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Article
Publication date: 1 February 1992

KEVIN M. O'CONNOR and CHARLES H. DOWDING

To simulate the kinematics associated with mining‐induced subsidence in a blocky rock mass, a hybrid rigid block model was developed by combining a small displacement code…

Abstract

To simulate the kinematics associated with mining‐induced subsidence in a blocky rock mass, a hybrid rigid block model was developed by combining a small displacement code with a large displacement code. Gravity was applied to a rigid block mesh using an implicit formulation and the equilibrium displacements are then used as initial conditions for an explicit analysis in which excavation of a longwall mine panel and subsequent subsidence was simulated. A parameter study was performed to evaluate the influence of rigid block contact stiffness, vertical joint density, and contact roughness on mining‐induced strata movements for comparison with previously obtained field measurements. The best agreement between measured and calculated displacements was obtained when a relatively low stiffness value was maintained constant for all contacts. A surprising result was that neither increasing the density of vertical joints nor reducing the rigid block contact roughness improved the agreement between measured and simulated displacements.

Details

Engineering Computations, vol. 9 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 February 1992

PETER A. CUNDALL and ROGER D. HART

Discrete element methods are numerical procedures for simulating the complete behaviour of systems of discrete, interacting bodies. Three important aspects of discrete…

2309

Abstract

Discrete element methods are numerical procedures for simulating the complete behaviour of systems of discrete, interacting bodies. Three important aspects of discrete element programs are examined: (1) the representation of contacts; (2) the representation of solid material; and (3) the scheme used to detect and revise the set of contacts. A proposal is made to define what constitutes a discrete element program, and four classes of such programs are described: the distinct element method, modal methods, discontinuous deformation analysis and the momentum‐exchange method. Several applications and examples are presented, and a list is given of suggestions for future developments.

Details

Engineering Computations, vol. 9 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 January 1995

P. Drazétic, R. Tassin and Y. Ravalard

Rigid multibody modelling is used to study the crash‐relatedglobal behaviour of transport vehicles. These models are made up rigidbodies, joints and springs. Distinct…

Abstract

Rigid multibody modelling is used to study the crash‐related global behaviour of transport vehicles. These models are made up rigid bodies, joints and springs. Distinct kinematic models have been developed in order to analytically determine the resistance to collapse of thin‐walled structures of simple geometry subjected to compression or bending loading. The modeller must position these different elements but has no information on their numbers and their locations. For this reason, a modelling aiding tool, based on the elastic buckling analysis, has been developed. This method is used to resolve a problem of an “S” frame undergoing a collision against a rigid block to estimate its validity.

Details

Engineering Computations, vol. 12 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 March 2004

J.P. Morris, M.B. Rubin, S.C. Blair, L.A. Glenn and F.E. Heuze

We present the preliminary results from a parameter study investigating the stability of underground structures in response to explosion‐induced strong ground motions. In…

1642

Abstract

We present the preliminary results from a parameter study investigating the stability of underground structures in response to explosion‐induced strong ground motions. In practice, even the most sophisticated site characterization may lack key details regarding precise joint properties and orientations within the rock mass. Thus, in order to place bounds upon the predicted behavior of a given facility, an extensive series of simulations representing different realizations may be required. The influence of both construction parameters (reinforcement, rock bolts, liners) and geological parameters (joint stiffness, joint spacing and orientation, and tunnel diameter to block size ratio) must be considered. We discuss the distinct element method (DEM) with particular emphasis on techniques for achieving improved computational efficiency, including the handling of contact detection and approaches to parallelization. We introduce a new approach for simulating deformation of the discrete blocks using the theory of a Cosserat point, which does not require internal discretization of the blocks. We also outline the continuum techniques we employ to obtain boundary conditions for the distinct element simulations. We present results from simulations of dynamic loading of several generic subterranean facilities in hard rock, demonstrating the suitability of the DEM for this application. These results demonstrate the significant role that joint geometry plays in determining the response of a given facility.

Details

Engineering Computations, vol. 21 no. 2/3/4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 15 October 2018

Irum Inayat, Rooh ul Amin and Malik Mazhar Ali

This paper aims to propose an improved and computationally efficient motion simulation of a flexible variable sweep aircraft.

Abstract

Purpose

This paper aims to propose an improved and computationally efficient motion simulation of a flexible variable sweep aircraft.

Design/methodology/approach

The motion simulation is performed on hardware-in-the-loop simulation setup using 6 degree-of-freedom motion platform. The dynamic model of a flexible variable sweep aircraft, Rockwell B-1 Lancer is presented using equations of motions for combined rigid and flexible motions. The peak filter is introduced as a new method to separate flexible motion from aircraft motion data. Standard adaptive washout filter is modified and redesigned for an accurate flexible aircraft flight simulation. The flight data are generated using FlightGear software. Another motion profile with significant oscillations is also tested. The peak filter and the modified adaptive washout filter both are used to process the data according to the motion envelop of motion platform.

Findings

The performance of the modified adaptive washout filter is evaluated using hardware-in-the-loop simulation setup and results are compared with the standard adaptive washout filter. Results exhibit that the proposed method is computationally cost-effective and improves the motion simulation of flexible aircraft with close to realistic motion cues.

Originality/value

The proposed work presents motion simulation of a flexible aircraft by introducing a peak filter to extract flexible motion in contrast to the traditional motion separation methods. Also, a modified adaptive washout filter is designed and implemented in place of the traditional washout filters for improved flexible aircraft flight motion simulation.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 9
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 August 1998

Jaroslav Mackerle

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder…

4004

Abstract

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder metallurgy and composite material processing are briefly discussed. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for 1994‐1996, where 1,370 references are listed. This bibliography is an updating of the paper written by Brannberg and Mackerle which has been published in Engineering Computations, Vol. 11 No. 5, 1994, pp. 413‐55.

Details

Engineering Computations, vol. 15 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 9 March 2015

Lidui Wei, Haijun Wei, Shulin Duan and Yu Zhang

The purpose of this paper is to develop a good calculation model to accurately predict the lubrication characteristic of main bearings of diesel engine and improve the…

Abstract

Purpose

The purpose of this paper is to develop a good calculation model to accurately predict the lubrication characteristic of main bearings of diesel engine and improve the service life.

Design/methodology/approach

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the Component Mode Synthesis (CMS) method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an elastohydrodynamic (EHD)-mixed lubrication model of the main bearings for the diesel engine is developed and researched with the finite volume method and the finite element method.

Findings

Obviously, the mixed lubrication of bearings is normal, while full hydrodynamic lubrication is transient. The results show that under the whole flexible block model, maximum oil film pressure, maximum asperity contact pressure and radial shell deformation decrease, while minimum oil film thickness increases. Oil flow over edge decreases, and so does friction loss. Therefore, coordination deformation ability of whole engine block is favorable to mean load. In the whole block model, friction contact happens on both upper shell and lower shell positions. In addition, average oil film fill ratio at the key position becomes smaller in the whole engine block model, and consequently increases the chances of cavitations erosion more. So, wearing resistance of both upper and lower shells and anti-cavitations erosion ability must be enhanced simultaneously.

Originality/value

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the CMS method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an EHD-mixed lubrication model of the main bearings for the diesel engine is built, which can predict the lubrication of journal bearings more accurately.

Details

Industrial Lubrication and Tribology, vol. 67 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 May 1994

N. Brännberg and J. Mackerle

This paper gives a review of the finite element techniques (FE)applied in the area of material processing. The latest trends in metalforming, non‐metal forming and powder…

1404

Abstract

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming and powder metallurgy are briefly discussed. The range of applications of finite elements on the subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for the last five years, and more than 1100 references are listed.

Details

Engineering Computations, vol. 11 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 February 2013

M. Mahbubur Razzaque and Muhannad Mustafa

The purpose of this paper is to present a parametric study of the effects of permeability and surface roughness on the hydrodynamic force and the leakage flow rate in an…

Abstract

Purpose

The purpose of this paper is to present a parametric study of the effects of permeability and surface roughness on the hydrodynamic force and the leakage flow rate in an oscillating squeeze film between a rigid surface and a rubber surface.

Design/methodology/approach

The study is conducted numerically using a squeeze film model that incorporates the effects of viscoelasticity, permeability and surface roughness.

Findings

It is seen that with increasing permeability of the porous rubber block, both the hydrodynamic force and the leakage flow rate decrease. Increasing center line average (CLA) of surface roughness height distribution decreases the leakage flow rate slightly but increases the hydrodynamic force. The decrease in the hydrodynamic force due to using permeable material in squeeze film may be compensated for by deliberately increasing the surface roughness. The effect of variation in frequency of system vibration may be minimized by using optimally selected permeable materials with rough surface.

Originality/value

The paper reports the extension of previous work of the authors and the results of this portion were never published. The findings of this paper are based on original work and have practical value.

Details

Industrial Lubrication and Tribology, vol. 65 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 February 1992

R. BARBOSA and J. GHABOUSSI

A numerical technique is described for the analysis of multiple interacting deformable bodies undergoing large displacements and rotations. Each body is considered an…

Abstract

A numerical technique is described for the analysis of multiple interacting deformable bodies undergoing large displacements and rotations. Each body is considered an individual discrete unit, which is idealized by a finite element model. Discrete finite element models interact with their surroundings through contact stresses, which are continually updated as the elements move and deform. The method of analysis consists of a finite element formulation based on a generalized explicit updated Lagrangian method. This formulation is a general finite element formulation, that permits the large deformation analysis of both continuum and discontinuum systems. Different validations of the proposed method of analysis, including cases that involve very large rotations, as well as some examples that demonstrate the application of the discrete finite element method to problems in rock mechanics are presented and discussed in the paper.

Details

Engineering Computations, vol. 9 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

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