Shape Optimization Method Of Space Gird Structures Based On Plant Growth Simulation Algorithm

Space grid structures are widely used in large-span space buildings.It has the characteristics of great stiffness,light weight,flexible bar arrangement,novel form,etc.However,with the further increasing of structural span and more complex of structural form,the traditional structural design concepts and methods can not fully consider the rationality and safety of structural form,and structural morphology has become one of the research hotspots in the field of space structure.Thus,focusing on the frontier optimization theories,plant growth simulation algorithm is introduced to the field of structural shape optimization for the first time and the shape optimization problem of space gird structures is studied.The aim of this paper is to break through the limitations of traditional structural design methods and promote the development of structural optimization design method.Aiming at the defects of PGSA and its improved algorithms,combined with the characteristics of complex structural optimization problems,two new algorithm mechanisms(double growth point parallel growth mechanism and iterative stability judgment mechanism)are proposed based on the basic principle of PGSA and the actual growth law of plants.The new mechanisms are also integrated with GSL&PS-PGSA algorithm(based on growth space limitation and parallel search)to form the improved GSL&PS-PGSA algorithm.The effectiveness of the proposed mechanisms are verified by the analysis of typical mathematic examples and structural example of space truss.The results show that the new mechanisms can increase search paths,widen search area,reduce the probability of falling into local optimal solution,and provides a more effective termination mechanism for the algorithm.The improved GSL&PS-PGSA algorithm with the new mechanisms has more significant optimization efficiency and global search ability,which shows fine adaptability and effectiveness in structural optimization problems.Direct at the shape optimization problem of conventional space grid structures,a new shape optimization method of space grid structures based on improved GSL&PS-PGSA is proposed.The shape optimization examples of conventional trusses and latticed shells are analyzed by the proposed method.The optimization results are remarkable.The rational structural forms of the structures are effectively explored.In addition,the stiffness and bearing capacity of the structures are significantly improved on the basis of ensuring the economic efficiency.On this basis,a combined optimization method of shape and section is proposed to further consider the coupling relationship between shape and section.The above researches provides a new approach for the research and application of shape optimization of space grid structures.Furthermore,aiming at the structural shape optimization problem of free-form space grid structures,generalized shape parameters are proposed to represent the shape optimization design variables.Based on the conventional shape optimization method of space gird structures,the enhanced random multi-direction search mechanism is introduced.And taking the generalized shape parameters as the design variables,a shape optimization method of free-form space grid structure based on improved GSL&PS-PSGA is proposed.The analysis shows that the optimization results of the proposed method is obvious,the stiffness and bearing capacity of the structures are further improved,and the mechanical properties of the structures are improved.The proposed method can be applied to the shape optimization problems of large-scale free-form space grid structures with multiple variables,multiple load combinations and complex constraints.It can provide a new way for the design and form selection of complex space structures.