Session: Poster Session

Paper Number: 162885

Influence of Dimensional Tolerances on Additively Manufactured Hybrid Thrust Bearing Performance 

This study investigates the static load characteristics of additively manufactured hybrid thrust bearings, focusing on the influence of dimensional tolerances inherent to the additive manufacturing process. The study aims to evaluate the feasibility of employing additive manufacturing for producing these critical components in liquid rocket engine turbopumps, offering potential benefits in terms of simplified design, weight reduction, and cost-effectiveness. A hybrid thrust bearing with an outer diameter of 145 mm, inner diameter of 63 mm, and a length of 15 mm was designed and fabricated using additive manufacturing. The bearing features eight recesses and orifices for fluid supply. Due to manufacturing tolerances, deviations in recess depth and orifice diameter from the design specifications were observed. Recess depths, designed to be 0.51 mm, varied from 0.52 mm to 0.53 mm (up to 4% deviation). Orifice diameters, designed to be 1.5 mm, ranged from 1.43 mm to 1.09 mm (up to 27% deviation). A finite element analysis (FEA) model was developed incorporating the as-built dimensions obtained through precise measurements of the additively manufactured bearing. The model considered the compressibility of air as the working fluid and solved the modified Reynolds equation using the finite element method under laminar, isothermal, and compressible fluid conditions. Static load capacity is predicted by integrating the pressure field over the bearing surface area. Stiffness is calculated by considering the change in load capacity due to small perturbations in displacement. Numerical simulations are conducted at supply pressures of 2 bar(g), 3 bar(g), and 4 bar(g) to predict the film thickness under various static loads. The predicted static load characteristics of the additively manufactured bearing are compared with experimental and numerical results obtained for a conventionally manufactured (machined) hybrid thrust bearing. The results indicate that the load capacity and stiffness of the additively manufactured bearing do not significantly differ from those of the machined bearing, despite the dimensional deviations in recess depth and orifice diameter. Future work will focus on incorporating the effects of surface roughness, flatness, and material-induced deformation in the analysis of additively manufactured hybrid thrust bearings. This approach can lead to significant cost reductions in the manufacturing of critical components for space launch vehicles while maintaining performance comparable to traditionally manufactured components.

Presenting Author: Homin Lim Hanyang University

Presenting Author Biography: Graduate Research Assistant at Hanyang University

Authors:

Homin Lim Hanyang University
Keun Ryu Hanyang University