Morphogenesis And Mechanical Properties Of Novel Hybrid Inflatable Structures

Inflatable structures have the advantages of lightweight,fast construction,and beautiful appearance,and have been widely used in long-span space structures.At present,scholars all over the world have carried out a lot of studies on the structural systems and mechanical properties of inflatable structures and achieved fruitful results.However,the traditional inflatable structures have gradually exposed some intractable problems in recent decades of engineering practice,such as limited structural forms,poor overall stiffness,and insufficient load-bearing capacity.These increasingly prominent problems greatly limit their applications in the field of construction engineering.For this reason,this thesis fully considers the mechanical characteristics of the inflatable structure,and proposes novel hybrid inflatable structure systems that combine the traditional inflatable membrane structure with rigid components,and focuses on three possible realization forms of novel hybrid inflatable structures.Furthermore,the Combinatorial Equilibrium Modelling(CEM),which is based on graphic statics,is used for the morphological analysis of the hybrid inflatable membrane structures.Based on numerical simulation and experimental tests,the mechanical properties of the proposed structural systems are analyzed,and the design method of the hybrid inflatable structures is further summarized.The main content of this thesis includes:1.Introduction of novel hybrid inflatable structure systemsAccording to the overall structural functions of various kinds of inflatable membrane structures under the action of internal pressure and external forces,three kinds of novel hybrid inflatable structures,namely,hybrid air-supported structures,hybrid air-inflated structures,and hybrid air-inflated structures with multi-cushions,are realized in theory.Based on the structural concept and numerical simulation method,the optimal combinations of inflatable membrane structures and rigid components in proposed hybrid structures are discussed.The purpose is to improve the structural stiffness and load-bearing capacity of the inflatable membrane structure under external loads and to enrich the architectural forms of the proposed hybrid structures.2?Morphogenesis approach of hybrid inflatable structure systems based on Combinatorial Equilibrium ModellingDue to the variety of structural components and the complexity of forces in the proposed hybrid inflatable structures,it is difficult to visually and intuitively establish the structural models using traditional morphological analysis methods,and it is hard to express the explicit relationships between forms and forces in the structures.Therefore,an equilibrium-based morphogenesis approach,which is derived from vector-based three-dimensional graphic statics and CEM,is presented in this thesis.In combination with the iterative approach to deal with the internal air pressure,this morphogenesis approach can be used for the conceptual design of proposed hybrid inflatable structures.Possible design variations that can be implemented within the proposed morphogenesis approach are discussed for these three new structure systems,and the morphogenesis analyses are then performed by adjusting the relevant parameters of "form" and "force".From the results,it is found the proposed morphogenesis approach converges very fast,and allows designers to generate a large number of possible structural equilibrium forms in real-time.The proposed approach considers both the structural behaviour and the architectural potential,and is particularly suitable for the conceptual phase of the design process.3.Experimental research on static performance of the proposed hybrid airinflated structure systemsIn order to accurately investigate the structural performance of the hybrid airinflated structures,a 4m-span specimen was designed and fabricated.Static tests were conducted on the specimen to study the structural behaviour under inflation,full-span loading,and half-span loading.In the experiment,an automatic loading and measuring dig was designed and manufactured for the specimen.The stress and displacement of each component of the structure were measured during inflation and loading.The mechanical functions of the specimen under the action of external loads were discussed,and the change tendency of internal air pressure under the action of inflation and external loads was obtained.At the same time,a refined finite element model was established for nonlinear analysis and validated using the test results,which demonstrated the effectiveness of the numerical simulation method for the proposed hybrid inflatable structures.The experimental results show that the structures have a stable and reliable performance during inflation and static loading,and the inflated cushion can provide strong support to the upper rigid components.4.Numerical analyses of the static performance of the hybrid inflatable structure systemsIn order to understand the mechanical properties of the proposed hybrid structures,refined nonlinear finite element models considering membrane materials are established.The results of the FEM analyses under the action of internal pressure are compared with the CEM models,and the corresponding relationship of internal forces between the two models is discussed.Furthermore,the finite element analysis results are compared with the experimental data to verify the effectiveness of the numerical simulation method.In the numerical analyses,two conditions are considered during external loading: constant internal air mass and constant internal air pressure,and the beneficial effects on the static performance are discussed if the cushion is divided into multiple air chambers.The results show that the proposed structure systems have good mechanical properties.On this basis,an innovative design method for hybrid inflatable structures from the conceptual phase to the advanced phase is discussed.