Abstract: Projectiles with fixed canard trajectory correction kit use Brushless DC motor (BLDC) with position sensorless to control fixed canard. Through the roll in the process of fixed canard trajectory correction kit flight direction by moment analysis and simulation, then electromagnetic torque values range is determined. Control effect of electromagnetic torque simulation, determine from the electromagnetic torque to meet the requirements in the process of correction.
Abstract: Unlike commercial sliding rails, space sliding rails need to meet complex mechanical requirements in the state of ground tooling, launch and on-orbit. The former could slide smoothly while their carrying capacity is low. As a result, they cannot be applied directly to the space stations, manned spacecrafts and other space probes. Hence, it is necessary to design a kind of full-pulling sliding rails which can be suitable for three completely different mechanical conditions. In this paper, we firstly built the mechanical models of the ground tooling, launch and on-orbit state, then a kind of sliding rails is designed according to the mechanical models, finally, a simulation analysis was carried out on the designed sliding rail. The result shows that this kind of sliding rails meets all the design requirements, which verifies the validity of the models.
Abstract: The paper deals with numerical analysis of the process of roller straightening of rails. The problem of repeated elasto-plastic bending is solved by a program in MATLAB based on FEM algorithm with Eulerian description of material flow through the straightening machine. Beam element formulation with a shear deformation effect is used for the rail discretization. The results are compared with literature and standard FE analysis with Lagrangian description of material flow. Effectiveness of presented formulation is discussed and its applicability for fast iterative optimization of the straightening process is illustrated.
Abstract: The paper discusses life prediction of pressurized cylindrical container because of its dangerous failure during usage. The fatigue of material and crack propagation were obvious from the fracture surface. Crack initiation was located in the notch root of the thread. Our goal was to review the vessel structural design based on its technical documentation.Two approaches for estimating the crack initiation period were used. As input parameters, stress-strain relations in the notch were obtained from FEM analysis, done in ANSYS Workbench. The first approach makes use of Neuber’s rule based on elastic-plastic shakedown and cyclic stress-strain curve. The second concept (which is described in ČSN EN 13445-3 or AD 2000 Mekblatt S2 respectively) uses elastic shakedown. Included stress-life curves leads to the number of cycles to crack initiation.Finally the subcritical crack growth period and final fracture were estimated = the total life was evaluated.
Abstract: To reduce the energy consumption and blood damage of a centrifugal blood pump, this paper uses a permanent magnet bearing and blood flow pressure bearing to support blood pump impeller, design a magnetic fluid suspension centrifugal blood pump, three-dimensional numerical simulation of a magnetic fluid suspension centrifugal blood pump internal flow field, achieve the pressure of the blood pump flow channel and the velocity distribution, get the relationship between blood pressure and flow rate of the pump. The results can provide a theoretical basis for centrifugal blood pump design and improvement.
Abstract: In order to understand the energy absorption characteristics of various types of steel tubes and provide certain basis for model selection in the engineering application, this paper adopts the experimental study to conduct the comparative study on lateral quasi-static compression energy absorption characteristics of three types of steel tubes, i.e. round steel tube, square steel tube and hexagonal steel tube. Through analysis of the test phenomenon, the total energy absorbed by equal deformation and the energy absorbed per unit mass, the result shows that the steel tube with hexagonal cross section is provided with such advantages as steady absorption, stable deformation mode and high energy absorption ratio, and is more suitable for application in engineering than the round steel tube and the square steel tube.
Abstract: Aiming at researching aerodynamic characteristic of projectiles. This paper builds three simulation models with fins in different amount and appearance, by using CFD software to generate meshes of each model, it simulates the changing laws of drag coefficient, lift coefficient and pitching moment coefficient and analyses correct ability and flight stability of each model according to the data, simulation results indicate that projectile with folded fins have better aerodynamic appearance and can be studied deeper, it provides aerodynamic reference for future research.
Abstract: In this investigation, an improved Fourier series method (IFSM) is employed to predict the static and dynamic characteristics of annular sector plates with arbitrary boundary conditions. Regardless of boundary supports, the displacement function is invariantly expressed as a modified two-dimensional Fourier series containing sine and cosine function. It is capable of dealing with the possible discontinuities at elastic boundary edges. The unknown Fourier coefficients are treated as generalized coordinates, and determined using Rayleigh-Ritz method. Unlike most of the existing solution techniques, the current approach can be universally applied to a variety of edge restraints including all classical cases and their combinations. The accuracy and reliability of the current method are fully illustrated through all the numerical examples.
Abstract: Wenzel-Kramers-Brillouin (WKB) method being an approximation method in quantum mechanics has been applied widely. For the potential problems WKB approximation method is taken as an effective technology. With the help of the WKB approximation method the quantum conditions of bound States particle being in three different typical one dimension (1D) potential well models are derived in this paper. In addition, the idea of the WKB approximation method and the procedures dealing with the potential problems are demonstrated clearly, which are very helpful for understanding the quantum conditions of 1D potential well models deeply and mastering the WKB approximation method to solve some related problems in quantum mechanics.
Abstract: This article has carried on the simulation research of tool wear in electrical discharge machining (EDM) small holes on titanium alloy with the finite element method. Aiming at electrode material removal process in EDM, a 3D thermodynamics model of single pulse discharge material removal is established with Ansys software. By simulating the Gaussian distribution of heat flux and thermal convection loads of discharge channel, the same type of surface heat source is exerted on both positive and negative electrodes with different distribution coefficients and different material characteristics, to analyze the surface temperature field in the region of tool and workpiece processing area, and respectively obtain the heat distribution law along the radius and depth directions of copper and titanium alloy electrodes, in the condition of small hole positive polarity EDM machining on TC4 with copper as the tool electrode. Using the birth and death element method, the volumes of material removal on both electrodes are calculated to analyze the tool wear. The experiments of small hole EDM machining on TC4 are carried out, and the results of simulation and experiment are compared. It is shown that the simulation model can not only accurately predict the relative wear of both electrodes, the simulation results of material removal volumes on both electrodes are also almost accurate.