Development and assessment of an adhesively bonded assembly geometry adapted for both ELS test and toward hygro-mechanical aging evaluation

Abstract

International audienceStructural adhesive bonding has gained significant attention in recent years. However, its durability in harsh environments, such as marine ones, remains insufficiently examined due to a lack of comprehensive research. One reliable approach for assessing the strength of bonded assemblies is the fracture mechanics, which involves conducting experimental tests in different loading modes to determine their fracture toughness. These tests can be performed before and after aging conditions to evaluate the mechanical properties evolution of the bonded assembly in response to aging. While mode I may occur, mode II is usually dominant in bonded joints; thus, only mode II is considered in this study. The selected mode II test is the End-Loaded Split (ELS) test. Most studies have focused on either the mechanical test setup or the aging setup, but have lacked a combined approach. This paper introduces a new sample configuration that merges both the ELS test setup and the hygro-mechanical frame. To validate the new sample design, a comparison of the fracture toughness values and of the cohesive zone models (CZMs), obtained after fracture data elaboration, is made between this new configuration and a standard ELS sample geometry. For the fracture toughness measurement, all specimens were instrumented with distributed optical fiber sensor to monitor crack propagation as well as Digital Image Correlation system to calculate the J-integral values from which the CZM can be derived. One major conclusion is that the results are repeatable, confirming that the new sample design is valid for the upcoming aging study