Abstract: The result of an extensive research on this material is the achievement of approaching 20% efficiency by the co-evaporation of copper, indium, gallium and selenium elements. Recently, photoluminescence (PL) spectra have been studied on Cu (In,Ga) Se2 (CIGS) thin films and CIGS solar cells, to clarify the carrier recombination process. The CIGS layers were grown on the Mo-coated soda-lime glass substrate by the three stage process and four sources co-evaporation of constituent elements onto a heated substrate. It has found that the structural and optical properties of the CIGS thin film was influenced by the Cu/Ga ratio (RCu/Ga) of the CIGS thin film compositional variation. The X-ray diffraction and PL spectra were used to characterize the structure property and carrier recombination mechanism of CIGS thin film.
Abstract: Soil can be modified with Phase Change materials (PCM) in order to enhance its thermo-physical properties and energy storage for ground source heat pump applications. This paper studies thermo-physical properties of soil modified with different amount of microencapsulated PCM. It is shown that increasing PCM amount in soil lead to lower thermal conductivity and increase of volumetric heat capacity of PCM-modified soil across the PCM melting temperature range. In addition, numerical simulation is performed to study the potential application of PCM-modified soil for reduction of temperature variations in ground. The result of numerical simulation revealed that temperature variation under PCM-modified soil can be reduced by up to 3°C compared to conventional soil. This could improve the Coefficient of performance of a heat pump system by more than 17%.
Abstract: Till to date, fabrication of Ionic Polymer-Metal Composites (IPMC) are carried out successfully using noble metal such as platinum/gold as the surface electrode. In this work we have proposed cost effective fabrication method for IPMC actuator using non-precious metal electrode of silver (Ag). Chemical decomposition method is followed using Nafion as the ion exchange membrane to fabricate pure Ag-electrode IPMC. Microscopic and morphological analyses reveal that, silver particles penetrate well through the surface of Nafion membrane. The bending deformation measurement and analysis of the thermo-mechanical properties of the fabricated IPMC is carried out. The experiment results and performance of the IPMC actuator confirm that the fabrication of pure Ag-IPMC is feasible and can be used as artificial muscle material.
Abstract: Anti-bacterial property is a major concern of material use in many areas, such as food industries, hospitals, and kitchenware. It is well known that Ag owns the ability to destroy the cell walls and cell membranes of bacteria to inhibit their breeding. Therefore, Ag implanted on the material surfaces is a popular process in biomedical application. Once the implanted layer is destroyed, the well-effective antibacterial property is also ceased. In order to improve the effectiveness of bacterial characteristics, adding Ag in 2205 duplex stainless steel can maintain the bacterial property for a long period of time than Ag-implanted process. 2205 duplex stainless steel possesses excellent corrosion resistance, high strength, and superior workability, owing to possess both austenite and ferrite phase. Among them, 2205 duplex stainless steel was adopted as the test material, doping various Ag contents in this study. The result reveals that Ag content increased with ferrite phase fraction increasing. It showed Ag is the stabilizer of ferrite. In addition, the solubility of Ag into Fe was extremely low and Ag particles were distributed randomly. However, polarization test was carried out to investigate the ability of corrosion resistance. The test result showed adding Ag in 2205 duplex stainless steel had obvious contribution to decrease its corrosion resistance.
Abstract: Polyester matrix composites reinforced by ceramic fillers have significantly better characteristics such as super wear resistance, high strength and low density than unreinforced materials. However, prohibitive costs and stability of properties pose challenge for the researchers in the process of development of composites. To address these issues, composites are being developed using waste materials as reinforcement for effective utilization of industrial wastes. The present investigation aims to develop red mud filled polyester composites (with different weight fraction) and characterize its mechanical and tribological properties. The engineering application of composites demands that it should have high wear resistance, low density and high tensile strength. In order to assess the behavior of composites satisfying multiple performance measures, grey-based Taguchi approach has been adopted in the present work. Optimal factor setting has been suggested to improve multiple responses viz., specific wear rate, density and tensile strength of the composite product. Optimal setting has been validated using confirmatory test.
Abstract: In this study, acoustic emission (AE) monitoring with a Fuzzy C-Means (FCM) clustering is developed to detect the delamination process during quasi-static 3-point bending test on glass/epoxy composite materials. The main fracture mode that should be emphasized and has an effect on the residual strength of composite materials is delamination. The 3-point bending test simulates thrust force due to drilling process without backup plate. In this work, two types of specimen at different layups, woven [0,90] s and unidirectional  s, leading to different levels of damage evolution, were studied. Using acoustic emission monitoring can help to detect these fracture mechanisms. The obtained AE signals were classified using FCM. Dependency percentage of damages in each class is different in two specimens. Three parameters (Peak Amplitude, Count, and Average Frequency) were used to validate the FCM based classification. The results show that there is a good agreement with the FCM classification and microscopic observation by SEM.
Abstract: Sandwich plates have been extensively used in many engineering applications such as automotive and aerospace. In the present paper, an accurate finite element model is presented for bending analysis of soft-core rectangular sandwich plates. The sandwich plate is composed of three layers: top and bottom skins and core layer. The core is assumed as a soft orthotropic material and skins are assumed generally unequal laminated composites. Finite element model of the problem has been constructed in the ANSYS 11.0 standard code area. Continuity conditions of transverse shear stresses at the interfaces are satisfied as well as the conditions of zero transverse shear stresses on the upper and lower surfaces of plate. Also transverse flexibility and transverse normal strain and stress of core are considered. The effect of geometrical parameters of the sandwich plate are studied. Comparison of the present results with those of plate theories confirms the accuracy of the proposed model.
Abstract: The effect of diameter, chirality and volume fraction of SWCNTs on the tensile behavior of nanocomposites is studied. Multi-scale material modeling is applied to assemble different RVEs composed of various SWCNTs embedded in polymer. Nanotubes are modeled in continuum mechanics, based on their atomic structures as space frame structures. Beam elements in this structure are defined based on carbon bonds characteristics in molecular mechanics. Polymer portion of the RVE is modeled as a linear elastic continuum material, with lower accuracy regarding to the multi-scale modeling technique. Attained stress-strain curves obtained from modeled nanocomposites revealed that using Armchair SWCNTs in RVEs makes nanocomposites tougher rather than Zigzags. Also, diameter of CNT has an inverse effect on the curves level. Moreover, the effect of diameter is more obvious at higher volume fraction of CNTs.
Abstract: This paper presents investigation of piezoelectric proprieties of polypropylene PP and polyvinylidene fluoride PVDF films at an angle of their application as micropower generators and foot pressure sensors in walking process. Obtaind micropower from single layer is about 1.7W and 5.3W for polypropylene film and about 1.7W and 3.3W for polyvinylidene fluoride film. Obtained voltage from single film layer is 8.9V to 14V for PP film and 2 to 3.4V for PVDF film. Obtained micropower from piezoelectric film and course character of voltage in function of time during walking process, depends from used film and shoe insole construction, where active element was sandwich. Recived data record of voltage, power and foot movement images from measuring system, can be use in dynamic investigations of posture defects.
Abstract: Article presents research methods and their results for 100μm polyethylene terephthalate PET film, from a certain angle of its application as pressure sensors. Film was polarized at 150V/μm electric field intensity in dwo different temperatures: 60°C and 90°C. Direction of polarization was measured by thermally stimulated depolarization current TSDC. Results shows presence of homo-and heterocharge. Relaxation was calculated by two methods: from relationship ln J (T) = const – W/kT and from relationship (T) = P (T) / J (T). Activation energy for heterocharge calculated by first relationship is 6.14 eV to 6.77 eV and its relaxation time in 24°C is ~1020 years. For second one relationship, relaxation time in 24°C is ~1035 years. Piezoelectric voltage in 33 direction is 74V for termination resistance 1014Ω and 30V for termination resistance 109Ωfor applied stress 10N/cm2 from 10 cm2 surface. Obtained results for studied PET film, encourage to use it in practice as pressure sensors.