Session: 02-05-01: Session #1: 7th Symposium on Fastening and Joining Research and Advanced Technology

Paper Number: 94447

94447 - Effect of Salt Spray Cyclic Corrosion on the Mechanical and Reversibility Performance of Mixed Material Joints With Modified Adhesive 

This paper provides an experimental investigation of the effect of Thermally Expandable Particles (TEPs) adhesive additive and the effect of cyclic salt spray corrosion, on the mechanical and reversibility performance of epoxy-bonded Single Lap Joints (SLJs). The variables that are investigated are the concentration by weight of the additive and the duration of time of salt spray corrosion on the SLJs, for their effect on static strength and reversibility performance, as compared to those SLJs bonded with the baseline adhesive with no additives and no salt spray corrosion cycling.

Each test joint is made up of two substrates, the first substrate is Aluminum 6061 which is adhesively bonded to a composite substrate of woven carbon fiber reinforced plastic 0/90/0 (CFRP). The adhesive used to bond the joints is a commercially available two-part epoxy, which is modified with TEP additives at concentrations of 5, 15, and 25 percent by weight. The joints are subjected to the GMW 14872 test, which is an accelerated corrosion testing method to evaluate assemblies and components.

Very large volumetric expansion of the hollow spherical TEPs would significantly reduce adhesive strength and lead to joint debonding under a minimal load of 100 N. Lap shear tests are conducted to evaluate the maximum static Load Transfer Capacity (LTC) to evaluate the static strength of the joints. Results show that particle enrichment, when the particles have not yet expanded, worsens the adhesive performance. The results also show that salt spray corrosion cycling does not have a significant impact on the mechanical strength performance of the adhesive. Particle addition did not have an effect on the failure mode of the joints.

Reversibility performance is evaluated using a charged RF coil which heats the substrate at the bond line by induction, which results in the particles expanding and aiding in the debonding of the joint. The time to complete debonding is used to assess the reversibility performance as affected by the concentration and duration of corrosion cycling. Adhesive joints that did not have successful joint separation after the debonding testing were then tested for their residual static strength. Results show that the addition of particles allows for joint separation for weight concentrations of 15 and 25 percent, while joints with 5 percent concentration of particles did not successfully separate. The reversibility performance of the joints was reliant on the particle concentration and the corrosion cycling had a significant impact on the ability to achieve joint separation for certain particle concentrations.

Presenting Author: Matthew Burczyk Oakland University

Presenting Author Biography: Matthew earned his master's degree in Mechanical Engineering from Oakland University in December of 2021. He also earned his bachelor's degree in Mechanical Engineering from Oakland University in 2019 as well as a bachelor's degree in Physics from Kalamazoo College. He is currently a Research Associate under Dr. Sayed Nassar at the Fastening and Joining Research Institute (FAJRI) at Oakland University. His research has mainly been focused on modified adhesive performance and reversibility.

Authors:

Matthew Burczyk Oakland University
Sayed Nassar Oakland University