Effect Of Cellular Structure Research Articles

Cellular structure assisted enhanced deformation-induced martensitic transformation in laser-directed energy deposited ferrous medium-entropy alloy

The effect of cellular structure on the deformation behavior of laser-directed energy deposited Fe60(CoNi)30Cr10 medium-entropy alloys was comprehensively analyzed. High dislocation density and elemental segregation at cellular boundaries significantly promoted deformation-induced martensitic transformation and enhanced heterogeneous deformation-induced strengthening. This highlights the potential to optimize the mechanical performance of the alloy through cellular engineering.

The role of network topology on the uniaxial tensile behaviour of low density random open cellular structures

The effect of cellular structure on the mechanical properties of cellular solids is included in the prefactors of the relative density term in the Gibson and Ashby scaling laws. The effect of cell shape, cell size distribution, cell shape anisotropy, cell wall curvature and strut cross sectional variation have been known to affect these prefactors. This paper investigates the dependence of these prefactors on the network connectivity in random honeycombs and three-dimensional random open cellular structures. Beginning with intact structures, the network connectivity is reduced by randomly removing struts. A scaled genus density, that remains independent of sample volume, absolute cell size, and the relative density, has been defined and taken as a quantitative measure of the global connectivity. The variation in the overall stiffness and offset yield stress due to loss in connectivity was found to clearly depend on the scaled genus density when the relative density is kept constant, indicating that the geometric prefactors are functions of scaled genus density. The prefactors for intact perturbed cubic voronoi, perturbed BCC voronoi structures, and perturbed cubic body diagonal lattices with widely differing scaled genus density also confirm this strong correlation. We also show that the prefactors can be factored to quantitatively decouple the effects of anisotropy and scaled genus density.

The effect of cellular structure on the strength and combustion properties of SiC porous ceramics

SiC porous ceramics (SPCs) are key functional medium materials, which are widely applied as porous burners. However, SPCs produced via the polyurethane sponge replica technique usually exhibit a randomly distributed cellular structure, leading to vulnerability and a low combustion efficiency for the porous burners. In this study, SPCs were structurally designed via novel 3D printed resin template technique; this endowed the SPCs with synergistically optimized strength and combustion characteristics. SPCs containing tetrakaidecahedron, octahedron and cubic cells were successfully prepared via SiC slurry coating and sintering in air. The cell parameters determined the strength and combustion properties of the SPCs. The SPCs containing cubic cells exhibited the largest strength and strain, because more struts were present parallel to the loading direction; this is more advantageous for stress bearing compared to those vertical to the loading direction. The tetrakaidecahedron cell facilitated the formation of a disturbance effect within the SPCs to a higher extent than the cubic and octahedron cells, thereby enhancing the heat exchange performance between the fluid and porous framework. Hence, the SPC with tetrakaidecahedron cells exhibited the best combustion properties, which resulted in the highest surface temperature and lowest pollution emission.

Effect of Cellular Structure on Mechanical Properties of Polyurethane Foam Curing Materials

Based on the mechanical properties and microstructure of polyurethane foam solidified material, a two-dimensional model of polyurethane foam solidified material was constructed. Polyurethane foam was obtained by fully and uniformly mixing the two components. The research was carried out through the combination of experimental test and finite element simulation. The experimental results show that when the pore density is constant, the size of the bubble hole is an important factor affecting the mechanical properties of the model. The smaller the size of the bubble hole, the less likely it is to produce stress concentration inside the model, and the stronger the resistance to material deformation. Under the random distribution, the lower the density of the polyurethane cured material, the higher the probability of damage between the adjacent bubbles, which is not conducive to the stability of the material. The density of the cured material should not be lower than 199 kg/m3.

Effect of cellular structure on deformation mechanism for urethane foam

Effect of cellular structure on deformation mechanism for urethane foam

Role of melt pool boundary condition in determining the mechanical properties of selective laser melting AlSi10Mg alloy

We describe here a comprehensive study on the effect of cellular structure and melt pool boundary (MPB) condition on the mechanical properties, deformation and failure behavior of AlSi10Mg alloy processed by selective laser melting (SLM). The morphology of melt pool (MP) on the load bearing face of tensile samples was significantly different with build directions. It resulted in different mechanical properties of the samples with different build directions. Furthermore, the microstructure analysis revealed that the MP in the SLM AlSi10Mg alloy mainly consisted of columnar α-Al grains which were made of ultra-fine elongated cellular structure. Electron back-scatter diffraction (EBSD) analysis revealed that the long axis of cellular structure and columnar grains were parallel to < 100 >, which resulted in < 100 > fiber texture in SLM AlSi10Mg alloy. However, Schmid factor calculation demonstrated that the anisotropy of mechanical properties of the SLM AlSi10Mg alloy built with different direction was mainly dependent on the distribution of MPB on the load bearing face, and not texture. The defects including pores, residual stress and heat affected zone (HAZ) located at MPB made it the weakest part in the SLM AlSi10Mg. The sample built along horizontal direction exhibited good combination of strength and plasticity and is attributed to the lowest fraction of MPBs that withstand load during tensile. MPB had strong influence on the mechanical properties and failure behavior of SLM AlSi10Mg built with different directions.

Reflection and transmission of visible light by sugi wood: effects of cellular structure and densification

Transmittance and reflectance of visible light by sugi wood (Cryptomeria japonica) were investigated in the longitudinal (L) and tangential (T) directions. Transmittance was the highest in the L direction and reflectance was the highest in the T direction, suggesting that structural anisotropy influences transmittance and reflectance. Intra-ring variations observed with a microspectrometer indicated that T transmittance was higher for latewood than for earlywood, but there was no such trend in for L transmittance in which the highest levels occurred near the annual ring boundaries, on either the earlywood or latewood side, and the lowest at the transition from earlywood to latewood. Dependence of L transmittance on wavelength also showed variations according to the intra-ring position. The increasing of transmittance of earlywood at wavelengths < 500 nm with increasing wavelength was observed, but this was not confirmed for latewood because of absorption by lignin. These observations supported a previously published finding, which was based on measurements in the radial direction, that the number of internal cell wall reflections, rather than density, determines wood lightness. Indeed, in the L direction, most of the incident light passes through lumens in earlywood and through cell walls in latewood, while it is subjected to numerous internal reflections at the interface between lumens and cell walls. This was further confirmed by the transmittance of earlywood being greatly decreased by radial compression.

Effect of cellular structure on the optical properties of wood

To construct robust calibrations of wood properties by near infrared spectroscopy, one must independently evaluate the spectral contributions of light absorption and light scattering. However, the light propagation in wooden cellular structures is difficult to interpret because these structures are complex, heterogeneous, and anisotropic. This study investigates the reduced scattering coefficients of softwood and hardwood (with ring-porous or diffuse-porous vessels) at 846 nm by time-resolved spectroscopy. It also evaluates the effect of wooden cellular structure and air-dry density on the light propagation. After determining the reduced scattering coefficients, we observed cross-sectional microscopic images of the wood samples. Eighty-five percent of the variation in the reduced scattering coefficients was explainable by the air-dry density, area ratio of the cell wall, and the median pore area. Monte Carlo simulations of the light propagation through wood revealed that most of the photon transport occurs in the cell-wall substance.

Effect of cellular structure on the mechanical property of Al0.2Co1.5CrFeNi1.5Ti0.3 high-entropy alloy

In this study, Al0.2Co1.5CrFeNi1.5Ti0.3 high-entropy alloys (HEAs) that contain γ matrix phase and γ′ precipitates were heavily deformed and then annealed at different temperatures. Cellular structures were incubated and grown in a shear band below recrystallization temperature. These cellular structures, which are also referred to as discontinuous precipitation, were observed in some nickel-based superalloys. The γ/γ′ microstructure in the recrystallized area is much coarser than the spherical γ′ embedded in the γ matrix, thus leading to the reduction of the γ/γ′ interface and degradation of the precipitation hardening effect. However, results show that these structures can be eliminated by a slow cooling process, as demonstrated in this study. Annealing treatment at 1000 °C just below the γ′ solvus for different durations shows fall-first-and-rise-later hardness, which is due to the dissolution of the precipitates into the migrating grain boundary (GB) caused by static recrystallization, and then subsequently reprecipitates behind the moving boundary. However, this effect on the HEAs is shown at an annealing temperature of 1000 °C, which is higher than that in nickel-based superalloys, due to the sluggish diffusion, which would lower the mobility of GB.

Effect of Cellular Structure on Non-uniform Deformation Behavior of Low Density Polyethylene Foam

Effect of Cellular Structure on Non-uniform Deformation Behavior of Low Density Polyethylene Foam

Low‐cycle fatigue behaviour of ductile closed‐cell aluminium alloy foams

AbstractThis work investigates the fatigue response of a class of ductile closed‐cell aluminium alloy foams, known by their commercial name Alulight M8. In order to determine the yield stress of the used foams, preliminary experimental tests were performed, at room temperature, in monotonic compression on cylindrical specimens of 25 mm diameter and 25 mm height, with a loading speed of 10 mm/min. Fatigue tests were performed in uniaxial compression on cylindrical specimens (25 mm × 25 mm) with a stress ratio of R = 0.1, at a frequency of 10 Hz. The peak stress was varied from 110 to 135% of the yield stress in compression. Tested specimens were cut from the same cylindrical bar, and the density of the investigated material was 500 kg/m3 ± 10%, or a total of 18 specimens being investigated. With the gathered experimental data, S–N curve was generated, and the effect of cellular structure (e.g. structure irregularity–the number and the size of cells) being investigated and discussed.

Integrating optical measurement and modelling for quantitative analysis of the micromechanical load transfer in the wood-adhesive bond interphase

By combining advanced imaging tools with morphology-based numerical modelling, a methodology has been proposed to measure the wood-adhesive bond performance at the micro level. Through this integration of multi-modal and multi-scale tools, this methodology provides a tool to understand the complex interactions between wood and adhesive phases at a microscale. Focusing all measurements and modelling on matched physical specimens avoided many simplifying assumptions. Direct measurement of strain development validated that the model was capable of representing the effects of cellular structure and adhesive penetration. With this measurement tool one can analyse stress and strain distribution patterns throughout adhesively bonded materials and virtually experiment with a range of variables like adhesive properties, wood species, compression levels, processing parameters, penetration patters, etc.

Effects of cellular structure and cell wall components on water holding capacity of mushrooms

In a sequel of papers we have investigated effects of different physical contributions to the water holding capacity of foods by considering the common white button mushroom (Agaricus bisporus). In the current paper of our sequel, we consider individual contributions of the cellular phase to water holding. The water holding capacity of hydrated mushroom is studied in relation to cell membrane integrity loss and change of state of structural polymers of the cell wall. We show that the loss in water holding capacity after heat treatment is closely correlated with cell membrane integrity loss. The intrinsic water holding capacity of the cell wall components, mostly chitin and proteins also play a role. The contribution of protein manifests largely via a significant response of WHC towards change in pH.

Sound absorption behavior of flexible polyurethane foams with distinct cellular structures

The effect of cellular structure in the flexible polyurethane foams on the sound absorption behavior is investigated for improved sound environment within vehicles. Two types of gelling catalyst and water are used for producing well-defined cavity and pore structure in the foams. The catalyst, having high activity in urethane reaction, produces a larger number of small cavities and pores in the foams compared to the catalyst having low activity. A high number of small cavities can also be obtained at high water content from the restraint of neighboring cavities due to actively formed urethane matrix. The foam density decreases with increasing water and catalyst contents. Sound absorption efficiency is usually low at low foam density, but the results show improved sound absorption efficiency even at the reduced foam density because of the high number of well dispersed small cells in the foams.

Effect of cellular structure on the water absorption of rigid foamed polyurethanes

Effect of cellular structure on the water absorption of rigid foamed polyurethanes

Special features of the effect of cellular structure on the mechanical properties of foamed plastics

On the basis of the cell model proposed the mechanical characteristics of high-density foamed plastics are calculated. Assuming the general application of the foaming mechanism and the formation of macrostructure, the principle of structural-mechanical superposition of foamed plastics is established. This enables the equivalence of changes in their strength and elastic properties to be indicated over a wide range of variation of the stiffness of the polymer base and the apparent density of the foamed material.

Effect of cellular structure on the mechanical properties of plastic foams

A generalized equation for the compressive stress-strain diagrams of plastic foams is derived on the basis of a 14-faced model of the cell. The results obtained make it possible to predict the polymer base and type of cellular structure required to obtain a foam with predetermined mechanical properties in compression. The calculated values are shown to be in satisfactory agreement with the experimental data.