Exploration of ULTEM 9085 as a Candidate Material for Aerospace Applications

High-temperature fused deposition modeling (FDM) with ULTEM 9085 enables rapid fabrication of aeroelastic test articles and secondary aerospace structures, but reliable design use requires process-specific mechanical and fatigue allowables rather than bulk datasheet values. This study experimentally characterizes ULTEM 9085 printed on a custom high-temperature FDM system through quasi-static tension and fully compressive fatigue testing, and then demonstrates how those measured properties manifest at the component level in a geometry-controlled wind-tunnel comparison. ASTM D638 Type IV coupons were printed with 0° and 45° raster orientations and tested in tension on an Instron 5882. The 0° group exhibited E = 961 ± 150 MPa, UTS = 46.1 ± 6.4 MPa, and εb = 0.057 ± 0.016 mm/mm, while the 45° group exhibited E = 396 ± 94 MPa, UTS = 35.3 ± 8.9 MPa, and εb = 0.103 ± 0.033 mm/mm, with failures dominated by gauge-section fracture and raster-interface delamination. Fully compressive fatigue tests on ASTM D7791-based cylinders (3 Hz, σmax = 30–40 MPa) produced lives from ~5×10^3 to ~1.3×10^5 cycles and were captured over the tested range by a Basquin relation σmax = 85.96 Nf^(-0.090) MPa (R^2 = 0.9879). Finally, an instrumented ULTEM 9085 wing spar was tested in a low-speed wind tunnel at Re ≈ 80,000 and compared directly to an aluminum 6061-T6 spar of identical geometry using six-axis balance loads and distributed fiber-optic strain. The results establish process-anchored tensile and compressive fatigue behavior for the printed material system and provide an experimentally grounded view of the stiffness-mass tradeoffs that govern aeroelastic strain response when substituting printed ULTEM 9085 for a conventional metallic baseline.