Assessing the natural-healing behavior of adhesively bonded structures under dynamic loading. (1st October 2019)

• Record Type: Journal Article
• Authors: Brandtner-Hafner, M.H.
• Is Part Of: Engineering structures. Volume 196(2019)
• Publication Date: 2019-10-01
• Subjects: Bonded structures -- Dynamic loading -- Industrial adhesives -- Fracture resistance -- Damage tolerance -- GF-concept -- Natural-healing behavior -- Residual strength -- Fracture healing -- Healing efficiency; CMOD crack mouth opening displacement -- δ mathematical expression of CMOD -- GF non-linear elastic-plastic specific fracture energy (crack growth resistance) -- GI linear-elastic strain energy release rate for mode-I loading -- KI linear-elastic stress intensify factor (SIF) for mode-I loading -- H0 virgin cycle 0 -- H1 healing cycle 1 H2, healing cycle 2 H3, healing cycle 3 -- σb adhesive tensile strength of bulk -- σc cohesive tensile strength of interface -- η fracture healing efficiency -- ηK linear-elastic fracture healing efficiency based on K-factors -- ηF non-linear elastic-plastic fracture healing efficiency based on GF; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2019.109303
• Languages: English
• ISSNs: 0141-0296

Abstract

Abstract: For adhesively bonded structures, maximizing their longevity under the aspect of minimizing costs of maintenance and repair are basically of high interest for the operator. Specifically, high-tech industries such as aeronautical, automotive or medicine are subject to very high standards in terms of quality, performance and safety. Hence, for stakeholders of such industries it is crucial to know how repeating damage cycles affect the structural integrity of a glued structure. The question which might arise is what minimum significant residual strength and fracture-healing recovery rate is needed in order to prevent a total structural collapse. To pursue such crucial issues, a novel study has been conducted for investigating the natural fracture-healing behavior of several well-established types of industrial adhesives. In doing so, an innovative test setup was utilized to identify new sophisticated damage parameters, which cannot be found in any technical data sheet of adhesive manufacturers. Thanks to both the utilization of an innovative test device and the application of the G F -concept, an independent material parameter was thereby ascertained, which is highly representative and suitable for characterizing dynamic damage behavior of real structures outside the lab. The remarkable findings revealed that only one distinct type of adhesive was suitable for showing significant fracture-healing behavior. This was empirically verified by different mechanical and fracture analytical benchmarks, such as bulk tensile strength, interface tensile strength and fracture resistance. The results obtained demonstrated the efficacy of the novel applied G F -concept for successfully evaluating both the damage tolerance and healing behavior of adhesively bonded structures. In conclusion, this examination showed that the inclusion of fracture analysis already in the adhesive selection and evaluation process is crucial for maximizing the quality, performance and safety of glued structures during lifetime operation.