Session: 03-03-01: Damage, Fatigue, and Fracture I

Paper Number: 105653

105653 - A Micro-Scale Numerical Investigation of Internal and Interfacial Void Defects in Adhesive on Failure Behavior of Adhesively-Bonded Materials With Rough Surfaces 

To bond complex structure components of metals and polymer composites (i.e., fiber-reinforced thermoset or thermoplastic polymers) in aviation and automobile industries, adhesive joining has been replacing some conventional joining methods (e.g., screws, spot welds, rivets, etc.) due to its excellent bonding and corrosion resistance and design flexibility. With the countless efforts into developing different surface modification methods (e.g., plasma treatment, laser treatment, surface patterning, etc.), surface-modified and adhesively-bonded bi-materials have been shown to exhibit excellent debonding resistance under various loading conditions, even causing the bonded regions not the critical parts in a structure.

These surface modification methods can largely roughen and/or pattern the substrate surface (one of the enhanced mechanisms), depending on treatment methods and parameters, and then generate more energy dissipation during the fracturing process of adhesively-bonded structures under shear particularly. However, the changes of surface roughness and morphology can possibly affect the adhesive flowability in the consolidation process and then lead to more void defects close to the substrate/adhesive interface. In this context, how does the surface roughness and/or patterning interact(s) with the void defects in adhesive with different void volume fraction? This question remains unclear and no related studies were found in the literature. The answer may partially explain the worse adhesive bonding of materials after surface modification(s) as sometimes reported in the literature.

To this end, a micro-scale numerical investigation was conducted as a first step towards answering the foregoing question by taking the surface roughness distribution, spatial autocorrelation length of surface heights, and spherical void defects with different void volume fractions and sizes into considerations. In addition, the correlation of adhesive and interfacial properties with the effects of void defects in adhesive were also investigated in the modeling. Based on this study, adhesive bonding behavior of the materials can be very dependent on the void defects close to the interface of roughed and/or patterned substrate and adhesive, depending on the void fraction and surface physics. The results are important for adhesively-bonded bi-materials with surface modification(s).

Presenting Author: Yao Qiao Pacific Northwest National Laboratory

Presenting Author Biography: Yao Qiao is a materials scientist at Pacific Northwest National Laboratory (PNNL). Before PNNL, he obtained his PhD in aerospace engineering from the department of Aeronautics and Astronautics at the University of Washington (Seattle, WA, USA), and his MS degree in structural, mechanical engineering, and infrastructure materials from Northwestern University (Evanston, IL, WA). His research interests are experimental, theoretical, and computational mechanics and materials.

Authors:

Yao Qiao Pacific Northwest National Laboratory
Seunghyun Ko Pacific Northwest National Laboratory
Avik Samanta Pacific Northwest National Laboratory
Daniel Merkel Pacific Northwest National Laboratory
Yongsoon Shin Pacific Northwest National Laboratory
Anthony Guzman Pacific Northwest National Laboratory
Ethan Nickerson Pacific Northwest National Laboratory
Jose Ramos Pacific Northwest National Laboratory
Kevin Simmons Pacific Northwest National Laboratory