Failure Analysis and Redesign of a 3D Printed Intake Manifold in a Formula SAE Racing Team Using High-Performance Polymers

Fused filament fabrication (FFF) 3D printing has proven to be an affordable method for producing customized and lightweight parts and an accessible method to validate new composite materials. As a rapid prototyping method, it can be used to manufacture and replace defective and/or damaged parts in places with limited infrastructure or logistical support. However, the layer-by-layer deposition inherent to the FFF process introduces anisotropy and residual stresses, which can compromise part performance under high temperatures or vibrational loads. This article aims to analyze the failure of a 3D printed intake runner and address the problems found. The analyzed part was 3D printed in acrylonitrile butadiene styrene (ABS), which had a high volumetric contraction during the printing process. Although ABS exhibits a high heat deflection temperature (HDT) compared to other polymers, prolonged exposure to elevated temperatures during operation led to unintentional embrittlement, reducing interlayer adhesion and releasing residual stress through deformation. The appearance of softened polymer at the intake connections indicates that there was a chemical reaction of polymer with fuel components (hydrocarbons). This chemical reaction, associated with exposure to the high operational temperature during long periods, was the most likely root causes of the failure of the part (combined effects). A new material (Tritan HT) was evaluated for its mechanical strength and the redesigned part was then produced using the Sovol SV 04 printer (a dual extruder 3D printer), replacing the original material (ABS) with the new filament. This change offers lower chemical reactivity with hydrocarbons and presents high HDT temperatures, which allows the integrity of the internal structure of the part even at high temperatures. Assembly tests have shown that the greater sturdiness provided from optimized printing parameters and Tritan HT filament as an unexpected benefit by allowing higher elastic deformation than the original part with ABS. This benefit reduced the risk of damage to the part and surrounding components and helped to ensure the formula SAE team's competitive capacity.