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Industrial Management & Data Systems, vol. 100 no. 6
Type: Research Article
ISSN: 0263-5577

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M. Kleiber, T.D. Hien, H. Antúnez and P. Kowalczyk

The general problem of sizing, material and loading parameter sensitivity of non‐linear systems is presented. Both kinematic and path‐dependent material non‐linearities…

Abstract

The general problem of sizing, material and loading parameter sensitivity of non‐linear systems is presented. Both kinematic and path‐dependent material non‐linearities are considered; non‐linear sensitivity path is traced by an incremental solution strategy. The variational approach employed is quite general and can be employed for studying sensitivity of various path‐dependent highly non‐linear phenomena. Both the direct differentiation method (DDM) and adjoint system method (ASM) are discussed in the context of continuum and finite element mechanics. The merits of using the consistent tangent matrix and the necessity of accumulation of design derivatives of stresses and internal parameters are indicated. Aspects of sensitivity problems in metal forming are also discussed. A number of examples illustrate the paper.

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Engineering Computations, vol. 12 no. 3
Type: Research Article
ISSN: 0264-4401

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N.J. Marais and J.B. Martin

A solution algorithm for the transient analysis of bodies undergoing creep under constant or time varying loads is presented. The constitutive equation adopted is of the…

Abstract

A solution algorithm for the transient analysis of bodies undergoing creep under constant or time varying loads is presented. The constitutive equation adopted is of the form: έc=γσm. The finite element formulation is carried out in terms of displacements and creep strains as internal variables. The time discretization is achieved with a trapezoidal time integration scheme. The creep strains are condensed out to give an equation for displacement increments involving a modified stiffness matrix and force vector. A Newton—Raphson iterative scheme is used for the non‐linear creep strain rate‐stress relation, and creep strains are updated at the end of the time step. The algorithm has been implemented in NOSTRUM for two‐dimensional structural and plane continuum problems, with a von Mises type potential function governing the multiaxial creep constitutive relationship. Numerical results are presented.

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

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Dott. Albano Mainardi

La preparazione sia scolastica o extrascolastica, destinata ai giovani e agli adulti che iniziano o dovrebbero iniziare la loro carriera professionale nel turismo al…

Abstract

La preparazione sia scolastica o extrascolastica, destinata ai giovani e agli adulti che iniziano o dovrebbero iniziare la loro carriera professionale nel turismo al livello di apprendistato, forma oggetto del presente studio.

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The Tourist Review, vol. 19 no. 4
Type: Research Article
ISSN: 0251-3102

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The one‐step precision blasting method of glass bead cleaning, peening and corrosion removal involves impelling micron size spherical glass particles at controlled…

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The one‐step precision blasting method of glass bead cleaning, peening and corrosion removal involves impelling micron size spherical glass particles at controlled velocities against a work‐piece. The impact of the glass beads on the surface of the object pulverises and removes all forms of oxidation, corrosion and other foreign matter, including pit corrosion and corrosion in recessed and hidden areas around and under items such as rivets, The removal of all foreign matter down to the base metal is accomplished far more rapidly, hence far more economically, than currently utilised methods. There is no removal of base metal, no dimensional change and no contamination. Peening is achieved in a similar manner, as will be described later.

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Aircraft Engineering and Aerospace Technology, vol. 47 no. 10
Type: Research Article
ISSN: 0002-2667

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D.W. Kelly and M. Elsley

The determination of load paths is an essential element of structuraldesign. Load paths provide insight into the way the structure is performingits prescribed function…

Abstract

The determination of load paths is an essential element of structural design. Load paths provide insight into the way the structure is performing its prescribed function. They can also indicate possibilities for shape optimization and the effect of component modification or damage. They are relatively easy to define in simple structures such as trusses which comprise a finite number of clearly defined members which carry only axial load. The load path is given simply by tracing the higher axial loads through the structure. However, for continua such as plates or solids, there is currently no systematic procedure for determining the path of load from the point of application to the constrained boundaries. This paper addresses the problem of defining the path of loads in plates with geometric discontinuities and in simple joints. The theory associated with the determination of the load path is first introduced, and then integrated into a finite element package to provide pictorial contours.

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Engineering Computations, vol. 12 no. 5
Type: Research Article
ISSN: 0264-4401

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S. Oller, S. Botello, J. Miquel and E. Oñate

This paper shows a generalization of the classic isotropic plasticitytheory to be applied to orthotropic or anisotropic materials. This approachassumes the existence of a…

Abstract

This paper shows a generalization of the classic isotropic plasticity theory to be applied to orthotropic or anisotropic materials. This approach assumes the existence of a real anisotropic space, and other fictitious isotropic space where a mapped fictitious problem is solved. Both spaces are related by means of a linear transformation using a fourth order transformation tensor that contains all the information concerning the real anisotropic material. The paper describes the basis of the spaces transformation proposed and the expressions of the resulting secant and tangent constitutive equations. Also details of the numerical integration of the constitutive equation are provided. Examples of application showing the good performance of the model for analysis of orthotropic materials and fibre‐reinforced composites are given.

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Engineering Computations, vol. 12 no. 3
Type: Research Article
ISSN: 0264-4401

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The flow of money generated through tourism receipts can be traced by the multiplier effect, showing the relationship between consumption and income. Each time there is a…

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The flow of money generated through tourism receipts can be traced by the multiplier effect, showing the relationship between consumption and income. Each time there is a change in income the multiplier shows the number of times such income is likely to be re‐spent and how much new income will be generated. Since “any change in any spending has a multiplier effect” it is possible to formulate a tourism multiplier.

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The Tourist Review, vol. 21 no. 3
Type: Research Article
ISSN: 0251-3102

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P. Lequeu, P. Lassince, T. Warner and G.M. Raynaud

Over the past several years, Pechiney has launched intensive R&D activities, in close connection with its main customers, aimed at tailoring property balances to specific…

Abstract

Over the past several years, Pechiney has launched intensive R&D activities, in close connection with its main customers, aimed at tailoring property balances to specific applications and at reducing the overall cost of manufactured aircraft parts. These close partnerships led to the development of a number of new alloys and tempers covering all the major aircraft structural parts, all of them bringing benefits in one or more design properties, and all of them having being chosen for new aircraft. Similarly, new special qualities were designed to reduce customer costs: low residual stress, high formability, age formable and weldable solutions were developed and chosen for their efficiency in lean manufacturing. It is the purpose of this paper to review these cost reduction and weight saving initiatives conducted by Pechiney. The main design property improvements for the newly developed alloys and tempers and practical applications of the special material qualities will be reported. In addition, the underlying metallurgical principles of the performance improvements will be discussed.

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Aircraft Engineering and Aerospace Technology, vol. 73 no. 2
Type: Research Article
ISSN: 0002-2667

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Article

Dragan D. Milasinovic

The paper deals with the rheological‐dynamical analogy in which the three‐dimensional stress‐strain relations are defined under cyclic variation of stress for Hencky’s…

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The paper deals with the rheological‐dynamical analogy in which the three‐dimensional stress‐strain relations are defined under cyclic variation of stress for Hencky’s total strain theory. In many practical visco‐elasto‐plastic problems, like as multiaxial fatigue under loading at constant stress amplitude and constant stress ratio, the load‐carrying members are subjected to proportional loading. The classical Hencky’s theory has the advantage of mathematical convenience but its disadvantage is that the deformations predicted for the volume element are independent of the loading path. The existing formulations of the constitutive models for metals are mainly based on the Prandtl‐Reuss incremental theory of elasto‐plasticity, slip theory of plasticity or continuum damage mechanics. They have been shown capable of reproducing satisfactorily most experimental results available for metallic specimens. However, from the theoretical viewpoint little has been said about how these formulations relate to realistic predicting many different inelastic and time dependent problems of two‐ or threedimensional solids, such as fatigue, discontinuous plastic deformation etc. In this paper, fundamentally new aspect of isochronous constitutive relations for Hencky’s theory, which are dependent of the each loading path, is achieved by systematically introducing RDA concept into the continuum framework. Specific inelastic and fatigue formulation of triaxial state of stress is developed and discussed within the new theoretical tool and related to von Mises plasticity..

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Multidiscipline Modeling in Materials and Structures, vol. 2 no. 2
Type: Research Article
ISSN: 1573-6105

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