Search results for "Elastic"
showing 10 items of 2162 documents
Elastic-plastic fatigue crack growth in 18G2A steel under proportional bending with torsion loading
2006
The paper presents the results of fatigue crack growth on low-alloy 18G2A steel under proportional bending with torsion loading. Specimens with square sections and a stress concentration in the form of external one-sided sharp notch were used. The tests were performed under the stress ratios R = -1, -0.5 and 0. The test results were described by the ΔJ-integral range and compared with the ΔK stress intensity factor range. It has been found that there is a good agreement between the test results and the model of crack growth rate, which includes the ΔJ-integral range.
Analysis of static friction and elastic forces in a nanowire bent on a flat surface: A comparative study
2014
ZnO nanowires bent to a complex shape and held in place by static friction force from supporting flat surface are investigated experimentally and theoretically. The complex shapes are obtained by bending the nanowires inside a scanning electron microscope with a sharp tip attached to a nanopositioner. Several methods previously described in the literature are applied along with author's original method to calculate the distributed friction force and stored elastic energy in the nanowires from the bending profile. This comparative study evidences the importance of the usage of appropriate models for accurate analysis of the nanowires profile. It is demonstrated that incomplete models can lea…
Laser light scattering and polydispersity of polymers
1977
The application of lasers to light scattering improves the potentials of elastic scattering, especially in the high molecular weight range and enables the technique of inelastic scattering to be used. For elastic light scattering an experimental arrangement and an evaluation method is described which allows, within appropriate molecular weight ranges, the determination of the ratio Mw/Mn from the experimental scattering function with an accuracy down to 0.02. The newer technique of inelastic light scattering yields the coefficient of translational diffusion D. Besides D, the friction coefficient f is also directly accessible. The basic equations are reported, as well as an application to mi…
Boundary element modeling and analysis of adhesive bonded structural joints
2007
In this paper, a boundary element technique for modeling and analysis of adhesive bonded structural joints is presented. The formulation is developed in the framework of the anisotropic elasticity and attention is focused on the application to composite structural joints built with the splicing concept technique. To model and analyze composite bonded joints a multidomain implementation of the boundary element method has been used. It has been proven well suited and very effective for the characterization of the mechanical behavior of spliced joints, allowing the analysis of the high gradient stress and strain fields near the splice lines as well as the prediction of the overall distribution…
Theoretical and Experimental Research on Mechanical Behavior of Layered Composites Laminates
2014
The aim of the research of the experiment was to determine the mechanical characteristics of the composite layered material. There has been two types of experimental tests i.e. test for determining the tensile modulus of elasticity of the material, the maximum voltage and the elongation at break of the material. The second type of test is the flexural test was intended to determine the maximum load that the breaking is produced by bending.
Prediction of Dissipative Properties of Flax Fibers Reinforced Laminates by Vibration Analysis
2016
This study proposes an experimental-numeric method to identify the viscoelastic properties of flax fibres reinforced composite laminate (flax/epoxide). The used method consists in identifying the evolutions of both loss factor and stiffness when vibrational frequency changes. In this way, several free-free symmetrically guided beams are excited on a dynamic range of 10 to 4000 Hz with sweep sine excitation focused around the 4-first’s modes. Fractional derivative Zener model is used to identify the on-axis ply complex moduli and describe the laminate dissipative linear behavior with the classical laminate theory. Results obtained on a quasi-isotropic laminate show that this model adequately…
Magnetic excitations in an exchange-coupled tetramer cluster of cobalt (II): a study by inelastic neutron scattering
1992
Abstract The polyoxometalate K 10 [Co 4 (H 2 O) 2 (PW 9 O 34 ) 2 ].20H 2 O contains a ferromagnetically exchange-coupled tetramer of Co 11 encapsulated in between two diamagnetic molecules (PW 9 O 34 -9 . At 2.5K several inelastic peaks are observed in the energy range 1.5–7 meV, which are assigned to magnetic excitations in the cluster. A tentative interpretation of these data from an anisotropic exchange model yields a cobalt-cobalt interaction of 3meV (24cm -1 ) and an amount of anisotropy J xy / J z ≌0.6. These values are consistent with the magnetic susceptibility measurements.
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…
Coffee grounds as filler for pectin: Green composites with competitive performances dependent on the UV irradiation.
2017
Novel composite bioplastics were successfully prepared by filling pectin matrix with treated coffee grounds. The amount of coffee dispersed into the pectin was changed within a wide filler range. The morphology of the pectin/coffee hybrid films was studied by microscopic techniques in order to investigate their mesoscopic structure as well as the sizes distribution of the particles dispersed into the matrix. The micrographs showed that the coffee grounds are uniformly dispersed within the polymeric matrix. The morphological characteristics of the biocomposite films were correlated to their properties, such as wettability, water uptake, thermal behavior and mechanical performances. Dynamic m…
Filling of Mater-Bi with Nanoclays to Enhance the Biofilm Rigidity
2018
We investigated the efficacy of several nanoclays (halloysite, sepiolite and laponite) as nanofillers for Mater-Bi, which is a commercial bioplastic extensively used within food packaging applications. The preparation of Mater-Bi/nanoclay nanocomposite films was easily achieved by means of the solvent casting method from dichloroethane. The prepared bio-nanocomposites were characterized by dynamic mechanical analysis (DMA) in order to explore the effect of the addition of the nanoclays on the mechanical behavior of the Mater-Bi-based films. Tensile tests found that filling Mater-Bi with halloysite induced the most significant improvement of the mechanical performances under traction force, …