Mode II Delamination under Static and Fatigue Loading of Adhesive Joints in Composite Materials Exposed to Saline Environment

Paula Vigón; Antonio Argüelles; Miguel Lozano; Jaime Viña

doi:10.3390/ma16247606

Mode II Delamination under Static and Fatigue Loading of Adhesive Joints in Composite Materials Exposed to Saline Environment

Materials (Basel). 2023 Dec 12;16(24):7606. doi: 10.3390/ma16247606.

Authors

Paula Vigón¹, Antonio Argüelles¹, Miguel Lozano¹, Jaime Viña²

Affiliations

¹ Department of Construction and Manufacturing Engineering, University of Oviedo, 33203 Gijón, Spain.
² Department of Materials Science and Metallurgical Engineering, University of Oviedo, 33203 Gijón, Spain.

Abstract

This study investigates the fatigue delamination behavior of adhesive joints in epoxy carbon composite materials under Mode II fracture loading. The joints were characterized using the End-Notched Flexure (ENF) test, comprising adhesive joints formed by bonding two unidirectional carbon fiber epoxy matrix laminates with epoxy adhesive. These joints were subjected to different exposure periods (1, 2, 4, and 12 weeks) in a saline environment. Prior to dynamic fatigue testing, critical Mode II energy release rate values were determined through quasi-static tests, serving as a reference for subsequent fatigue characterization. This study aimed to comprehend how exposure duration to a saline environment affected the initial stage of fatigue delamination growth and employed a probabilistic model based on the Weibull distribution to analyze the experimental data. The results, gathered over a two-year experimental program, revealed varying behaviors in adhesive joint resistance to delamination based on exposure duration. A noteworthy reduction in fatigue strength capacity was observed, with fracture energies for infinite fatigue life reaching approximately 20% of their static loading capacity. This study sheds light on the deterioration of adhesive joints when exposed to a saline environment.

Keywords: adhesives; composites materials; fatigue; fracture; mode II.

Grants and funding

The authors would like to thank the Vice-Rectorate for Research at the University of Oviedo, through the Research Support and Promotion Plan, for their financial support through the project PAPI-22-TESIS-16.