Applied Mechanics and Materials Vols. 271-272

Abstract: The existing hydraulic excitation mode of valve controlled cylinder or pump controlled motor used in the excitation device of high-speed railway dynamic test system is difficult to meet the requirements of high exciting frequency, high exciting force and high amplitude. To solve these problems, the paper puts forward a bicyclic surface hydraulic cylinder, and designs the corresponding electro-hydraulic servo excitation system. According to the test system parameters，it establishes the mathematical model of the hydraulic system. It uses Matlab/Simulink to carry out theoretical analysis and digital simulation and uses PID Tuner to adjust the PID controller parameters. The simulation results show that the hydraulic excitation system designed meets the performance requirements of the high-speed railway dynamic test system excitation device.

Abstract: As an MLRS (Multiple Launch Rocket System) cage is moved with a uniform speed through an elevation mechanism for MRLS operated using ball screws, its stick-slip behavior can be observed by the friction in a ball screw actuator. In this study, a single-degree of freedom mathematical model of an MLRS elevation system is designed and its stick-slip behavior is analyzed using a friction force model considering the Stribeck effect. The stability of a vibration system is analyzed through deriving an equation of normalized motion for the mathematical model and the influences of mechanical parameters and friction parameters on the vibration response and stability are theoretically analyzed.

Abstract: The device is designed for the solutions of the ready-deformation, hard feeding of the boring rod of conical deep-hole boring, and of impossible boring by the gun drill, BTA drill and DF drill during conical deep-hole boring. The central hole of the boring rod is fitted with boring cutter, rod with double cones, cylindrical rod, threaded and splined rod. The front cone of the rod with double cones is set through the conical hole of boring cutter and reaches only one side of the hole. The rear one of the rod with double cones is in contact with the one end of the springing rod of which the other reaches the surface of bored work piece. The industrial endoscope is set within the hole drilled in boring rod. The servo motor, by the way of NC device, is linked with pulse generator, which connects the principal axis of lathe. The design is advantaged with a springing rod which prevents the deformation of boring rod, and with servo motor, NC device, and industrial endoscope supporting conical deep-hole boring of high precision.

Abstract: The design process comprises the Conceptual Phase, the Embodiment Phase and the Detail Design Phase in which commercial PLM/CAD systems mainly support the latter ones. This situation causes the discontinuity in the overall design information flow: Customer Needs (CNs) - Functional Requirements (FRs) – Design Parameters (DPs) – Key Characteristics (KCs) – Geometric Parameters (GPs). There is also a lack of knowledge reuse in routine design process, resulting in large cost-waste of the overall design process. Aiming to enhance the continuity of the design information flow and facilitate the knowledge reuse, this paper makes use of a knowledge-based framework to integrate conceptual design tools: Quality Function Deployment (QFD), Axiomatic Design (AD), Failure Mode and Effects Analysis (FMEA) and the MOKA methodology into CATIA v5 system. A knowledge-based application (KBA) on the large aircraft y-bolt component design is presented as a case study to validate the proposed framework. The result shows how this novel integrated framework and KBA system could benefit designers in a practical way.

Abstract: Frame structure is widely used in practical projects. For jitter of the frame structure excited by median and high frequency disturbances, firstly, the dynamic model of thin plate substructure is built by wave method, and then the dynamic model of frame structure is established by combining wave method and substructure technique. At last, the accurate dynamic response was obtained. The simulation of dynamic characteristic is made, and simulation results are compared with FEM results. On this basis, modal experiment and frequency response experiment is done to verify theoretical results. In comparison to FEM, the results by wave method are accurate in low frequency regions, and the results are more accurate in the median and high frequency regions. The experiment proves wave method is correct and effective for jitter transmission analysis of frame structure in the median and high frequency regions.

Abstract: The role the rimming fixture is to ensure the models and the front cover having no relative motion in rolling process, and quality of fixture layout can influence if the cover edge has quality defects such as undulated in rimming process. First, this paper analyzes composition of the rimming bottom die and positioning clamping mechanism in rimming fixture, and obtains stressed situation of front cover edge under the action of rimming and stamping by the roll head by using the result of finite element analysis to the rimming process of front cover, combining with the design requirement of processing datum graph, the production program of engine hood, production class system and actuating rate 、failure rate and production rhythm of production lines, establishes distribution points of rimming fixture and finally designs the rimming fixture of engine hood. The fixture is currently used in actual production with stable and reliable performance.

Abstract: In order to control the 6-DOF Stewart mechanisms to move accurately with given position and pose, technology of virtual reality, simulation and modeling are adopted, kinematic/dynamic model of Stewart mechanisms is built, under the physical displacement its movement is computed and simulated, by which the difficult problem of solving the normal kinematics solution of Stewart mechanisms is solved. Compare the pose curves of mechanisms top platform which are initialized and solved by simulation, the resemblance of two curves shows that the solving method of Stewart mechanisms is correct and accurate, and it can be used in controlling of real mechanisms.

Abstract: In order to study the influence of key hinge point’s positions to the kinematical performance of the face-shovel hydraulic excavator working device, a forward kinematics model of the working device is presented firstly. And then the simulation model is established in ADAMS. The working processes are simulated and the bucket digging envelope diagram is drawn. Then different simulation models in ADAMS are established by using Monte Carlo method to sample data which are the range of key hinge point’s position. According to a certain order and requirement of objective response, the model with better motive performance can be chosen. The results show that the chosen model has better kinematical performance than that of the initial model where all of important objective responses can be improved differently.

Abstract: New type of 2PPRR-ST-2PPRR mechanism in singular configuration,kinetics equations and Euler’s equations constructed,complete analysis of each jointed points of the moving platform carried out,inverse kinetics solution can be obtained with the given parameters,which include the position and orientation of the manipulator,applied force on the output shaft,parameters of motion of output shaft and connecting bar and sliding block,Newton-Euler method adopted to analysis its kinetics,program used to get the intuitionistic graph result of analysis,conclusion deduced from the result,difference exist in the changing rule of force of joints on upper layer platform and under layer platform,the changing rule of force of joints on the same platform is the same,sensitive exist in direction of axis x,y,z of force of joints on under layer platform,while sensitive exist in direction of axis z of force of joints on upper layer platform only.

Abstract: To tackle process knowledge discovery difficulty in machining process, this paper studies knowledge discovery method of 2.5–dimensional machining characteristics based on process model with model based definition technology, and finds out machining process design knowledge with the natural structured process description ability of MBD process model. Firstly, the composition of machining geometry ontology and process ontology is analyzed. Secondly, decision tree between ontology are obtained by analyzing abundant samples of MBD process model. Thus, the process and method of reasoning from geometry ontology to process ontology is achieved. Finally, the validity of process knowledge discovery method is exemplified with a group of MBD process models.