Session: 03-12-01: Testing and Characterization

Paper Number: 121492

121492 - Nanoscale Property Characterization of Composite Adhesive Bonding Systems With Long-Term Environmental Exposures 

This preliminary research was directed toward understanding the fundamental science behind polymer matrix-adhesive interactions in adhesively bonded composite aircraft materials throughout the product’s lifecycle. Nanoindentation were used to characterize various regions of adhesively bonded carbon fiber/epoxy composite samples including the matrix resin, adhesive, and bondline mixing zones (interface/interphase). Since bondlines are heterogeneous in nature and are composed of multiple micron-scale subregions, subtle interactions and variations at the bond interface/interphase region can influence the performance of the bonded joint.  Characterizing these regions may provide more understanding of process dependent variables, as well as potentially expand the operating limits for these bonded systems. For this study, adhesive bonded composite materials from carbon fiber specimens with long-term on-aircraft time temperature and stress exposures (scrapped parts) as well as specimens with on-ground, outdoor environmental exposures were compared to lab-produced baseline samples.  The materials were evaluated using nanomechanical testing to understand the differences between initial interface and/or interphase development and the adhesive interface/interphase after on-aircraft time temperature and stress exposures (scrapped parts) and environmental exposure conditions. Previous studies using standard mechanical property characterization methods have not been able to isolate the adhesive/adherend interphase, due to the micron-sized scale of these regions. Nanomechanical test methods can be used to measure the adhesive/adherend interphase specific properties. Future work is to further understand how these nanoscale properties can be related to bond quality and performance.

Presenting Author: Rita Olander University of Washington

Presenting Author Biography: Rita currently is an engineer with the materials and manufacturing technologies team at Boeing. Rita has 10+ years working experience in aerospace with a focus on propulsion systems, advance materials and manufacturing processes, adhesive bonding, and composite manufacturing technologies. She is also continuing her academic studies with a dual title PhD in Materials Science & Engineering and Nanotechnology & Molecular Engineering at UW.