• Title/Summary/Keyword: sequential quadratic programming

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Stability analysis of homogeneous slopes with benches

  • Zhao, Lianheng;Xia, Peng;Xie, Rongfu;Li, Liang;Zhang, Yingbin;Cheng, Xiao
    • Geomechanics and Engineering
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    • v.13 no.3
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    • pp.517-533
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    • 2017
  • In this paper, with a graphical approach, a series of stability charts for homogeneous slopes with benches are presented based on the upper bound limit analysis theory and strength reduction technique. The objective function of the slope safety factor $F_s$ is optimized by the nonlinear sequential quadratic programming, and a substantial number of examples are illustrated to use the stability charts for homogeneous slopes with benches driven by only the action of the soil weight. These charts can be applied to quick and accurate estimations of the stability status of homogeneous slopes with benches. Moreover, the failure modes and the formula for safety factor Fs of homogeneous slopes with benches are provided to illustrate the stability analysis of slopes with benches, which is validated by samples.

New explicit formulas for optimum design of concrete gravity dams

  • Habibi, Alireza;Zarei, Sajad;Khaledy, Nima
    • Computers and Concrete
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    • v.27 no.2
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    • pp.143-152
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    • 2021
  • Large dams are a part of the infrastructure of any society, and a huge amount of resources are consumed to build them. Among the various types of dams, the optimum design of concrete gravity dams requires special attention because these types of dams require a huge amount of concrete for their construction. On the other hand, concrete gravity dams are among the structures whose design, regarding the acting forces, geometric parameters, and resistance and stability criteria, has some complexities. In the present study, an optimization methodology is proposed based on Sequential Quadratic Programming (SQP), and a computer program is developed to perform optimization of concrete gravity dams. The optimum results for 45 concrete gravity dams are studied and regression analyses are performed to obtain some explicit formulas for optimization of the gravity dams. The optimization of concrete gravity dams can be provided easily using the developed formulas, without the need to perform any more optimization process.

Thickness Optimization for Spar Cap of Composite Tidal Current Turbine Blade using SQP Method (SQP법을 사용한 복합재 조류력 발전용 블레이드의 스파 캡에 대한 두께 최적화)

  • Cha, Myung-Chan;Kim, Sang-Woo;Jeong, Min-Soo;Lee, In;Yoo, Seung-Jae;Park, Cheon-Jin
    • Composites Research
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    • v.26 no.4
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    • pp.207-212
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    • 2013
  • In this study, the thickness optimization for uni-directional (UD) glass fiber reinforced polymer (GFRP) laminates of the spar cap of composite tidal blades was performed under the tip deflection constrains. The spar cap was composed of GFRP composites and carbon fiber reinforced polymer (CFRP) composites. The stress distributions in the blade as well as its material costs for the optimized results were additionally investigated. The optimized thickness was obtained by interacting a sequential quadratic programming (SQP) algorithm and an ABAQUS software to calculate an objective function. It was confirmed that the thickness of UD GFRP increased with a decrease of the restrained tip deflection when a thickness of UD CFRP laminates was constrained to 9 mm. The weight of the optimized spar-cap increased up to 96.2% while the maximum longitudinal tensile stress decreased up to 24.6%. The thickness of UD GFRP laminates increased with a decrease of the thickness of UD CFRP laminates when the tip deflection was constrained to 126.83 mm. The weight increased up to 40.1%, but the material cost decreased up to 16.97%. Finally, the relationships among the weight, internal tensile stress, and material costs were presented based on the optimized thicknesses of the spar cap.

Drift Design Method of Steel Moment Frames by using Column-Beam Strength Ratios and Unit-Load Method (기둥-보 휨강도비와 단위하중법을 이용한 철골모멘트골조의 강성설계기법)

  • Oh, Byung-Kwan;Park, Hyo-Seon;Choi, Se-Woon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.6
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    • pp.563-569
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    • 2016
  • This paper presents the resizing method of columns and beams that considers column-to-beam strength ratios to simultaneously control the initial stiffness and ductility of steel moment frames. The proposed method minimizes the top-floor displacement of a structure while satisfying the constraint conditions with respect to the total structural weight and column-to-beam strength ratios. The design variable considered in this method is the sectional area of structural members, and the sequential quadratic programming(SQP) technique is used to obtain optimal results from the problem formulation. The unit load method is applied to determine the displacement participation factor of each member for the top floor lateral displacement; based on this, the sectional area of each member undergoes a resizing process to minimize the top-floor lateral displacement. Resizing members by using the displacement participation factor of each member leads to increasing the initial stiffness of the structure. Additionally, the proposed method enables the ductility control of a structure by adjusting the column-to-beam strength ratio. The applicability of the proposed optimal drift design method is validated by applying it to the steel moment frame example. As a result, it is confirmed that the initial stiffness and ductility could be controlled by the proposed method without the repetitive structural analysis and the increment of structural weights.

A Study on the Task-Oriented Optimal Configuration of an ROV Mounted Manipulator Based on the Manipulability Measure (조작지수에 근거한 수중로봇팔의 작업지향적 최적자세에 관한 연구)

  • KIM Insik;JEON Bong-Hwan;LEE Pan Mook;LEE Jihong
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2004.05a
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    • pp.48-53
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    • 2004
  • In this paper, the task-oriented optimal configuration in the sense of Velocity and Force manipulability measure of manipulator mounted on ROV is considered. Manipulability is a quantitative measure of manipulator's capability obtained under the limits of joint velocities or torques. The base arrangements and optimal joint configuration of manipulator, that maximize the manipulability measure under the constraints of given task, are investigated. With the two types of base arrangements of manipulator, workspace analysis is carried out to investigate merits and demerits of each arrangement on the view of manipulability measure. To find optimal joint configuration for a given task with each arrangement, the SQP(Sequential Quadratic Programming) optimization are performed. Weighted linear combination of velocity and force manipulability measure is object function for SQP optimization. The kinematic parameters of Dual Orion manipulator which will be mounted on KORDI ROV are used for simulation.

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Optimal Shape Design of Hub Edge Contact Profile in a Press-Fitted Shaft (압입축 접촉압력 최소화를 위한 허브 접촉부 형상 최적화)

  • Choi, Ha-Young;Lee, Dong-Hyung;Kwon, Seok-Jin;Seo, Jeong-Won
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.7
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    • pp.559-564
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    • 2016
  • The objectives of this paper are to develop a finite element analysis model to analyze press-fitted and bending load conditions in a press-fitted assembly, and propose a hub shape optimization method to minimize contact pressure near the shaft contact edge. Numerical asymmetric-axisymmetric finite element models have been developed to predict contact stress on press-fitted shafts. The global optimization method, genetic algorithm, local optimization method, and sequential quadratic programming were applied to a press-fitted assembly to optimize the hub contact edge geometry. The results showed that the maximum contact pressure with the optimized hub shape decreased more than 60 % compared to conventional hubs and the maximum contact stress affecting fatigue life was reduced about 47 %. Hub shape optimization can be useful to increase the load capability of press fits in terms of wear and fatigue behavior.

Design and Optimization of Prestressed Precast Double-tee Beams (프리스트레스트 프리캐스트 더블 티형보의 최적설계)

  • 유승룡;민창식
    • Journal of the Korea Concrete Institute
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    • v.11 no.6
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    • pp.57-67
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    • 1999
  • Optimization scheme is presented for the design of precast prestressed double-tee beams used as slabs in the parking or market structures. The objective considered is defined by a function that minimizes the hight of the double-tee beam, including the prefabricated element and the concrete topping poured in a second phase. The Sequential Quadratic Programming method is adopted to solve the problem. As an example 12 double-tee beams are designed with the design loads of the current design code of our country. The results from optimization process show that at least 29cm less in overall height than that designed by PCI design handbook. The section determined from the optimization process was refined for practical considerations. A MathCad 7.0 Pro Spreadsheet was prepared to verify all ACI requirements for flexure, shear and deflections. Flexural tests are performed on four full-scale 12.5m prototype models and show that all the specimens are fully comply the flexural strength requirements as specified by ACI 318-95. The present optimization scheme can be used for wider application of the design of precast prestressed double-tee beams with different materials and configurations particularly for in a large scale or for important designs.

Optimum Design of the Friction Stir Welding Process on A6005 Extruded Alloy for Railway Vehicles to Improve Mechanical Properties (마찰 교반 용접된 철도 차량용 A6005 압출재의 기계적 성능 향상을 위한 최적 공법 설계)

  • Won, Si-Tea;Kim, Weon-Kyong
    • Journal of Welding and Joining
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    • v.27 no.5
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    • pp.81-87
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    • 2009
  • Recently, extruded aluminium-alloy panels have been used in the car bodies for the purpose of the light-weight of railway vehicles and FSW(Friction Stir Welding), which is superior to the arc weldings, has been applied in the railway vehicles. This paper presents the optimum design of the FSW process on A6005 extruded alloy for railway vehicles to improve its mechanical properties. Rotational speed, welding speed and tilting angle of the tool tip were chosen as design parameters. Three objective functions were determined; maximizing the tensile strength, minimizing the hardness and maximizing the difference between the normalized tensile strength and hardness. The tensile tests and the hardness tests for fifteen FSW experiments were carried out according to the central composite design table. Recursive model functions on three characteristic values, such as the tensile strength, the hardness difference(${\Delta}Hv$) and the difference of normalized tensile strength and ${\Delta}Hv$, were estimated according to the classical response surface analysis methodology. The reliability of each recursive function was verified by F-test using the analysis of variance table. Sensitivity analysis on each characteristic value was done. Finally, the optimum values of three design parameters were found using Sequential Quadratic Programming algorithm.

Optimal Design for the Thermal Deformation of Disk Brake by Using Design of Experiments and Finite Element Analysis (실험계획법과 유한요소해석에 의한 디스크 브레이크의 열변형 최적설계)

  • Lee, Tae-Hui;Lee, Gwang-Gi;Jeong, Sang-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.12
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    • pp.1960-1965
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    • 2001
  • In the practical design, it is important to extract the design space information of a complex system in order to optimize the design because the design contains huge amount of design conflicts in general. In this research FEA (finite element analysis) has been successfully implemented and integrated with a statistical approach such as DOE (design of experiments) based RSM (response surface model) to optimize the thermal deformation of an automotive disk brake. The DOE is used for exploring the engineer's design space and for building the RSM in order to facilitate the effective solution of multi-objective optimization problems. The RSM is utilized as an efficient means to rapidly model the trade-off among many conflicting goals existed in the FEA applications. To reduce the computational burden associated with the FEA, the second-order regression models are generated to derive the objective functions and constraints. In this approach, the multiple objective functions and constraints represented by RSM are solved using the sequential quadratic programming to archive the optimal design of disk brake.

Shape Optimization of a Plate-Fin Type Heat Sink with Triangular-Shaped Vortex Generator

  • Park, Kyoungwoo;Park, Dong-Hoon
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1590-1603
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    • 2004
  • In this study the optimization of plate-fin type heat sink with vortex generator for the thermal stability is performed numerically. The optimum solutions in the heat sink are obtained when the temperature rise and the pressure drop are minimized simultaneously. Thermal performance of heat sink is influenced by the heat sink shape such as the base-part fin width, lower-part fin width, and basement thickness. To acquire the optimal design variables automatically, CFD and mathematical optimization are integrated. The flow and thermal fields are predicted using the finite volume method. The optimization is carried out by means of the sequential quadratic programming (SQP) method which is widely used for the constrained nonlinear optimization problem. The results show that the optimal design variables are as follows; B$_1$=2.584 mm, B$_2$=1.741 mm, and t=7.914 mm when the temperature rise is less than 40 K. Comparing with the initial design, the temperature rise is reduced by 4.2 K, while the pressure drop is increased by 9.43 Pa. The relationship between the pressure drop and the temperature rise is also presented to select the heat sink shape for the designers.