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Article
Publication date: 20 April 2015

Nikolay Asmolovskiy, Anton Tkachuk and Manfred Bischoff

Current procedures of buckling load estimation for thin-walled structures may provide very conservative estimates. Their refinement offers the potential to use structure…

Abstract

Purpose

Current procedures of buckling load estimation for thin-walled structures may provide very conservative estimates. Their refinement offers the potential to use structure and material properties more efficiently. Due to the large variety of design variables, for example laminate layup in composite structures, a prohibitively large number of tests would be required for experimental assessment, and thus reliable numerical techniques are of particular interest. The purpose of this paper is to analyze different methods of numerical buckling load estimation, formulate simulation procedures suitable for commercial software and give recommendations regarding their application. All investigations have been carried out for cylindrical composite shells; however similar approaches are feasible for other structures as well.

Design/methodology/approach

The authors develop a concept to apply artificial load imperfections with the aim to estimate as good as possible lower bounds for the buckling loads of shells for which the actual physical imperfections are not known. Single and triple perturbation load approach, global and local dynamic perturbation approach and path following techniques are applied to the analysis of a cylindrical composite shell with known buckling characteristics. Results of simulations are compared with published experimental data.

Findings

A single perturbation load approach is reproduced and modified. Buckling behavior for negative values of the perturbation load is examined and a pattern similar to a positive perturbation load is observed. Simulations with three perturbation forces show a decreased (i. e. more critical) value of the buckling load compared to the single perturbation load approach. Global and local dynamic perturbation approaches exhibit a behavior suitable for lower bound estimation for structures with arbitrary geometries.

Originality/value

Various load imperfection approaches to buckling load estimation are validated and compared. All investigated methods do not require knowledge of the real geometrical imperfections of the structure. Simulations were performed using a commercial finite element code. Investigations of sensitivity with respect to a single perturbation load are extended to the negative range of the perturbation load amplitude. A specific pattern for a global perturbation approach was developed, and based on it a novel simulation procedure is proposed.

Details

Engineering Computations, vol. 32 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 January 1990

M. Papadrakakis and N. Nomikos

The application of the preconditioned Lanczos method is proposed for the solution of the linearized equations resulting from a non‐linear solution routine based on Newton…

Abstract

The application of the preconditioned Lanczos method is proposed for the solution of the linearized equations resulting from a non‐linear solution routine based on Newton methods. A path‐following solution algorithm with an arc length method is employed for tracing all types of post‐critical branches of a load‐displacement curve. The proposed methodology retains all characteristics of an iterative method by avoiding the complete factorization of the current stiffness matrix. The necessary eigenvalue information is retained in the tridiagonal matrix of the Lanczos approach.

Details

Engineering Computations, vol. 7 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 7 March 2016

Stefan May, Julien Vignollet and René de Borst

– The purpose of this paper is to introduce a new arc-length control method for physically non-linear problems based on the rates of the internal and the dissipated energy.

Abstract

Purpose

The purpose of this paper is to introduce a new arc-length control method for physically non-linear problems based on the rates of the internal and the dissipated energy.

Design/methodology/approach

In this paper, the authors derive from the second law of thermodynamics the arc-length method based on the rate of the dissipated energy and from the time derivative of the energy density the arc-length method based on the rate of the internal energy.

Findings

The method requires only two parameters and can automatically trace equilibrium paths which display multiple snap-through and/or snap-back phenomena.

Originality/value

A fully energy-based control procedure is developed, which facilitates switching between dissipative and non-dissipative arc-length control equations in a natural way. The method is applied to a plate with an eccentric hole using the phase field model for brittle fracture and to a perforated beam using interface elements with decohesion.

Details

Engineering Computations, vol. 33 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 14 May 2020

Subhradip Mukherjee, R. Kumar and Siddhanta Borah

The purpose of this work is to propose quad wheel robot with path navigation using an intelligent novel algorithm named as obstacle-avoiding intelligent algorithm (OAIA).

Abstract

Purpose

The purpose of this work is to propose quad wheel robot with path navigation using an intelligent novel algorithm named as obstacle-avoiding intelligent algorithm (OAIA).

Design/methodology/approach

The paper proposes OAIA algorithm, which is used to minimize the path distance and elapsed time between source and goal.

Findings

The hardware implementation of the Quad Wheel Robot design includes a global positioning system (GPS) module for path navigation. An ultrasonic module (HC SR04) is mainly used as the sensing unit for the system. In the proposed scheme, the GPS locator (L80) is used to obtain the current location of the robot, and the ultrasonic sensor is utilized to avoid the obstacles. An ARM processor serves as the heart of the Quad Wheel Robot.

Practical implications

This paper includes real-time implementation of quad wheel robot for various coordinate values, and the movement of the robot is captured and analysed.

Originality/value

The proposed OAIA is capable of estimating the mobile robot position exactly under ideal circumstances. Simulation and hardware implementation are carried out to evaluate the performance of the proposed system.

Details

International Journal of Intelligent Unmanned Systems, vol. 9 no. 1
Type: Research Article
ISSN: 2049-6427

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Article
Publication date: 1 June 1997

Jaroslav Mackerle

Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the…

Abstract

Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore aims to give the reader an encyclopaedic view on the subject. The bibliography at the end of the paper contains 2,025 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1992‐1995.

Details

Engineering Computations, vol. 14 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 December 2003

J.M. Zhan and Y.S. Li

A numerical scheme is proposed to solve double‐diffusive problems using a boundary‐fitted coordinate system to introduce finer grids in the boundary layer regions and an…

Abstract

A numerical scheme is proposed to solve double‐diffusive problems using a boundary‐fitted coordinate system to introduce finer grids in the boundary layer regions and an accurate high‐order difference method. Numerical stability is improved by using fourth‐order accurate upwind‐biased differences to approximate the convection terms. The other terms in the governing differential equations are discretized using fourth‐order central difference. To demonstrate the versatility of the boundary‐fitted coordinate system, natural convection in an eccentric annulus is first simulated. The numerical results are consistent with the experimental results by Kuehn and Goldstein and better than the numerical results by Projahn et al. for eccentric cases. Secondly, the symmetry breaking and overturning states in thermohaline‐driven flows in a two‐dimensional rectangular cavity are simulated first to validate the numerical scheme. The numerical results agree well with those by Dijkstra and Molemaker and Quon and Ghil. Finally, the effect of the Lewis number on the flow system is investigated in detail. Depending on the value of the Lewis number, the flow pattern is either stable and symmetric, periodic and oscillatory, or unsymmetric and random.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 13 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 16 October 2020

Nanshan Wang, Heng Liu, Yi Liu, Qidan Wang, Shemiao Qi and Zhidong Xu

This paper aims to examine the dynamic behaviours of a three-dimensional (3D) rod-fastening rotor bearing system (RFBS) with a crack in a fastening rod.

Abstract

Purpose

This paper aims to examine the dynamic behaviours of a three-dimensional (3D) rod-fastening rotor bearing system (RFBS) with a crack in a fastening rod.

Design/methodology/approach

Based on the 3D finite element method model and stress analysis of a cracked RFBS, a 3D dynamic model of the RFBS with a crack in a fastening rod is established with considering the initial bending and stress redistribution caused by the crack. A combined numerical simulation technology is used to investigate the dynamic behaviours of the system.

Findings

The distribution of contact stress between the two disks will be not uniform, and the initial bending of the system will occur due to the presence of a crack. This will lead to the change of system stiffness and the dynamic behaviours such as vibration amplitude, and motion orbits will change significantly.

Research limitations/implications

A 3D finite element method dynamic model is proposed for the study of dynamic characteristics of complex combined rotor bearing system with cracks.

Practical implications

It is helpful and significant to master the dynamic behaviours of cracked RFBS. It is helpful to detect the presence of a crack of the rotor bearing system.

Social implications

Some of the losses caused by crack failure may be reduced.

Originality/value

The proposed 3D method can provide a useful reference for the study of dynamic characteristics of complex combined rotor bearing system with cracks.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0189

Details

Industrial Lubrication and Tribology, vol. 73 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 August 2000

Michael A. Lewis

Today, “lean” may no longer be fashionable but its core principles (flow, value, pull, minimizing waste etc.) have become the paradigm for many manufacturing (and service…

Abstract

Today, “lean” may no longer be fashionable but its core principles (flow, value, pull, minimizing waste etc.) have become the paradigm for many manufacturing (and service) operations. Given this pre‐eminence, the paper seeks to establish what impact it has had on the overall competitive positions of adopter firms. Combining normative and critical theory (from lean production and resource‐based view of the firm literature) with empirical material drawn from three case studies, the paper argues that lean production can underpin competitive advantage if the firm is able to appropriate the productivity savings it creates. Similarly, the ambiguity of lean production in practice means that the implementation process can create strategic resources to underpin sustainable competitive advantage. Problematically, however, the paper also suggests that being “lean” can curtail the firm’s ability to achieve long‐term flexibility. It concludes with suggestions for further work.

Details

International Journal of Operations & Production Management, vol. 20 no. 8
Type: Research Article
ISSN: 0144-3577

Keywords

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Article
Publication date: 5 November 2018

Víctor H. Andaluz, Cristian M. Gallardo, Fernando A. Chicaiza, Christian P. Carvajal, José Morales, Giovanny Cuzco, Vicente Morales, Byron E. Vaca and Nicolay Samaniego

This paper aims to present a unified motion control scheme for quadcopters which not only solves the point stabilization and trajectory tracking problems but also the path

Abstract

Purpose

This paper aims to present a unified motion control scheme for quadcopters which not only solves the point stabilization and trajectory tracking problems but also the path following problem.

Design/methodology/approach

The control problem is solved based on the kinematic model of the unmanned aerial vehicles (UAV). Next, a dynamic compensation controller is considered through of a quadcopter-inner-loop system to independently track four velocity commands: forward, lateral, up/downward and heading rate. Stability and robustness of the whole control system are proved through the Lyapunov’s method. To evaluate the controller’s performance, a multi-user application which allows bilateral communication between a ground station and the Phantom 3 PRO quadrotor is developed.

Findings

The performance of the proposed unified controller is shown through real experiments for the different motion control objectives: point stabilization, trajectory tracking and path following. The experiments confirm the capability of the unified controller to solve different motion problems by an adequate selection of the control references.

Originality/value

This work proposes the design of three types of motion controllers, which can be switched to comply a task in outdoor. Based on the software development kit provided by the company DJI, an application to get and send data to the UAV is developed. By means of this application, the three tasks are tested and the robustness of the controllers is proved.

Details

Assembly Automation, vol. 38 no. 5
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 7 September 2010

Sanghyo Lee, Am Cho and Changdon Kee

The purpose of this paper is to present an efficient method to integrate path generation and following for an unmanned aerial vehicle.

Abstract

Purpose

The purpose of this paper is to present an efficient method to integrate path generation and following for an unmanned aerial vehicle.

Design/methodology/approach

The shortest path is briefly reviewed using a straight line and a circular arc in a horizontal plane. Based on shortest paths, various path generation algorithms using oriented waypoints are described. Path design unit, which is structured concatenations of line segments and circular arcs, is proposed to represent different paths as one structure. Simple path following controller to follow a straight line and a circle was also implemented with linear‐quadratic regulator control laws. Some flight tests were conducted to verify the efficiency of proposed algorithm.

Findings

Proposed method represents various paths between given waypoints efficiently by a small number of parameters. It does not need a large amount of memory storage and computation time to run in real time on a low‐cost microprocessor.

Originality/value

This paper provides new structured method to generate different paths efficiently including Dubins' set, which makes path following easy by simple switching logic. It needs small computational time to run in real time. The proposed algorithm in this paper could be used as a basis of other applications such as air traffic control and curved landing approach, which require more accurate path control.

Details

Aircraft Engineering and Aerospace Technology, vol. 82 no. 5
Type: Research Article
ISSN: 0002-2667

Keywords

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