Multi-stage mechanical behavior and damage mechanism of composite interference-fit joints subject to long-term low-temperature aging

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering Vol. 45; no. 11
• Main Authors: Li, Jian, Guo, Wei, Zou, Peng, Zhou, Zhihui, Fan, Yibiao
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2023; Springer Nature B.V
• Subjects: Aging; Carbon fiber reinforced plastics; Crack initiation; Damage; Engineering; Exposure; Failure mechanisms; Fiber composites; Fiber reinforced polymers; Fracture mechanics; Interference; Interference fit; Low temperature; Mechanical Engineering; Mechanical properties; Residual stress; Stiffness; Technical Paper; Temperature; Tensile tests; Three dimensional analysis; Three dimensional models; Interference-fit; Long-term low-temperature exposure; Thermal residual stress; Damage mechanism; Crack propagation
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1007/s40430-023-04439-9

Carbon fiber-reinforced polymer (CFRP) composite joint structures based on interference fit exhibit superior mechanical properties compared to equivalent joint geometries utilizing clearance fits. The present research investigates the mechanical properties and failure mechanism of CFRP interference-fit joints subject to long-term exposure to low temperatures. A series of studies were designed to examine with interference-fit sizes ranging from 0 to 2.11%, subjected to temperatures between − 60 and 20 °C, and aging periods from 0 to 18 months. Tensile tests were conducted on these samples. Using a microscale analysis, three-dimensional representative volume elements (3D-RVEs) models were constructed to analyze the internal state, distribution of thermal residual stress, and damage initiation mechanism of CFRP subjected to low-temperature exposure. The results show that the strength and stiffness of the CFRP joints initially increase, reach a peak, and subsequently decrease with an increase in either the interference-fit size or aging time. The strength and stiffness of the considered geometries exhibit an approximately linear increase with decreasing temperature. Inside the CFRP, exposure to low temperatures causes the formation of thermal residual stress, which is particularly high in areas with closely spaced fibers. Short-term low temperature enhances the bonding force between the fiber and matrix, thereby improving the mechanical properties of the CFRP interference-fit joint structures. Following prolonged exposure to low temperatures, the debonding cracks formation increase in regions with concentrated residual stress, thereby decreasing the strength and stiffness of the structure.