With the implementation of new-generation launch vehicles,space stations,lunar and deep space exploration,etc.,the development of spacecraft structures will face new challenges. In order to reduce the spacecraft weigh...With the implementation of new-generation launch vehicles,space stations,lunar and deep space exploration,etc.,the development of spacecraft structures will face new challenges. In order to reduce the spacecraft weight and increase the payload,composite material structures will be widely used. It is difficult to evaluate the strength and life of composite materials due to their complex mechanism and various phenomena in damage and failure.Meanwhile,the structures of composite materials used in spacecrafts will bear complex loads,including the coupling loads of tension,pressure,bending,shear,and torsion. Static loads,thermal loads,and vibration loads may occur at the same time,which asks for verification requirements to ensure the structure safety. Therefore,it is necessary to carry out a systematic multi-level experimental study. In this paper,the building block approach (BBA) is used to investigate the multilevel composite material structures for spacecrafts. The advanced measurement technology is adopted based on digital image correlation (DIC) and piezoelectric and optical fiber sensors to measure the composite material structure deformation. The virtual experiment technology is applied to provide sufficient and reliable data for the evaluation of the composite material structures of spacecrafts.展开更多
An ultrasonic evaluation method of echo feature of diffusion bond joint between two dissimilar materials is presented. The echo signal was acquired by an automatic ultrasonic C-scan test system. It is found that the i...An ultrasonic evaluation method of echo feature of diffusion bond joint between two dissimilar materials is presented. The echo signal was acquired by an automatic ultrasonic C-scan test system. It is found that the intensity of echo and its phase can be used to evaluate the joint quality, and interface products of dissimilar materials bonding can be evaluated by ultrasonic method.展开更多
Electroless nickel(EN)plating can give rise to the severe galvanic corrosion of the magnesium(Mg)alloy matrix,owing to its nobler electrochemical potential than Mg alloy.To hinder the formation of galvanic couple,an i...Electroless nickel(EN)plating can give rise to the severe galvanic corrosion of the magnesium(Mg)alloy matrix,owing to its nobler electrochemical potential than Mg alloy.To hinder the formation of galvanic couple,an intermediate phosphate conversion coating(PCC)layer is introduced between the EN layer and the Mg alloy matrix.Since the ceramic-like PCC layer cannot be catalyzed,a low-cost Ag-activation technique is used to process the PCC layer before electroless plating.The cross-section morphology and element distribution of the PCC-EN composite coating indicate that the PCC intermediate layer can effectively separate the Mg alloy from the EN layer.Moreover,the results of electrochemical tests suggest that the PCC-EN composite coating has a better corrosion resistance in comparison with the EN coating and AZ91D Mg alloy.展开更多
文摘With the implementation of new-generation launch vehicles,space stations,lunar and deep space exploration,etc.,the development of spacecraft structures will face new challenges. In order to reduce the spacecraft weight and increase the payload,composite material structures will be widely used. It is difficult to evaluate the strength and life of composite materials due to their complex mechanism and various phenomena in damage and failure.Meanwhile,the structures of composite materials used in spacecrafts will bear complex loads,including the coupling loads of tension,pressure,bending,shear,and torsion. Static loads,thermal loads,and vibration loads may occur at the same time,which asks for verification requirements to ensure the structure safety. Therefore,it is necessary to carry out a systematic multi-level experimental study. In this paper,the building block approach (BBA) is used to investigate the multilevel composite material structures for spacecrafts. The advanced measurement technology is adopted based on digital image correlation (DIC) and piezoelectric and optical fiber sensors to measure the composite material structure deformation. The virtual experiment technology is applied to provide sufficient and reliable data for the evaluation of the composite material structures of spacecrafts.
文摘An ultrasonic evaluation method of echo feature of diffusion bond joint between two dissimilar materials is presented. The echo signal was acquired by an automatic ultrasonic C-scan test system. It is found that the intensity of echo and its phase can be used to evaluate the joint quality, and interface products of dissimilar materials bonding can be evaluated by ultrasonic method.
基金the National Natural Science Foundation of China(Nos.51771050 and 51531007)the Liaoning Revitalization Talents Program of China(No.XLYC2002071)the Shanghai Aerospace Science and Technology Innovation Fund of China(No.SAST2020-046)。
文摘Electroless nickel(EN)plating can give rise to the severe galvanic corrosion of the magnesium(Mg)alloy matrix,owing to its nobler electrochemical potential than Mg alloy.To hinder the formation of galvanic couple,an intermediate phosphate conversion coating(PCC)layer is introduced between the EN layer and the Mg alloy matrix.Since the ceramic-like PCC layer cannot be catalyzed,a low-cost Ag-activation technique is used to process the PCC layer before electroless plating.The cross-section morphology and element distribution of the PCC-EN composite coating indicate that the PCC intermediate layer can effectively separate the Mg alloy from the EN layer.Moreover,the results of electrochemical tests suggest that the PCC-EN composite coating has a better corrosion resistance in comparison with the EN coating and AZ91D Mg alloy.
