Adnan Ibrahimbegović, Igor Grešovnik, Damijan Markovič, Sergiy Melnyk and Tomaž Rodič
Proposes a methodology for dealing with the problem of designing a material microstructure the best suitable for a given goal.
Abstract
Purpose
Proposes a methodology for dealing with the problem of designing a material microstructure the best suitable for a given goal.
Design/methodology/approach
The chosen model problem for the design is a two‐phase material, with one phase related to plasticity and another to damage. The design problem is set in terms of shape optimization of the interface between two phases. The solution procedure proposed herein is compatible with the multi‐scale interpretation of the inelastic mechanisms characterizing the chosen two‐phase material and it is thus capable of providing the optimal form of the material microstructure. The original approach based upon a simultaneous/sequential solution procedure for the coupled mechanics‐optimization problem is proposed.
Findings
Several numerical examples show a very satisfying performance of the proposed methodology. The latter can easily be adapted to other choices of design variables.
Originality/value
Confirms that one can thus achieve the optimal design of the nonlinear behavior of a given two‐phase material with respect to the goal specified by a cost function, by computing the optimal form of the shape interface between the phases.
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Tomaž Rodič, Domen Cukjati and Igor Grešovnik
To present numerical techniques and results of finite element based optimisation of material forming process for production of shaped food and beverage cans.
Abstract
Purpose
To present numerical techniques and results of finite element based optimisation of material forming process for production of shaped food and beverage cans.
Design/methodology/approach
The objectives were achieved by combining finite element system ELFEN with optimisation shell INVERSE. These computer systems were applied to optimisation of preform design, optimisation of tribological conditions between can body and individual segments of the tooling system as well as to optimisation of kinematics of the tooling segments.
Findings
Numerical analyses show that preform design offers the highest optimisation potential. For preform shape optimisation a very efficient algorithm has been developed which enables effective minimisation of the objective function.
Originality/value
The paper identifies three main technological possibilities to optimise production process for shaped cans and quantifies the effects of each option. It also identifies the most efficient optimisation techniques to improve the investigated process.
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T. Rodič and I. Grešovnik
A system for solving a wide variety of inverse and optimization problems in solid mechanics is introduced. The system consists of a general purpose finite element method (FEM…
Abstract
A system for solving a wide variety of inverse and optimization problems in solid mechanics is introduced. The system consists of a general purpose finite element method (FEM) analysis system “Elfen” and a shell which controls this system. The shell functions as a stand‐alone programme, so the system is physically divided into two separated parts. The “optimization part”, which corresponds to the shell, possesses optimization and inverse problem solution algorithms. The “analysis part”, which corresponds to an FEM system, serves for the definition of the objective function to which these algorithms are applied. The shell has a user interface implemented in the form of file interpreter which imposes a great flexibility at the definition of various optimization and inverse problems, including parameter identification in constitutive modelling, frictional contact problems and heat transfer. Concepts of the shell are discussed in detail.
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Roberto Spallino, Giuseppe Giambanco and Santi Rizzo
This paper is devoted to the optimal design of laminated composite structures. The goal of the study is to assess the quality and the performance of an algorithm based on the…
Abstract
This paper is devoted to the optimal design of laminated composite structures. The goal of the study is to assess the quality and the performance of an algorithm based on the directional derivative method. Particular attention is paid to the one‐dimensional search, a critical step of the process, performed by cubic splines approximation. The optimization problem is formulated as weight minimization, under constraints on the mechanical behavior of the structure. The assumed design variables are the ply thicknesses, treated as continuous design variables, constrained by technological requirements. The structural analysis is performed making use of quadrilateral four‐node composite elements, based on the first order shear deformation theory. The algorithm is applied to the optimization of a rectangular laminated plate. The results obtained are compared with those obtained by other similar studies and show the effectiveness and accuracy of the proposed approach.
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Catarina F. Castro, Luísa Costa Sousa, C.A.C. António and J.M.A. César de Sá
An optimisation method for design of intermediate die shapes needed in some forging operations is presented. The basic problem consists of finding an optimal two‐step forging…
Abstract
An optimisation method for design of intermediate die shapes needed in some forging operations is presented. The basic problem consists of finding an optimal two‐step forging sequence by automatically designing the shape of the preforming tools. The optimisation problem is defined based on an inverse formulation. The objective function of the optimisation problem is a function describing the quality of the obtained part by measuring the die underfill. The finite element method is used to simulate the forging problem. The optimisation method is based on a modified sequential unconstrained minimisation technique and a gradient method. The sensitivity‐dependent algorithm requires computing the derivatives of the objective function with respect to the design variables defining the preform shapes. A direct differentiation method has been developed for this purpose. The optimisation scheme is demonstrated with two axisymmetric forging examples in which optimal preform dies are obtained.
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M. Poursina, C.A.C. António, C.F. Castro, J. Parvizian and L.C. Sousa
A numerical method for shape optimisation in forging is presented. The goal of the optimisation is to eliminate work‐piece defects that may arise during the forging process. A…
Abstract
A numerical method for shape optimisation in forging is presented. The goal of the optimisation is to eliminate work‐piece defects that may arise during the forging process. A two‐dimensional finite element code has been developed for the simulation of the mechanical process. The material is incompressible and it follows the Norton‐Hoff law. To deal with contact constraint the velocity projection algorithm is used. The optimisation process is conducted using a genetic algorithm supported by an elitist strategy. A new genetic operator called adaptive mutation has been developed to increase the efficiency of the search. The developed scheme is used to design optimal preform shapes for several axisymmetric examples. Continuous and discrete design variables are considered. The objective function of the optimisation problem is associated with the quality of the final product. Comparing the obtained optimal results with the literature validates the proposed optimisation method.