Wyniki wyszukiwania - BazTech

1

Research on optimum design method of cushion thickness in composite foundation under rigid base

Xiao Yaoting, Wang Jing

Archives of Civil Engineering

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2023

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Vol. 69, nr 2

471--482

EN

At present, the cushion thickness of composite foundation under rigid base is mostly selected by the experience of the engineer, which is of great arbitrariness. In order to improve this problem, the optimum design method of cushion thickness is proposed by theoretical research. First, the stress diffusion line in the cushion is assumed to be a quadratic curve, and the critical diffusion thickness of the pile top stress is obtained. Then, by analyzing the relative deformation between soil and pile, pile top penetration into the critical cushion thickness is proposed. Finally, based on the relationship between stress ratio of pile to soil and cushion thickness, the calculation method of optimum cushion thickness is put forward. The application of engineering cases shows that the proposed method has better calculation results, which attests to the correctness of the method. The method can be used for the optimal design of cushion thickness of single-type-pile or multi-type-pile composite foundation.

2

An optimal design of thermal protection basedon materials morphology

Salosina Margarita O., Alifanov Oleg M., Nenarokomov Aleksey V.

Computer Assisted Methods in Engineering and Science

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2019

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Vol. 26, no. 1

49--60

EN

The paper presents a methodology for the optimal design of multilayer thermal protection based on high-porosity open-cell foam, taking into account the foam morphology. The vector of design parameters includes the thicknesses of layers, porosity and cell diameter of open-cell foam and should ensure required operation temperature on the boundaries of layers and a minimum of the total mass of the system. The optimization problem is solved using a computational scheme, which combines the projected Lagrangian method with the quadratic subproblem and the penalty function method. The penalty function method provides a good initial estimate of the optimal parameters’ values for the projected Lagrangian method with excellent local convergence properties. To illustrate the implementation of the developed algorithm and the corresponding software, the problem of choosing the optimal layer thicknesses for the multilayer thermal protection of a spacecraft along with the cell diameter and porosity of foam is considered.

3

Comparison of optimal costs of axially loaded RC tension members using Indian and Euro standards

Karthiga Shenbagam N., Arunachalam N.

Archives of Civil Engineering

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2017

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Vol. 63, nr 1

99--113

EN

The aim of this study is to find the cost design of RC tension with varying conditions using the Artificial Neural Network. Design constraints were used to cover all reliable design parameters, such as limiting cross sectional dimensions and; their reinforcement ratio and even the beahviour of optimally designed sections. The design of the RC tension members were made using Indian and European standard specifications which were discussed. The designed tension members according to both codes satisfy the strength and serviceability criteria. While no literature is available on the optimal design of RC tension members, the cross-sectional dimensions of the tension membersfor different grades of concrete and steel, and area of formwork are considered as the variables in the present optimum design model. A design example is explained and the results are presented. It is concluded that the proposed optimum design model yields rational, reliable, and practical designs.

PL

Niniejsza praca została poświęcona optymalnemu projektowi zbrojonych cięgien. Zaprojektowano blisko pięćset zbrojonych cięgien zgodnie ze standardem indyjskim IS 456:2000 i standardem europejskim EN1992, ręcznie przy użyciu arkuszy kalkulacyjnych Microsoft Excel. Uwzględnione zmienne stanowią charakterystyczną wytrzymałość betonu, wahającą się od 25 do 50N/mm2 dla obu specyfikacji kodału? (codal?). Wytrzymałość plastyczna stali waha się pomiędzy 250, 415, 500 i 550 N/mm2 w przypadku IS 456:2000 i pomiędzy 235, 275, 355, 420 i 460 N/mm2 w przypadku standardu europejskiego. Obciążenie osiowe wahało się od 500kN do 3000 kN. Teoretyczne wyniki uzyskane na podstawie ręcznego projektu zostały wyjaśnione poniżej.

4

The optimal design of micro-punching die by using abductive and SA methods

Lin J.-Ch., Lee K.-S., Lin W.-S.

Archives of Computational Materials Science and Surface Engineering

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2009

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Vol. 1, nr 2

92-99

EN

Purpose: Punching process currently plays an important role in industrial mass production. The current study focuses on increasing accuracy, performance and extending service life of punches and dies. Optimizing the design of the punch and die has been a common topic for scholars. Design/methodology/approach: The input parameters (punching times, clearance) and output results (wear) were used to construct a training database. The abductive network formulation established a relationship between input parameters and output results. By using the abductive modeling technique, the complicated and uncertain relationships between the input and output variables can be formulated into a useful mathematical model. Once the abductive network model was constructed, the relationships between input and output parameters variables became available. A simulated annealing algorithm (SA) with a performance index was established to optimize this process and find the best result as compared with the actual experiment values. Findings: This study aims to establish the relationship between punching times, clearance and wear of micro punches using the abductive network, and to find relational model involving input parameters and output result of punching die in composite blanking processes. This model can be used to estimate wear between punch and die for industrial applications. Research limitations/implications: Setting up the relational expression of punching times, clearance and wear requires a well-established database covering sufficient relevant parameters and data. In training the database, it is helpful to establish a good relational model among punching parameters. Incorrect data will cause abnormal wear. As a result, the mathematics model is difficult to converge and the neural network will inaccurately predict wear. In addition, the punching die may be changed prematurely, which increases production costs. Delay in replacing a worn punching die can result in poor quality of products. Originality/value: As electronic production becomes increasingly smaller, the opportunity to use micro punches and dies will expand accordingly. This study established the relational expression of input and output, which can be used to correctly estimate any wear condition. This result is based on an abductive network and SA method.

5

On the fundamental problem of optimum design of anisotropic plates

Lewiński T.

Foundations of Civil and Environmental Engineering

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2006

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No. 7

215-226

EN

The paper deals with the free material design problem of minimum compliance of an anisotropic clastic plate loaded in-plane. All the characteristics of the plate stiffness tensor or of the form of the Hookc tensor for plane case, are treated as design variables. The cost function is expressed in terms of the Kelvin moduli. The necessary conditions of optimality are discussed. They imply that the deformation state within the optimal plate must satisfy the condition of colinearity of stress and strain tensors.

6

On modeling and optimal design of beam - bridge structures

Pedersen P., Pedersen N. L.

Foundations of Civil and Environmental Engineering

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2006

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No. 7

273-291

EN

To obtain black and white solutions (material or non-material) penalizations are applied, and due to problems of low density we can see a clear tendency toward solutions which more or less are truss or frame structures. Often, the accuracy of the finite element models for the continuum is then at its limits. For multiple load cases the formulation with a combination of individual load cases is in reality just as simple as for single load cases, but the design solution naturally depends on the selected combination factors, and we can illustrate this by a 3 D bridge example. It is still possible to obtain solutions by simple optimality criterion iterations which to a large extend, are used in this study. At first, the purpose of the presented paper is to make a comparison between optimal designs found by known methods for topology optimization of continuum structures and optimal designs of structures modeled as trusses. For a statically determined truss each bar can be designed independently and therefore must be fully stressed in an optimal design. We want to focus on the basic knowledge which gives an optimality criterion for single load eases with only a single constraint. Truss and continuum examples are analyzed, optimized, and evaluated to get further insight into the influence from the basic modeling, being truss or continuum. Stiffness as well as strength are important aspects of an optimal design.