1. |
Tauzowski P., Błachowski B., Lógó J.^{♦}, Topology optimization of elasto-plastic structures under reliability constraints: a first order approach,
COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2020.106406, Vol.243, pp.106406-1-15, 2021Streszczenie: The objective of this study is to propose a relatively simple and efficient method for reliability based topology optimization for structures made of elasto-plastic material. The process of determining the optimal topology of elasto-perfectly plastic structures is associated with the removal of material from the structure. Such a process leads to weakening of structural strength and stiffness causing at the same time increase the likelihood of structural failure. An important aspect of engineering design is to track this probability during the optimization process and not allow the structure safety to exceed a certain level specified by the designer. The purpose of this work is to combine the previously developed yield-limited topology optimization method with reliability analysis using first order approach. Effectiveness of the proposed methodology is demonstrated on benchmark problems proposed by Rozvany and Maute, and the elasto-plastic topology design of L-shape structure which is frequently used in different approaches for stress constrained topology optimization. Słowa kluczowe: topology optimization, reliability analysis, elasto-plastic analysis Afiliacje autorów:
Tauzowski P. | - | IPPT PAN | Błachowski B. | - | IPPT PAN | Lógó J. | - | University of Technology and Economics (HU) |
| | 140p. |
2. |
Błachowski B., Świercz A., Ostrowski M., Tauzowski P., Olaszek P.^{♦}, Jankowski Ł., Convex relaxation for efficient sensor layout optimization in large‐scale structures subjected to moving loads,
Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12553, Vol.35, No.10, pp.1085-1100, 2020Streszczenie: This paper proposes a computationally effective framework for load‐dependent optimal sensor placement in large‐scale civil engineering structures subjected to moving loads. Two common problems are addressed: selection of modes to be monitored and computational effectiveness. Typical sensor placement methods assume that the set of modes to be monitored is known. In practice, determination of such modes of interest is not straightforward. A practical approach is proposed that facilitates the selection of modes in a quasi‐automatic way based on the structural response at the candidate sensor locations to typical operational loads. The criterion used to assess sensor placement is based on Kammer's Effective Independence (EFI). However, in contrast to typical implementations of EFI, which treat the problem as a computationally demanding discrete problem and use greedy optimization, an approach based on convex relaxation is proposed. A notion of sensor density is applied, which converts the original combinatorial problem into a computationally tractable continuous optimization problem. The proposed framework is tested in application to a real tied‐arch railway bridge located in central Poland. Słowa kluczowe: optimal sensor placement, effective independence method, Fisher information matrix Afiliacje autorów:
Błachowski B. | - | IPPT PAN | Świercz A. | - | IPPT PAN | Ostrowski M. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Olaszek P. | - | Instytut Badawczy Dróg i Mostów (PL) | Jankowski Ł. | - | IPPT PAN |
| | 140p. |
3. |
Błachowski B., Tauzowski P., Lógó J.^{♦}, Yield limited optimal topology design of elastoplastic structures,
STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, ISSN: 1615-147X, DOI: 10.1007/s00158-019-02447-9, pp.1-24, 2020Streszczenie: This study is devoted to a novel method for topology optimization of elastoplastic structures subjected to stress constraints. It should be noted that in spite of the classical solutions of the different type of elastoplastic topology problems are more than 70 years old, the integration of the Prandtl-Reuss constitutive equations into the topology optimization process is not very often investigated in the last three decades. In the presented methodology where the classical variational principles of plasticity and the functor-oriented programming technique are applied in topology design, the aim is to find a minimum weight structure which is able to carry a given load, fulfills the allowable stress limit, and is made of a linearly elastic, perfectly plastic material. The optimal structure is found in an iterative way using only a stress intensity distribution and a return mapping algorithm. The method determines representative stresses at every Gaussian point, averages them inside every finite element using the von Mises yield criterion, and removes material proportionally to the stress intensities in individual finite elements. The procedure is repeated until the limit load capacity is exceeded under a given loading. The effectiveness of the methodology is illustrated with three numerical examples. Additionally, different topologies are presented for a purely elastic and an elastoplastic material, respectively. It is also demonstrated that the proposed method is able to find the optimal elastoplastic topology for a problem with a computational mesh of the order of tens of thousands of finite elements. Słowa kluczowe: topology optimization, elastoplastic structures, minimum-weight design, stress constraints Afiliacje autorów:
Błachowski B. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Lógó J. | - | University of Technology and Economics (HU) |
| | 100p. |
4. |
Błachowski B., Ostrowski M., Tauzowski P., Świercz A., Jankowski Ł., Sensor placement for structural damage identification by means of topology optimization,
AIP Conference Proceedings, ISSN: 0094-243X, DOI: 10.1063/5.0007817, Vol.2239, No.1, pp.020002-1-11, 2020Streszczenie: The success of virtually all structural health monitoring (SHM) methods depends on the information content of the measurements, and thus on the placement of the available sensors. This paper presents an efficient method for finding optimal sensor distribution over structural system with many degrees of freedom (DOFs). The objective function is based on the classical Fisher information matrix. Originally, this yields a computationally hard discrete optimization problem. However, the proposed numerical solution method is based on a concept taken from structural topology optimization, where a discrete optimization problem is replaced with a continuous one. Two numerical examples demonstrate the effectiveness of the proposed methodology. These are a 5-bay truss with 24 DOFs and a two-story frame structure whose finite element model has been condensed to 14 DOFs. Słowa kluczowe: optimal sensor placement, structural damage identification, topology optimization Afiliacje autorów:
Błachowski B. | - | IPPT PAN | Ostrowski M. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Świercz A. | - | IPPT PAN | Jankowski Ł. | - | IPPT PAN |
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5. |
Tauzowski P., Błachowski B., Lógó J.^{♦}, Functor-oriented topology optimization of elasto-plastic structures,
Advances in Engineering Software, ISSN: 0965-9978, DOI: 10.1016/j.advengsoft.2019.102690, Vol.135, pp.102690-1-11, 2019Streszczenie: The paper deals with a novel approach to development of optimality criteria based finite element code for topology optimization of elasto-plastic structures. The novelty of this work is related to the concept of function object called functor and its application to efficient FE code development. First, the general problem of topology optimization under stress constraints is briefly formulated. Then, the programming aspects of topology optimization using traditional object-oriented and functor based programming are discussed. The advantages of the functor based approach are related to simplicity of designing the FE code architecture and reusability of this code. In particular the metric known as 'Lack of cohesion of methods' is useful in comparing these two different paradigms. Finally, the paper is also illustrated with numerical examples of topology optimization using the proposed methodology. Słowa kluczowe: topology optimization, function object, functor programming, optimal design, elasto-plastic structures, finite element programming Afiliacje autorów:
Tauzowski P. | - | IPPT PAN | Błachowski B. | - | IPPT PAN | Lógó J. | - | University of Technology and Economics (HU) |
| | 140p. |
6. |
Tauzowski P., Lógó J.^{♦}, Pintér E.^{♦}, Parametric Study on the Element Size Effect for Optimal Topologies,
Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.11551, Vol.62, No.1, pp.267-276, 2018 | | 15p. |
7. |
Błachowski B., Tauzowski P., Lógó J.^{♦}, Modal Approximation Based Optimal Design of Dynamically Loaded Plastic Structures,
Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.11016, Vol.61, No.4, pp.987-992, 2017Streszczenie: The purpose of this study is to present an optimal design procedure for elasto-plastic structures subjected to impact loading. The proposed method is based on mode approximation of the displacement field and assumption of constant acceleration of impacted structure during whole time of deformation process until the plastic displacement limit is reached. Derivation of the method begins with the application of the principle of conservation of linear momentum, followed by determination of inertial forces. The final stage of the method utilizes an optimization technique in order to find a minimum weight structure. Eventually, effectiveness and usefulness of the proposed method is demonstrated on the example of a planar truss structure subjected to dynamic loading caused by a mass impacting the structure with a given initial velocity. Słowa kluczowe: structural dynamics, optimal design, elasto-plastic structures, short-time dynamic loading Afiliacje autorów:
Błachowski B. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Lógó J. | - | University of Technology and Economics (HU) |
| | 15p. |
8. |
Lasota R., Stocki R.^{♦}, Tauzowski P., Szolc T., Polynomial chaos expansion method in estimating probability distribution of rotor-shaft dynamic responses,
BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.1515/bpasts-2015-0047, Vol.63, No.2, pp.413-422, 2015Streszczenie: The main purpose of the study is an assessment of computational efficiency of selected numerical methods for estimation of vibrational response statistics of a large multi-bearing turbo-generator rotor-shaft system. The effective estimation of the probability distribution of structural responses is essential for robust design optimization and reliability analysis of such systems. The analyzed scatter of responses is caused by random residual unbalances as well as random stiffness and damping parameters of the journal bearings. A proper representation of these uncertain parameters leads to multidimensional stochastic models. Three estimation techniques are compared: Monte Carlo sampling, Latin hypercube sampling and the sparse polynomial chaos expansion method. Based on the estimated values of the first four statistical moments the probability density function of the maximal vibration amplitude is evaluated by the maximal entropy principle method. The method is inherently suited for an accurate representation of the probability density functions with an exponential behavior, which appears to be characteristic for the investigated rotor-shaft responses. Performing multiple numerical tests for a range of sample sizes it was found that the sparse polynomial chaos method provides the best balance between the accuracy and computational effectiveness in estimating the unknown probability distribution of the maximal vibration amplitude. Słowa kluczowe: stochastic moment estimation, sparse polynomial chaos expansion, maximum entropy principle, rotor, uncertainties, hybrid mechanical model, random unbalance distribution Afiliacje autorów:
Lasota R. | - | IPPT PAN | Stocki R. | - | inna afiliacja | Tauzowski P. | - | IPPT PAN | Szolc T. | - | IPPT PAN |
| | 20p. |
9. |
Kowalczyk P., Rojek J., Stocki R., Bednarek T., Tauzowski P., Lasota R., Lumelskyj D., Wawrzyk K., NUMPRESS − integrated computer system for analysis and optimization of industrial sheet metal forming processes,
HUTNIK - WIADOMOŚCI HUTNICZE, ISSN: 1230-3534, Vol.81, No.1, pp.56-63, 2014Streszczenie: The NUMPRESS System has been developed in IPPT PAN as a result of a project financially supported by European Regional Development Fund (within the Innovative Economy Programme) and is dedicated to small and middle enterprises dealing with sheet metal forming. The program consists of (i) an analytical module for analysis of forming processes with the finite element method, (ii) an optimization module controlling execution of the analytical module and performing optimization with respect to selected process parameters, in both deterministic and robust formulation, (iii) a reliability analysis module controlling execution of the analytical module to assess how random distribution of design parameters affects forming results, and (iv) a graphical user interface enabling communication between modules and easy definition of design parameters and optimization criteria. The analytical module consists of two independent programs up to the user's choice: NUMPRESS-Flow, a faster and less accurate program for implicit quasi-static analysis of rigid-viscoplastic shells (based on the flow approach) and NUMPRESS-Explicit, a program for explicit dynamical analysis of elastic-plastic and elastic-viscoplastic shells. Both programs are interfaced to a well-known commercial graphical pre- and postprocessor GiD. Fundamentals of formulations employed in the system and numerical examples are presented in the paper. Słowa kluczowe: sheet metal forming, finite element method, deterministic and robust design optimization, reliability analysis Afiliacje autorów:
Kowalczyk P. | - | IPPT PAN | Rojek J. | - | IPPT PAN | Stocki R. | - | IPPT PAN | Bednarek T. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Lasota R. | - | IPPT PAN | Lumelskyj D. | - | IPPT PAN | Wawrzyk K. | - | IPPT PAN |
| | 6p. |
10. |
Stocki R., Szolc T., Tauzowski P., Knabel J., Robust design optimization of the vibrating rotor shaft system subjected to selected dynamic constraints,
MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2011.07.023, Vol.29, pp.34-44, 2012Streszczenie: The commonly observed nowadays tendency to weight minimization of rotor-shafts of the rotating machinery leads to a decrease of shaft bending rigidity making a risk of dangerous stress concentrations and rubbing effects more probable. Thus, a determination of the optimal balance between reducing the rotor-shaft weight and assuring its admissible bending flexibility is a major goal of this study. The random nature of residual unbalances of the rotor-shaft as well as randomness of journal-bearing stiffness have been taken into account in the framework of robust design optimization. Such a formulation of the optimization problem leads to the optimal design that combines an acceptable structural weight with the robustness with respect to uncertainties of residual unbalances – the main source of bending vibrations causing the rubbing effects. The applied robust optimization technique is based on using Latin hypercubes in scatter analysis of the vibration response. The so-called optimal Latin hypercubes are used as experimental plans for building kriging approximations of the objective and constraint functions. The proposed method has been applied for the optimization of the typical single-span rotor-shaft of the 8-stage centrifugal compressor. Słowa kluczowe: Rotor-shaft system, Robust design optimization, Lateral vibrations, Rubbing effects, Random unbalance distribution Afiliacje autorów:
Stocki R. | - | IPPT PAN | Szolc T. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Knabel J. | - | IPPT PAN |
| | 45p. |
11. |
Stocki R., Lasota R., Tauzowski P., Szolc T., Scatter assessment of rotating system vibrations due to uncertain residual unbalances and bearing properties,
COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, Vol.19, pp.95-120, 2012Streszczenie: The main objective of the presented study is an evaluation of the effectiveness of various methods for estimating statistics of rotor-shaft vibration responses. The computational effectiveness as well as the accuracy of statistical moment estimation are essential for efficient robust design optimization of the rotor-shaft systems. The compared methods include sampling techniques, the perturbation approach, the dimension reduction method and the polynomial chaos expansion method. For comparison, two problems of the rotor-shaft vibration analysis are considered: a typical single-span rotor-shaft of the 8-stage centrifugal compressor driven by the electric motor and a large multi-bearing rotor-shaft system of the steam turbo-generator. The most important reason for the observed scatter of the rotor-shaft vibration responses is the inherently random nature of residual unbalances as well as stiffness and damping properties of the journal bearings. A proper representation of these uncertain parameters leads to multidimensional stochastic models. It was found that methods that provide a satisfactory balance between the estimation accuracy and computational effectiveness are sampling techniques. On the other hand, methods based on Taylor series expansion in most of the analysed cases fail to approximate the rotor-shaft response statistics. Słowa kluczowe: Scatter analysis, rotor-shaft vibrations Afiliacje autorów:
Stocki R. | - | IPPT PAN | Lasota R. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Szolc T. | - | IPPT PAN |
| | 6p. |
12. |
Lógó J.^{♦}, Movahedi Rad M.^{♦}, Knabel J., Tauzowski P., Reliability based design of frames with limited residual strain energy capacity,
Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, Vol.55, No.1, pp.13-20, 2011Streszczenie: The aim of this paper is to create new type of plastic limit design procedures where the influence of the limited load carrying capacity of the beam-to-column connections of elasto-plastic steel (or composite) frames under multi-parameter static loading and probabilistically given conditions are taken into consideration. In addition to the plastic limit design to control the plastic behaviour of the structure, bound on the complementary strain energy of the residual forces is also applied. If the design uncertainties (manufacturing, strength, geometrical) are taken into consideration at the computation of the complementary strain energy of the residual forces the reliability based extended plastic limit design problems can be formed. Two numerical procedures are elaborated. The formulations of the problems yield to nonlinear mathematical programming which are solved by the use of sequential quadratic algorithm. Słowa kluczowe: reliability analysis, limit analysis, residual strain energy, Monte Carlo simulation, optimal design Afiliacje autorów:
Lógó J. | - | University of Technology and Economics (HU) | Movahedi Rad M. | - | University of Technology and Economics (HU) | Knabel J. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN |
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13. |
Szolc T., Tauzowski P., Stocki R., Knabel J., Damage identification in vibrating rotor-shaft systems by efficient sampling approach,
MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, Vol.23, pp.1615-1633, 2009Streszczenie: In the paper a stochastic method for fault detection and identification in the shafts of rotating machines is proposed. This approach is based on the Monte Carlo simulations of rotor-shaft lateral–torsional–longitudinal vibrations mutually coupled by transverse cracks of various possible and randomly selected depths and locations on the shaft. For this purpose the structural hybrid model of a real faulty object is applied. This model is characterized by a high practical reliability and great computational efficiency, so important for many hundred thousand single numerical simulations necessary for a creation of the databases applied for inverse problem solution finally leading to crack identification. These databases are created with an arbitrary assumed probability densities of crack parameters which ensures appropriate spread of the dynamic responses of the considered faulty mechanical system. A sufficiently large database determined for the investigated object enable us to estimate almost immediately, i.e. within less than 1 s, the crack depth and axial position with identification errors not exceeding 9% and 5%, respectively. Thus, the proposed method seems to be a very convenient diagnostic tool for engineering applications in the industry. Słowa kluczowe: Rotor-shaft system, Dynamic diagnostics, Crack identification, Monte Carlo simulation, Coupled vibration analysis Afiliacje autorów:
Szolc T. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Stocki R. | - | IPPT PAN | Knabel J. | - | IPPT PAN |
| | 32p. |
14. |
Szolc T., Tauzowski P., Knabel J., Stocki R., Nonlinear and parametric coupled vibrations of the rotor-shaft system as fault identification symptom using stochastic methods,
NONLINEAR DYNAMICS, ISSN: 0924-090X, Vol.57, pp.533-557, 2009Streszczenie: In the paper several stochastic methods for detection and identification of cracks in the shafts of rotating machines are proposed. All these methods are based on the Monte Carlo simulations of the rotor-shaft lateral-torsional-longitudinal vibrations mutually coupled by transverse cracks of randomly selected depths and locations on the shaft. For this purpose there is applied a structural hybrid model of a real cracked rotor-shaft. This model is characterized by a high practical reliability and great computational effi-ciency, so important for hundreds of thousands numerical simulations necessary to build databases used in solving the inverse problem, i.e. crack parameter identifications. In order to ensure a good identification accuracy, for creating the Monte Carlo samples of data points there are proposed special probability density functions for locations and depths of the crack. Such an approach helps in enhancing databases corresponding to the most probable faults of the rotor-shaft system of the considered rotor machine. In the presentedstudy six different database sizes are considered to compare identification efficiency and accuracy of considered methods. A sufficiently large database enables us to estimate almost immediately (usually in less than one second) the crack parameters with precision that is in most of the cases acceptable in practice. Then, as a next stage, one of the proposed fast improvement algorithms can be applied to refine identification results in a reasonable time. The proposed methods seem to provide very convenient diagnostic tools for industrial applications. Słowa kluczowe: Crack rotor dynamics, Nonlinear and parametric vibrations, Hybrid modeling, Monte Carlo simulation, Crack identification methods Afiliacje autorów:
Szolc T. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Knabel J. | - | IPPT PAN | Stocki R. | - | IPPT PAN |
| | 32p. |
15. |
Stocki R., Kolanek K., Knabel J., Tauzowski P., FE based structural reliability analysis using STAND environment,
COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, Vol.16, pp.35-58, 2009Streszczenie: An assessment of structural reliability requires multiple evaluations of the limit state function for various realizations of random parameters of the structural system. In the majority of industrial applications the limit state functions cannot be expressed explicitly in terms of the random parameters but they are specified using selected outcomes of the FE analysis. In consequence, in order to be useful in practice, a structural reliability analysis program should be closely integrated with a FE module or it should be interfaced with an advanced external FE program. When the FE source code is not available, which is usually the case, the only option is to establish a communication between the reliability analysis program and an external FE software through the batch mechanism of data modification, job submission and results extraction. The main subject of this article is to present the reliability analysis capabilities of STAND software, which is being developed in the Institute of Fundamental Tech no logical Research of Polish Academy of Sciences. A special emphasis is put on the issues related to it s interfacing with external general purpose FE codes. It is shown that when shape type random variables are used, leading to modifications of the FE mesh, or when the limit state function contains numerical noise, standard algorithms for localizing the design point often fail to converge and a special method based on some response surface approximation is needed. A proposition of such a strategy that employs an adaptive response surface approximation of the limit state function is presented in this article. Development of a reliability analysis program is a challenging project and calls for such a code organization, which would facilitate a simultaneous work of many programmers and allow for easy maintenance and modifications. The so-called object-oriented programming seems to provide a convenient framework to realize these objectives. The object-oriented approach is used in STAND development. The advantages of this programming paradigm and a short description of the STAND’s class hierarchy are presented in the text. The study is concluded with two numerical examples of interfacing STAND with state of the art commercial FE programs. Słowa kluczowe: Reliability, optimization software Afiliacje autorów:
Stocki R. | - | IPPT PAN | Kolanek K. | - | IPPT PAN | Knabel J. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN |
| | 6p. |
16. |
Movahedi Rad M.^{♦}, Lógó J.^{♦}, Knabel J., Tauzowski P., Reliability based limit design of frames with limited residual strain energy capacity,
Proceedings in Applied Mathematics and Mechanics, ISSN: 1617-7061, DOI: 10.1002/pamm.200910323, Vol.9, pp.709-710, 2009Streszczenie: The aim of this paper is to take into consideration the influence of the limited load carrying capacity of the connections on the plastic limit state of elasto-plastic steel (or composite) framed structures under multi-parameter stochastic loading and probabilistically given conditions. In addition to the plastic limit design to control the plastic behaviour of the structure, bound on the complementary strain energy of the residual forces is also applied. This bound has significant effect for the load parameter. If the design uncertainties (manufacturing, strength, geometrical) are expressed by the calculation of the complementary strain energy of the residual forces a reliability based extended limit design problem is formed. The formulations of the problems yield to nonlinear mathematical programming which are solved by the use of sequential quadratic algorithm. The bi-level optimization procedure governed by the reliability index calculation. Słowa kluczowe: limit analysis of frames, reliability analysis, optimization Afiliacje autorów:
Movahedi Rad M. | - | University of Technology and Economics (HU) | Lógó J. | - | University of Technology and Economics (HU) | Knabel J. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN |
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17. |
Stocki R., Tauzowski P., Knabel J., Reliability analysis of a crashed thin-walled s-rail accounting for random spot weld failures,
INTERNATIONAL JOURNAL OF CRASHWORTHINESS, ISSN: 1358-8265, DOI: 10.1080/13588260802055213, Vol.13, No.6, pp.693-706, 2008Streszczenie: Possibly the most common application of spot welding is in the automobile manufacturing industry, where it is almost universally used to weld the sheet-metal car components. However, due to manufacturing inaccuracies and fatigue failures an important number of spot welds may be missing in an operational vehicle. It seems that to properly analyse the reliability of such structures, in particular crashworthiness reliability, the spot weld failures must be considered. Representing properties of each spot weld in a stochastic model by corresponding random variables is extremely inefficient. Therefore, in this article an approach is proposed for handling spot-weld defects in the reliability analysis by accounting for their averaged influence on a failure criterion. The approach consists of the appropriate treatment of a random noise component of the limit state function. The noise results from the strategy of deleting a certain number of randomly selected spot-weld elements from the finite element model each time the limit state function value is computed. Dealing with noisy limit state functions in structural reliability analysis is a challenging task. The only method that seems to be insensitive to this phenomenon is Monte Carlo sampling, which for most of the applications of practical interest is prohibitively expensive. Having this in mind, a method based on the algorithm proposed by Zou et al. and published in the journal of Reliability Engineering and System Safety in 2002 is investigated in this article. The method combines the best features of the first-order reliability method, the response surface technique and the importance sampling method to achieve both accuracy and efficiency. A detailed study on the reliability of thin-walled s-rail subjected to crash is performed. Some suggestions concerning the modification of the original algorithm are proposed.
Słowa kluczowe: crashworthiness reliability, response surface approximation, adaptive importance sampling, spot weld failures Afiliacje autorów:
Stocki R. | - | IPPT PAN | Tauzowski P. | - | IPPT PAN | Knabel J. | - | IPPT PAN |
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18. |
Tauzowski P., Kleiber M., Parameter and shape sensitivity of thermo-viscoelastic response,
COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2005.09.026, Vol.84, pp.385-399, 2006Streszczenie: Gradient-based optimization methods are still most efficient methods for solving structural optimization problems. The sensitivity formulation has been one of the central issues in the gradient-based optimization algorithm. Thermo-viscoelastic constitutive and parameter sensitivity formulation are presented in this paper. The model considered is composed of two coupled subproblems: the transient heat transfer problem and a rheological, viscoelastic material model known in literature as the standard model. Design variables considered are with material and shape-defining parameters. The investigation includes a finite element formulation and implementation in an object-oriented finite element environment. Results of numerical analysis are presented. Słowa kluczowe: Finite element method, Sensitivity analysis, Viscoelasticity Afiliacje autorów:
Tauzowski P. | - | IPPT PAN | Kleiber M. | - | IPPT PAN |
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