Applied Mechanics and Materials Vols. 271-272

Abstract: The sandstone extraction is an essential activity to the production of specific products. It is employed in the civil construction sector. However, there is still a deficiency in physical and geological characterization. This research develops two experiments in the sandstone matrix located in São Carlos region (City of São Paulo State – Brazil). The first experiment is related to the geological aspect of the specific sandstone. It identified the geographic location and investigated the porosity and absorption rates of the Brazilian sandstone rock, besides verifying its compressive strength. The purpose was to identify and evaluate possibilities of sandstone use in the structural concrete composition. The second experiment tested the concrete strength with this aggregate. Some quantities of crushed sandstone were used as fine aggregate in the manufactured concrete. The experiments presented sandstone properties and sandstone aggregate possibilities in concrete composition. The present study is a result of an undergraduate project, aiming to contribute with new information on the Brazilian sandstone characterization and concrete strength application with the sedimentary aggregate. This work showed some possibilities to use this type of yellow and red sandstone as aggregate.

Abstract: Joining of very thin metallic foils is required in vast applications such as fuel cell plates, micro reactor carriers, heat exchanger etc. Pressure welding is found to be an efficient method. However, some metals (e.g., stainless steel) are difficult to achieve successful solid state bond at room temperature. In present study, a novel electric assisted pressure welding (EAPW) process was proposed. In the EAPW process, electric current was introduced to the metal sheets under pressure welding in the purpose of reducing welding difficulty. An EAPW experimental setup was developed to study the joining process of Stainless Steel (SS) 316 sheets. The effects of electric current as well as process conditions on the final bond strength were experimentally studied. It was found that SS316 sheets could not be bonded without current at room temperature. However, they were successfully joined with electric current introduced. The co-effects of temperature and electric current were also investigated experimentally. It was found that elevated temperature caused by Joule heat is not the only reason for the improvement of the welding performance. The so-called electro-plastic effect also makes a contribution in EAPW process. Finite element method (FEM) was also employed to analyze the process and the welding behavior was discussed.

Abstract: Now insulation films are often prepared by smooth rubberroll on the surface of non-oriented silicon steel sheet. Though the surface resistance is enough high to ensure the quality, it will dramatically decrease after stress relief annealing. In order to understand the related mechanism, the film’s microstructure was characterized by SEM. The results show that the main composition of semi-inorganic coating is Cr, Mg C and O, in which C come from the organic polymer. According to the composition, the insulation film can be divided into two parts, the outer one is organic polymer and the inner one is chromate. The main reason for the unstable surface resistance is that the coating in the thickness direction is not uniformity.

Abstract: The different geometric sizes, different adhesive thickness and different surface treatments have great influence on the properties of aluminum alloy 6063 bonding joints. This paper takes single lap joint for object, adopts the tensile shear test, takes the tensile shear strength as the judgment basis, and exploresthe variation inperformance of aluminum alloy 6063 bondingjoints. The test results show that: Aluminum alloy 6063 bonding joints occur serrated yielding phenomenon inthe tensile shear test; In a certain layer thickness range, tensile shear strength of aluminum alloy 6063 bondingjoints correspondingly increaseswiththe thickness of samples increasing; Different surface treatments on aluminum alloy 6063 have a great influence on tensile-shear strength, and mechanical polishing and skim can significantly improve tensile shear strength of aluminum alloy 6063 bonding joints.

Abstract: This paper first introduces the latest application of numerical modeling method in polymer processing, and then discusses the related research problems and the main open issues. Finally, requirements and prospects are proposed for the realization of the development direction of Wood–fiber/Plastic Composites (WPCs).

Abstract: This Liquid submerged fermentation method was applied to culture the Grifola frondosa mycelium and the effects of temperature, pH and inorganic salts on the autolysis of fresh Grifola frondosa mycelium were examined. The single-factor experiment and orthogonal design were used to optimize the autolytic conditions. The results showed that the optimal conditions for the mycelium autolysis were 50°C, pH5.0, 0.05% MgSO₄ and 0.1% CaCO₃. This research provides the basis for further investigation of the Grifola frondosa mycelium autolysis mechanism.

Abstract: Microcellular unsaturated polyester was prepared by different foaming agents was studied. Compared with the cell size and density of microcellular unsaturated polyester prepared using azodicarbonamide (AC), the ones of microcellular unsaturated polyester prepared using NaHCO3 were small. For NaHCO3, the cell density of microcellular unsaturated polyester decreased with the increasing temperature. For microcellular unsaturated polyester prepared using NaHCO3 at 100 °C, the average cell size was about 18 μm and the cell density was 1.1×1010 cells/cm3. The compression strength at 100 °C is strongest among that of the materials at the other temperature. The average compression strength was 24.2 MPa. The compression strength-to-weight ratio of microcellular unsaturated polyester prepared at 90 °C and 100 °Cwas about twice that of unsaturated polyester.

Abstract: Through the analysis and research on the Microstructure of copper matrix composites, according to the fractal theory, calculated microstructure friction dimension of cross section and parallel pressed power side of copper matrix composites under different experimental conditions. The results show that, for parallel pressed power side, fractal dimension reflects the distribution laws of graphite in the sample, the fractal dimension is more larger, the organization chart is more complex, the distribution of graphite is more irregular, so the irregularity of graphite distribution can be described by fractal dimension, fractal dimension can be used as a characterization parameter of organizational form for copper matrix composites. Under the condition of virtually expanded sample，in the view that Sn,Zn and SiO2 is not changed respectively, and the sum of Cu and graphite is 85%,by use of linear regression model to estimate parallel pressed power side of microstructure fractal dimension of different composition in copper matrix composites.

Abstract: The tractive lithium ion batteries were gradually become the main energy provider for the Electric vehicles (EVs) and hybrid electric vehicles (HEVs) in recent years. However, it was urgent and important to remove the heat generated from the tractive lithium ion batteries during charge-discharge processes for its future application in EVs and HEVs. In this study, the heat release and indirect liquid cooling of tractive lithium ion batteries was investigated. The temperatures of batteries at different positions were recorded under different discharge rates and environmental temperatures. The results showed that indirect liquid cooling could effectively decrease the temperatures of battery. The decreasing ratios of temperature at different positions of battery were varied from 1.9% to 8.1%. It presented preferable cooling effects at the positive and negative of battery.

Abstract: Dynamic load experiments of the disc-shaped metal rubber isolation component are performed. Through analyzing variation law of the parameters with amplitude and frequency, which are stiffness coefficient, damping coefficient and damping component factor, the hysteresis restoring force model which is able to fully reveal the dynamic characteristics of the component is established. The experimental verification results show that the theoretic calculations are consistent with the experimental data, which verifies the practicability and effectiveness of mathematical model and parameter identification. It has important practical significance for design of vibration isolation component with different requirements.