Advanced Materials Research Vols. 139-141

Abstract: The forming process and dynamic behaviors of droplets in gas metal arc welding (GMAW) were numerically simulated by using weak electromagnetic coupling method, with considering the gravity, the electromagnetic force, the free surface and the turbulent flow in the droplets. The shape update of the droplets was calculated on basis of VOF and CSF theories. The Gaussian electric current density was identified as boundary conditions for calculating electromagnetic force. A weak electromagnetic coupling model was used to study the characteristics of relevant physical variables and their roles in metal transfer. The simulation results suggest that the maximal value of electric current density lies in the neck of droplets, and the electromagnetic force has great effects of accelerating droplets’ contraction and shortening their falling time. Under the action of strong electromagnetic force, the metal transfer is in a spray form rather than a globular one in GMAW process. The simulated results agree well with theoretical analyses and predecessors’ experiments.

Abstract: The stress distribution of adhesively-bonded single lap joints under tensile shear loading is analyzed using 2-dimensional elastic-plastic finite element method (FEM). Special attentions have been put on the influence of void in adhesive on the stress distribution of adhesively-bonded joints. The results show that the stress concentration of the void is less than that of the end part of the joints when adhesive layer’s deformation was in the range of elastic. Moreover, the influence of the void on the stress distribution becomes less when the void moving from the end-part to the middle. The stress concentration becomes larger and the stress distribution of adhesive’s mid-thickness region becomes flatter when adhesive layer has biggish plastic deformation. Finite element results show an agreement with the theoretical results.

Abstract: This paper proposes an effective method to determine the optimal parameters settings of reflow soldering profile and helps reduce the try-and-error time in practical application. Due to the complex nonlinear relationship between reflow thermal profile and process parameters in this problem, BPNN is adopted to establish the model for description of this intricate relationship between inputs and outputs. According to the requirements of the reflow soldering profile, GA is used to calculate the best input parameters with its strong global research ability. Thus, a combined model with BPNN and GA is proposed for parameters optimization and contributes to reduction of decision time of input parameter for reflow soldering profile. In addition, a case study is given to prove the accuracy of the proposed method.

Abstract: To design a machine tool successfully, its essential parts should be analyzed and evaluated during the process of design. The liner motion guide is one of the most essential parts of the machine tool. So it is very important to analyze the dynamic-static characteristic of the machine tool consider linear motion guide and to study the effect on machinery function. The paper’s research is based on a NC machine tool produced by a certain plant of machine tools. Methods of simulating the linear rolling guide support are studied, and the configuration of the spring damper elements of the bearing supports are also studied, and the finite element analysis on the CKS6125 machine tool has been made to confirm its dynamic characteristics. Then the finite element analysis models are validated by some experiments.

Abstract: Based on the kinematic model with Cartesian structure, Newton-Euler like algo¬rithm being employed to solve the nonlinear equations of motion and constraints in real-time application, and dynamic multibody simulation, a novel integrated design for a 6-DOF ro¬bot is investigated, and the interfaces required for the implementation of different computer aided engineering (CAE) tools used in the design is addressed [1].The presented method in this paper was analyzed and verified by the numerical and physical 6-DOF robot model, the result shows that the topologic projection me-thod [2] is stable. The design experience accumulated will be very useful for the future product de-sign.

Abstract: For the single crystal (SC) Ni-based superalloys, it is difficult to avoid orientation variation along airfoil stacking line of the SC turbine blade. At the mean time, the loading of turbine blade is uncertainly during the working. In this work, the creep life of the SC turbine blade is determined by the finite element analysis (FEA) based on the crystal slip theory. The orientation variations are measured based larger numbers commercial turbine blade made of SC superalloys. Furthermore, Monte-Carlo method and the forth moment method are presented to analysis the reliability for creep life of SC turbine blade under random crystal orientations and random loads based on the FEA method. The basic variables sensitivity are comprehensively analyzed by the forth moment method.

Abstract: Developed a device used to assist workover rig in lifting stuck tubing strings from the well during workover treatment, it can create well economic benefit for oil field. The device adopts remote hydraulic control, which is safe and reliable. The structure and work principle of the device is illustrated. The jam release device is mainly made up of hydraulic cylinders, hydraulic pump and hydraulic control valves. With the coordination between lifting hydraulic cylinders and hydraulic slips, the device can lift tubing strings from the well. The important loading unit of the device is analyzed by finite element. The working pressure is made from 5MPa to 20MPa, corresponding to lifting force range of 229kN to 915.6kN, which can meet the jam release force in workover treatment.

Abstract: So as to design the pavement planer, it is necessary to study the milling performance of asphalt concrete. In this work, a coupled thermo-mechanical plane-strain large deformation orthogonal cutting finite element model is presented to simulate the asphalt concrete milling process and predict the stress and temperature field on the cutter. Chip separation is considered by applying shear fracture failure criteria and element deletion and adaptive mesh technique. Two contact pairs are defined. Contact pair 1 defines the milling path, and contact pair 2 defines to prevent the formed chip enter into the workpiece. The Johnson-Cook’s constitutive relation is adopted for the asphalt material. The cutter surface friction and heat conduction are considered. The computation indicates that the maximal cutting force will change from 3.967KN to 10.494KN if the cutting speed is between 1000mm/s and 2000mm/s for the pavement planer of BG2000.

Abstract: The breech mechanism is a very important part of artillery with a high failure rate. It is planned to build a test-platform for the investigation of the breech mechanism. By this test-platform the motion of the breech, while the artillery is shooting, can be simulated as the same. While the artillery is shooting, the energy for the opening and shutting action of the breechblock comes from the impact between the breechblock operating cam and crank, when the breech is returning. But this action of a hugely heavy thing is very difficult to simulate. So the negative direction action is considered, which makes the breechblock operating cam moved to impact the crank. In this paper the virtual prototype model based on ADAMS is used to measure the load etc. of the key-parts of the breech mechanism by simulation experimentations.

Abstract: To our knowledge, there is no paper in the open literature dealing with the topic in the title. This paper provides an Information Coding Ontology Model (ICOM) to shield semantic heterogeneous of information resources, and to achieve information integration. Sections 1 and 2 of the full paper present the information coding ontology model and its formal definition, then design the mapping framework of the information coding ontology model. Section 3 discusses the mapping algorithm of the information coding ontology model from three aspects: semantic similarity analysis, obtaining semantic similarity algorithm, and semantic mapping and its implementation. Section 4 gives Fig. 7 as the mapping flow chart of the information coding ontology model and uses a numerical example to illustrate the four-step procedure of the mapping implementation process.