Thesis
The investigation of toughness and its role in fatigue performance of adhesively bonded joints
Washington State University
Master of Science (MS), Washington State University
12/2015
Handle:
https://hdl.handle.net/2376/102768
Abstract
Quasi-static properties of an adhesive can be obtained with minimal time and therefore cost, but fatigue testing can take much longer and the outcomes are not always expected. This research aimed to study the connection between fatigue performance, static performance and adhesive toughness for the purpose of decreasing FAA certification time and cost. The use of a ten-degree angle scarf joint coupon minimized normal stress and maximized shear stress while remaining feasible to manufacture. The results of the scarf joint tests showed that the four adhesives had similar shear strengths despite the manufacturer's data sheets using ASTM D1002. While less obvious, it was observed that the more toughened adhesives exhibited a knee point in their static stress response during testing. This knee point correlated well to the performance in fatigue loading as the two adhesives exhibiting this behavior performed highest. A DCB coupon configuration was used and tested using ASTM D3433 to quantify the static fracture strength of each adhesive. Next, the fatigue response was investigated to see the correlation between static fracture strength and da/dN response. Results showed that normalizing the fatigue data using GIC worked well and suggests that DCB fatigue is not an essential test as it can be reasonably inferred from the static results. A WALS coupon configuration was used as a mixed mode test. The mixture of normal and shear stresses made the static test an efficient predictor of both scarf joint and DCB fatigue performance but a poor predictor of the static scarf joint response. In the scope of this project, the most effective approach for predicting the fatigue performance of an adhesive using a static test was a WALS configuration. This configuration allows for rotation and thus normal stresses but yields a good correlation with both DCB and scarf joints in the fatigue loading regime.
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Details
- Title
- The investigation of toughness and its role in fatigue performance of adhesively bonded joints
- Creators
- Harrison Lee Scarborough
- Contributors
- Lloyd V. Smith (Chair)David P Field (Committee Member) - Washington State University, Mechanical and Materials Engineering, School ofVikram Yadama (Committee Member) - Washington State University, Civil and Environmental Engineering, Department of
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Number of pages
- 66
- Identifiers
- 99900525163601842
- Language
- English
- Resource Type
- Thesis