Proposal of a modified optimality criteria method for topology optimization analysis in 3‐dimensional dynamic oscillation problems

Facility layout problems deal with layout of facilities or departments in a shop floor. This article studies unequal-area static facility layout problems in order to minimize the sum of the material handling costs and unequal-area dynamic facility layout problems so as to minimize the sum of the material handling costs and rearrangement costs. Unequal-area static and dynamic facility layout problems are NP-hard. Therefore, a modified particle swarm optimization was suggested to solve them where the departments have fixed shapes and areas throughout the time horizon. The modified particle swarm optimization was tested using the available problem instances chosen from the literature. The proposed algorithm applied two local search methods and the department swapping method to improve the quality of solutions and to prevent local optima for dynamic and static problems. It also utilized the period swapping method to improve the solutions for dynamic problems. The results showed that the proposed algorithm has created encouraging layouts in comparison with other approaches.

In this chapter we discuss the ant colony optimization meta-heuristic (ACO) and its application to static and dynamic constraint satisfaction optimization problems, in particular the static and dynamic maximum satisfiability problems (MAX-SAT). In the first part of the chapter we give an introduction to meta-heuristics in general and ant colony optimization in particular, followed by an introduction to constraint satisfaction and static and dynamic constraint satisfaction optimization problems. Then, we describe how to apply the ACO algorithm to the problems, and do an analysis of the results obtained for several benchmarks. The adapted ant colony optimization accomplishes very well the task of dealing with systematic changes of dynamic MAX-SAT instances derived from static problems.

An optimal topology design method for multiple inputs and multiple outputs compliant micro-manipulation system is presented. Firstly, the topology design problem is posed in terms of a multiple inputs load and several specified output deflections. The compliance and stiffness of the system are expressed by the mutual potential energy and strain energy, respectively, which can be controlled by a multi-criteria objective function. Secondly, based on the optimality criteria method, a model solution algorithm is presented. Finally, a numerical example is presented to show the validity of the presented technique. The optimal topology of a 4 inputs and 4 outputs compliant mechanism is obtained by using the method, and the corresponding micro-positioning stage system is further designed.

A new topology optimization scheme based on a Harmony search (HS) as a metaheuristic method was proposed and applied to static stiffness topology optimization problems. To apply the HS to topology optimization, the variables in HS were transformed to those in topology optimization. Compliance was used as an objective function, and harmony memory was defined as the set of the optimized topology. Also, a parametric study for Harmony memory considering rate (HMCR), Pitch adjusting rate (PAR), and Bandwidth (BW) was performed to find the appropriate range for topology optimization. Various techniques were employed such as a filtering scheme, simple average scheme and harmony rate. To provide a robust optimized topology, the concept of the harmony rate update rule was also implemented. Numerical examples are provided to verify the effectiveness of the HS by comparing the optimal layouts of the HS with those of Bidirectional evolutionary structural optimization (BESO) and Artificial bee colony algorithm (ABCA). The following conclusions could be made: (1) The proposed topology scheme is very effective for static stiffness topology optimization problems in terms of stability, robustness and convergence rate. (2) The suggested method provides a symmetric optimized topology despite the fact that the HS is a stochastic method like the ABCA. (3) The proposed scheme is applicable and practical in manufacturing since it produces a solid-void design of the optimized topology. (4) The suggested method appears to be very effective for large scale problems like topology optimization.

In this paper, an optimum rib layout design method for reducing radiated noise is proposed based on topology optimization and acoustic contribution analysis. According to radiated noise depends on acoustic transfer vector (ATV) and normal velocity, the influence of rib layout on ATV is analyzed and it is found rib layout has little influence on ATV. Only if a region has maximum acoustic contribution, the normal velocities on this region can have the most remarkable influence on radiated noise. So the determination procedure of region with maximum acoustic contribution is introduced. Based on this, the topology optimization model is established to minimize the normal velocities on this region. Ribs can be arranged according to the optimum topologies to reduce the normal velocities, which in turn results in a reduction of radiated noise. The topology optimization model is used to obtain the optimal rib layout by taking a plate-like structure as an example. The plate is fixed along all side edges and excited by a time-harmonic external point load with different prescribed frequencies. The radiated noise is simulated using the finite element method and boundary element method. Four plates are manufactured according to the optimal rib layouts for different single frequency excitation. Modal test and sound measurement are conducted to validate the proposed method. The influence of loading position on the topology optimization results is also investigated and discussed.

SummaryThis paper presents an alternative topology optimization method based on an efficient meshless smoothed particle hydrodynamics (SPH) algorithm. To currently calculate the objective compliance, the deficiencies in standard SPH method are eliminated by introducing corrective smoothed particle method and total Lagrangian formulation. The compliance is established relative to a designed density variable at each SPH particle which is updated by optimality criteria method. Topology optimization is realized by minimizing the compliance using a modified solid isotropic material with penalization approach. Some numerical examples of plane elastic structure are carried out and the results demonstrate the suitability and effectiveness of the proposed SPH method in the topology optimization problem. Copyright © 2016 John Wiley & Sons, Ltd.

Certain dynamic and static contact problems of the theory of elasticity for a circular cylinder of finite size

A topology optimization approach based on the boundary element method (BEM) and the optimality criteria (OC) method is proposed for the optimal design of sound absorbing material distribution within sound barrier structures. The acoustical effect of the absorbing material is simplified as the acoustical impedance boundary condition. Based on the solid isotropic material with penalization (SIMP) method, a topology optimization model is established by selecting the densities of absorbing material elements as design variables, volumes of absorbing material as constraints, and the minimization of sound pressure at reference surface as design objective. A smoothed Heaviside-like function is proposed to help the SIMP method to obtain a clear 0---1 distribution. The BEM is applied for acoustic analysis and the sensitivities with respect to design variables are obtained by the direct differentiation method. The Burton---Miller formulation is used to overcome the fictitious eigen-frequency problem for exterior boundary-value problems. A relaxed form of OC is used for solving the optimization problem to find the optimal absorbing material distribution. Numerical tests are provided to illustrate the application of the optimization procedure for 2D sound barriers. Results show that the optimal distribution of the sound absorbing material is strongly frequency dependent, and performing an optimization in a frequency band is generally needed.

This paper deals with an efficient optimization method of combining fiber orientation and topology for constant-stiffness composite laminated plates. The optimal topology and fiber orientation can be simultaneously obtained, using the proposed method. To overcome the non-monotonous behaviors derived from directly optimizing fiber orientation, the lamination parameters are selected as design variable. The proposed method mainly includes two steps. Initially, lamination parameters and density are taken as the design variables for determining the fiber orientation and topology shape. A combined optimization model is built based on the penalization theory. The optimal lamination parameter and topology shape can be achieved simultaneously in this step. Then, solving nonlinear equations is transformed into a least squares optimization problem. The optimal fiber orientation is obtained and matched with the optimal lamination parameter. Finally, numerical examples of designing short cantilever beam and compliant inverter are performed to illustrate the validity of this method.

The solution of a combined static and dynamic optimization problem is considered in this paper. By means of a feasible decomposition procedure this combined problem is first decomposed into a two-level optimization problem. In this new problem the first-level subproblem is found to be one of conventional optimal control and mathematical programming which can be solved using known techniques. For the solution of the second-level problem a computational algorithm is developed using the gradient projection method. The existence of the solution is investigated. To illustrate the applicability of the method, a simplified gantry crane yard design problem is considered and some computational results are given.

Topology optimization is a numerical approach that optimizes material arrangement within a given design space, for a given set of loads and periphery conditions such that the resulting layout meets a approved set of concert targets. Using topology optimization, engineers can find the best perception design that meets the design necessities. Topology optimization has been developed through the use of finite element methods of the analysis, and optimization techniques based on the method of moving asymptotes, genetic algorithms, optimality criteria method, level sets, and derivatives. Topology optimization is used at the idea level of the design process to appear at an intangible design plan that is then fine-tuned for concert and manufacturability. This thesis work correlated to the lay out optimization of internal combustion engine piston. Piston is one of the significant apparatus of engine. The multiple type of piston using through the automobile sectors. The various different type of piston is i) Equivalents lands thickness piston ii) Without crown piston (flat piston), iii) Without undercut piston, iv) With skirt land piston v) Dissimilar land thickness the analyzed this research work the Computer Aided Designing model initially created by CATIA, then Finite Element Analysis done by ANSYS.

Topology optimization is one of the most important methods of reducing the weight of structure. Optimality Criteria method (OC) as a heuristic way can be used to deal with this problem efficiently. Popular SIMP method implements micro-structural density as the design variable. During the process of optimization, numerical instabilities are always observed; Moreover, higher penalty factor is not better for decreasing intermediate density elements. In this paper a penalty factor is imposed in OC method, and a relation between the filtering area and elements is also obtained. Meanwhile, the nodal density is used as design variable for more smoothing boundary. The results show that numerical stability can be obtained, checkerboard patterns haven’t been observed, and the clear boundary of structure has been developed.

Purpose This research presents a design method for designing greenhouse structures based on topology optimization. Moreover, the structural design of a gothic greenhouse is proposed in which its structural strength has been improved by using this proposed method. In this method, the design of the structure is done mathematically; therefore, in the design process, more attention can be focused on the constraint space and boundary conditions. It was also shown how the static reliability and fatigue coefficients will change as a result of the design of the greenhouse structure with this method. Another purpose of this study is to find the weakest part of the greenhouse structure against lateral winds and other general loads on the greenhouse structure. Design/methodology/approach In the proposed method, the outer surface and the allowable volume as a constraint domain were considered. The desired loads can be located on the constraint domain. The topology optimization was used to minimize the mass and structural compliance as the objective function. The obtained volume was modified for simplifying the construction. The changes in the shape of the greenhouse structure were investigated by choosing three different penalty numbers for the topology optimization algorithm. The final design of the proposed structure was performed based on the total simultaneous critical loads on the structure. The results of the proposed method were compared in the order of different volume fractions. This showed that the volume fraction approach can significantly reduce the weight of the structure while maintaining its strength and stability. Findings Topology optimization results showed different strut and chords composition because of the changes in maximum mass limit and volume fraction. The results showed that the fatigue was more hazardous, and it decreased the strength of structure nearly three times more than a static analysis. Further, it was noticed that how the penalty numbers can affect topology optimization results. An optimal design based on topology optimization results was presented to improve the proposed greenhouse design against destruction and demolition. Furthermore, this study shows the most sensitive part of the greenhouse against the standard loads of wind, snow, and crop. Originality/value The obtained designs were compared with a conventional arch greenhouse, and then the structural performances were shown based on standard loads. The results showed that in designing the proposed structure, the optimized changes increased the structure strength against the standard loads compared to a simple arch greenhouse. Moreover, the stress safety factor and fatigue safety factor because of different designs of this structure were also compared with each other.

Aiming at the problems such as low computational efficiency and long process in dynamic topology optimization, combined with bi-directional evolutional structure optimization, the dynamic optimization problem is transformed into the static optimization problem in multiple load cases. Newmark method is used to analyze the structure dynamics load. The topology optimization model based on equivalent static load is established. On the basis of the equivalent static load, multi-objective dynamics evolutionary structure optimization is studied. And the mathematical model of the dynamic stiffness and natural frequency about the multi-objective optimization is established. The mathematical formula of the sensitivity is deduced. Then a complete optimization iterative process is given. The numerical example illustrates that it is feasible to solve the multi-objective dynamic topology optimization with equivalent static loads. Modal tracking technique is introduced to the multi-objective dynamic topology optimization. The numerical example shows that modal tracking technology can track the required modal in the optimization process.

A review of homogenization and topology optimization III—topology optimization using optimality criteria