Search results for "Compres"

Beta-forging of Ti6Al4V titanium alloy powders consolidated by HIP: Plastic flow and strain-rate relation

2014

Ti6Al4V is probably the best known and studied titanium alloy, not only for aerospace applications. Nevertheless the deformation behavior still represents a challenge if any modification in the deformation process is required or introduced. This work deals with deformation behavior description of Ti6Al4V HIPped powders during high temperature deformation tests carried on in the Beta-region. Laboratory compression and tensile tests have been coupled with relaxation tests in order to achieve robust data about strain rate sensibility m-coefficient and activation energy Q. These results have been fitted for the assessment of a more general exponential deformation law. The final result is a “Dor…

Can metals be a liquid glass?

2009

The melting of transition metals on compression is a challenging topic. Computer simulations suggest that hot-compressed tantalum becomes a one-dimensional, liquid-like glass, with important implications for understanding planetary interiors.

Validation of frictional studies by double-cup extrusion tests in cold-forming

1996

Abstract Studies on frictional conditions in cold-forming have shown that, for a given lubricant, friction factor values are strongly affected by the test method. In the present paper, different cold-forging processes of an aluminium alloy, are modelled by a FEM numerical code using the m values obtained by both the double cup extrusion and ring compression tests. It appears that the m values given by the ring tests can be effectively used in the simulation of upsetting processes, while the m values derived by the double cup extrusion tests are more appropriate for predictions in extrusion and closed-die forging operations.

Drying and Compression under Confining Pressure Effects on Structural Rearrangement of Wood

1996

On the Use of L-shaped Granular Chains for the Assessment of Thermal Stress in Slender Structures

2014

Slender beams subjected to compressive load are common in civil engineering. The rapid in-situ measurement of this stress may help preventing structural anomalies. In this article, we describe the coupling mechanism between highly nonlinear solitary waves (HNSWs) propagating along an L- shaped granular system and a beam in contact with the gran- ular medium. We evaluate the use of these waves to measure stress in thermally loaded structures and to estimate the neutral temperature, i.e. the temperature at which the stress is null. We investigate numerically and experimentally one and two L- shaped chains of spherical particles in contact with a prismatic beam subjected to heat. We find that …

Enhanced nonlinear spectral compression in fibre by external sinusoidal phase modulation

2016

International audience; We propose a new, simple approach to enhance the spectral compression process arising from nonlinear pulse propagation in an optical fibre. We numerically show that an additional sinusoidal temporal phase modulation of the pulse enables efficient reduction of the intensity level of the side lobes in the spectrum that are produced by the mismatch between the initial linear negative chirp of the pulse and the self-phase modulation-induced nonlinear positive chirp. Remarkable increase of both the extent of spectrum narrowing and the quality of the compressed spectrum is afforded by the proposed approach across a wide range of experimentally accessible parameters.

Influence of the parameters molecular structure and granularity on the compactibility of a powder

1995

Drug Dev. Ind. Pharm. ISI Document Delivery No.: RP128 Times Cited: 3 Cited Reference Count: 14 Andres, c ndiaye, a thomas, c tromelin, a chaillot, b pourcelot, y; International audience; The aim of this study was to determine whether it is possible to obtain better characterization of materials in order to find out if these one are suitable in Quality Assurance for direct tableting. We tried to show that a methodological approach combining chemical, physical and technological aspects could control the direct compression process. We chose orthoboric acid as a study model for the direct compression. From a chemical point of view, our findings show only one crystalline molecular structure (RX…

Stability of the fergusonite phase in GdNbO 4 by high pressure XRD and Raman experiments

2017

Abstract We describe the results of high pressure x-ray diffraction and Raman measurements on gadolinium orthoniobate. The ambient pressure monoclinic fergusonite phase remains stable in a remarkable large pressure range. There is no significative evolution of the monoclinic distortion up to 25 GPa , the maximum pressure achieved. Instead, the anisotropic compressibility is associated to the stiffness of NbO 4 tetrahedra in respect to the GdO 8 polyhedra. The high pressure evolution of external modes parallels the wavenumber dependence on ionic radius along the lanthanide series. The chemical pressure analogy is attributed to the compression of GdO 8 polyhedra. There is no evidence of any p…

Buckling of a coating strip of finite width bonded to elastic half-space

2008

AbstractA solution for buckling of a stiff strip of finite width bonded to a compliant elastic half-space and subjected to uniform axial compression is presented. Approximate semi-analytical and finite element solutions are obtained and compared with a two-dimensional case of a plate on elastic foundation. The comparison demonstrates that the two-dimensional solution can be applied to predict the buckling wavelength and critical compressive strain when the width of the strip is equal to or larger than the buckling wavelength. For narrow strips, the wavelength is smaller and critical strain is higher than that of a plate on foundation.

Simplified Model for Compressive Behavior of Concrete Columns Strengthened by Steel Angles and Strips

2010

This paper presents an analytical model to determine the compressive response of concrete members, having a square transverse cross section and reinforced with steel angles at the corners and steel strips connecting the steel angles. The model evaluates the effects of transverse strips and steel angles on confinement pressures, including strength and buckling phenomena. Compressive response was evaluated in cases of directly and indirectly loaded elements. The data produced correlate well with available experimental data.