after filtering the initial signal using Walsh-Hadamard numerical filter.

Carbon fiber reinforced plastics (CFRP) have become an indispensable part of modern life. CFRP materials continue to be used in a large number of applications ranging from aerospace systems to automotive, industrial and consumer products. CFRP have evolved both in reinforcement and matrix. The epoxy resin was the most usually matrix for CFRP. The reliability of these materials is essential, especially when it comes to safety-relevant components. The service life of CFRP components is affected by aging processes or improper use. Nondestructive evaluation methods which can be applied for examination carbon/epoxy laminates, manufactured by autoclave processing method with different ply stacking sequences [0]8 and [(45/0)2]s are presented. The samples were realized from 4 plates of carbon-epoxy manufactured at the Faculty of Mechanical Engineering, University of Ljubljana, Slovenia. The paper present influence of thermal treatment and stacking sequence on damage delamination’s due to impact about mechanical properties. Ultrasound and electromagnetic nondestructive evaluation methods are used for good localization of damage and characterization composite materials and other techniques can provide complementary information once the damage location is known.

The medical prosthesis components made from (ZrO2)-based ceramics present a good biocompatibility as well as especially mechanical properties. Much more, the problems of nondestructive evaluation for these elements, which assure both comfort and maximum safety to the patient, are imperative for these medical implants. In this study, we investigate the structure and the mechanical properties of Zr1-x(Ce/Y)xO2 , (x=0.0;0.09;0.13;0.17) materials as well as the modification of their crystallographic structure due to various thermal treatments and variation of Ce/Y concentrations in the samples. The substitution of Zr with Ce and the thermal treatment at 1000°C produced important transformation in the phase composition and the microstructure of the sample. A large decrease of the microstrains was observed at the treated samples. Combining characterization techniques based on XRD and ND with non-destructive evaluation methods based on Resonant Ultrasound Spectroscopy (RUS) and Acoustic Emission (AE), we emphasize a unique approach on evaluating the physical properties of these ceramics. Performed evaluation tests of Zr1-x(Ce/Y)xO2 ceramics have shown big influence of composition on their fracture behavior and resulting strength due to different damage mechanisms.

In this work the reversion of the strain-induced ?’-martensite to ?’-austenite was studied in a series of AISI 316 stainless steels (SS) specimens. The samples were submitted to 63% reduction in thickness by rolling at a temperature of -70oC, to achieve high martensite content. The reversion of martensite to austenite was made by means of isochronic, isothermal heat treatments at temperatures between 200 and 900oC, so as to induce partial martensite-austenite phase transformation. The samples were studied by optical and electronic microscopy, X-ray diffraction, magnetization measurements, microhardness, and electromagnetic non destructive methods: feritscope, conductivity measurements using Van der Pauw’s technique, and magnetic permeability assessments by an eddy current inverse method. The metalography study showed an ?’ lath martensite type structure and a similar one for the reverted austenite (?’). Magnetization measurements and magnetic permeability showed that the reversion is active between 400 and 800°C. From the magnetic saturation measurements, a new calibration curve for the assessment of %?’ through the feritscope readings was obtained. The results of the different techniques were com-pared, in order to assess the scope of the studied techniques in the characterization of rolled SS products, and in the evaluation of progress of reversion reaction.

Wind turbine blades (WTB) are one of the most damageable components of a wind turbine system and due to their importance must be tested during the fabrication and before installing. WTB are produced from composite materials with polymeric matrices, most of the stages of producing are manufacturing and can result in different types of defects. Therefore, non-destructive testing (NDT) techniques that provide surface and internal information of the blade are required. In this paper, ultrasonic testing using noncontact transducers for the control of composites type Glass Fiber Reinforced Plastics (GFRP) with orthophthalic polyester resins matrix is presented in order to prove its capabilities for such applications. The mechanical properties determined by above mentioned method are confirmed by destructive tests using Dynamic Mechanical Analysis.

Testing cruciform specimens under static biaxial loading conditions is the method with the best results used to determine the mechanical behavior of materials. A static stress with nonlinear material analysis was applied for only one-eighth of the specimen geometry, due to symmetry conditions, to evaluate stress state from different cruciform specimens subjected to equi-biaxial tension. For the majority of isotropic materials with ductile behavior, such as metals, the most suitable yield criterion used to predict failure is von Mises.

Multiaxial experiments are necessary to determine materials behavior subjected to complex stress state corresponding to real operating conditions under complex loadings. Stresses applied in biaxial experiments are closely to the stresses that materials experience during their function life. Because of reduced acquisition cost, operation cost and maintenance costs devices attached to the universal testing machine are beginning to be used in ever more applications. The present paper examines a new type of mechanism used to test biaxial cruciform specimens in order to evaluate stress state in planar biaxial tensile testing.

The Mohr-Coulomb failure theory presents the major drawback that can be applied only for plane state of stress. In this paper, we propose a modification of the Mohr-Coulomb theory that might eliminate this disadvantage. It is proposed to replace the three Mohr's circles for spatial state of stress with one “virtual circle” with diameter σ1-σ3±2ρ, concentric with the circle that has the diameter σ1-σ3. The triaxial state of stress and biaxial state of stress are considered to be equivalent dangerous.

This paper presents two methods for electromagnetic nondestructive evaluation (eNDE) of composite materials reinforced with carbon woven fibers using a sensor with orthogonal coils and a sensor with metamaterials lens. The samples were impacted with low energy in order to study delamination influence. The electromagnetic behavior of composite was simulated by finite-difference time-domain (FDTD) software, showing a very good concordance with eNDE tests.

In this paper there are presented a series of methods and algorithms for signal processing (A-scan) and image processing (B-scan) which allow an easier and more accurate interpretation of the inspection results. The methods and the algorithms were tested for detection of a buried pipe, made of glass fiber polyester composite with a diameter of 1.3m, first when the survey conditions allowed only the scanning along the pipe, the most disadvantageous situation, but it has imposed by the configuration of the examined zone. After a few days of construction works, the site was prepared for inspection, orthogonally on the first scan direction.

Zinc oxide nanostructured materials, such as films and nanoparticles, could provide a suitable platform for development of high performance biosensing material due to their unique fundamental material properties. This paper presents the characterization of ZnO thin film as biosensing material by metallic strip grating structure (MSG), for the real-time detection. In this work, high quality ZnO films were grown on ITO/glass substrates by vacuum thermal evaporation method. We characterized by X-ray diffraction (XRD) the film crystalline quality and by scanning electron microscopy (SEM) the film morphology.

In this study the effect of moisture absorption on the mechanical properties of glass-reinforced polyester composites is evaluated using both destructive and nondestructive tests. The composite resins were produced with two different production processes, while the mechanical properties of the composite materials were measured using DMA destruction tests. According to the DMA tests, the dependency in terms of temperature for the real component of the complex elastic modulus ( E ′), the imaginary component of the complex elastic modulus ( E ″), as well as tan( δ ) can be traced. For a more efficient use of the composite materials, the compliance tensor was obtained with nondestructive tests based on ultrasound. A method for the generation and reception of Lamb waves in plates of composite materials is described, based on using air-coupling, low-frequency, ultrasound transducers in a pitch–catch configuration. The results of the nondestructive measurements made in this study are in good agreement with those obtained when using the DMA destructive tests.

The purpose of this work was to find out to what extent the knowledge of dependence of impedance on the crack depth observed by means of microwave frequencies can be used as noninvasive techniques for biocompatible materials which are used in bone replacement. Primary quantity usable for this assessment was the reflection coefficient obtained from the standing wave ratio measurement. The measured and calculated results are given in the graphic form and are compared each other in common graphs which provide a good overview about basic quantities and simultaneously give an initiative for orientation on practical applications in the process of defect presence finding in materials used in bone replacement.

The paper investigates the formation of evanescent waves in metallic strip gratings on the Ag/ZnO/SiO 2 /Si structure with silver strips when TEz incident wave in the radiofrequency range was used. The Ag/ZnO/SiO 2 /Si structure was fabricated by vacuum thermal evaporation technique and Scanning Electron Microscopy was used to evidenceits high quality structure with parallel silver strips of same width and thickness. Simulation of the evanescent wave formation at the edge of Ag strips, with thicknesses in the range of micrometers, was performed, before performing the test in the subwavelength regime by the mean of a new transducer improved with metamaterials lens. The generation in slits, in air, of the electric evanescent mode, when metallic strip grating was excited with a TEz polarized wave at a frequency of 474 MHz, was successfully demonstrated.

International audience; Zirconia (ZrO2)-based ceramics are preferred due to their advanced mechanical properties such as high-fracture toughness and bulk modulus, corrosion resistance, high dielectric constant, chemical inertness, low chemical conductivity and biocompatibility. The medical prosthesis components made from ZrO2 oxides present a very good biocompatibility as well as especially mechanical properties. In order to ensure implant safety of these prostheses, wide ranges of examinations based on nondestructive testing are imperative for these medical implants. In this study, we aim to emphasize the improvement of Zr-based ceramics properties as a function of addition of Ce ions in the structure of the original ceramics. The substitution of the Zr with Ce in the Zr1-xCexO2 compounds, where x = 0.0-0.17, leads to a change of the phase composition, a gradual transition from the monoclinic to tetragonal structure, at room temperature. The structural investigations proposed in this paper are based on X-ray and neutron diffraction in order to establish a first indication of the variation of the phase composition and the structural parameters, as well as micro-hardness measurements and nondestructive evaluations in order to establish a correlation between the structural parameters and mechanical properties of the samples. These ranges of tests are imperative in order to ensure the safety and reliability of these composite materials, which are widely used as hip-implants or dental implants/coatings. In combination of Resonant Ultrasound Spectroscopy, which makes use of the resonance frequencies corresponding to the normal vibrational modes of a solid in order to evaluate the elastic constants of the materials, we emphasize a unique approach on evaluating the physical properties of these ceramics, which could help in advancing the understanding of properties and applications in medical fields.

The most important part of wind turbine is the blade that must be tested during fabrication and functioning when can be damaged by moisture absorption, fatigue, wind guests or lightning strikes. The fibers can also appear and develop under moderated loads or cracks and delaminating due to the low energy impacts etc. The aim of this paper is to identify the modal behavior of small wind turbine blade in terms of the signal convergence, modal evolutions and frequency spectra. There are numerous methods for monitoring and detecting structural damage of the wind blades, but in this study it was used the impact hammer method. The results emphasized the natural frequencies, the modal shape of structure and the signal coherence captured in different points.

In the paper the investigation of the dielectric properties of dielectric material will be described, using an artificial metamaterial structure over the aperture of waveguide sensor with aim of increasing the sensitivity of classical waveguide sensor. The possibility to use a metamaterial structure for upgrading properties of classical waveguide sensor will be emphasized by numerical simulation of 2D metamaterial structure properties and experimental measurements to determine dielectric properties of dielectric materials. The mechanical properties of the dielectric samples, alder wood in our case, are determined also by Dynamic Mechanical Analysis, in order to validate the microwave approach.

There are a number of factors influencing the bending process such as: the rolling direction of the blank; the minimum bend radius of the piece; the radii of the bending plate (of the mold); the play between the die and the punch, the recoverable strain of the piece after bending. The paper presents the experimental results regarding the influence of the lamination direction on the rheological behaviour of the cold bending parts, using the Lloyd LS100 Plus universal machine and the Nexygen Plus program. Thus, two categories of samples were analyzed: some being cutted off in the direction of rolling of the sheet at which the bending occurred on an axis perpendicular to the direction of rolling and others cutted on cross direction of rolling, the bending being produced along the axis parallel to the rolling direction. As an elasto-plastic process, after the loading process during experiment, the samples recorded an elastic strain recovery due to the kinetic energy stored during stresses. Thus, the recovered elastic deformation (springback) is more pronounced in the case of specimens cutted of in cross direction on the rolling fiber where the bending moment is produced in the direction parallel to the laminating fiber of materials.

Biodegradable materials are used as alternative implants for orthopedic applications due suitable strength, fatigue resistance, ductility and biocorrosion resistance which are features for biodegradable implants. Mechanical properties can be improved by adding alloying elements. Mg alloys have been designed to meet the requirements of bone repair implant materials by adding Calcium and Yttrium. Usually Ca is added to control corrosion rate of Mg alloys and thinning grain boundaries. The system is defined as Mg-0.5Ca-xY (x=0.5, 1, 1.5), varying the Y concentration in order to slow the degradation process. Beside morphological characterization with SEM, EDX, noninvasive testing is required to be carried out the determination of mechanical characteristics. The paper presents the influence of Yttrium over elastic properties of these alloys in order to choose the best values appropriate with human bones, using Resonant Ultrasound Spectroscopy and ultrasound method.