Applied Mechanics and Materials Vol. 680

Abstract: In order to improve the output characteristics of active piezoelectric pump valve, Research on dual-chamber tandem piezoelectric pump of combination of active and passive valves is proposed, And dual-chamber tandem piezoelectric pump of combination of active and passive valves is designed and study. The results show that maximum output flow of dual-chamber tandem piezoelectric pump of combination of active and passive valves is 540ml/min, the most output pressure is 27kPa,the maximum output flow of single-cavity active valve piezoelectric pump is 160ml/min;the most output pressure is 9.8kPa, obtained the conclusion that output flow and output pressure of the dual-chamber tandem of combination of active and passive valve is superior to single chamber active valve piezoelectric pump.

Abstract: CFRP has been commonly used in aeronautic and astronautic structures. However, for the character of anisotropy and low interlaminar strength, mechanical joint (such as bolted connection) process’s mechanical behavior for CFRP laminated structure is complicate, and the process parameters of bolt joining is the basis of structural reliability and safety design. In this article, Bolt installation process was analyzed, and theoretical model of pressure force for CFRP laminated plate interference-fit joining has been established.

Abstract: Finite element analysis (FEA) has become an increasingly important tool in evaluating structural performance of platforms. This includes the use of this tool to perform strength, stability checks, optimisation of structural design upon subjected to design loads as well as to perform failure investigation of platforms upon subjected to special loading conditions such as impacts. Traditionally, small and medium enterprises utilises laboratory (physical) testing and heuristic experience to fabricate and test the platforms, nonetheless this approach is deemed too time consuming and cost demanding. Therefore, this study aims at reconstructing the actual design based on engineering drawings as well as performing stress analysis by means of a commercial FEA software package, ANSYS v14.0 by investigating the effects of two distinct loading impacts on a mild steel platform. The maximum stress and maximum displacement values obtained via the FEA simulation was then compared with values obtained via theoretical computation. The results obtained via the FEA simulation was found to be in good agreement with the exact solution. The present study is non-trivial as it contributes towards the knowledge in the design and optimisation of complex steel structures.

Abstract: A trigonometric shear deformation theory is presented to analyze the free vibration of functionally graded plate. The Navier-type analytical method is used to solve the governing differential equations. The natural frequencies of simply supported functionally graded plates are calculated and compared with the available results.

Abstract: Extremely flourishing roots of aeroponic plant lead droplets difficult to penetrate into the core of roots. This phenomenon is so-called “external is wet but internal is dry” and seriously affects areoponic efficiency, even result in aeroponic culture failure. In order to research droplets penetrating roots performance in ultrasonic aeroponic system, an intelligent test device was developed. This device included two ultrasonic nozzles whose working frequencies were 1.7MHz and 40kHz respectively, nozzles’ drive circuit, acquisition system of humidity and temperature based on ARM 9.0 and axial flow fan. The following conclusions were suggested: under the mature cherry tomatoes root system density cultured in aeroponic system, droplets generated by 1.7MHz ultrasonic atomizing nozzle were easier to penetrate into the core of the root; both size and concentration of droplets influenced droplets penetrating into the root; when 1.7MHz nozzle was used to atomization, the best penetrating condition was found in supply air rate 0.021and spray volume 0.4L/h; for 40kHz atomizing nozzle , the best penetrating condition was found in supply air rate 0.021and spray volume 1.2L/h; for 1.7MHz nozzle the worst work conditions of penetrating into the root were that supply air rate was 0.014and spray volume was 0.8L/h and for 40kHz nozzle that was supply air rate 0.033and spray volume 1.2L/h.

Abstract: This paper presents an investigation on cold bending process using simulation and experimental study. The experimental and simulation was performed on stainless steel 304 sheet metal in air V-bending. The factors involved in the process are punch radius, die radius, die gap, punch travel and punch velocity. The aim of this paper is to investigate the factors that affect the springback behavior of stainless steel in air V-bending using Finite Element Method (FEM) software Simufact-Forming^TM version 11.0 and material database MatILDa. The simulation parameters followed the actual setting under consideration of the machine characteristic and friction. The simufact.forming^TM simulation was further verified using hydraulic press machine with determine the desired speed of the forming punch. As the final result, comparison effect of springback between simulation and experiment is presented. It can be concluded that Simufact.forming^TM software can gave fast solution analysis time in prediction of springback affact with good agreement between simulation and experimental.

Abstract: Kinematics parameters calculation is the basis of piston pump design and performance analysis. Taking an axial piston pump with incline piston and spherical swash plate as the research object, Aimed at the deficiency of current formula for calculating piston pump kinematics parameters which included displacement, velocity and acceleration. In this paper, according to piston pump part motion geometry relationship, a correction kinematics algorithm is deduced by using the the spherical coordinate and cartesian coordinate transformation method, the analyse method and deduction procedure ensure the new calculating formula are precise in theory. Applying the calculating formula to an aero engine fuel axial piston pump, results show that. The displacement, velocity, acceleration according to the kinematics principle of piston pump, it can be used in the kind of piston pump kinematics parameters calculation and current calculating method evaluation.

Abstract: With the development of the aero engine control technique, aero fuel centrifugal pump with integrated inducer and impeller meet the requirements better than the divided pump. This paper established the hybrid network of the centrifugal pump which adopted multi-block topology structure and octree format, analyzed the internal flow field performance of the pump based on numerical simulation. The simulation datas compared with test datas show that under different calculation conditions, head error of the simulation data and experimental data is less than 1%, and the efficiency value of error is less than 5%. The simulation method can accurately calculate the performance of the pump. The simulation analysis shows that the asymmetry of the impeller internal pressure is appreciable under different flow conditions because of the inlet length, under other small flow conditions. The most dramatic change is the pressure in the impeller channel, and the pressure under large flow conditions is lower than that under other flow conditions. In fixed location of the pressure side, there may produce low speed flow group, the situation is the same as in the entrance to the attachment of back pressure side.

Abstract: Exhaust gas temperature (EGT) is an important parameter for aeroengine. By monitoring the change in trend, can effectively predict the engine take-off performance. The characteristics of takeoff EGT were introdeced firstly. Two methods of estimating takeoff performance were analyzed subsequently. According to the statistical data, EGT can be used for takeoff performance prediction.

Abstract: Precision feeding is essential for micro-stamping, especially in multi-stage progressive forming operations, where necessary feeding rates also have to be maintained. Research in micro-stamping of thinner sheet metals (<100 microns) led to investigations of the performance of existing sheet-metal feeders, regarding their accuracy and repeatability in high speed micro-stamping. The results indicated that the pursuance of higher feeding accuracy and repeatability which aimed at 5-15% of the strip thickness was unachievable with the existing micro-feeders. A new high-precision and high-speed feeder was, therefore, developed for micro-sheet-forming. Initial non-optimized experimental results had showed high accuracy and repeatability were achieved.