Design And Performance Characterization Of Adjustable Thermal Expansion Structure Based On Bistable Mechanism

The thermal deformations of structures can bring the stability problems of engineering structures and affect the measurement accuracy of precision equipment.Owing to its excellent shape stability and adjustable coefficient of thermal expansion(CET),the adjustable thermal expansion structures can effectively solve various problems caused by the thermal deformations of the structures.However,there are few researches on the design,preparation and test of the controllable thermal expansion structures.At the same time,the structures with bi-stable effect have attracted extensive researches due to the unique property of multiple stability.A novel type of structure with adjustable thermal expansion is designed,which combines the adjustable thermal expansion with the bi-stable effect,and the mechanical properties are studied through theoretical method,numerical simulation and experimental verification.The main contents are as follows:According to the existing researches on adjustable thermal expansion,a novel type of controllable thermal expansion structure with bi-stable effect is designed.The structure is composed of compressed curved beams and rigid support frames.Through theoretical analysis,the analytical expressions of the thermal expansion coefficient are derived in detail.The thermal expansion in the vertical direction can be controlled.According to the numerical simulations and experimental tests,the influences of geometric parameters and material properties on the CET are discussed.By introducing different concave and convex configurations of the bi-stable beam,a wide range of thermal expansion from negative to positive can be controlled.The size of the control interval mainly depends on the geometric parameters and material properties of the bistable beams.In order to better adapt to the needs of different environments,the composite structure of bi-material beam is proposed,and the structure is studied by numerical simulations and experiments,and the results are in good agreement.In terms of thermal expansion coefficient and stiffness,the bi-material composite bi-stable structure has some advantages over the common single material structure.It reflects the advantages and potential of composite design in future applications.