Advanced Materials Research Vols. 383-390

Abstract: This research proposes a new application of 3-axis CNC milling machine for polishing the 60 HRC hardness steels. The rotary polishing tools are designed by refer to the end-mill ball nose’s design. And the diamond powder was coated in rotary polishing tools. The L12 orthogonal array of the Taguchi’s method is selected to conduct the matrix experiment to determine the optimal polishing process parameters. The result show that polishing time was a dominant parameter for the surface roughness and the next was depth of penetration. The response surface design is then used to build the relationship between the input parameters and output responses. The experimental results show that the integrated approach does indeed find the optimal parameters that result in very good output responses in the rotary polishing tools polished hardness mould steel using CNC milling machine.

Abstract: In dissimilar material joints, failure often occurs along the interface between two materials due to stress singularity. Stress distribution and its concentration depend on materials and geometry of the junction as the stress concentration depends on grain orientation and its stiffness matrix of neighboring grains in micro-scale. Inhomogenity of stress distribution at the interface of junction of two materials with different elastic modules and stress concentration in this zone are the main factors resulting in rupture of the junction. Effect of materials properties, thickness, and joining angle at the interface of aluminum-polycarbonate will be discussed in this paper. Computer simulation and finite element analysis by ABAQUS showed that convex interfacial joint leads to stress reduction at junction corners in compare with straight joint. This finding is confirmed by photoelastic experimental results.

Abstract: Surface treatment is a new improved treatment procedure which espouses the mitigation of root cause of failures and improves the internal properties of case-hardened alloy steel. Coating is one of the Surface treatment processes applied on the case hardened alloy steel by which a sign of tremendous improvement is shown in wear resistance. This is due to increase in hardness by coating fine particles of oxides of ceramics (OC) and tungsten carbide (WC) on the surface of alloy steel. The coating makes the surface of alloy steel completely devoid of retain austenite formation which is usually formed in other conventional heat treatment processes. An analysis has been made on the surface treated alloy steel which is coated with diverse blends of fine particles of OC and WC. The investigation of coating consists of numerous metallurgical processes to identify the coating powder specification, coating process, coating characteristics, micro-structure and wear resistance property for the surface treated alloy steel. The exploration reveals the best alternative among the coating blends of fine particles which are taken for analysis on base alloy steel.

Abstract: In this study, a Cu/Ni porous composite was introduced when brazing sapphire to Inconel 600 using a special active filler metal of BAg-8 + 2Ti. The aim of the research is to investigate the Ti distributionin the Cu/Niporous composite and braze joint. The brazing was carried out in brazingtemperature of 830°C for 30 minutes by a vacuum environment (10-4 Pa). The interface of braze joint/sapphire and braze joint/Inconel 600 were observed by an electron microscope followed by elements analyzing using SEM-EDS. The observation and analysis shows that there is a black and thin reaction layer at braze joint/sapphire interface and a non-uniform of reaction layer was formed at braze joint/Inconel 600 interface. The formation of reaction layer is influenced by thermodynamic activity of Ti during brazing.

Abstract: Al thin films were prepared over different substrates at various process conditions using DC sputtering. The surface topography of all prepared films was examined using AFM technique. Very smooth, uniform and dense surface were observed for Al films coated over Glass substrates. The observed particle size was nano scale (20 -70 nm) for Glass substrates. Sputtering power showed immense effect on surface roughness with respective to Ar gas flow rate. Noticeable change on surface with large particles was observed in Copper substrates at various sputtering power and gas flow rate.

Abstract: Geopolymers are man-made aluminosilicate materials with many exceptional properties. The preparation of geopolymer, using SDRMS as main raw material, lime (CaO) and gypsum (CaSO4ּ2H2O) as activators in analytical grade, was carried out, and the hydration products of which were characterized by XRD and SEM simultaneously in this study. The results revealed that compressive strength of geopolymer paste obtained by the combined excitation of lime and gypsum, was higher than that obtained by only excitation of lime. The former was in the range of 46-70 MPa, the latter was 5–28 MPa after 28d maintenance of geopolymer paste. The highest strength of 70MPa was obtained when the weight ratio of SDRMS/ lime/ gypsum was at 70:20:10 in the geopolymer paste. By the combined excitation of lime and gypsum, the SiO2 and Al2O3 in SDRMS were changed into the hydrates of ettringite, gismondine, killalaite and other based on XRD, which were observed with the acupuncture-like, fibrous, tabular and dendritic microstructure based on SEM.

Abstract: Firstly, the characteristics of person-parachute sys-tem (PPS) in free-fall phase are analyzed. Then, the particle motion equations of PPS are built up. The motion law of PPS in free-fall phase is found by computing. Fall synthesis velocity decreases firstly, then gradually increases, so there is a minimum value of synthesis velocity when is favorable parachute opening moment. Results and actual test show good agreement, which provides an evidence for determining parachute opening moment.

Abstract: Through the structural analysis of hand, using mechatronics ideas, robot fingers based on Pneumatic Muscle Actuators (PMA) is designed and manufactured. Referring to the proportion of manual hand, the finger has three degrees of freedom. The far and middle finger joints are coupled of steel wire transmission mechanism, while the middle finger knuckle and the root are driven by a pair of artificial muscles. In order to realize the feedback control of displacement and the tactile force, the finger’s three joints are installed with three R24HS potentiometer and the fingertip is installed with the touch force sensor. The finger design integrates with mechanical structure, sensing, control and driving system. It achieves the integration and modularization in a maximum extent and completes the full theoretical support and experimental verification for the next step integration design of the flexible bionic robot hand.

Abstract: In order to improve the forecasting accuracy of indoor thermal comfort, the basic principle of fuzzy c-means clustering algorithm (FCM) and support vector machines (SVM) is analyzed. A kind of SVM forecasting method based on FCM data preprocess is proposed in this paper. The large data sets can be divided into multiple mixed groups and each group is represented by a single regression model using the proposed method. The support vector machines based on fuzzy c-means clustering algorithm (FCM+SVM) and the BP neural network based on fuzzy c-means clustering algorithm (FCM+BPNN) are respectively applied to forecast PMV index. The experimental results demonstrate that the FCM+SVM method has better forecasting accuracy compared with FCM+BPNN method.

Abstract: The purpose of this paper is to evaluate the effective mechanical properties of composite ceramic with randomly distributed multi-phase inclusions. The RVE finite element subcell technique based on numerical homogenization theory is used to separate the multi-phase composite into the layered unit cell models which are generated by a modified random sequential adsorption algorithm (RSA). The numerical results are also compared and verified with experiment data.