Shape Optimization Of Trusses Research Articles

Modified genetic algorithm for optimal design of truss structures

In this paper, topology and shape optimization of truss or frame structures is discussed. The optimization starts from a structure, into which a finite number of nodesare set; all the nodes are connected together by trusses in all possible variants. Unfit variants of the truss system are rejected. Two alternative ways of the optimization are compared: topology optimization starting from initial structure with a larger number of nodes, and topology optimization starting from initial structure with smaller number of nodes but with additional shape optimization of the obtained topology. The topology optimization is solved with original modified genetic algorithm, giving better results in comparison with classical genetic algorithm. Instead of further development of constraint system, the additional step is introduced into algorithm – purification of genotype, which allows complementary improvement of particular population individuals, and together for the optimization process retains more possibilities than stiffening of constraints. The shape optimization is solved by classical genetic algorithm. Both strategies effectively improve the solution, however the common topology/shape optimization requires less computer resources. All numerical examples are obtained with original software developed by the authors.

System-reliability-based sizing and shape optimization of trusses considering millions of failure sequences

System-Reliability-Based Design Optimization (S-RBDO) of structures considering progressive collapse is a complex problem, as the number of potential failure sequences increases geometrically with the degree of static indeterminacy of the structure. Existing methods for identifying failure sequences in structural systems are computationally expensive and prone to missing some critical failure sequences, especially within an optimization framework. In this context, identifying the most critical failure sequences to simplify the problem is fundamental. Herein, we propose a novel system-reliability-based framework for sizing and shape optimization of trusses. The procedure identifies minimal cut sets using the recently developed null space method, which has been proven more efficient than traditional failure path-based methods. The most probable failure sequence is selected from each identified minimal cut set. System reliability is estimated using the dominant failure sequences for the whole structure, selected based on their correlations using the Probabilistic Network Evaluation Technique (PNET). Craziness-Based Particle Swarm Optimization (CRPSO) is employed as the optimization algorithm. Numerical examples involving hundreds to millions of failure sequences demonstrate applicability and efficiency of the proposed framework on truss optimization problems with different material post-failure behaviors. Results suggest that, in a system-reliability analysis considering progressive collapse, the most critical failure sequences are those obtained from minimal cut sets. Furthermore, results show that the procedure proposed herein can outperform other frameworks based on traditional failure path-based methods. Simple truss sizing and shape optimization is considered herein, but the conclusions have immediate relevance to the optimal design of realistic structures considering progressive collapse.

A novel topology framework for simultaneous topology, size and shape optimization of trusses under static, free vibration and transient behavior

A novel topology framework for simultaneous topology, size and shape optimization of trusses under static, free vibration and transient behavior

Mixed genetic algorithm for optimization of trusses

In this paper two strategies of optimization are compared: sequential and synchronous topology and shape optimization of trusses. Genetic algorithms are used for optimization. A task of optimization of truss withtwelve possible nodes is solved. Finite elements method is used to calculate an objective function value. Software used in calculations was created by the author.

Shape Optimization of Trusses

A method is presented for the optimum shape design of trusses. This method obtains the optimum locations of the joints while it employs the concept of ground structure. In the formulation of the design problem the displacements of the joints are treated as design variable in addition to member areas and joint coordinates. For the solution of the nonlinear design problem an approximating program is adopted. The proposed design procedure does not require the structural analysis equations to be solved during the design process. Examples are given to demonstrate the flexibility of the method.