Fracture rate dependency of an adhesive under dynamic loading. (August 2020)

• Record Type: Journal Article
• Authors: Dagorn, Noëlig; Portemont, Gérald; Joudon, Vincent; Bourel, Benjamin; Lauro, Franck
• Is Part Of: Engineering fracture mechanics. Volume 235(2020)
• Publication Date: 2020-08
• Subjects: Adhesive fracture energy -- Dynamic loading -- Crack velocity -- Beam theory; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2020.107082
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: The fracture toughness of a viscoelastic-viscoplastic epoxy adhesive decreases under higher loading rates. Even under constant loading rate with a constant fracture toughness, the crack speed decreases with time during a Double Cantilever Beam test. The crack speed exhibits oscillations whose amplitude rise when increasing the loading rate. The transition from stable to unstable growth scatters on several decades of loading rate. Abstract: Adhesive joints are widely developed in aeronautic and automotive design applications. When subjected to impact loading, the rate sensitivity of adhesively bonded joints becomes a subject of interest. In this study, the Mode I fracture behavior of an aeronautic adhesive is characterized. Double Cantilever Beam tests are performed under various displacement rates. A new protocol is developed to accurately measure the fracture toughness. The corrected beam theory with effective crack length is extended to measure the energy release rate during the crack growth stage. The main advantage of this new protocol is to accurately determine the crack speed without a direct experimental error. The validity of the analysis scheme is discussed considering dynamic effects. The crack speed measurement is validated by comparison to a conventional camera monitoring. The crack velocity is found to decrease with the crack length, while the fracture toughness remains unchanged.