Instytut Podstawowych Problemów Techniki
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J. Logo



Prace konferencyjne
1.  Logo J., Tauzowski P., Błachowski B., Reliability based elasto-plastic topology optimization, WCSMO-13, 13th World Congress of Structural and Multidisciplinary Optimization, 2019-05-20/05-24, Beijing (CN), No.A210492, pp.1-6, 2019

Streszczenie:
This paper present elasto-plastic topology optimization with reliability constraint. It recalls fundamental concepts from first order reliability analysis and introduces an algorithm for topology optimization of elasto-plastic structures. The presented numerical example shows dependence of the volume fraction on probability of failure.

Słowa kluczowe:
Structural topology optimization, Elastoplastic analysis, Reliability based optimization

Afiliacje autorów:
Logo J. - inna afiliacja
Tauzowski P. - IPPT PAN
Błachowski B. - IPPT PAN
2.  Błachowski B., Tauzowski P., Logo J., Stress intensity driven topology optimization for morphogenesis of 3d elastoplastic structures, LSCE 2018, XXIV LIGHTWEIGHT STRUCTURES in CIVIL ENGINEERING - International Seminar Organized by Polish Chapters of International Association for Shell and Spatial Structures (IASS), 2018-12-07/12-07, Łódź (PL), pp.22-26, 2018

Streszczenie:
The purpose of this study is a practical engineering formulation of the topology optimization problem for three dimensional elastoplastic structures. The present study constitutes a comprehensive approach to topology optimization of elastoplastic structures, including both the mechanical problem statement and its efficient computer implementation. Instead of the traditional approach based on compliance minimization the aim of this work is to find a minimum weight structure, which is able to carry a given load while satisfying the condition that the corresponding stresses do not exceed an allowable limit. The general form of the problem is based on the classical limit design formulations of plasticity. The proposed method finds the optimal structure in an iterative way using only stress intensity distribution and does not require from the User explicit knowledge of any gradients or sensitivities. The effectiveness of the proposed methodology has been illustrated on two representative examples including simply supported and cantilever beams.

Słowa kluczowe:
topology optimization, computational morphogenesis, elastoplastic FE analysis

Afiliacje autorów:
Błachowski B. - IPPT PAN
Tauzowski P. - IPPT PAN
Logo J. - inna afiliacja

Abstrakty konferencyjne
1.  Logo J., Tauzowski P., Błachowski B., Topology optimization of elastoplastic structures under reliability constraints: A first order approach, CIVIL-COMP-OPTI 2019, Fifth International Conference on Soft Computing & Optimisation in Civil, Structural and Environmental Engineering, 2019-09-16/09-19, Riva del Garda (IT), pp.1-3, 2019

Streszczenie:
Structural safety is a critical aspect in modern engineering practice. One of the factors leading to the risk of failure is the variability of design parameters. To be able to estimate the risk of failure, this variability should be taken into account in design process. One way to tackle this issue is to assume a random nature of selected design parameters. These parameters can represent: loads acting on a structure, material properties or shape parameters. Minimizing the structural mass in the process of topology optimization is equivalent to removing the material from the initial, usually regular design space. This process can lead also to a reduction of the structural safety. Therefore, apart from deterministic constraints (such as stresses, displacements or load capacity), it is also worth to control the probabilistic ones. The purpose of this work is to introduce in topology optimization of elastoplastic structures an additional constraint on the probability of failure. Deterministic constraints, in the form of constraints on stresses, are imposed on elastoplastic analysis and utilized by the return mapping algorithm. One of the difficulties coming from the application of these random effects in the process topology optimization is its numerical complexity. Topological optimization itself is a complex issue. Adding a structural safety estimation can extend this process significantly. Fortunately, in the field of reliability analysis, which deals with determining reliability, there are methods that allow for relatively fast estimation of the probability of failure. These are First and Second Order Reliability Methods (FORM, SORM). Only several finite element iterations are sufficient to determine the probability of failure. These methods are based on the concept of the design point or the most probable point. This is the point on the limit state surface that lies closest to the mean point, and represents the most probable failure scenario. Moreover, approximation of limit state surface is linear (FORM) or quadratic (SORM). This allows to estimate quite accurately low probabilities of failure. Such a low probability of failure should characterized a safe structure. The search for a design point is based on the iterative formula developed by Rackwitz and Fiesler. The paper will present the formulation of the elasto-plastic problem of structural analysis as well as the detailed description of the algorithm for topology optimization under reliability constraint. The paper will be illustrated by examples, in which we will demonstrate, how probability of failure changes in the topological optimization process.

Słowa kluczowe:
topology optimization, elasto-plastic structures, reliability analysis, probabilistic design

Afiliacje autorów:
Logo J. - inna afiliacja
Tauzowski P. - IPPT PAN
Błachowski B. - IPPT PAN
2.  Tauzowski P., Błachowski B., Logo J., Stress constrained structural topology optimization with functor-oriented finite element implementation, Workshop on Semidefinite Programming: Theory and Applications, 2018-10-19/10-19, Edinburgh (GB), pp.1, 2018

Streszczenie:
Classical programming of finite elements contains usual class, which duty is not only to approximate some physical field of interest (displacements, accelerations or temperature), but also definition of matrices necessary for particular analysis. It often leads to sophisticated class hierarchy of finite elements. In our approach matrices necessary for FE analysis are in separate classes. Hierarchy of these classes can be developed almost separately from declaration of the finite element class. Also finite elements hierarchy is much smaller, because each class represents one kind of matrix computed in FE analysis. In our opinion the functor is best suited object for this kind of approach. The functor represents one subroutine and it can also be invoked as function. The study presents application of functor oriented programming to finite element analysis.

Słowa kluczowe:
stress constrained topology optimization, finite element programming, functor-oriented implemenetation

Afiliacje autorów:
Tauzowski P. - IPPT PAN
Błachowski B. - IPPT PAN
Logo J. - inna afiliacja

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