Modeling and simulation methods for MDOF structures and rotating machinery with impact dampers

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Journal of Engineering for Gas Turbines and Power

DOI:https://doi.org/10.1115/1.2815594· OSTI ID:522397

McElhaney, J M; Palazzolo, A ^[1]; Kascak, A ^[2]

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1. Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering
2. Army, Cleveland, OH (United States)

Previously published work on applied impact damping typically relates to SDOF models or simple MDOF models such as the classical cantilever beam. Structural models often require an extremely large number of DOF with mode shapes that are generally very complex. Dynamics simulation of these typically becomes both complicated and time consuming. The nonlinear behavior of impact dampers further complicates such simulation in that standard linear solutions are not possible. The primary objective in this research extends previous work by applying impact dampers to MDOF structures that are modeled with general three-dimensional beam finite elements. Modal-based models of the MDOF systems and efficient impact damper tracking algorithms were also developed that significantly reduced CPU time for simulation. Significant among the objectives was obtaining an impact damper design for the MDOF casing structure of the Space Shuttle Main Engine (SSME), High-Pressure Oxygen Turbo-Pump (HPOTP), subject to pump rotor shaft unbalance. Impact damper performance is based on suppression of vibration at casing critical frequencies for rotor speed ranges, at rotor full speed, and very high unbalance to simulate a defect such as losing an impeller blade fragment or a cracked bearing. Simulations show significant reductions in vibration at the casing critical frequencies and very high unbalance levels while little or no improvement was observed off resonance. Additionally, the previous work with an experimental rotor bearing system (RBS) and impact damper was modeled using the developed modal-based methods. Simulation of the resulting model response shows remarkable agreement with the experimental. Finally, both the RBS and the HPOTP were modeled and simulated as unstable systems with attached impact dampers. The simulations predict that the impact damper is an excellent stabilizing mechanism for a range of instability driver values.

• Sponsoring Organization: USDOE
• OSTI ID: 522397
• Report Number(s): CONF-950629--
• Journal Information: Journal of Engineering for Gas Turbines and Power, Journal Name: Journal of Engineering for Gas Turbines and Power Journal Issue: 2 Vol. 119; ISSN JETPEZ; ISSN 0742-4795
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
COMPUTERIZED SIMULATION
DAMPING
MATHEMATICAL MODELS
PUMPS
RESPONSE FUNCTIONS
ROCKET ENGINES
SPACE SHUTTLES
TRANSIENTS