This Small Business Innovation Research Phase I project shall develop analytical fatigue models as applied to the performance analysis of remanufactured gearbox coponents under NSF SBIR Phase I Solicitation 11-577 (Topic NM?Nanotechnology, Advanced Materials, and Manufacturing, Subtopic M3-Modeling and Simulation). The first step in developing this technology involves demonstrating basic model capability through the simulation of a worn gear, remanufactured using an isotropic superfinish (ISF) process, as described in this proposal. This model will be based on the fundamental research of the applicability of the ISF process to worn gears, the effects of ISF on gear characteristics (material mictrostructure, microgeometry, residual stress, surface roughness), and the subsequent effect on damage resistance. The model will be used to predict the fatigue life of the remanufactured component, thus quantifying the benefits of such processing and demonstrating the feasibility of such a tool. The results will lay the groundwork for expanding Sentient?s simulation technology to include various other remanufacturing processes in a more comprehensive design and analysis framework capable of optimizing reman operations to extend the useful life of high value added components.
The proposed development has immediate impact on industries that rely on the reliable function of highly engineered (and thus expensive) gearboxes ? aerospace, energy, and transportation. Components must operate in extreme environments, often leading to premature removal or overhaul. Though worn or damaged, these components still have the ability to function given the appropriate remanufacturing processes are deployed. Doing so reduces a significant amount of resources (materials, energy, manpower) otherwise required to produce a replacement part. Furthermore, it is thought that the application of certain remanufacturing processes can actually enhance durability of certain components. Unfortunately, current design and analysis approaches require extensive testing and evaluation to validate the effectiveness and safety of a component that has been used in the field then processed outside of original OEM specification. To test all possible combination of component coupled with various levels of potential damage repaired through various options of processing would be an impossibly expensive and time consuming feat, thus prohibiting a broad deployment of remanufacturing processes across industry. However, as postulated in this proposed effort, such evaluation and validation can occur through modeling and simulation. The resulting advancement in technology will provide immediate value in safely reclaiming useful life of gearbox components.
1. Executive Summary In Phase I and Phase IB, Sentient developed and demonstrated DigitalClone Component Life Prediction (CLP) and Component Fault Prediction (CFP) models to predict the fatigue life of the remanufactured (repaired/refurbished) gearbox components and optimal time-to-remanufacture, thus quantifying the benefits of such processing and demonstrating the feasibility of such a tool. This DigitalClone tool assists in remanufacturing of high value, high demand rotorcraft, automotive and wind turbine gears. The objectives of this SBIR technology were to: - Decrease the energy, material resources, and costs associated with manufacturing; - Ensure product performance is maintained/improved as a result of the process modification or enhancement; and - Reduce physical testing using virtual testing. The DigitalClone model predicts crack initiation and propagation life by modeling the gearbox components material microstructure and variations in the fatigue lives that are vital for the design and analysis of a gearbox system (Figure 1). This was achieved by modeling the material manufacturing process-microstructure-property relationship. The outcome of this project supports the goals of United States Integrated Computational Materials Engineering (ICME) and the Materials Genome Initiative (MGI). Under the Phase I and Phase IB, Sentient successfully demonstrated commercialization of the DigitalClone Remanufacture technology for a rotorcraft Spiral Bevel Gear System. This provided a good platform and support from rotorcraft and Wind Turbine OEMs for commercialization of this SBIR technology. High value spiral bevel gears are widely used in the tail rotor drive trains of most rotorcraft. The loads associated with the tail rotor drive train are generally much more variable than those in the main rotor drive train primarily resulting from maneuvers. These variable load operating conditions may cause severe or slight surface damage to the gears. The slight surface damaged gears are rejected during inspection and order is placed to obtain new parts, which is expensive ($40k - $80k) and time consuming (6-9 months lead time). An effort was conducted by the Army Aviation Applied Technology Directorate (AATD) to investigate an emerging remanufacturing technique to repair and put back the rejected parts in service. This remanufacturing process costs less than $1000.00 per part. However, the current physical testing method to evaluate, quantify and certify the remanufacturing process is very expensive and time consuming. Industry needs a virtual modeling and performance simulation methods to accelerate research and deployment of the remanufacturing techniques. Sentient demonstrated Phase I technology by comparing simulation results with AATD test data. The simulation results have shown that the remanufactured spiral bevel gear set have acceptable bending fatigue and surface durability at powers up to 800 HP, in agreement with AATD physical test observations. This demonstrates that DigitalClone can be used as the alternative to physical testing (Figure 2). Phase I results laid the groundwork for expanding Sentient’s simulation technology to include various other remanufacturing processes in a more comprehensive design and analysis framework capable of optimizing remanufacturing operations to extend the useful life of high value added components. Such expansion is proposed under Phase II project. In summary, as illustrated in Figure 3, Sentient’s DigitalClone technology analyzes gearbox components and systems for safety, longevity, reliability and cost by predicting (1) New gear performance, and optimal time-to-remanufacture (refurbish), (2) Qualification of used gears for remanufacturing process and (3) Predicting the remanufactured gear performance. 2. NSF SBIR Work - Publications Sentient published the following two papers, an outcome of this SBIR work. Publication #1: R. V. Pulikollu et. al., Analytical Modeling and Performance Prediction of Remanufactured Gearbox Components, ICME in Practice, Issues with Application of ICME and Success Stories, 2nd World Congress on Integrated Computational Materials Engineering, 2013 Publication #2: E. C. Ames, R. V. Pulikollu. Virtual Life and Performance Modeling of Aerospace Spiral Bevel Gears, American Society of Mechanical Engineers Power Transmission and Gearing Conference, 2013
