Characterizing Static and Dynamic Mechanical Properties for Additive Manufactured ULTEM 9085 Used to Construct Flow Control Devices for Turbomachinery Applications

Extrusion additive manufacturing technologies may be utilized to fabricate complex geometry devices to control the flow distortions at the inlets of gas turbine engines. However, the success of these devices depends upon their ability to withstand the dynamic mechanical loads experienced in service. One such device is a StreamVane^®. A current candidate material for StreamVane fabrication is ULTEM 9085 — a thermoplastic polymer material. ULTEM 9085 was selected as the material of choice for StreamVane production because of its high strength-to-weight ratio. In this study, quasi-static and cyclic fatigue tests were performed on ULTEM 9085 samples fabricated by fused deposition modeling. First, ASTM D638 tensile-tensile material tests were conducted on three different build orientations to verify the mechanical strength of ULTEM 9085 listed by Stratasys. The three different orientations that were tested were Orientation XZZ, Orientation XYZ, and Orientation ZXY with measured ultimate tensile strengths of 69.6 MPa, 56.3 MPa, and 37.6 MPa, respectively. Fatigue properties were investigated utilizing the procedure outlined in ASTM D7791. S-N curves were generated using data collected at stress levels of 80%, 60%, 30% and 20% of the ultimate tensile stress with an R-ratio of 0.1 for the build orientation XZY. Next, the modified Goodman approach was used to estimate the fully reversed (R = −1) fatigue life. The initial data suggested that the modified Goodman approach was very conservative. Therefore, four different stress levels of 25%, 20%, 15% and 10% of ultimate tensile stress were used to characterize the fully reversed fatigue properties. Because of the extreme conservatism of the modified Goodman model for this material, a simple phenomenological model was developed to estimate the fatigue life of ULTEM 9085 subjected to fatigue at different R-ratios. The calculated fatigue life using the model and the data collected for the fully reversed test correlated very well. The data from this investigation demonstrated that StreamVane designs using ULTEM 9085 are more than capable of withstanding the static and dynamic loads in currently planned turbomachinery applications.