Search results for "deformation"

Ellipsoidal core-shell cylindrical microphases in PS-b -PB-b -PCL triblock copolymers with a crystallizable matrix

1997

Polystyrene-block-polybutadiene-block-poly(e-caprolactone) SBC triblock copolymers with a PCL matrix exhibit microphase separation into three different phases within the spherulitic superstructures. Mixing of the PS-block can occur upon melting of the PCL-block if the molecular weight is low enough. Even though the crystallization takes place well below the PS-glass transition, a deformation of the amorphous microphases into ellipsoidal core-shell cylindrical microdomains is observed by TEM. These copolymers have mechanical properties which are dominated by the PCL (Poly(e-caprolactone)) matrix with an influence of the amorphous blocks.

Compressive recovery behaviour of a polycarbonate

1978

Abstract Polycarbonate samples were subjected to large compression strains (beyond yielding) and were unloaded after some degree of stress relaxation. The subsequent deformation recovery was measured for several values of strain, loading rate and duration of stress relaxation. All the data could be reported as a single curve by normalizing the recovered strain with the stress at the end of the relaxation period.

Strain mapping near a triple junction in strained Ni-based alloy using EBSD and biaxial nanogauges

2011

A key element for analyzing the crack initiation in strained polycrystalline alloys is the local quantification of the surface strain distribution according to the grain texture. Using electron backscattered diffraction, the local microstructure was determined to both localize a triple junction and deduce the local Schmid factors. Kernel average misorientation (KAM) was also used to map the areas of defect concentration. The maximum principal strain and the in-plane shear strain were quantified using the biaxial nanogauge. Distortions of the array of nanodots used as spot markers were analyzed near the triple junction. The crystallographic orientation and the surface strain were then invest…

Investigation into the Effects of Deformation on Proton Emission Rates via Lifetime Measurements

2014

Deformation behavior of nanostructured ZnO films on glass

2012

Abstract Nanostructured ZnO films on glass substrate were studied by nanoindentation, scanning electron and atomic force microscopy. The films were obtained by a straightforward mechanoactivated oxidation method. The morphology of the obtained films was grained with a grain size in the range 50–100 nm and the thickness was approximately 2 μm. A detailed deformation behavior of ZnO films, critical parameters and indentation induced plastic deformation mechanisms were determined in correlation to bulk ZnO, Si single crystal and commercial ZnO films. In comparison to a single crystal ZnO, nanostructured films exhibit increased hardness (9 GPa); however, the Young's modulus is decreased (120 GP…

Investigation on Application of Basalt Materials as Reinforcement for Flexural Elements of Concrete Bridges

2015

Basalt polymers are rather new materials for civil engineering; therefore, identification of peculiarities and limitations of application of such polymers in concrete structures (particularly bridges) is of vital importance. This paper experimentally investigates deformation behaviour and cracking of flexural elements, which are predominant parameters governing serviceability of the bridges. Unlike a common practice, the present study is not limited by the analysis of concrete beams reinforced with the polymer bars; it also considers effectiveness of basalt fibre reinforced polymer sheets for repairing the beams. The analysis has revealed that a combination of the high strength and elastici…

Electromechanical Behavior of Single and Multiwall Carbon Nanotubes

2008

Carbon nanotubes (CNTs) can be metallic or semiconductors depending simply on geometric characteristics. This peculiar electronic behavior, combined with high mechanical strength, make them potential building blocks of a new nano-electronic technology. High resolution images of CNTs often disclose structural deformations such as bent, twisted, or collapsed tubes. These deformations break the tube symmetry, and a change in their electronic properties should result. A computationally effective mixed finite element-tight-binding approach able to simulate the electromechanical behavior of single and multiwall nanotubes used in nano-electronic devices is presented. The finite element (FE) comput…

Theoretical and Experimental Researches Regarding Multilayer Materials Used for Incremental Forming

2014

Although this represents a relatively recent development in the industry, the composite multilayer sheets are currently encountered in almost all industrial domains, due to the density, mechanical strength and energy absorption properties that are higher than those of the blanks realised from a single material. These materials are useful especially in domains such a the automotive industry, where the vehicles must fulfil simultaneously conditions of increased passenger safety, increased comfort, increase of the loading capacity in conditions of a reduced energy consumption. First of all the paper shows the types of multilayer sheets and their areas and areas of use, then the paper analyzes …

Deformation-Free Topography from Combined Scanning Force and Tunnelling Experiments

1993

We show that by measuring force and stiffness on a constant-current scanning tunnelling microscopy (STM) contour a deformation-free topography can be extracted. With reference to mono- and bicomponent self-assembled monolayers, we find that the characteristic depression pattern and the protrusions on a multicomponent film found in STM are to a great extent due to electronic effects.

Investigations on Load Capacity and stability of deformation of rubber cylindrical shells under internal pressure

1994

The paper presents a wide analysis of conditions under which a loss of deformation stability can be observed as well as local bulges form in axially-symmetric (rotational) shells of any length. Analytical relations of the theory of shells were used for the analysis. If the maximum pressure in the shell was exceeded, the deformation process was investigated too. In such a case, strains begin to develop more intensely in the central part of a long cylindrical shell and, owing to that, one or more superimposed bulges (blisters) form. Symmetry of the shell deformation in relation to the centre of its length can be disturbed. A set of algebraic equations was derived for determination of critical…