The 11th Global Conference on Polymer and Composite Materials (PCM 2024)

Abstract: The use of composite adhesive joints increased in the last decades through structural applications, comprising the aeronautical and automotive industries. Contrary to the static loading case, in many real situations, adhesive joints are subjected to impact loads, such as in the event of vehicle crashes. Despite this fact, numerical modelling of this loading type is seldom addressed in the literature. Additionally, sandwich structure applications also find application in different industries which, thanks to the inclusion of a low apparent density core, manage to achieve good mechanical properties in bending (increasing the second moment of area) with a low weight compromise. However, this type of material poses additional challenges due to its heterogeneous nature, generally due to stacking, resulting in complex damage mechanisms and the necessity to use failure criteria especially formulated for the evaluation and design of composite structure. This work initially evaluates the effect of the overlap length (LO) and adhesive type on the strength of composite single-lap joints (SLJ), when impact loaded, through experimental tests and cohesive zone models (CZM). The joints were subjected to a drop test and validated through the numerical model, by the analysis of stresses and damage, predicting the joints’ strength for different geometries and adhesives. It was concluded that the increase of LO increases the joint strength, especially in those with a more flexible adhesive. In a second stage, a solution is proposed that drastically reduce the lack of residual strength of composite materials, i.e., after initial impact, by combining laminates of hybrid carbon fibre/Dyneema® fabrics with an elastomeric adhesive Reverlink™, in a composite sandwich with a honeycomb core. Low and high-velocity impact tests were made, and the experimental results were compared with a CZM-based numerical predictive model, showing the improved residual strength capacity of the proposed solution, compared to using typical epoxy adhesives.

Biography: Raul Duarte Salgueiral Gomes Campilho completed his M.Sc. degree in 2006 and his Ph.D. degree in 2009, both of which at Faculdade de Engenharia da Universidade do Porto. He has authored 280 articles in journals, 27 sections of books and 9 books, and received about 9,164 citations with 51 h-index (Google Scholar). He has received 16 awards and/or honors. Raul D.S.G. Campilho spends much of his time researching Composite material, Adhesive, Structural engineering, Finite element method and Fracture mechanics. His Composite material study is mostly concerned with Fracture toughness, Adhesive bonding and Failure mode and effects analysis.