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Adhesively bonded joints contain stress concentrations at geometric and material discontinuities within the joint, causing the joint to be inefficient. This study investigates a method to grade the material properties of an adhesive across the bondline to have a soft, flexible adhesive near the stress concentration and a stiff, strong adhesive elsewhere. Theoretical studies and a few experiemental studies have shown an that the load is distributed more evenly along the joint and strength is increased. Adhesive gradation is achieved through a secondary crosslinking system in the adhesive which is activated via radiation. After an adhesive is initially cured, the joint can be exposed to varying levels of radiation to grade the properties. Initial results demonstrate the ability to grade stiffness using radiation shielding, and final results will demonstrate the application in an adhesively bonded joint.
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Characterization of Functionally Graded Adhesives Using Radiation Curing
Grading adhesive properties across a bondline can lead to more unniform stresses and increased strength without altering the geometry of the adherends. In this research, radiation sensitizers have been added to adhesives to create a secondary cross-linking possibility that is activated with radiation. In this way the adhesive stiffness and strength can be controlled by controlling the exposure to radition. In this paper, a system of grading adhesive properties is introduced and the double cantilver beam test results show that the gradation not only changes stiffness and strength, but also mode I fracture properties. Additionally, specimens were created with graded properties along the bondline and test results will be presented in the final paper.
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- Award ID(s):
- 1663502
- PAR ID:
- 10216211
- Date Published:
- Journal Name:
- AIAA Scitech 2021 Forum
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/https://doi.org/10.2514/6.2021-1403
