Session: 17-01-01: Research Posters

Paper Number: 149822

149822 - A Pilot Study on the Force and Torque Profiles During the Mechanical Fastening Process on Hybrid Aerospace Structure Joining 

Aircraft final assembly mostly relies on mechanical fastening, which is a crucial process to ensure the aircraft’s structural integrity, reliability, and compliance with industry standards. When it comes to an operational point of view, mechanical fastening is a complex and time-consuming process involving multiple operations with a range of tooling, all of which require high accuracy and precision. Understanding the mechanisms of the mechanical fastening process is crucial to improving process efficiency. This study examines the thrust force and torque profiles of the mechanical fastening process in joining a hybrid aerospace structure consisting of carbon-fiber reinforced polymer composite (CFRP) and an aluminum alloy as one potential variation commonly found as an industry standard. During the experimental process a 4.763 mm (3/16 inch) cadmium-coated alloy-steel Hi-Lite pin system is used to fasten a woven CFRP and 2024-T351 aluminum coupon in a single shear application. This is accomplished utilizing a jig designed to hold each coupon in a stacked orientation, while eliminating any motion except for the vertical displacement of a commercially available pin installation tool used to engage the end of the pin being installed, as well as applying a torque to the pin systems collar for final installation of each fastener. The resultant thrust force and torsional moment during the installation process are recorded using a two-channel torque and thrust sensor attached to the experimental jig fixture. In the initial experiments, each coupon has an initial part thickness of 5.25 mm (0.207 in) for a total “stack” thickness or grip length of 10.5mm (0.414 in). The experimental input variables chosen include un-shimmed gaps and countersink depths. These variable levels are established and set forth by a U.S. Federal Aviation Administration (FAA) report, while the geometric tolerances such as the hole diameter, countersink diameter, and countersink depths are provided by published documents from aerospace manufacturers. This pilot study will include six separate configurations of the parameters previously listed, with three fasteners per configuration resulting in a total of eighteen separate thrust force and torque profiles. Each of these profiles will be analyzed to evaluate the significance of each input parameter and discussed respectively. In addition to the experiments, finite element analysis (FEA) of the fastening process will be conducted to numerically simulate the thrust force and torque profiles. This modeling will be performed using Abaqus modeling software and will utilize boundary conditions matching the experimental configuration. The analysis performed will be a dynamic explicit regime with each of the component models (bodies) treated as plastically deformable. The Johnson-Cook failure model will be employed to evaluate potential failure modes of the independent materials (primarily composite related damages) evaluated during this study. Lastly, the correlations between the FEA simulations and experimental data are to be compared for validation, as well as establishing future experimental conditions.

Presenting Author: Chris Miskell Washington State University Vancouver

Presenting Author Biography: Chris Miskell is currently a graduate student with Washington State University Vancouver, working towards a master in mechanical engineering degree. His primary focus or interest is working in the area of materials science and manufacturing, with an emphasis on the aerospace sector, primarily in researching composites manufacturing and their applications.

Authors:

Chris Miskell Washington State University Vancouver
Dr. Pardeep Pankaj Washington State University Vancouver
Dr. Dave Kim Washington State University Vancouver