scholarly journals Decreasing Shear Stresses of the Solder Joints for Mechanical and Thermal Loads by Topological Optimization

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1862
Author(s):  
Jan Awrejcewicz ◽  
Sergey P. Pavlov ◽  
Anton V. Krysko ◽  
Maxim V. Zhigalov ◽  
Kseniya S. Bodyagina ◽  
...  
Keyword(s):  
Finite Elements ◽  
Stress Level ◽  
Wide Class ◽  
Structural Characteristics ◽  
Optimization Methods ◽  
Topological Optimization ◽  
Shear Stresses ◽  
Robust Designs ◽  
Moving Asymptotes ◽  
Soldered Joint

A methodology for obtaining the optimal structure and distribution for the gradient properties of a material in order to reduce the stress level in a soldered joint was constructed. The developed methodology was based on a combination of topological optimization methods (the moving asymptotes method) and the finite elements method; it was first implemented to solve problems of optimizing soldered joints. Using the proposed methodology, a number of problems were solved, allowing one to obtain optimal structural characteristics, in which a decrease in stress is revealed. Designing compounds using this technique will provide more robust designs. The proposed technique can be applied to a wide class of practical problems.

scholarly journals Topological Optimization of Microstructure of Adhesives under Thermal and Mechanical Loads

2019 ◽  
pp. 1-28
Author(s):  
K. S. Bodyagina ◽  
S. P. Pavlov
Keyword(s):  
A Priori ◽  
Adhesive Layer ◽  
Optimization Methods ◽  
Topological Optimization ◽  
Shear Stresses ◽  
The Finite Element Method ◽  
Mechanical Loads ◽  
Promising Strategy ◽  
Solder Microstructure ◽  
Thickness Shear

The paper presents a mathematical model and method for solving a wide class of problems in topological optimization of an adhesive joint to obtain an optimal microstructure and gradient properties in order to reduce the level of stresses arising from both thermal and mechanical loads therein.Adhesive joints have advantages over alternative bonding methods. The paper shows that the introduction of graduating properties in thickness or along the adhesive layer is the most promising strategy to optimize the adhesive. The approach is to modify the material properties or the geometry of the adhesive, varying along the joint.In all the papers known to authors, the shape of the elements to be joined, or the shape and location of the adhesive layer, were subject to optimization. The topological optimization methods to determine the optimal distribution / change of the gradient properties of the adhesive layer itself were not used.In the paper, the stresses arising in the solder joints are analyzed; it is shown that due to the small solder thickness, shear stresses are basic in it. The shear stresses are concentrated near the ends of the solder, and have the lowest values in the middle. The objective of the optimization problem is to reduce the peak values of the shear and peeling stresses in the solder layer. The topological optimization of the solder microstructure is to find the best distribution of a given amount of solder in the region in order to reach minimum peak values of stresses. The advantage of using topological optimization is that the microstructure of the solder should not be known a priori, and, thus, any designs can be optimized without first studying the effect of the original geometric parameters on the strength of the joint.The algorithm is implemented using the finite element method and the method of movable asymptotes. A number of examples are considered in order to obtain the solder microstructure to be optimal for reducing the peak values of shear stresses and delamination in a three-layer package.The results show that optimal microstructures significantly reduce peak stresses compared to a uniform layer. The obtained results reveal the potential of the developed algorithm and show that it can find practical use.

scholarly journals Оптимизация алюминиевой крышки люкового закрытия сухогрузного судна

2020 ◽  
Author(s):  
G.B. Kryzhevich ◽  
A.R. Filatov
Keyword(s):  
Shape Optimization ◽  
Parametric Optimization ◽  
Optimization Methods ◽  
Topological Optimization ◽  
Design And Technology ◽  
Bulk Carrier ◽  
Material Consumption ◽  
Considerable Decrease ◽  
Bulk Carriers ◽  
Cargo Transportation

Объектом исследования является крышка люкового закрытия сухогрузного судна, служащая для обеспечения непроницаемости грузовых помещений и перевозки на ней грузов и обеспечивающая безопасность сухогрузных судов и осуществляемой на них морской перевозки грузов. Большая материалоемкость крышек снижает экономическую эффективность судна, ведет к необходимости использования мощных и массогабаритных средств подъема крышек (для съемных люковых закрытий), либо поворота и передвижения крышек (для шарнирно-откидных закрытий). Целью статьи является существенное снижение материалоемкости крышек люкового закрытия за счет рационального выбора их материала и конструктивного оформления при одновременном обеспечении требуемого уровня их надежности. Параметрическая оптимизация традиционной стальной крышки люкового закрытия сухогрузного судна проекта RSD59 может привести к снижению ее массы не более чем на 15-17. Поэтому для достижения цели работы решается задача оптимизации конструкции алюминиевой крышки на основе комплексного подхода, состоящего в последовательном использовании топологических и параметрических оптимизационных методов и выполнении на последней стадии работы снижения уровня концентрации напряжений путем оптимизации формы узлов крышки. При этом на стадии выбора конструктивно-силовой схемы крышки применяются приёмы топологической оптимизации, на стадии выбора толщин и параметров силовых элементов способы параметрической оптимизации, а на стадии конструктивно-технологического оформления узлов методы оптимизации формы. Выполненные расчетные исследования привели к следующим основным результатам: к выявлению прогрессивных конструктивно-силовых схем и конструктивно-технологических решений, обеспечивающих значительное снижению массы крышек люковых закрытий при умеренных затратах на их изготовление к высоким оценкам эффективности использования современных алюминиевых сплавов для изготовления люковых закрытий, способствующим существенному снижению их материалоемкости (примерно двукратному и более по сравнению с использованием стали), улучшению условий их функционирования и проведения погрузочно-разгрузочных работ на сухогрузных судах к выводу об эффективности использования разработанных конструкторских решений для крышек люковых закрытий при создании перспективных сухогрузных судов.A bulk carrier hatch cover, which provides cargo compartments impermeability and cargo transportation on the cover, as well as safety of bulk carriers and sea cargo transportation in them, is studied. Cover high material consumption decreases vessel profitability, causes the necessity to use either powerful and mass-dimensional cover lifting devices (for removable hatch covers) or covers rotation and movement (for hinged covers). The purpose of this paper consists in considerable decrease of hatch cover material consumption through rational selection of covers material and design at provision of the required covers reliability level. Parametric optimization of a conventional steel cover of RSD59 project bulk carrier could result in cover mass decrease by more than 15 to 17. Therefore, to achieve the work purpose, a problem of aluminum cover structural optimization was solved based on a comprehensive approach that consisted in successive use of topologic and parametric optimization methods and decrease of the stress concentration level at the last step via cover assemblies shape optimization. At that topological optimization methods were applied at the stage of selecting cover structural arrangement parametric optimization methods were applied at the stage of selecting load-carrying elements thickness and parameters, and shape optimization methods were used at the stage of structural and technology design of assemblies. The performed calculation studies resulted in the following: revealing the advanced structural arrangements and design and technology solutions that provide considerable hatch covers mass decrease at reasonable costs for their manufacture high assessment of using advanced aluminum alloys for manufacturing hatch covers that promote considerable decrease of their material consumption (approximately up to twofold or greater in comparison with steel), improving conditions of cover functioning and handling operation in bulk carriers conclusion on effectiveness of using developed design solutions for hatch covers when creating prospective bulk carriers.

scholarly journals High-Strength Behavior of the Al0.3CoCrFeNi High-Entropy Alloy Single Crystals

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1149
Author(s):  
Irina V. Kireeva ◽  
Yuriy I. Chumlyakov ◽  
Zinaida V. Pobedennaya ◽  
Anna V. Vyrodova ◽  
Anastasia A. Saraeva
Keyword(s):  
Single Crystals ◽  
Yield Point ◽  
Stress Level ◽  
High Stress ◽  
High Strength ◽  
Orientation Dependence ◽  
Temperature Deformation ◽  
High Entropy Alloy ◽  
Shear Stresses ◽  
High Entropy

The main disadvantage of fcc (face-centred cubic lattice) high-entropy alloys is the low stress level at the yield point (σ0.1) at a test temperature above room temperature. This restricts their practical application at high test temperatures from 773 K to 973 K. In this study, we found that a high stress level was reached at the yield point σ0.1 ≈ G/100–G/160 (G is the shear modulus) of the [001]- and [1¯44]-oriented crystals of the Co23.36Cr23.29Fe23.80Ni21.88Al7.67 (Al0.3CoCrFeNi) high-entropy alloy (HEA) within a wide temperature range of 77–973 K under tension, due to the occurrence, of nanotwins, multipoles, dislocations under plastic deformation at 77 K and the subsequent precipitation of ordered L12 and B2 particles. It was shown that grain boundaries are not formed and the samples remain in a single-crystal state after low-temperature deformation and subsequent ageing at 893 K for 50 h. Achieving a high-strength state in the Al0.3CoCrFeNi HEA single crystals induces the orientation dependence of the critical resolved shear stresses (τcr) at T ≥ 200 K (τcr[1¯44] > τcr[001]), which is absent in the initial single-phase crystals, weakens the temperature dependence of σ0.1 above 573 K, and reduces plasticity to 5–13% in the [1¯44] orientation and 15–20% in the [001] orientation.

New Expressions for Fillet Weld Torsion Shear Stresses Calculation

2005 ◽  
Author(s):  
Rafael Goytisolo ◽  
Hernan Hernandez ◽  
Jorge Moya ◽  
Inga M. Jackson
Keyword(s):  
Shear Stress ◽  
Finite Elements ◽  
Fracture Mechanics ◽  
Welded Joints ◽  
Shear Stresses ◽  
Fillet Weld ◽  
Engineering Construction ◽  
Weld Joints ◽  
Thin Walls ◽  
Better Than

The fillet welds are conventionally calculated to shear stress in the weakest section: the throat area of the weld. This consideration is a simplification for any fillet weld. Nevertheless, this procedure is internationally accepted as a justified procedure, mainly, for the simplification that makes the calculation of the welded joints of an engineering construction an easy procedure. This premise has motivated that different authors try to obtain calculation expressions for different cases that are presented in the practice, looking to facilitate the work of the industry technicians and engineers in charge of carrying out the calculation of these unions, however, in this pawn they don’t always use the most appropriate methods settled down by the Mechanics of the Materials introducing inaccuracies in these expressions. The Fracture Mechanics has outlined a new necessity: the development of methods of predicting defects that could exist in the welding cords. In order to do that, it is required to determine the stresses that arise in the welding with a superior accuracy. In this paper, the Theory of the Torsion of Thin Walls Profiles is applied to the calculation of the torsion shear stresses of the fillet weld joints. New calculation expressions are obtained that belong together better than the classic expressions with relationship to the values obtained by the Finite Elements Method.

Validating Analysis on Influence of Vehicle Structure in Considering Crash Compatibility

2012 ◽  
Vol 209-211 ◽  
pp. 2113-2116 ◽  
Author(s):  
Zheng Bao Lei ◽  
Ru He ◽  
Mu Xi Lei
Keyword(s):  
Finite Elements ◽  
Contact Surface ◽  
Optimization Algorithm ◽  
Geometric Structure ◽  
Mass Fraction ◽  
Impact Force ◽  
Topological Optimization ◽  
Finite Elements Analysis ◽  
Vehicle Structure ◽  
Compatibility Constraint

With the finite elements analysis and topological optimization algorithm, the head structure of four-wheel independent drive pure electric vehicle is regarded as optimization objective. The vehicle’s head structure is optimized by LS-DYNA and LS-TASC on the condition that whether considering the compatibility constraint. The mass fraction curve, the mass distribution convergence curve and optimization results are used to analyze the influence of vehicle structure when considering crash compatibility, and verify that good crash compatibility means homogeneous geometric structure and homogeneous impact force in contact surface.

scholarly journals GENERATIVE DESIGN OF A FRAME TYPE CONSTRUCTION

2021 ◽  
Author(s):  
Ihor V. Mastenko ◽  
Nataliia V. Stelmakh
Keyword(s):  
Rational Design ◽  
Rapid Development ◽  
Optimization Methods ◽  
Geometric Constraints ◽  
Topological Optimization ◽  
Design Stage ◽  
Physical Constraints ◽  
Specific Strength ◽  
Cad Cam ◽  
Type Construction

Background. In recent years, there has been a rapid development of the domestic military industry. Reducing the mass and increasing the specific strength of military products used in the field – the most pressing challenges facing engineers and scientists today. The rapid development of adaptive production has significantly expanded the possibilities of methods of topological optimization in the design of new products or improvement of existing design and technological solutions in order to reduce weight. Objective. The purpose of the paper is to improve the efficiency of designing the technology of manufacturing a frame type construction based on the method of topological optimization, which will reduce the weight of the product, while maintaining all the specified functional parameters. Methods. The paper presents an analysis of topological optimization methods and offers the interaction of modern ADS, namely CAD, CAM, CAE modules at the stage of design and technological preparation of production, which once again demonstrated its effectiveness in solving problems to reduce product weight. Results. The main tasks of topological optimization were solved for the frame type constructions, such as the minimization of volume and mass under physical constraints, as well as the optimization of other parameters with given geometric constraints. As a result, the proposed method of reducing the weight of the product is improved, which due to rational design and technological measures ensured a 56 % reduction in the weight of the frame type structure from the original and reduced the complexity of the manufacturing process by 22 % due to its effective adaptation to new technological conditions. Conclusions. The application of methods of topological optimization and rational establishment of design and technological constraints on products at the design stage can be very effective in solving problems of reducing the weight of products and optimizing manufacturing processes.

scholarly journals Finding a weak solution of the heat diffusion differential equation for turbulent flow by Galerkin's variation method using p-version finite elements

2021 ◽  
Vol 16 (2) ◽  
pp. 129-157
Author(s):  
István Páczelt
Keyword(s):  
Heat Transfer ◽  
Differential Equation ◽  
Weak Solution ◽  
Finite Elements ◽  
Turbulent Flow ◽  
Turbulence Model ◽  
Symmetric Domain ◽  
Heat Diffusion ◽  
Variation Method ◽  
Shear Stresses

The stochastic turbulence model developed by Professor Czibere provides a means of clarifying the flow conditions in pipes and of describing the heat evolution caused by shear stresses in the fluid. An important part of the theory is a consideration of the heat transfer-diffusion caused by heat generation. Most of the heat is generated around the pipe wall. One part of the heat enters its environment through the wall of the tube (heat transfer), the other part spreads in the form of diffusion in the liquid, increasing its temperature. The heat conduction differential equation related to the model contains the characteristics describing the turbulent flow, which decisively influence the resulting temperature field, appear. A weak solution of the boundary value problem is provided by Bubnov-Galerkin’s variational principle. The axially symmetric domain analyzed is discretized by a geometrically graded mesh of a high degree of p-version finite elements, this method is capable of describing substantial changes in the temperature gradient in the boundary layer. The novelty of this paper is the application of the p-version finite element method to the heat diffusion problem using Czibere’s turbulence model. Since the material properties depend on temperature, the problem is nonlinear, therefore its solution can be obtained by iteration. The temperature states of the pipes are analyzed for a variety of technical parameters, and useful suggestions are proposed for engineering designs.

Finite Element Calculation of the Polymer Stamp Material Redistribution under Restrictions on Fatigue Life

2022 ◽  
Vol 1049 ◽  
pp. 248-254
Author(s):  
Ivan Andrianov
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Stress State ◽  
Geometric Model ◽  
Optimization Methods ◽  
Optimization Method ◽  
Topological Optimization ◽  
Optimal Topology ◽  
Calculation Results ◽  
Rejection Coefficient

The numerical method of stamp topological optimization taking into account fatigue strength is presented in the work. It is proposed to take into account the restrictions on the stress state in accordance with the curve of the dependence of the maximum stresses on the number of loading cycles in the ESO topological optimization method. An approach to the selection of the evolutionary coefficient with a step-by-step increase in the rejection coefficient is proposed when constructing an iterative scheme for the rejection of elements by the method of topological optimization. The calculation of the stamp optimal topology with a decrease in volume due to the removal and redistribution of material was carried out in the study. The new geometric model of the optimal topology stamp is based on the predicted distribution of elements with a minimum stress level. The verification calculation of the stress state of the stamp of optimal topology with an assessment of fatigue strength was carried out in the work. The numerical calculation was carried out using the finite element method in the Ansys software package. The minimized stamp volume decreased by 35% according to the calculation results. The results of the study can be further applied in the development of topological optimization methods and in the design of stamping tools of optimal topology.

Design of Architectured Sandwich Core Materials using Topological Optimization Methods

2009 ◽  
Vol 1188 ◽  
Author(s):  
Laurent Laszczyk ◽  
Rémy Dendievel ◽  
Olivier Bouaziz ◽  
Yves Bréchet ◽  
Guillaume Parry
Keyword(s):  
Optimization Problems ◽  
Optimization Methods ◽  
Numerical Approach ◽  
Optimization Techniques ◽  
Topological Optimization ◽  
The Core ◽  
Level Set Function ◽  
General Geometry ◽  
Sandwich Core ◽  
Core Materials

AbstractSandwich structures are especially interesting when multiple functionalities (such as stiffness and thermal insulation) are required. Properties of these structures are strongly dependent on the general geometry of the sandwich, but also on the detailed patterns of matter partitioning within the core. Therefore it seems possible to tailor the core pattern in order to obtain the desired properties. But multi-functional specifications and the infinite number of possible shapes, leads to non-trivial selection and/or optimization problems. In this context of “material by design”, we propose a numerical approach, based on structural optimization techniques, to find the core pattern that leads to the best performances for a given set of conflicting specifications. The distribution of matter is defined thanks to a level-set function, and the convergence toward the optimized pattern is performed through the evolution of this function on a fixed grid. It is shown that the solutions of optimization are strongly dependent on the formulation of the problem, which have to be chosen with respect to the physics. A first application of this approach is presented for the design of sandwich core materials, in order to obtain the best compromise between flexural stiffness and relative density. The influence of both the initialization (starting geometry) and the formulation of the optimization problem are detailed.

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