A 99 line topology optimization code written in Matlab

The paper presents a compact Matlab implementation of a topology optimization code for compliance minimization of statically loaded structures. The total number of Matlab input lines is 99 including optimizer and Finite Element subroutine. The 99 lines are divided into 36 lines for the main program, 12 lines for the Optimality Criteria based optimizer, 16 lines for a mesh-independency filter and 35 lines for the finite element code. In fact, excluding comment lines and lines associated with output and finite element analysis, it is shown that only 49 Matlab input lines are required for solving a well-posed topology optimization problem. By adding three additional lines, the program can solve problems with multiple load cases. The code is intended for educational purposes. The complete Matlab code is given in the Appendix and can be down-loaded from the web-site http://www.topopt.dtu.dk. Received October 22, 1999     

A 2589 line topology optimization code written for the graphics card

We investigate topology optimization based on the solid isotropic material with penalization approach on compute unified device architecture enabled graphics cards in three dimensions. Linear elasticity is solved entirely on the GPU by a matrix-free conjugate gradient method using finite elements. Due to the unique requirements of the single instruction, multiple data stream processors, special attention is given to the procedural generation of matrix?Cvector products entirely on the graphics card. The GPU code is found to be extremely efficient, being faster than a 48 core shared memory CPU system. CPU and GPU implementations show different performance bottlenecks. The sources are available at http://www.mathematik.uni-trier.de/~schmidt/gputop.     

A discrete level-set topology optimization code written in Matlab

This paper presents a compact Matlab implementation of the level-set method for topology optimization. The code can be used to minimize the compliance of a statically loaded structure. Simple code modifications to extend the code for different and multiple load cases are given. The code is inspired by a Matlab implementation of the solid isotropic material with penalization (SIMP) method for topology optimization (Sigmund, Struct Multidiscipl Optim 21:120–127, 2001). Including the finite element solver and comments, the code is 129 lines long. The code is intended for educational purposes, and in particular it could be used alongside the Matlab implementation of the SIMP method for topology optimization to demonstrate the similarities and differences between the two approaches.     

A Mathematica interface for FormCalc-generated code

This note describes a Mathematica interface for Fortran code generated by FormCalc. The interfacing code is set up automatically so that only minuscule changes in the driver files are required. The interface makes a function to compute the cross-section or decay rate available in Mathematica. This function depends on the model parameters chosen for interfacing in the Fortran code.     

The exact weight of discretized Michell trusses for a central point load

A discretized optimal structure is derived in a closed analytical form based on Michell truss. The result shows that the discretized optimal structure is most similar to Michell truss in topology and shape. The difference in volume, displacement and strain energy between the discretized optimal structure and Michell truss decreased sharply as the number of members increased in discretized structure. A discretized optimal structure may be obtained from Michell truss by using finite members. This work is meaningful for studying discretized optimal topology based on Michell truss. This result is useful for engineering structural design.     

A general boundary approach to the construction of Michell truss structures

The goal of the present study is to provide a building block approach which will enable the synthesis of new Michell truss structure solutions. Curved support boundaries for Michell truss structures are categorized into four types. Each type is graphically illustrated as a simple example structure. A general matrix operator method is developed to solve the layout of each type. Numerical solutions that use the matrix method are compared with analytical solutions in a case study that comprises complimentary logarithmic spirals on a circular arc boundary. To illustrate the applications of this study, numerical layout solutions on a circular support boundary are explored that produce a family of globally-optimal Michell cantilever solutions for the support of a distributed load along a straight cantilever flange.     

A sequential element rejection and admission (SERA) topology optimization code written in Matlab

Structural and Multidisciplinary Optimization - This paper presents the Matlab implementation of the Sequential Element Rejection and Admission (SERA) method for topology optimization of structures...     

Randomized line search techniques in combined GA for discrete sizing optimization of truss structures

This paper presents two randomized line search techniques, each combined with a genetic algorithm (GA), to improve the convergence and the accuracy ratio for discrete sizing optimization of truss structures. The first technique is a simple one-dimensional line search in which design variable axes are selected randomly as search directions. The second is a line search technique whose search direction is determined randomly by fitness function values and differences in the genotypes of individuals. To apply the above-mentioned line search techniques without difficulty, real coding is adopted for discrete problems. The line search techniques are applied to discrete optimization problems of minimum-weight truss structures subjected to stress and displacement constraints. The proposed techniques provide convergence to better solutions than a conventional GA.     

Rocking Block线碰撞离散化研究

针对Rocking Block中的线碰撞问题,首先采用离散化思想将线碰撞问题离散为多点碰撞系统,而后基于LZB方法对所建多点碰撞系统进行动力学建模.仿真结果表明随着离散点数的增加,基于LZB方法的多点碰撞模型能够很好地刻画Rocking Block中的相关线碰撞问题,且精度与离散程度紧密相关.     

A note on stress-constrained truss topology optimization

The purpose of this brief note is to demonstrate that general-purpose optimization methods and codes should not be discarded when dealing with stress-constrained truss topology optimization. By using a disaggregated formulation of the considered problem, such methods may find also “singular optima”, without using perturbation techniques like the ε-relaxed approach. Received February 19, 2002     

Exact Michell layouts for various combinations of line supports — Part II

In this paper, a systematic exploration of Michell layouts for various combinations of line supports is continued. The solutions discussed include those for reentrant corners, a line support and two free edges, line supports forming any convex polygon, supports consisting of two symmetric curves, and finally, rectangular domains bounded by one line support and three free edges.The material presented in this paper was completed in 1991 but, owing to more urgent research and organizational activities, it was put aside until recently. Due to the relevance of the results to much current work in topology optimization, it was decided to prepare the final text, incorporating the referees' suggestions.Currently in private consulting practice     

Implementation of polynomial multi-objective optimization in Mathematica

We describe implementation of main methods for solving polynomial multi-objective optimization problems by means of symbolic processing available in the programming language MATHEMATICA. Symbolic transformations of unevaluated expressions, representing objective functions and constraints, into the corresponding representation of the single-objective constrained problem are especially emphasized. We also describe a function for the verification of Pareto optimality conditions and a function for graphical illustration of Pareto optimal points and given constraint set.     

A ground-structure-based representation with an element-removal algorithm for truss topology optimization

In this study, a new ground-structure-based representation for truss topology optimization is proposed. The proposed representation employs an algorithm that removes unwanted elements from trusses to obtain the final trusses. These unwanted elements include kinematically unstable elements and useless zero-force elements. Since the element-removal algorithm is used in the translation of representation codes into corresponding trusses, this results in more representation codes in the search space that are mapped into kinematically stable and efficient trusses. Since more representation codes in the search space represent stable and efficient trusses, the strategy increases meaningful competition among representation codes. This remapping strategy alleviates the problem of having large search spaces using ground structures, and encourages faster convergences. To test the effectiveness of the proposed representation, it is used with a simple multi-population particle swarm optimization algorithm to solve several truss topology optimization problems. It is found that the proposed representation can significantly improve the performance of the optimization process.     

Design complexity control in truss optimization

Truss optimization based on the ground structure approach often leads to designs that are too complex for practical purposes. In this paper we present an approach for design complexity control in truss optimization. The approach is based on design complexity measures related to the number of bars (similar to Asadpoure et al. Struct Multidisc Optim 51(2):385–396 2015) and a novel complexity measure related to the number of nodes of the structure. Both complexity measures are continuously differentiable and thus can be used together with gradient based optimization algorithms. The numerical examples show that the proposed approach is able to reduce design complexity, leading to solutions that are more fit for engineering practice. Besides, the examples also indicate that in some cases it is possible to significantly reduce design complexity with little impact on structural performance. Since the complexity measures are non convex, a global gradient based optimization algorithm is employed. Finally, a detailed comparison to a classical approach is presented.     

A strain tensor method for three-dimensional Michell structures

In the design of discrete structures such as trusses and frames, important quantitative goals such as minimal weight or minimal compliance often dominate. Many numerical techniques exist to address these needs. However, an analytical approach exists to meet similar goals, which was initiated by Michell (1904) and has been mostly used for two-dimensional structures so far. This paper develops a method to extend the existing mainly two-dimensional approach to apply to three-dimensional structures. It will be referred as the Michell strain tensor method (MSTM). First, the proof that MSTM is consistent with the existing theory in two dimensions is provided. Second, two- and three-dimensional known solutions will be replicated based on MSTM. Finally, MSTM will be used to solve new three-dimensional cases.     

Multi-objective heat transfer search algorithm for truss optimization

Engineering with Computers - In the real world, we often come across conditions like optimization of more than one objective functions concurrently which are of conflicting nature and that makes...     

A 199-line Matlab code for Pareto-optimal tracing in topology optimization

The paper ‘A 99-line topology optimization code written in Matlab’ by Sigmund (Struct Multidisc Optim 21(2):120–127, 2001) demonstrated that SIMP-based topology optimization can be easily implemented in less than hundred lines of Matlab code. The published method and code has been used even since by numerous researchers to advance the field of topology optimization. Inspired by the above paper, we demonstrate here that, by exploiting the notion of topological-sensitivity (an alternate to SIMP), one can generate Pareto-optimal topologies in about twice the number of lines of Matlab code. In other words, optimal topologies for various volume fractions can be generated in a highly efficient manner, by directly tracing the Pareto-optimal curve.     

Image-based truss recognition for density-based topology optimization approach

Structural and Multidisciplinary Optimization - Topology optimization is a tool that supports the creativity of structural-designers and is used in various industries, from automotive to...     

A heuristic particle swarm optimization method for truss structures with discrete variables

A heuristic particle swarm optimizer (HPSO) algorithm for truss structures with discrete variables is presented based on the standard particle swarm optimizer (PSO) and the harmony search (HS) scheme. The HPSO is tested on several truss structures with discrete variables and is compared with the PSO and the particle swarm optimizer with passive congregation (PSOPC), respectively. The results show that the HPSO is able to accelerate the convergence rate effectively and has the fastest convergence rate among these three algorithms. The research shows the proposed HPSO can be effectively used to solve optimization problems for steel structures with discrete variables.