Applied Mechanics and Materials Vols. 10-12

Abstract: The development of a flight simulator is a challenging work because of its complexity and tremendous cost. We implement a prototype composed of PC cluster and have proved its coordination character as a flight training device. This paper describes the architecture of the flight simulator, the software development tools and hardware platform. These software and hardware constitute a PC based simulation environment and make the expense of the simulation application affordable. We also present the simulation modeling process. For the integrity of the cueing system, we designed a virtual prototype of motion system and connected it to the flight simulator. The integrated system gave us a chance to testify the coordination of the simulator. The verification method and result are presented to show the feasibility of the design based on PC.

Abstract: Due to cutting parameters playing an important role in machining economics and machining qualities, much attention has been paid to select optimum cutting parameters. In this paper, cutting parameters optimization for constant cutting force was discussed based-on virtual machining comprehensively. Particle swarm optimization (PSO) was used to seek for the optimal spindle speed and feed rate. The framework of virtual machining based cutting parameters optimization was established. Then two controlled experiments were conducted to demonstrate the effectiveness of cutting parameters optimization both with physical cutting and computer simulation. The results of experiments show that machining process with constant cutting force can be achieved via cutting parameters optimization based on virtual machining.

Abstract: It is very important to improve machining efficiency and ensure manufacture quality through testing NC program of aspherical elements machining with simulation software. For ultra -precision NC machining tool, we analyzed the tool path of ultra-precision grind for aspherical elements, edited a simulation software of the path, got a structural chart of the software, analyzed some important module of the software. In fact the software is able to imitate tool path, test the correctness of numerical control code according to numerical control code edited.

Abstract: Shot peening is a cold-work process in which a stream of small spherical shot is blasted against a metallic component to generate a high compressive residual stress regime at the surface of the target. This paper presents a computational modelling of the shot peening process, in which the finite element (FE) method was employed to study the elastic-plastic dynamic process of the shot impact on a metallic target, and the discrete element (DE) method was used to study the multiple particles dynamics. Statistical analyses of the shot impact data reveal the relationships between peening process parameters and peening intensity, which can be used to optimise these process parameters to produce an improved outcome.

Abstract: For the application of STEP-NC in NC system, an STEP-NC code translator is exploited. Firstly, summarizes the limitation of conventional standard ISO6983 and the superiority of STEP-NC. After an analysis on two different generating methods of STEP-NC program, introduces the exploited STEP-NC code translator based on ISO14649. According to inner logical relation, the code translator is composed by six functional modules, an operating principle chart is presented, function and realizing method of every module is disserted on. At last, exampled with a program which includes planar face, pocket, slot, Bezier surface and replicate feature of round hole, planning the whole toolpath of the program using extracted information about workingstep, feature and operation by the exploited STEP-NC code translator. A cutting simulation is made to the toolpath and the workpiece model. The result proves the feasibility of the STEP-NC code translator.

Abstract: With the development of the modern medical imaging technology and the computer technology, and their interaction as well, rapid prototyping manufacturing, and to design or product a 3D visualized accessory system have become reality. Currently, the information of human body obtained by various medical image equipments such as CT, MRI, is limited to 2D plane image of each layer. In order to ascertain the space relation, size, shape of pathologic body, it will have important theoretic and clinic practical meaning when using computer to take 3D reconstruction and rapid prototyping manufacturing from human organs and pathologic body. Aiming at the key technologies of 3D reconstruction from medical CT images, this paper analyzes and uses the isosurface construction method to construct its 3D models. The paper indicates the shortage of the normal MC algorithm that causes huge consumption of operation and is hard to work out, and applies SMC algorithm to take 3D reconstruction from medical spiral CT images. MC method mainly exists some problems, one is that the triangular facets are only approximate to the isosurface, two is that it is also approximate to connect two close edges’ intersection in the same cube with straight line, next, in the method, if the vertex with 0 value and the vertex with 1 value are at both ends of diagonal line respectively, there will be two kinds of possible connecting methods, thus ambiguity exists [1]. Among a few different methods to judge and eliminate ambiguity, the asymptote method [2] is in common use. Aiming at the shortage of MC algorithm and the characteristics of medical CT images, there is another special MC algorithm called SMC, it connects the triangular facets through estimating state value of each vertex of cube, avoids estimating ambiguity by calculating asymptotic line of hyperbolic curve, simultaneously reduces the calculation to the needless cubes, thereby simplifies the reconstruction method. The SMC method is proved to be simple and effective with two samples in this paper.

Abstract: The detecting instrument for surface quality of steel ball bases on embedded control system and image detection technique, and is applied to detect surface defect region of steel ball in bearing. Its control system requires excellent real-time character and control accuracy. This paper puts forward a new design for controller of detecting instrument. We adopted TMS320LF2407A which produced by company TI as main processor, and integrated CPLD to develop an embedded controller. We used the Ziegler–Nichols tuning methods to get PID control and designed hardware circuit. We realized the function of correlative logic elements through programming, and constructed an embedded multitask operating system based on the transplant of μC/OS-II on TMS320LF2407A. It solved problems about intricate structure and bad real-time character existed in traditional control module. The result of simulation and experiment indicates that this control system satisfied excellently the requirement of high speed and real-time image detection.

Abstract: In industrial practice, for the designers and researchers of the electro-hydraulic servo system, it is desirable to boost the reliability of controllers, to shorten the design cycle of control algorithms, to simplify the modification of control algorithms during experiments and to shorten training period for operators. In this paper, we present a new, complete and integrated method based on the rapid control prototyping for the real-time digital control applied in electro-hydraulic servo system. The approach uses a collection of tools that include both software (LabVIEW and Matlab) and hardware (a host industrial computer and a target developed digital signal processor controller). An application example of the methodology, synchronous loading test system based on artificial neural networks, completes the discussion about the performance of the designed system.

Abstract: Nano-hardness test device has the ability to make the load-displacement measurement with sub-nanometer indentation depth sensitivity, and the nanohardness of the material can be got from the load-displacement curve by Oliver-Pharr method. In order to measure the small displacement accurately, we designed a capacitive displacement measuring system. This capacitance micrometer has a resolution of 0.1nm, and is suitable for our nano-hardness test device.

Abstract: Flight simulator is a complex man-in-the-loop (MIL) simulation system. With several decades of development, it has already become important tools of aircraft design and development, and necessary means of pilot training. And simulation credibility and reliability of the flight simulator have been considerably improved in comparison with the past. However, the system of flight simulator has become increasingly complex and difficult to be described clearly. This paper presents the concepts of conceptual layer and achieving layer, analyzes the composition and principle of the commercial aircraft flight simulator for pilot training from the two layers, describes the system architecture in detail. According to the system architecture, three aspects are very important to develop the flight simulator, the first is the fidelity of the simulation models, the second is the performance of cueing devices, and the last are the computing capacity of the host computers and the time delay over the communication networks.