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Article
Publication date: 1 January 1984

M. Geradin and N. Kill

A 3‐dimensional formalism adapted to critical speed and stability analysis of rotating machinery is presented. Gyroscopic effects are properly taken into account in the expression…

557

Abstract

A 3‐dimensional formalism adapted to critical speed and stability analysis of rotating machinery is presented. Gyroscopic effects are properly taken into account in the expression of the kinetic energy through a proper kinematic description which takes account of the local changes of angular velocity induced by the deformation. Two approaches are suggested according to the respective stiffness and geometric properties of the rotating and fixed parts: the rotating frame approach and the inertial frame approach. In both cases, an axisymmetric finite element modelling of the rotor is proposed which takes into account the 3‐dimensional nature of the system while keeping the number of degrees of freedom to a reasonable level. In order to perform the stability analysis, a preliminary reduction of the system is achieved using the component mode method. Critical speeds are calculated next either by the classical sweeping procedure or by a direct method when the restrictive conditions of its applicability are met. The concepts proposed are then applied to an example in order to demonstrate their adequacy.

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

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Article
Publication date: 1 February 1984

M. Geradin, G. Robert and A. Huck

The computer implementation of a method for calculating coupled vibration eigenmodes and eigenfrequencies and the transient response of an elastic enclosure filled with a…

105

Abstract

The computer implementation of a method for calculating coupled vibration eigenmodes and eigenfrequencies and the transient response of an elastic enclosure filled with a compressible fluid is described. The formalism is based on a simultaneous discretization of the fluid pressure and the fluid displacement potential. Attention is focused on the resulting form of the dynamic equilibrium equations and on their solution both in free vibration and transient analyses. In the eigenvalue analysis, an adapted Lanczos iteration scheme is proposed which takes account of the specific form of the equations. Applications are presented which demonstrate the effectiveness of the method.

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Engineering Computations, vol. 1 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 September 1997

S.L. Chen and M. Géradin

The non‐linear dynamics due to rotor‐stator contact is simulated using the finite element method. Develops and describes a general contact finite element. By implementing this…

613

Abstract

The non‐linear dynamics due to rotor‐stator contact is simulated using the finite element method. Develops and describes a general contact finite element. By implementing this element into a powerful multibody dynamics software, different rotor global motions are analysed. Special attention is also given to determine the effects of rotation speed and friction on the rotor orbit during contact.

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Engineering Computations, vol. 14 no. 6
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 April 1994

A. Cardona, I. Klapka and M. Geradin

This paper presents the architecture for a new finite element program written in the C++ programming language. A powerful command interpreter allows the user not only to introduce…

108

Abstract

This paper presents the architecture for a new finite element program written in the C++ programming language. A powerful command interpreter allows the user not only to introduce data, but also to define the algorithms that will treat this data to obtain the desired results. In this way, the program can be very easily configured to new computational strategies. By following an object‐oriented programming technique, we expect the program would not fall into the “stagnation” state that affects large finite element codes currently in use.

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Engineering Computations, vol. 11 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 March 1994

V.E. Sonzogni and M. Géradin

An elastoplastic hinge model for transient beam response analysis hasbeen developed. A variety of monotonic curves as well as hystereutic cyclescan be constructed. Special models…

53

Abstract

An elastoplastic hinge model for transient beam response analysis has been developed. A variety of monotonic curves as well as hystereutic cycles can be constructed. Special models for unstable cycles of constitutive relationships are offered by this model. Practical cases such as impact of a hollow section or cracking of a reinforced concrete beam can be handled. The application to the analysis of the impact of a rectangular hollow section is shown. Good performance is obtained and comparison is made with the use of an explicit impact code.

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Engineering Computations, vol. 11 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 October 2005

Alessio Bonelli and Oreste S. Bursi

To propose novel predictor‐corrector time‐integration algorithms for pseudo‐dynamic testing.

672

Abstract

Purpose

To propose novel predictor‐corrector time‐integration algorithms for pseudo‐dynamic testing.

Design/methodology/approach

The novel predictor‐corrector time‐integration algorithms are based on both the implicit and the explicit version of the generalized‐α method. In the non‐linear unforced case second‐order accuracy, stability in energy, energy decay in the high‐frequency range as well as asymptotic annihilation are distinctive properties of the generalized‐α scheme; while in the non‐linear forced case they are the limited error near the resonance in terms of frequency location and intensity of the resonant peak. The implicit generalized‐α algorithm has been implemented in a predictor‐one corrector form giving rise to the implicit IPC‐ρ method, able to avoid iterative corrections which are expensive from an experimental standpoint and load oscillations of numerical origin. Moreover, the scheme embodies a secant stiffness formula able to approximate closely the actual stiffness of a structure. Also an explicit algorithm has been implemented, the EPC‐ρb method, endowed with user‐controlled dissipation properties. The resulting schemes have been tested experimentally both on a two‐ and on a six‐degrees‐of‐freedom system, exploiting substructuring techniques.

Findings

The analytical findings and the tests have indicated that the proposed numerical strategies enhance the performance of the pseudo‐dynamic test (PDT) method even in an environment characterized by considerable experimental errors. Moreover, the schemes have been tested numerically on strongly non‐linear multiple‐degrees‐of‐freedom systems reproduced with the Bouc‐Wen hysteretic model, showing that the proposed algorithms reap the benefits of the parent generalized‐α methods.

Research limitations/implications

Further developments envisaged for this study are the application of the IPC‐ρ method and of EPC‐ρb scheme to partitioned procedures for high‐speed pseudo‐dynamic testing with substructuring.

Practical implications

The implicit IPC‐ρ and the explicit EPC‐ρb methods allow a user to have defined dissipation which reduces the effects of experimental error in the PDT without needing onerous iterations.

Originality/value

The paper proposes novel time‐integration algorithms for pseudo‐dynamic testing. Thanks to a predictor‐corrector form of the generalized‐α method, the proposed schemes maintain a high computational efficiency and accuracy.

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Engineering Computations, vol. 22 no. 7
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 September 1996

Nielen Stander and Erwin Stein

Using examples of flexible mechanisms, demonstrates that while the Newmark method is unstable for nonlinear dynamics, time step refinement could in some cases lead to even earlier…

297

Abstract

Using examples of flexible mechanisms, demonstrates that while the Newmark method is unstable for nonlinear dynamics, time step refinement could in some cases lead to even earlier onset of instability in the form of a blown‐up response. As a remedy, develops a plane finite beam element based on the Simo‐Vu Quoc formulation for dynamics and integrates it with an energy‐conserving midpoint time‐stepping rule for solving problems in nonlinear dynamics. Shows that this combination produces a consistently stable and accurate dynamic analysis method even for large time steps.

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Engineering Computations, vol. 13 no. 6
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 June 1992

KJELL MAGNE MATHISEN and PÅL G. BERGAN

This paper discusses algorithms for large displacement analysis of interconnected flexible and rigid multibody systems. Hydrostatic and hydrodynamic loads for systems being…

90

Abstract

This paper discusses algorithms for large displacement analysis of interconnected flexible and rigid multibody systems. Hydrostatic and hydrodynamic loads for systems being submerged in water are also considered. The systems may consist of cables and beams and may combine very flexible parts with rigid parts. Various ways of introducing structural joints are discussed. A special implementation of the Hilber‐Hughes‐Taylor time integration scheme for constrained non‐linear systems is outlined. The formulation is general and allows for displacements and rotational motion of unlimited size. Aspects concerning efficient solution of constrained dynamic problems are discussed. These capabilities have been implemented in a general purpose non‐linear finite element program. Applications involving static and dynamic analysis of a bi‐articulated tower and a floating tripod platform kept in place by three anchor lines are discussed.

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Engineering Computations, vol. 9 no. 6
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 February 1996

Jaroslav Mackerle

Presents a review on implementing finite element methods on supercomputers, workstations and PCs and gives main trends in hardware and software developments. An appendix included…

677

Abstract

Presents a review on implementing finite element methods on supercomputers, workstations and PCs and gives main trends in hardware and software developments. An appendix included at the end of the paper presents a bibliography on the subjects retrospectively to 1985 and approximately 1,100 references are listed.

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Engineering Computations, vol. 13 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 March 1998

Alberto Cardona and Alfredo Huespe

Presents an implementation of continuation methods in the context of a code for flexible multibody systems analysis. These systems are characterized by the simultaneous presence…

551

Abstract

Presents an implementation of continuation methods in the context of a code for flexible multibody systems analysis. These systems are characterized by the simultaneous presence of elastic deformation terms and rigid constraints. In our formulation, the latter terms are introduced by an augmented Lagrangian technique, resulting in the presence of Lagrange multipliers in the set of unknowns, together with displacement and rotation associated terms. Essential aspects for a successful implementation are discussed: e.g. the selection of an appropriate metric for computing the path following constraint, a flexible description of control parameters which accounts for conservative and nonconservative loads, imposed displacements and imposed temperatures (dilatation effects), and the inclusion of second order derivatives of rigid constraints in the Jacobian. A large set of examples is presented, with the objective of evaluating the numerical effectiveness of the implemented schemes.

Details

Engineering Computations, vol. 15 no. 2
Type: Research Article
ISSN: 0264-4401

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