Search results for "Impact."
showing 10 items of 1677 documents
Tensile strength and impact strength of color modified acrylic resin reinforced with titanium dioxide nanoparticles
2017
Background Poor mechanical properties are among the main limitations of acrylic resins. Addition of titanium dioxide (TiO2) nanoparticles to acrylic resin has been shown to improve its mechanical properties with an adverse effect on its color. Thus, this study sought to assess the tensile and impact strength of a color modified heat cure acrylic resin reinforced with TiO2 nanoparticles. Material and Methods In this in vitroexperimental study, 1wt% TiO2 nanoparticles were added to SR Triplex Hot heat-cure acrylic resin powder and mixed. Pigments and color fibers were also added and 18 samples were fabricated of this paste for tensile and impact strength testing (n=9) according to ISO5271. Ei…
Aging resistance of bio-epoxy jute-basalt hybrid composites as novel multilayer structures for cladding
2017
Abstract Aging resistance of jute reinforced laminates is compared with two jute/basalt hybrid laminates prepared with different stacking sequences (i.e., sandwich and intercalated configuration). To this aim, composites are exposed to cyclic conditions comprising hygrothermal stress and UV radiation to promote an accelerated aging, for a period of 84 days. Specimens of each laminate are tested after 14, 28, 56 and 84 days, respectively. Quasi-static flexural tests, Charpy impact tests and dynamic mechanical tests are performed according to international ASTM and ISO standards. Furthermore, scanning electron microscopy and differential scanning calorimetry are used to evaluate the morpholog…
The effect of wear on the tetragonal-to-monoclinic transformation and the residual stress distribution in zirconia-toughened alumina cutting tools
1998
Abstract Zirconia-toughened alumina cutting tools have been examined after machining an AISI 1040 steel. The Raman spectrum of zirconia and the fluorescence spectrum from alumina have been used to determine the extent of the tetragonal-to-monoclinic (t-m) transformation and the residual stresses in and around the worn-out crater, respectively. Although about 15% vol. m-zirconia is present even in a brand new cutting tool, it was shown that the crater region undergoes the t-m transformation up to 40% vol. In both cases, the transformed zone is concentrated near the surface. The residual stresses in alumina are slightly compressive in the new cutting tool and away from the crater region, but …
Experimental Investigation and Finite Element Analysis of Dynamic Behavior and Damage of Glass/Epoxy Tubular Structures
2011
This paper presents finite element analysis (FEA) of static and dynamic tests of thick filament wound glass/epoxy tubes. The first part involves the validation of elastic properties and identification of damage initiation and its development in dynamic tests. The results of FEA of the dynamic tests without damage appeared satisfactory. An impact model, including material property degradation, is used for damage prediction. The simulated damage is compared with that obtained experimentally. The sizes of projected and cumulated surfaces are of the same order of magnitude as in the experimental measurements.
The Influence of Ageing on the Impact Damage of Carbon Epoxy Composites
2011
Abstract This study looks into the influence of ageing on the carbon epoxy composite when impact is applied. Three different stacking sequences were investigated, one sequence with the classic lay-up, whereas the other two have quasi-isotropic and quasi-homogeneous behaviour. The specimens were aged up to 2100 h (3 months) in a climatic chamber with a temperature of 70 °C and relative humidity of 85%. The mass was measured regularly during the hygrothermal ageing treatment. The mass was always measured directly after exiting the climatic chamber and it was noted that for each stacking sequence, the same regular increase in mass is observed until stabilisation. The specimens were then impact…
Effect of adding wood flour to the physical properties of a biodegradable polymer
2008
Wood flour/polymer composites (WPC) gained a significant interest during the last decades, due to several advantages related to the use of a natural-organic filler rather than an inorganic-mineral one. However, most of the studies have been performed on composites based on polyolefin matrices. A further step is the use of biodegradable polymers instead of traditional ones. In this work, wood flour (WF), under the form of short fibers, with two different sizes (coarse and fine) was added to a corn starch based biodegradable polymer of the Mater-Bi family. The effect of WF size, WF content, thermal treatment on the mechanical properties was investigated. The tensile mechanical tests showed an…
Simulation of the relative atomic populations of elements 1 ≤ Z ≤89 following charge exchange tested with collinear resonance ionization spectroscopy…
2019
© 2019 The Authors Calculations of the neutralisation cross-section and relative population of atomic states were performed for ions beams (1 ≤ Z ≤ 89) at 5 and 40 keV incident on free sodium and potassium atoms. To test the validity of the calculations, the population distribution of indium ions incident on a vapour of sodium was measured at an intermediate energy of 20 keV. The relative populations of the 5s 2 5p 2 P 1/2 and 5s 2 5p 2 P 3/2 states in indium were measured using collinear resonance ionization spectroscopy and found to be consistent with the calculations. Charge exchange contributions to high-resolution lineshapes were also investigated and found to be reproduced by the calc…
Stochastic response of a fractional vibroimpact system
2017
Abstract The paper proposes a method to investigate the stochastic dynamics of a vibroimpact single-degree-of-freedom fractional system under a Gaussian white noise input. It is assumed that the system has a hard type impact against a one-sided motionless barrier, which is located at the system’s equilibrium position; furthermore, the system under study is endowed with an element modeled with fractional derivative. The proposed method is based on stochastic averaging technique and overcome the particular difficulty due to the presence of fractional derivative of an absolute value function; particularly an analytical expression for the system’s mean squared response amplitude is presented an…
First lamina hybridization of high performance CFRP with Kevlar fibers: Effect on impact behavior and nondestructive evaluation
2022
The impact behavior of a carbon-Kevlar hybrid composite, widely used in sport car manufacturing, was evaluated. To highlight the hybridization effect, comparative analyses were performed with the basic CFRP laminate having the same lay-up. Tensile, bending and low velocity impact tests, followed by nondestructive inspections, highlighted that Kevlar first lamina hybridization leads to an increment in specific impact strength, up to 55%. To assess the most reliable technique to detect the impact damage, nondestructive evaluation was performed by pulsed thermography, phased array ultrasonic technique, computed tomography and digital radiography. Phased array ultrasonic technique can be consid…
Carreras por montaña en la Comunitat Valenciana (1995-2019). Evolución, distribución territorial e incidencia en áreas naturales protegidas
2021
El rápido crecimiento de las carreras por montaña, ha motivado durante los últimos años su estudio. Aun son pocas las referencias bibliográficas que podemos encontrar a escala local, aunque algunas a nivel de España. Existen diferencias regionales, que demandan la necesidad de examinar este tipo de pruebas a una escala detallada. La Comunitat Valenciana, dada su extensión forestal y porcentaje de territorio montañoso (56 %), el número de espacios naturales (646) y superficie total protegida (40 %), se convierte en un buen ámbito de estudio. Una revisión bibliográfica y un análisis de la información recogida ha permitido determinar el número y la evolución de esta práctica en los últimos 25 …