FSAE Monocoque Design and Composite Materials Testing

This thesis focuses on the use of composite materials, particularly carbon fiber sandwich panels, in the monocoque of the Formula Student team at Politecnico di Torino. The main objective is the study of inserts within these panels, emphasizing the need to support localized loads near the attachments of components to the monocoque. This thesis provides a solid theoretical foundation on composite materials, starting from micromechanics and progressing to the Classical Laminate Theory, before examining sandwich panels and the significance of inserts. This introduction is crucial as the thesis serves as a valuable training tool for future students participating in the Squadra Corse team. Furthermore, this work is an extension of the study conducted by Stefano Manzi, who provided the basis for developing a linear numerical model for pull-out tests on inserts. This numerical model was compared with experimental data to validate its accuracy. The thesis details all the parameters used in the experimental tests, highlighting the fundamental role of production quality in achieving the desired mechanical performance. The experimental part of the thesis also demonstrates the effectiveness of using "potting" for the proper fixation and load transfer between the inserts and the surrounding sandwich panels. The numerical model serves a dual purpose: initially, it approximates the initial "quasi-linear" portion of the force/displacement curve obtained experimentally, providing a useful tool to determine the stiffness of the panel subjected to pull-out loads. Additionally, the model is valuable for analyzing the distribution of stresses in the honeycomb core, allowing for a detailed study of the experimental failure observed. The thesis concludes with a chapter entirely dedicated to the production aspects of the final monocoque. The frame is entirely hand-laminated by students, making it essential to document the process and emphasize the defects obtained. Being aware of the compromises and difficulties, it will be possible to design with a production-oriented mindset, reproducing all design details in the final component as originally conceived. Understanding defects is crucial, as they have a significant impact on the final mechanical characteristics of the piece, making it essential to represent them in numerical simulation models.