Available at: https://digitalcommons.calpoly.edu/theses/3380
Date of Award
6-2026
Degree Name
MS in Mechanical Engineering
Department/Program
Mechanical Engineering
College
College of Engineering
Advisor
Ramanan Sritharan
Advisor Department
Mechanical Engineering
Advisor College
College of Engineering
Abstract
Existing airfoil designs often use a solid foam core with Kevlar and carbon fiber composite skins. While the foam core supports laminate compaction during curing and provides internal support, it also adds weight, increases manufacturing complexity, and can contribute to surface defects after the curing process. This thesis investigates a reduced-foam composite airfoil design for a composite airfoil section with the goal of improving manufacturability while reducing weight and improving surface quality. The proposed design uses 12k carbon fiber prepreg, Kevlar reinforcement, Divinycell foam inserts, a silicone pressure intensifier, and an adhesive closeout process. A 14-inch airfoil subsection was manufactured through multiple design iterations to evaluate surface finish, leading-edge compaction, adhesive use, and final part weight. The physical models showed that the reduced-foam design is manufacturable, but the quality of the final part depends strongly on resin distribution, improved foam transition regions, and composite stackup. Some models achieved the greatest weight reduction, with a maximum measured weight difference of 11.70% when compared to the old design, while other models improved surface quality and leading-edge compaction but reduced the remaining weight savings to a minimum of 2.66%. Form the Classic laminate theory calculation, a preload of was determined for the 14” section. This gives insight into how the leading edge is being stressed and when combined with future testing data, it could show how close to a failure the leading edge is. Overall, this work demonstrates the feasibility of a reduced-foam composite airfoil manufacturing process and identifies the primary tradeoff between weight reduction, surface quality, manufacturing complexity, and local structural reinforcement requirements.
Included in
Manufacturing Commons, Other Materials Science and Engineering Commons, Other Mechanical Engineering Commons, Structural Materials Commons, Structures and Materials Commons