基于温度/变形场耦合测试的热屈曲行为研究

Investigation on Coupled Thermo-Mechanical Response Measurement of the Thermal Buckling Behavior

高速飞行器在服役期间面临着严酷的高温环境,引起飞行器薄壁结构屈曲失稳,从而严重影响飞行器结构的完整性和可靠性。本文开展瞬态热环境下薄壁结构热屈曲行为的试验研究,首先,结合红外测温和数字图像相关方法,建立温度/变形耦合测试方法,根据温度场分布及热膨胀系数除去虚应变,获得了机械热应变,并利用此方法研究了典型薄壁结构热屈曲行为特点;随后,把温度/变形耦合测试方法的精度与中温应变片进行了比对,验证了此测试方法的有效性;最后,通过位移随温度变化曲线和应变随温度变化曲线研究热屈曲临界温度判定方法,为航天飞行器薄壁结构抗屈曲性能设计以及航天飞行器结构的强度设计提供技术支撑。

Spacecraft thin-wall structures will be exposed to an extremely thermal environment during the service life,which will induce the thermal deflection since it is compressed by the thermal stress and the structure boundary.This would induce the thermal buckling behavior easily and change the load-bearing form of thin-wall structures in spacecraft,leading to challenges for structure integrity and safety of spacecraft.In order to investigate the thermal buckling behavior of spacecraft thin-wall structures,in our paper,a synchronous full-field displacement and temperature measurement system will be established and used to study the thermal buckling behavior of thin-wall structures.Since the strain calculated from digital image correlation is a combination of thermal strain and mechanical strain,the mechanical strain can be obtained by subtracting the total strain from the thermal strain determined from the temperature distribution measured with infrared thermograph.Further,the accuracy of the coupled thermo-mechanical response measurement method will be validated by the value from medium temperature strain gage.Finally,based on the temperature-displacement curve and the temperature-strain curve,critical buckling temperature criterion will be established.All the above research work would provide a technical support for the design of anti-buckling thin-wall structures and the strength design of spacecraft structures.