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Flow in unsaturated soil or soil stimulant, under different gravity conditions is investigated using a numerical model to ascertain the extent to which the lattice Boltzmann model observed flow behavior under reduced and variable gravity conditions. The results of the simulations indicate that the bulk behavior of unsaturated flow is predicted well by lattice Boltzmann equation. For the case of an...
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...
Based on CF-DSGZ viscoelastic constitutive and elastic prediction - plastic correction algorithm, an ABAQUS/Explicit user material subroutine called CF-IMD which can be applied to simulate the thermoforming process of in-mould decoration films, is discussed in the paper. The fundamental principle, program modules and the program flow chart of CF-IMD are introduced in detail. Finally, numerical simulation...
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...
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...
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...
Computational fluid dynamics (CFD) software FLUENT 6.3 has been employed in the present work to study the flow field and mixing process in a stirred tank equipped with four side-entering agitators. The multi-reference frame (MRF) and standard k-ε turbulent model were used in the simulation. The effects of tracer feeding, detecting positions and impeller speeds on mixing time were investigated. It...
This paper introduces Laser Micro Composite Texture on the surface of the Drawing Die, which is a new technology to effectively control the friction characteristics of different region. Geometry shape of the cylinder-shaped Drawing Die model has been established by the ABAQUS software. The effect of the flange and bottom materials flowing was analyzed in the sheet forming, and the sheet fracture and...
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...
Concrete fails in a localized pattern. In this paper, a uniaxial stress-strain relation incorporating hardening and stiffness degradation is developed for plastic-damage constitutive models for concrete, which reduces mesh sensitivity in the localized strain softening process, while a reasonable stress-strain curve is maintained for the uniform strain hardening process. The proposed formulation can...
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...
In the previous studies on heat transfer performance of the flat-tube and multi-louvered fin heat exchangers, most of the numerical studies generally select a heat transfer unit as the computational domain for the effective realization of CFD (Computational Fluid Dynamics). The majority of the numerical studies usually simply treated the flat-tube water side as fixed wall temperature or convective...
The combined steel lead damper (CSLD) is made up of steel and lead material skillfully. It is a high performance damper with merits of simple production process and economy. Based on the test study of I-section CSLD, take into account the nonlinear constitutive relationship of materials and the contact action between the two materials, finite element models were proposed to simulate the damper. The...
Strain mode is sensitivity to structure local characteristics and wavelet transform has high local property in time and frequency domain. By combining the character of strain mode and wavelet transform, strain mode is adopted as response signal to continuous wavelet analysis for damage identification. Damage location is detected by modulus maximum and damage extent is detected by Lipschitz exponent...
Generally, the geometric non-linearity is ignored in numerical simulation, especially in some numerical simulation of concrete structure, but now it is confirmed by a large number of experiments that the response of the concrete structure under ultimate load depends both on material nonlinearity and geometric non-linearity. So in order to analyze the fracturing behavior of the structures under ultimate...
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