Applied Mechanics and Materials Vols. 52-54

Abstract: This study proposes a new method—the ultrasonic vibration-assisted arc-submerged nanofluid synthesis system (VANSS). This method prepares for water-based TiO2 woodenware nano-coating and applies the nano-coating to medium density fiberboard (MDF) to measure the characteristics of the coatings on the woodenwares. For VANSS, water-based coating serves as dielectric fluid and anodes, while cathode electrodes use titanium rods (editor’s note: please check carefully and consider revising the above sentence. I’m confused by the multiple use of ‘and’ in this case). Electrodes soon vaporize under the influence of a high-temperature plasma arc and instantly condense into nanoparticles under the cool effect of low-temperature dielectric fluid to form Ti nano-coating with good suspension. Placed for two weeks, Ti nano-coating has transformed into TiO2 nano-coating. TiO2 nano-coating is applied to MDF to compare the coating with and without the addition of TiO2 nanoparticles. The results show that TiO2 nanoparticles have an average particle size of 20 nm. For the coating properties test, the results show that lightness rises from 49.7 to 69.32, increasing 39.5 % after the coating is added to the TiO2 nanoparticles. Chroma lowers from 37.1 to 33.3, decreasing 11.3 % after the coating is added to the TiO2 nanoparticles. However, hue difference is within 3 %, having little influence on vision. Adhesion enhances from 1B to 5B, increasing 4 grades when the aqueous polyurethane, AE-418, is added to the TiO2 nanoparticles; solvent resistance elevates from 46.3 % to 56.8 %, increasing 10.5 % after the coating is added to the TiO2 nanoparticles.

Abstract: This study develops a nanocomposite structure with magnetism and biocompatibility. Composite structures with magnetism can be applied for biomarkers, specific tissue cell detection and targeted drug therapy. This study adopts a chemical disposition method to prepare Fe3O4 magnetic nanoparticles with the average size of 20-25nm. The complex biocompatible chitosan-alginate membrane covers Fe3O4 magnetic nanoparticles and the thickness of the complex membrane is controlled at 50-80nm. The efficiency of the oligonucleotide (ODN) combination is increased through the high biocompatibility of this composite film. Two groups of different sequences of ODNs and a bridge ODN undergo hybridization. The results show that the intensity at which the Fe3O4 is covered by chitosan-alginate composite film conjugated with ODNs is 2300nN. Furthermore, Fe3O4 covered by complex membrane of chitosan-alginate hybridized with 30 μM ODNs to yield the optimum hybridization intensity of 4528 nN, and the average hybridization intensity of ODNs with different concentration is 3971 nN.

Abstract: This paper analyzes the phenomenal essence of the electronic components high temperature alarm in high computer density internet data center and the effect of controllable variables of microthermal environment around the computer racks, presents the risk index of electronic components high temperature alarm, i.e., unmatch ratio; carries out the onsite investigation on the situation of air distribution of two internet data centers in Xi’an city, and evaluates the probability of emerging the high temperature alarm, finally puts forward the suggestions of improving air distribution pattern.

Abstract: In this paper, vibration control performance of piezostack active engine mount system for unmanned aero vehicle (UAV) is evaluated via computer simulation. As a first step, the dynamic model of engine mount system which is supported at three points is derived. In the configuration of engine mount system, the inertia type of piezostack based active mount is installed for active vibration control. Then, the vibration level of UAV engine is measured. To attenuate the vibration which is transmitted from engine, a sliding mode controller which is robust to uncertain parameters is designed. Vibration control performances of active engine mount system are evaluated at each mount and center of gravity. Effective Control results are presented in both time and frequency domains.

Abstract: This paper proposes a new recursive based polynomial approach for modeling a hysteresis of a piezostack actuator. The formulation is based on two main curves of hysteresis that are identified experimentally. In the proposed model, an adjusting function that relates the outer curve and its next minor is given. Its coefficients are obtained from the boundary conditions and experiment. From this adjusting function, a recursive-based polynomial formula for the cases of monotonic increasing and decreasing of input excitation are developed to predict the hysteresis. To evaluate the accuracy of the proposed new model, experiments with two different waveforms are carried out.

Abstract: This research focuses on developing a new configuration and optimal design of magneto-rheological (MR) brake for a middle-sized motorcycle which can replace conventional drum-type brake. The proposed MR brake mechanism utilizes a hybrid concept of magnetic circuit (using both axial and radial magnetic flux) to generate braking force. In the optimization, the required braking torque, the temperature due to zero field friction of MR fluid, the mass of the brake system and all significant geometric dimensions are considered. After a brief introduction of the proposed MR brake configuration, the braking torque is derived based on Herschel-Bulkley rheological model of the MR fluid. The optimal design of the MR brake is then analyzed. An optimization procedure based on the finite element analysis (FEA) integrated with an optimization tool is used to obtain optimal geometric dimensions of the MR brake. From the results, discussions on the performance improvement of the optimized MR brake are described.

Abstract: Under high temperature conditions, such as fire, high performance concrete will undergo material degradation or even spalling. Spalling is the most detrimental damage to concrete structures. To prevent concrete from spalling, the mechanism should be understood. In this paper, an anisotropic damage model, in which both the thermal stress and vapor pressure are incorporated, is presented to analyze the spalling mechanism. The spalling phenomenon is studied based on two cases of different moisture contents. It is concluded that when the vapor pressure is present, concrete will behave much more brittlely.

Abstract: Hard and brittle materials such as ceramics and glass are not only difficult-to-machine but also occur easily cracks at the exit surface in through-hole drilling. This paper deals with through-hole drilling of glass plate for plasma display panel using an electroplated abrasive grain tool in order to find out drilling conditions for smaller cracks, higher drilling efficiency and longer tool life. In particular, the influence of the crack in two kinds of abrasive grain is examined. The main conclusions obtained in this study are as follows. The crack in diamond grain tool is smaller than that in CBN grain tool. Moreover, the tool life of diamond grain tool is longer than that of CBN grain tool. Adhered volume of chip increases with drilling numbers, so the crack size and the thrust force increases. The washing of tool is required in order to restrain crack and force.

Abstract: We consider a possible equilibrium configuration under dead load of a vertical cylindrical specimen which is composed of a mixture of two elastic materials. An energetic approach in the mixture evolution is performed and this particular approach can be utilized to describe the bi-phase characterization of the mixture material. Our final aim is to build a theoretical simple model to determine the decrease load bearing capacity of mixture.

Abstract: This study aimed to make the slurry droplets atomized by the ultrasonic atomization spray coating diversion system fall on the substrate surface of hot plate stably, instead of rebound or spill due to overly high pressure or speed that causes material waste and excessive or non-uniform spray coating. The lateral movement distance of the nozzle influences the uniformity of film thickness distribution, while the lateral movement distance influences the film uniformity and the spray coating efficiency; these two are important parameters to the efficiency of ultrasonic spraying equipments. Therefore, this study conducted a simulation analysis on the atomization flow field of ultrasonic atomization diversion systems, where the distribution of atomization flow field was analyzed at different lateral movement distances of the nozzle. By evaluating the performance of thin film coating, this study attempted to find out the optimal lateral movement distance of ultrasonic precision spray coating. The simulation analysis results were tested on a real machine for validation in order to identify the reliability of the simulation. The simulation result showed that the central part of the film in the position sprayed was thicker; therefore, the nozzle moved 1 cm horizontally at 0.1m/s to thicken the repeatedly sprayed area to improve the overall uniformity of the panel. The study analyzed the spray coating thicknesses according to 16 monitoring points in the repeatedly sprayed area on the panel. According to the thicknesses of the monitoring point positions, when the area that had been sprayed once was sprayed again by the nozzle moving 1cm laterally, the uniformity of overall film on the overall panel was improved significantly.