International Journal of Advanced Engineering Application

Mechanical, Fatigue, and Dimensional Performance of 3D-Printed PETG-Carbon Fiber Lattice Structures for Lightweight Automotive Mounting Brackets

Author(s):Aditya N. Rao

Affiliation: Department of Mechanical and Industrial Engineering, National Institute of Technology, Pune, India

Page No: 41-46

Volume issue & Publishing Year: Volume 3, Issue 7, 2026/07/07

Journal: International Journal of Advanced Engineering Application (IJAEA)

ISSN NO: 3048-6807

DOI:

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Abstract:
The automotive industry's pursuit of mass reduction without compromising structural reliability has renewed interest in fused filament fabrication (FFF) of fiber-reinforced thermoplastics with internally engineered lattice architectures, since topology-optimised infill can deliver favourable stiffness-to-weight ratios unattainable in solid machined or injection-moulded parts while remaining compatible with low-volume production runs typical of aftermarket and motorsport bracket manufacturing. This study characterises the compressive, fatigue, thermal, and dimensional behaviour of carbon-fiber-reinforced PETG (PETG-CF, 15 wt% short fiber) printed with three unit-cell lattice topologies — gyroid (triply periodic minimal surface), body-centred cubic (BCC), and octet-truss — across relative densities of 20-50%, benchmarked against solid PETG-CF brackets representative of a small-bridge engine-mount geometry. Quasi-static compression testing per ASTM D695, tension-tension fatigue testing per ASTM D7791 at R = 0.1, differential scanning calorimetry (DSC), and coordinate measuring machine (CMM) dimensional verification across three build orientations (0°, 45°, 90°) were used to generate a multi-property performance dataset. Octet-truss lattices at 35% relative density achieve the best combination of specific stiffness (0.68 GPa·cm³/g) and fatigue endurance among cellular topologies, while gyroid lattices at the same density offer the most favourable cost-mass trade-off, reducing part mass by 61.5% at 61% of solid-part material and print cost. Build orientation strongly affects dimensional accuracy: flat (0°) builds achieve mean deviation of 0.18% versus 0.67% for fully vertical (90°) builds, with corner warpage increasing nearly six-fold across the same range, identifying orientation control as a primary lever for dimensional quality assurance in production deployment of lattice-infilled brackets.

Keywords: PETG-carbon fiber, fused filament fabrication, lattice structures, gyroid, octet-truss, compressive strength, fatigue, dimensional accuracy, lightweighting, additive manufacturing

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