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The thermodynamics of the exhaust gas recirculation (EGR) cooler is very important for reducing oxides of nitrogen (NOx) emission of diesel engines. Using the CFDesign software, some 3-D fluid thermodynamic models of EGR coolers are established by using the finite element method (FEM); and the temperature, velocity and pressure fields of fluids in the EGR coolers are simulated and verified by experiments...
In order to improve the top-coal recovery in fully mechanized longwall face, the hard top-coal caving was simulated through particle flow program in three dimensions. According to the pressing cracking test of hard coal, the top-coal's fragmentation size and spatial distribution were simulated. Considering the condition of top-coal caving path, the shield beam angle, the friction coefficient between...
Aim to study the stretch forming of complex aircraft skin parts, a numerical method for the skin stretch forming of the aircraft skin parts is presented, which is based on the dynamic explicit method and the Belytschko-Wong-Chiang (BWC) shell element. The motion mechanism of the skin stretch machine is analyzed, and node velocity constraint as a method of the boundary treatment for the skin stretch...
A sliding wear simulation approach based on Archard's wear model was proposed, in which ABAQUS scripting interface was used to simulate the progressive accumulation of wear between contact surfaces. Removal of material caused by wear was implemented by moving boundary nodes. In order to measure wear rates of woven fabric liner, a pin-on-disk experiment was performed. The wear rate of 9.76 × 10-7mm...
Computer-Aided Engineering (CAE) methods are becoming more and more important for the modern industry. However, the applications in the extrusion industry are still limited because of the contradition between the slow simulation speed and the fast die delivery requirement. This paper presents a new fast simplified method for analyzing the exit velocity field of aluminum extrusion. Rigid-plastic finite...
Rapid heating cycle molding (RHCM) is a novel injection molding technology. The mold cavity is heated up to a high temperature before the filling stage, usually higher than the glass transition temperature of the polymer. This new technology can be used to inject plastic parts with a shiny surface, no weld lines and no flow marks. A Rapid Heating Cycle Molding Simulation System (RHCM-S) was developed...
New design method on curved channel of sintering machine is presented through the existing questions in traditional sintering machine, new curved channel shape is established, and deduces curve expressions of each arc in front and back curved channels. Parameterized design method of curved channel is researched based on Unigraphics NX (UG) software, realizes one-step forming for multi-curves, improves...
Three degrees of freedom air-bearing Spacecraft simulator have been used for spacecraft attitude determination and control hard verification and software development. In this paper, some details about the simulator are described. The equation of motion of the platform and proof masses on which are deduced according to the assumption that the total angular momentum is zero. An important feature of...
Three dimensional fluid flow between coalescence separator plates with different shapes have been numerically simulated by the standard K-ε turbulence model in Fluent CFD. The separation characteristics of different separators have been compared. The simulated results show that the corrugated plates and the trapezoidal plates both have relatively high separation efficiency and good effects on flow...
To simulate the cleats' effects of coalbed on gas flow, coalbed is considered as double-media composed of rock matrix and cleats. With Weilbull distribution the heterogeneity of young's modulus and strength of rock matrix are simulated, and the cleats (fractured media) are simulated with Desai thin elements. Based on elastic-plastic mechanical theory, gas flow theory and double-media model the seepage-stress...
The constraint force generated by process conditions, such as drawbead resistance and boundary friction are generally considered as positive force in dynamic explicit finite element method, which actually are not in accord with realistic effect. A constraint disposal method for constraint force in sheet metal forming simulation was proposed using linear spring element to build more accurate numerical...
According to the forming principle of helical surface and space analytic geometry, the mathematical model of helical surface was established. Based on the principle of coordinate conversion, the space envelope theory of single parameter surface, and theorem that the contact line between the cutter revolution surface and the helical surface is a space curve, the theoretical models of the helical surface...
According to the surrounding rock stability type determined through fuzzy comprehensive evaluation, bolt and cable support parameters for thick soft coal roadway were selected based on the engineering analogy method. Considering two conditions that the roadway was arranged along the roof and along the floor, the activity law of the roadway surrounding rock was simulated through Fast Lagrangian Analysis...
In this work, an optimization algorithm is presented for nonlinear analysis of space bar structures. The major character of the optimization algorithm is that the equilibrium state with elastic-plastic large deformation is chosen as the study object. Constitutive law adopts linearly elastic and power hardening model. The objective function is defined. The optimization problem is established for nonlinear...
Modeling by FEM, finite element method, is a new product modeling method, through level-constraint of parameter conditions of different anchors to get designed boundary line, and thus makes positive influence on front modeling methods of product design. Access to designed constraint boundary line affected by many factors, this evaluation based on the cognition system of existing model as well as the...
The dynamic working process of the chamber system of shield machine was modeled by discrete element method. Taking the shield machine tunneling in a railway line as the research object, the geometry structure and size of the model was determined. The particle model parameters were calibrated by the triaxial test curves of the soils from the railway ground. Comparing the numerical simulation results...
Introducing a soft region concept depicting the initiating damage of concrete, soft regions are distributed in matrix. Assuming concrete as two-phase composites including matrix and soft regions, considering material heterogeneity, matrix and soft regions' number obey WEIBULL distribution in terms of element failure strength. Changing shear transfer coefficient for an open crack, soft regions volume...
Because of the increasing trend towards deeper mining tunnel, the coalminer and the extraction equipment are working under extreme conditions. In case of accident it is very difficult to rescue the coalminer under these extreme conditions. A passive defense system which must be very strong to withstand various extreme conditions was proposed to prevent harm to labor in the mining accident. The spherical...
During the process of excavations, blasting can induce damage inside surrounding rock, which may change the mechanical properties of rock mass and influence the stability of structure. Considering the effects of material properties and loading conditions, two numerical models, a rock blasting excavation model with two excavation steps and a planar rock model with four boreholes, are developed through...
By using a multi-connected domain body-fitted curvilinear coordinate system, a B-type staggered grid and a technique of moving boundary, a 2D multi-connected domain flow mathematical model is developed to simulate the flow characteristics in complex boundary rivers. The physical domain is mapped into a uniform transformed space. The governing equations are firstly transformed from Cartesian coordinates...
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