Parametric Study of Shear Sleeves in Thick Composite Joints to Maximize Fatigue Life
Open Access
- Author:
- Jeffery, Luke
- Area of Honors:
- Mechanical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Matt Lear, Thesis Supervisor
Jean-Michel Mongeau, Thesis Honors Advisor - Keywords:
- Parametric study
Fatigue Life
Goodman
Shear sleeve
Composite - Abstract:
- Thick composites are increasingly used across multiple industries such as aerospace, automotive, marine, construction and defense due to their high strength-to-weight ratio and customizable material properties. These industries typically create large, long-lasting structures that are bolted together, necessitating the maximation of fatigue life in structural joints. Promising studies have highlighted the potential of using bolt sleeves to improve fatigue life by creating interference fits within the composite without causing installation damage. This study investigates how bolt sleeve geometry, specifically interference and sleeve thickness, can be optimized to maximize fatigue life. The objectives are to establish a method for evaluating fatigue performance in shear sleeves within composite joints, conduct a parametric sweep exploration of sleeve geometry, and evaluate the effects of shear sleeve geometry to recommend optimal designs. A finite element (FE) submodel of a larger, complex bolted composite joint is employed to efficiently conduct the parametric study. Fatigue life is estimated with the Goodman relation to account for alternating and mean stresses in the sleeve. Results confirm that both interference and thickness impact fatigue life. Increasing thickness reduces both alternating and mean stresses, enhancing fatigue life. In contract, increasing interference has a more complex effect: at high applied loads, it may reduce alternating stress, but at a certain threshold, it raises mean stress enough to ultimately lower fatigue life. The findings suggest that the optimal shear sleeve geometry for improved fatigue life combines minimal interference with maximized thickness. By providing practical design recommendations and identifying avenues for future research, this work contributes to improving joint fatigue performance in bolted thick composite joints.