Topology Optimization Method Of Space Structures Based On Plant Growth Simulation Algorithm

Combining mechanics,structural morphology,materials science and high-level constructional installation technology,space structure is an important standard for judging the civil and architecture science level of a country.But with the further increasing of structural span and more complex structural forms,the traditional design philosophy and approach of steel structures or space structures can not satisfy its developing requirements.Thus,combining frontier optimization theories,the basic principle of novel plant growth simulation algorithm(PGSA)is firstly introduced into the field of structural topology optimization and the topology optimization problem of space strutures is studied.The aim of this paper is to break through the limitation of traditional structural design methods and promote the development of high efficient structural design method.Based on the basic principle of PGSA,three novel innovative strategies(the limited strategy of growth point set,the elimination strategy of new growth points,the parallel search strategy of mixed step size)are proposed to satisfy the characteristics of large-scale complex optimization problems.Typical mathematic example is used to prove the improvement of the algorithm.On the basis of three strategies,a novel algorithm named Growth Space Limited & Parallel Search-based Plant Growth Simulation Algorithm(GSL&PS-PGSA)is formulated and the two key parameters(growth point set limited value and step-region ratio)of GSL&PS-PGSA are analyzed systematically.It is indicated that GSL&PS-PGSA has high calculation efficiency and global search capacity in both unimodal and multimodal problems.On this basis,the structural optimization method and flow based on GSL&PS-PGSA is provided and the corresponding optimization programs are compiled by the secondary development language-APDL of ANSYS and MATLAB according to its optimization algorithm process.Furthermore,the proposed structural optimization method is used for size optimization of plane truss structure,size optimization of single layer spherical latticed shell and prestress optimization of suspended dome.The systematic optimizations from plane to space,from simple truss structures to single layer latticed shell,from rigid structure to hybrid prestress space structure,are achieved.As for the structural topology optimization of simple discrete structures,based on the structural optimization method of GSL&PS-PGSA,the multi-dimensional parallel growth strategy,the random multi-direction search strategy and the judgement strategy of structural topology stability are introduced.And combining above method and strategies,a novel structural topology optimization method of simple discrete structures based on GSL&PS-PGSA is presented to consider the coupling relationship between structural topology and member section,and to further improve the global search capacity and stability of the algorithm.Through the classical topology and size optimization examples of twelve-bar plane truss and fifteen-bar plane truss structures,the applicability and high efficiency of the method are illustrated.Direct at the structural topology optimization of space structures(latticed shell),generalized topological parameters are introduced to uniformly describe the characteristics of space structures(topology,member section and so on),and used for integrative parametric modelling.Based on the abovementioned structural topology optimization of simple discrete structures,a new structural optimization method of lattice shell structrues based on GSL&PS-PGSA is proposed to realize the integrative synchronous coupled optimization of structural topology and member section.Moreover,according to the specialty of prestressed space structrues(suspended dome),considering the structural topology of the lower cable-strut system and combining the elastic support method of cable prestress determination,a novel structural topology optimization method of suspended dome based on GSL&PS-PGSA is formulated to achieve the integrative synchronous coupled optimization of structural topology,member section and cable prestress.Obvious optimization effectiveness is obtained in the typical examples of lattice shell and suspended dome structrues.On the premise of ensuring structural safety,the structural performances and economy are significantly improved and the optimization results can be directly applied to practical engineering.Therefore,the structural topology optimization method of space structrues based on generalized topological parameters is finally founded and presented as a new approach for the research and application of structural topology optimization.