Effect Of Cross-sectional Size Research Articles

On the Influence of Cross-Section Size on Measured Strength of SLM-Produced AlSi10Mg-Alloy

The freedom in choice of geometries in additive manufacturing (AM) favors the use of structures with large surface and small cross-section such as lattice structures and thin-walled hollow profiles. On the other hand, the practices of strength testing of metals require a certain bulk of the material to be printed to be able to produce a sample and test material properties. The size of the sample cross section might influence the strength and up to 30% decrease in strength for small struts was reported in the literature. Understanding the influence of the cross-section size on the strength of SLM-produced metal is crucial to be able to relate the strength determined through tensile testing and the strength of an SLM-produced component with complex geometry. This article deals with effect of cross-section size on the measured strength of the SLM-produced AlSi10Mg-alloy. It is demonstrated how the decrease in strength can be explained by the difference between measured and actual cross-section area induced by surface roughness rather than by the difference in microstructure between the samples of different sizes.

Behaviour of ultra-high strength concrete encased steel columns subject to ISO-834 fire

Ultra-high strength concrete (UHSC) encased steel columns are receiving growing interest in high-rise buildings owing to their economic and architectural advantages. However, UHSC encased steel columns are not covered by the modern fire safety design code. A total of 14 fire tests are conducted on UHSC (120 MPa) encased steel columns under constant axial loads and exposed to ISO-834 standard fire. The effect of load ratio, slenderness, stirrup spacing, cross-section size and concrete cover to core steel on the fire resistance and failure mode of the specimens are investigated. The applicability of the tabulated method in EC4 (EN 1994-1-2-2005) and regression formula in Chinese code (DBJ/T 15-81-2011) to fire resistance of UHSC encased steel columns are checked. Generally, the test results reveal that the vertical displacement-heating time curves can be divided into two phases, i.e. thermal expansion and shortening to failure. It is found that the fire resistance of column specimens increases with the increase of the cross-section size and concrete cover to core steel, but decreases with the increase of the load ratio and slenderness. The EC4 method overestimates the fire resistance up to 186% (220 min), while the Chinese code underestimates it down to 49%. The Chinese code has a better agreement than EC4 with the test results since the former considers the effect of the load ratio, slenderness, cross section size directly in its empirical formula. To estimate the fire resistance precisely can improve the economy of structural fire design of ultra-high strength concrete encased steel columns.

Effects of Cross-Sectional Size and Shape on the Longitudinal Tensile and Anchoring Properties of CFRP Cables

AbstractCarbon fiber–reinforced polymer (CFRP) is very suitable for use as a prestressed cable and can replace conventional steel cables in cable roofs. In engineering practice, the anchoring lengt...

Effect of cross-section size on flexural compressive failure of RC columns: Monotonic and cyclic tests

The paper presents the results of 12 groups of geometrically similar reinforced concrete (RC) squared columns subjected to the combined loading of compression and bending. The performances and characteristics of the test RC columns are investigated in terms of the capacity of dissipated energy, the ductility capacity, the flexural capacity, the stiffness degradation as well as the rotation capacity of plastic hinge. The study also examines the influences of structural size, axial load ratio and the loading types (involving monotonic and cyclic lateral loading) on the flexural compressive failure characteristic of columns. The test observations indicate that the failure patterns of the tested columns are closely similar in spite of the difference in cross-sectional dimensions, and the flexural compressive failure of the columns presents obvious size effect. As the structural size of the tested RC columns increases, the dimensionless nominal moments (involving the nominal yield moment, the maximum moment and the ultimate moment corresponding to ultimate displacement), the ultimate drift ratio, the displacement ductility and the rotation capacity of plastic hinge decrease significantly. Moreover, a larger axial load ratio leads to larger load carrying capacity and weaker deformation capacity.

Effect of Cross Section Size on Ductility and Fragmentation of Copper Ring at High Strain Rate Loading Conditions

In the present work, different copper ring samples geometries with a small aspect ratio of 0.5 or 1 were subjected to an experimental study under electromagnetic expanding ring test conditions. The experimental multiple ring tests were performed under similar loading conditions, that is, the applied maximum expansion velocities covered a range from 128 to 147 m/s (7.4 103s-1) for all ring samples geometries, with the exception of rings with a cross section of 1 mm x 0.5 mm. For these rings, the averaged maximum expansion velocity was higher and equal to 195 m/s (1.2 104s-1). The results of experimental investigations revealed a minor influence of the applied cross section sizes on ductility of copper rings, whereas its fragmentation seems to be dependent on a ring cross section area.

コンクリート充填角形鋼管短柱の軸圧縮性状に及ぼす断面寸法・形状の影響に関する実験的研究

The purpose of this research is to clarify the effect of cross sectional size and shape on the uni-axial compressive behavior of concrete filled square steel tube (CFT) short columns. Compression tests of square CFT short columns with cross sectional size 400mm have been conducted. This paper first presents the test results concerning compressive strength, and discusses the evaluation of the strength of square CFT short columns considering the effects of cross sectional size and shape. As a result, following have been found. i) effects of cross sectional size and shape on the square CFT short columns were clearly observed, ii) the compressive strength of various size square CFT short columns can be predicted by proposed numerical formula.

Numerical Simulation of the Freezing Process of Concrete

AbstractBased on the equilibrium, continuity, and energy principles of multiphase porous media, a thermal-hydro-mechanical coupling model was developed for concrete upon freezing. To solve the governing differential equations, a three-dimensional finite-element analysis is performed based on the software program Comsol Multiphysics. Finally, temperature distributions, frozen water contents, and strains as a function of freezing time are predicted. A comparison of the analytical results with available experimental data for concrete mortars illustrates the validity of the proposed model. This numerical model can be used to assess the effect of cooling rate, the role of pore-size distribution, the role of permeability, the effect of cross section size and shape, the effect of superimposed stresses attributable to applied loads, and other factors that cannot easily be evaluated by current tests.

Atomistic study of electronic structure of PbSe nanowires

Lead Selenide (PbSe) is an attractive ‘IV-VI’ semiconductor material to design optical sensors, lasers, and thermoelectric devices. Improved fabrication of PbSe nanowires (NWs) enables the utilization of low dimensional quantum effects. The effect of cross-section size (W) and channel orientation on the band structure of PbSe NWs is studied using an 18 band sp3d5 tight-binding theory. The band gap increases almost with the inverse of the W for all the orientations indicating weak symmetry dependence. [111] and [110] NWs show higher ballistic conductance for the conduction and valence band compared to [100] NWs due to the significant splitting of the projected L-valleys in [100] NWs.

Effect of industrial wood particle size on mechanical properties of wood-polyvinyl chloride composites

Wood-polyvinyl chloride (PVC) composites were prepared using industrial wood particles used for manufacturing three-layer particleboards. The effect of particle size (0.25–0.5, 0.5–1, 1–2, and 2–4 mm) on the mechanical properties of the composites was investigated. The effect of cross-section size (4×10, 6×15 and 8×20 mm2) of composite pieces made by an injection moulding method was also studied. Both the particle size and specimen cross-section area significantly influenced these properties. The tensile and flexural properties as well as the impact strength in general increased with increasing particle size, and decreased with increasing cross-section size.

A Note on a Camouflage Pursuit Problem

Motion camouflage is a pursuit strategy whereby a predator moves towards a prey while appearing stationary to the prey except for the change in its perceived cross section as it approaches. If the effect of cross section size with distance is ignored, then this means that the target is unable to discern that the aggressor is moving. The aggressor appears to be at its initial position or is camouflaged by a stationary object in the background. We shall derive a closed form solution to the problem of camouflage pursuit for a particular situation. Although general differential equations have already been derived for this strategy, they have not been solved in closed form.

Electron dynamics in silicon nanowire using a Monte-Carlo method

We present a theoretical study of electron transport in silicon nanowire (SNW). A self-consistent 2D-Poisson-Schrödinger solver provides the band structure. Then, both electron velocity and low-field electron mobility along the SNW axis are computed with an ensemble Monte-Carlo method. Scattering mechanisms due to phonons (acoustic phonons, zero-order and first-order intervalley phonons) and surface roughness are taken into account. We investigate the effect of cross section size and transverse electric field on electron mobility in SNW.

Proposed Design and Method for Providing Sealed Joint Performance under Relative Story Displacement

Abstract The fatigue resistance of sealed joints to relative story displacement movements caused by earthquakes was studied experimentally and analytically, and the new joint design method was proposed, providing adequate sealed joint performance over the joint’s service life. First, the story drift R of a curtain wall panel and the number of movement cycles of relative story displacement at a sealed joint over its service life were investigated using earthquake data of the Japan Meteorological Agency. The results indicate that the number of cyclic movements at a sealed joint over its service life is inversely proportional to the story drift of the adjacent curtain wall panels. In regions where earthquakes are numerous, R=1/300 cyclic movements of the total length of the curtain wall panel occur several thousand times over a period of 75 years, while R=1/100 cyclic movements occur only several tens of times. Second, the three criteria required to create a joint design method were investigated, i.e., type of sealant, effect of cross-sectional size and shape of the sealed joint, and fatigue resistance of the sealant at intersectional zones of sealed joints to the sliding and rocking motions of curtain wall panels. It was obvious that the fatigue resistance of sealed joints was lower in the intersectional area than in the linear sections of the joints, and was lowest in the event of the same movement occurring in both vertical and horizontal joints. The fatigue resistance of a sealant at the intersection of sealed joints is not sufficient to attain the targeted service life and the fatigue resistance of this area of the sealed joint must be improved by applying larger curvature radii at the corner of the curtain wall panel. Finally, the new joint design process for the linear section and the intersection of the sealed joints to relative story displacement movements was developed based on the experimental data. Further, we proposed the methodology to estimate the expected service life of a sealed joint.

634 矩形流路における好中球の流動に関する数値解析 : 流路断面形状が通過時間に与える影響(G02-6 シミュレーション(1),G02 バイオエンジニアリング)

634 矩形流路における好中球の流動に関する数値解析 : 流路断面形状が通過時間に与える影響(G02-6 シミュレーション(1),G02 バイオエンジニアリング)

Interfacial Bonding Strength of Graded ZrO2/NiCrAlY Coatings Accumulated by Detonation Gun Spraying

Functionally graded ZrO2/NiCrAlY coatings are produced by detonation gun spraying using spheroid powers as the feedstock. A commercial Ni-based alloy is used for metallic substrate. The composition and microstructure are changed gradually through the six-layer graded coatings that are beneficial for the improvement of mechanical and thermal properties of the coatings. The shear test is carried out to analyze the interfacial bonding strengths of graded coatings. And non-graded duplex coatings are tested for comparative study. The effects of cross-sectional size and crosshead speed on interfacial strength properties are also studied. Results show that interfacial strengths of graded coatings are increased gradually with increase of volumetric rate of NiCrAlY. The bonding strength of the functionally graded coating is about twice as high as that of the duplex coating. For duplex coating without metallic interlayer and below 5 mm/min, the interfacial bonding strength of ZrO2/NiCrAlY interface increase with increasing crosshead speed.