Papers by Keyword: Numerical Optimization

Abstract: Hybridization of aluminium matrix composite is with a view to offset the properties deficient in one composite reinforcement. The present investigation involves a comparative study of AA6063 matrix composites with single reinforcement of Al₂O₃, SiC, graphene respectively and various hybridized proportions of the same reinforcements. Physical (density and %porosity) and mechanical (tensile strength, fracture toughness, %elongation, elastic modulus, etc.) properties of composites developed via solidification processing technique were evaluated. The porosity of all the composites falls below the maximum acceptable limit for cast metal matrix composite. Maximum values for UTS, %elongation and absorbed energy at maximum stress was obtained by hybrid composite with 4wt% Al₂O₃, SiC and 2wt% graphene, while the composite with the highest single reinforcement of graphene have the highest value for elastic modulus and fracture toughness. Numerical optimization results show that a matrix and hybrid reinforcements contents of AA6063 (91.413wt.%), SiC (3.679wt.%), Al₂O₃ (0.277wt.%), and graphene (4.632wt.%) respectively, will result in optimal values for the evaluated properties.

Abstract: The new research trends are moving away from research works that are not directly connected with industrial applications. The Integrated Computational Materials Engineering (ICME) is an excellent example of the relationship between scientific research and the industrial sector.As an example of the design development of construction of a suspension component, an overview of the changes of a welded part replaced with cast component is presented. The identification of boundary conditions and forces operating on the nodes of the suspension element allowed determining the critical areas in the existing welded construction. Then the new design of casting for high performance applications was developed. Analysis of the kinematics of the suspension components also revealed the need for changes in the design of the mounting points of the suspension components to reduce the maximum values ​​of forces and enforced moments. As a result of successive stages of the topology optimization of analysed cast, control arms with significantly lower values ​​of maximum stresses were obtained. The material conversion of welded part with high strength AlZnMgCu aluminium alloy allowed the reduction of the weight by 25% for the lower control arm and 30% for upper control arm.

Abstract: Cylindrical pressure vessels with circular cross section are commonly used in the construction of various pressure apparatus; however in certain cases other cross sections are applied. The vessels with rectangular and elliptical perpendicular cross section are of the main interest and certain formulas for their calculations are stated in the respective codes [1, 2]. In these appliances flat ends of various shapes are usually used as the vessels caps. Similarly, as for the cylindrical boilers, flat end plates with stress relieve grooves are recommended. Like in the flat ends for cylindrical pipes certain variation of the groove parameters is possible but again no clear suggestion is given how to choose the optimal groove parameters providing the minimum stress concentration [3]. In this paper the numerical analysis and optimization of the admitted by code [1] groove parameters is presented for the pipe with the rectangular cross section subjected to the internal pressure.

Abstract: Differential evolution algorithm’s performance often depends heavily on the parameter settings. Based on analyzing the influence of the parameters setting in the experiment, the effects and the optimal selection of those major parameters on DE are analyzed, and some conclusions are derived. A new differential evolution algorithm which the scale constant (F) and crossover constant (CR) are generated as random numbers within a certain range in each iteration process is proposed. The experimental results shows that the new algorithm is simple, easy to realize and can get higher precision and better stability.

Abstract: The collection and management of dynamic traffic information is one of the most important part of ITS. Its a main task for it to improve the accuracy of the acquisition of the traffic information when facing up with different kinds of traffic detectors. Data fusion method can deal with data from different detectors and improve the accuracy. This paper first analyzed the characters of different traffic detectors, and proposed a method to repair the missing values which is a common phenomenon in the detect data. Then some improvements are made to adjust the BP neural network so that it could be suitable for data fusion. At last, the data fusion of traffic speed from the south of Jianguomen Qiao to the north of Chaoyangmen Qiao on the second ring road of Beijing is given as an example with the comparison of different improve methods of BP neural networks, and it shows that the method given in this passage is efficient in improving the accuracy of the traffic data detection.

Abstract: Flat ends in cylindrical pressure vessels are a certain alternative for commonly used in boilers dished ends. These ends can have different form and one of the admitted proposals is the plate with the internally introduced circumferential stress relief groove. In codes [1, the grooves of circular shape are recommended. Three parameters describe the groove configuration, namely the groove radius, the minimum endplate thickness under the relief groove and the chamfer angle. The respective formulas for calculations of the first two parameters are expressed in the form of inequalities. This means that a certain range of their variation is possible. The existing codes do not give the clear suggestion about the optimal choice of values of the groove parameters, leading to the minimal value of the stress concentration in the groove area. This is usually done by numerical analysis. The significant reduction of stress concentration is observed when changing the shape of the groove from the circular to the elliptical one, which is also shown in the paper.

Abstract: The rear characteristic angles of the passenger car in this study were defined as the inclination angle of rear window and the bottom inclination angle of aft based on the MIRA model. The numerical optimization method was used to analyze the influence of combined variation of two angles on the external flow field and the C_D of the passenger car, in which we combined genetic algorithm with the CFD simulation to reduce aerodynamic drag by seeking the relatively optimal combination of two parameters above. The study reveals that when the combination of the inclination angle of rear window and bottom inclination angle of aft is 25^oand 0.067^o, the total pressure and streamline distribution in the flow fields of the MIRA model are improved greatly and the C_D is reduced compared with the worst combination. This conclusion will have profound guiding significance in the aerodynamic design of the rear styling and shape of a car.

Abstract: A new project to analyse neutrino features is under development within the frame of the High Intensity Neutrino Oscillation EURONu project [. The final shape of the magnetic horns supporting system is proposed. This system is designed for four horns joined in one assembly. For the support structure a search for the optimal parameters is made with respect to the static loads. After that dynamic analysis is performed, this is used, if necessary, for the final tuning of the designing parameters. The above approach is investigated for two different materials used for the support system.

Abstract: The paper proposes a particle pair optimization (PPO) algorithm for numerical optimization. In the paper, a particle pair search(PPS) is designed. Based on PPS, the competitive roulette strategy is employed to the selection of particle pair from swarm, and a particle pair optimization algorithm is proposed. In the experiments, PPO is applied to solve the 12 benchmark problem, and compared with fast evolutionary programming (FEP). The results demonstrate that PPO algorithm can find optima or close-to-optimal solutions of the complex functions with high-dimension, and the search of PPO is stable and efficient.

Abstract: In this paper, to determine the dynamic strength model for steels, a new approach which does not rely on the Hopkinson bar test has been proposed. As the DH36 steel for example, using the results of Taylor impact test and the quasi-static compression test, the initial parameters of Johnson-Cook plastic strength model have been fitted out, then the initial strength parameters have been optimized using the optimization techniques of the sparse Taylor impact cylinder. It has been shown that the optimized results in numerical simulation are consistent with results of Taylor impact test, and the optimized Johnson-Cook model can also well describe flow stress curve fitted from the Hopkinson bar test.