Effect Of Foam Structure Research Articles

Thermomechanical Vibration Response of Solid and Foam FGM Nano Actuator/Sensor Plates

Abstract Purpose In this study, the effect of foam structure on the thermomechanical behaviour of high void ratio porous FGM piezoelectric smart nanoplates is investigated. Method The material of the smart nanoplate consists of PZT-4 on the bottom surface and BaTiO3 on the top surface and is formed by functional grading of these two materials along the thickness of the plate. Four different foam distribution models are modelled to examine the foam structure of the highly porous smart nanoplate, which has become widespread in biosensor applications. For this reason, uniform, symmetrical, top symmetrical and bottom symmetrical foam distribution models are created up to 75% void ratio. To determine the nano size, equations of motion are obtained by using nonlocal strain gradient elasticity and sinusoidal shear deformation theories together, and these equations are solved by the Navier method according to general boundary conditions. Result and Conclusions As a result of the analysis, it is observed that the applied external electric potential creates a softening effect on the plates with the piezoelectric elasticity effect and therefore reduces the thermal buckling temperatures. It is observed that the presence of the foam structure significantly improves the thermal resistance of the material and increases the buckling temperatures. It is also observed that the foam distribution model has significant effects on the thermomechanical behaviour.

Effect of foam structure on thermo-mechanical buckling of foam core sandwich nanoplates with layered face plates made of functionally graded material (FGM)

Effect of foam structure on thermo-mechanical buckling of foam core sandwich nanoplates with layered face plates made of functionally graded material (FGM)

Effects of chain composition of PBAT on the supercritical CO2 foaming and degradation behavior

Poly (butylene adipate-co-butylene terephthalate) (PBAT) with different copolymer compositions and molecular weights exhibits unique foaming behavior and dimensional stability when supercritical CO2 is used as a blowing agent. With an increase in the content of butylene glycol terephthalate (BT) from 43% to 61%, the melting point and crystallinity of PBAT increase. Consequently, the foaming temperature range of PBAT shifts toward a narrower, higher temperature zone, i.e., from 70 – 120 °C to 135 –160 °C under 13 MPa CO2 pressure. Additionally, CO2 solubility and desorption rate decrease, while PBAT exhibits a higher compression modulus and better foam dimensional stability. For similar BT contents, an increase in the molecular weight of PBAT widened the foaming temperature window and increased the cell density of the foam. It is noteworthy that increasing the BT content of PBAT to 52% not only ensures good dimensional stability of the PBAT foams, but also good biodegradability of PBAT. In addition, the effect of foam structure on degradation behavior was investigated. It was found that the PBAT foams with a higher volume expansion, larger cell size, and lower cell density degrade faster.

Effects of foam structure on thermochemical characteristics of porous-filled solar reactor

The foam-structured reactor is one which has hitherto been regarded as of great potential for industrial applications in the field of solar thermochemistry. The utilization mode of ceramic foam has, generally, a significant impact on energy conversion and storage efficiency. This study establishes a numerical model, coupled with computational fluid dynamics and dry reforming of methane reaction kinetics, to find the optimal structural parameters of the ceramic foam. A local thermal non-equilibrium model coupled with the P1 approximation has been developed to address the heat-transfer problems, and the non-Darcy flow effect has been considered to calculate the momentum dissipation in the porous zone. Based on ample simulation examples, the effects of porosity and foam cell size on the reaction temperature, surface heat loss, thermal efficiency, CH4/CO2 conversion, H2/CO yield, carbon deposition, and solar-to-chemical efficiency are illustrated in detail. The results indicate that using the ceramic foam with high porosity and large cell size is able to attain the best thermochemical characteristics, of which the validity can be assured, insofar as the various operating conditions in this study are concerned. Furthermore, as compared to the best single-layer structure, the application of the optimized double-layer foam structure is a more effective solution, which is able to further improve the energy storage efficiency by a remarkable 9.23%.

Mechanical and Electromagnetic Shielding Properties of Carbon Foam

More importance is being attached to the harm caused by electromagnetic interference (EMI) problems. Plenty of research in this field has used carbon foam materials to solve EMI, and some excellent results are obtained, whereas the mechanical properties of carbon foam are poor, which limit applications in particular fields. The physical mechanism of electromagnetic shielding is unanswered and further study is needed. Herein, a kind of carbon foam material is obtained by the templating method; the effect of foam structure on the electromagnetic shielding properties of the carbon foam material is investigated through experiment and simulation. The electromagnetic shielding performance, mechanical properties, and thermal stability of carbon foam are also studied. The electromagnetic shielding performance of carbon foam material is 20 dB in the X‐band range with the thickness and density as 2 mm and , respectively. In addition, the compressive strength of the carbon foam is 0.55 MPa.

Effects of foam structure on the wear behavior of co-continuous SiC3D/Al composite materials

Co-continuous composites show improved mechanical properties, thermal performance, and wear resistance owing to their special structural features, and thus they are considered potential wear-resistant materials. In this study, co-continuous SiC3D/Al composites were prepared via pressureless infiltration, and the effects of the foam structure on the friction and wear properties of the composites were investigated. The results revealed that the composites consisted of three phases: a matrix phase, a transition phase, and a strengthening phase. In addition, the transition phase resulted in a strong combination between the Al alloy matrix phase and the SiC strengthening phase. The SiC foam structure in the co-continuous SiC3D/Al composites exhibited an obvious influence on the wear behavior of the composites. The hardness of the composites, the inter-skeleton distance, and the skeleton distribution of the foam structure affected the dispersion and transmission of the load and friction heat during the wear process, which was closely related to the tribological behavior of the composites. Finally, the co-continuous SiC3D/Al composites with 20 pores per inch, which had proper hardness, shorter inter-skeleton distances and a more homogenous skeleton distribution, showed the best wear resistance (the volume wear rate was about 1.0 × 10−6 cm3·m−1·N−1) in this work.

Storage stability of dried raspberry foam as a snack product: Effect of foam structure and microwave-assisted freeze drying on the stability of plant bioactives and ascorbic acid

We compared the effects of the use of microwaves during freeze drying with conventional freeze drying on the structure and storage behavior of dried raspberry puree foam. The effects of hydrocolloids, such as potato protein (as a foaming agent), maltodextrin, pectin (as foam stabilizers), and the impact of foam structure on the stability of plant bioactives (namely anthocyanins and ascorbic acid) and color during storage was investigated. Dried samples were vacuum-packed and stored at 37 °C for 12 weeks. Water sorption and glass transition temperatures were also measured. The results suggest that the raspberry puree is not as stable as the foamed structure. Storage stability of microwave-assisted freeze-dried samples revealed equivalent or even slightly better characteristics when compared with those produced via the conventional freeze-drying method. It can be concluded that microwave freeze drying does not induce specific detrimental changes during storage as compared to the freeze-drying technology used as control.

Effect of Foam Structure on Impact Compressive Properties in Foamed Polyethylene Film

The purpose of this study is to elucidate the effect of foam structure on the impact compressive properties of foamed polyethylene film. Three types of foamed PE film were prepared, which have different foam structure: base type, spheral type and dense type. A quasi-static test was performed using a universal testing machine at the strain rate of 10-3~10-1s-1. Impact tests were carried out using a drop-weight testing machine at the strain rate of 101~102s-1 and using a split Hopkinson pressure bar method at the strain rate of approximately 103s-1. It was confirmed that the foamed PE film shows an increase of the flow stress with increasing of the strain rate, regardless of the specimen type. In the spheral type specimen, the elastic response is observed immediately after compression because the cell shape of this specimen has high bending resistance in comparison with the other two specimens. In addition, it is confirmed that the relative density and cell size affects the flow stress in the foamed PE film.

Effects of foam structure and material on the performance of premixed porous ceramic burner

An experimental setup was developed to investigate the physical characteristics of ceramic foam, used in reaction layer, on the performance of a porous burner. This premixed burner included mainly four sections: premixed, preheating, combustion zone and an integrated heat exchanger. The objective of this work was to investigate effects of different kinds of ceramic foams with various porosity, pore density and materials on the burner performance. The combustor was operated with natural gas and diverse structures of alumina and silicon carbide foam utilized in the reaction layer. Temperature distribution along the centerline, thermal efficiency, emission concentration and pressure drop were thoroughly investigated. Results showed a decrease in the porosity of ceramic foams, causing emission and pressure drop to increase while efficiency declined. More stable combustion was achieved by using finer foams with higher pore density. These foams indicated lower pollution and higher efficiency in low excess air, while coarser foams—ceramic foams with low pore density—resulted in lower pollution and higher efficiency in high excess air. Investigation effect of material exhibited silicon carbide foams causing higher temperature of the combustion and more temperature variation through the burner. Generally, material effect was negligible in terms of efficiency. But role of material highlighted in pollution where silicon carbide resulted in higher amount of NO.

Effects of Temperature and Volume Agglomerate Fraction on Mechanical Response of PEMFC Electrodes

To deal with the durability analysis of PEM fuel cell, it is necessary to carry out a further understanding of each component response, especially each layer of the MEA. So the main purpose of this paper is to understand the mechanical properties of electrode layer and find out the effect of temperature and the content of catalyst particles on the electrode yield stress. To overcome the experimental limitations, numerical method is used here. A 3-phase model of the electrode is built, which includes a user-defined material with catalyst particles. Due to the porosity of the electrode, the user-defined material is defined as a nafion ionomer glassy constitutive model by bringing in the effect of foam structure. Catalyst agglomerate particles are assumed as isotropic elastic spheres with relatively high Young’s modulus. The yield stress is extracted from the simulation, and the influences of temperature and agglomerate fraction on it are discussed.