Performance Optimization Analysis Of Tensegrity Structures By Changes Of Members' Length Under The Restricted Displacements

Scholars at home and abroad have done multi-aspect optimization researches on tensegrity structures, including prestressing optimization, sectional optimization, shape optimization, topological optimization et al. The objective of above-mentioned optimization is minimizing the cost under single load case. But steel comsumption per unit square in tensegrity structure was very small, so there was little practical meaning for these researches. In the paper, Actuators were introduced into the tensegrity structures for varying the member length to adjust structure shape, in order to ensure the structure working with its best performance at any time. Then the optimization model was established and the active adjustments of the actuators were solved for the required structureal states.In the second chapter, basic theoretical knowledge of tensegrity structures was introduced in detail for determinating selfstress modes of structures and the form of geometric topology. This part of work was prepared for the following investigation.In the third chapter, recurrence formula was concluded based on load increment method. The member internal forces and nodal displacements were obtained by solving nonlinear equations. An example was used to verify the correctness of the procedures and formulas by comparing with the ANSYS finite element method and relevant conclusions were put forward.Three strength optimizaiton models under the restricted displacements were established based on different theoretics and recurrence formula. The first model was found on finite element theoretics, the second model was based on the principle of virtual work, and the last one was from member stiffness matrix analysis. The goal of the above strength optimization was to minimize the working state coefficient of structure, subjected to the limited nodal displacements, internal forces and working parameters of the actuator. The nonlinearity strcuture strength optimization linear programming models were established and the relevant MATLAB programs were developed. Through the numerical analysis of example, these three models corresponding to theory and recurrence equations were evaluated respectively. In the fifth chapter, the optimization objective was to minimize the structural strain energy. Based on the principle of virtual work and compatibility of deformation the iterative relationships of the nodal displacements and internal forces with actuators' active adjustments were developed. On this basis, structural shape optimization models and procedures were constructed taking adjusting amount of the active actuator as design variables, while subjected to structural bar internal forces, nodal displacements and actuators" parameters. Comparative analysis between those in Chapter IV and this Chapter manifested that these two kinds of optimization models could all reached the goals to improve the structural performances under the restricted nodal diaplacements.Finally, the research contents and the main results were summarized, and pointed out that multi-objective optimization and optimal placements of the actuators may be valuable for further research activities...