Simplified analysis of a trifragment rotor disk interaction with a containment ring
Computerized analysis of shear failure at initial fragment collision during trifragment rotor disk interaction with containment rings
Mccallum, R. B.↗
SEARCH · Engineering Papers
Results for “failure analysis”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Cyclic stress analysis of an air-cooled turbine vane
The effects of gas pressure level, coolant temperature, and coolant flow rate on the stress-strain history and life of an air-cooled vane were analyzed using measured and calculated transient metal temperatures and a turbine blade stress analysis program. Predicted failure locations were compared to results from cyclic tests in a static cascade and engine. The results indicate that a high gas pressure was detrimental, a high coolant flow rate somewhat beneficial, and a low coolant temperature the most beneficial to vane life.
Kaufman, A.↗
Control optimization, stabilization and computer algorithms for aircraft applications
Research related to reliable aircraft design is summarized. Topics discussed include systems reliability optimization, failure detection algorithms, analysis of nonlinear filters, design of compensators incorporating time delays, digital compensator design, estimation for systems with echoes, low-order compensator design, descent-phase controller for 4-D navigation, infinite dimensional mathematical programming problems and optimal control problems with constraints, robust compensator design, numerical methods for the Lyapunov equations, and perturbation methods in linear filtering and control.
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Mini-BRU/BIPS foil bearing development
The analysis revealed the failure agent to be a combination of poor teflon coating adhesion, a decrease in bearing sway space and, possibly, lack of flushing flow through the bearing. A change in Teflon coating vendors provided substantially improved coating quality and surface finish. The sway space was increased and the cooling bleed flow was adjusted to flush the bearing. These changes were included in a test conducted in the WHL from 6 April to 22 May 1978 which resulted in the completion of 1006.9 hours of operation at temperature and load. Post-test inspection revealed the bearings to be in excellent condition and capable of completing a much longer test.
Dobler, F. X.↗
The ac propulsion system for an electric vehicle, phase 1
A functional prototype of an electric vehicle ac propulsion system was built consisting of a 18.65 kW rated ac induction traction motor, pulse width modulated (PWM) transistorized inverter, two speed mechanically shifted automatic transmission, and an overall drive/vehicle controller. Design developmental steps, and test results of individual components and the complex system on an instrumented test frame are described. Computer models were developed for the inverter, motor and a representative vehicle. A preliminary reliability model and failure modes effects analysis are given.
Geppert, S.↗
Accelerated fatigue durability of a high performance composite
The fatigue behavior of multidirectional graphite-epoxy laminates was analyzed theoretically and experimentally in an effort to establish an accelerated testing methodology. Analysis of the failure mechanism in fatigue of the laminates led to the determination of the failure mode governing fracture. The nonlinear, cyclic-dependent shear modulus was used to calculate the changing stress field in the laminate during the fatigue loading. Fatigue tests were performed at three different temperatures: 25 C, 74 C, and 114 C. The prediction of the S-N curves was made based on the artificial static strength artificial static strength at a reference temperature and the fatigue functions associated with them. The prediction of an S-N curve at other temperatures was performed using shifting factors determined for the specific failure mode. For multidirectional laminates, different S-N curves at different temperatures could be predicted using these shifting factors. Different S-N curves at different temperatures occur only when the fatigue failure mode is matrix dominated. It was found that whenever the fatigue failure mode is fiber dominated, temperature, over the range investigated, had no influence on the fatigue life. These results permit the prediction of long-time, low temperature fatigue behavior from data obtained in short time, high temperature testing, for laminates governed by a matrix failure mode.
Rotem, A.↗
Extension of the hole-drilling method to birefringent composites
A complete stress analysis and reliable failure criteria are essential for important structural applications of composites in order to fully utilize their unique properties. The inhomogeneity, anisotropy and inelasticity of many composites make the use of experimental methods indispensable. Among the experimental techniques, transmission photoelasticity has been extended to birefringent composites in recent years. The extension is not straight-forward, in view of the complex nature of the photoelastic response of such model materials. This paper very briefly reviews the important developments in the subject and then describes the theoretical basis for a new method of determining the individual values of principal stresses in composite models. The method consists in drilling very small holes at points where the state of stress has to be determined. Experiments are then described which verify the theoretical predictions. The limitations of the method are pointed out and it is concluded that valuable information concerning the state of stress in a composite model can be obtained through the suggested method.
Prabhakaran, R.↗
Demonstration Advanced Avionics System (DAAS). Phase 1 report
An integrated avionics system which provides expanded functional capabilities that significantly enhance the utility and safety of general aviation at a cost commensurate with the general aviation market is discussed. Displays and control were designed so that the pilot can use the system after minimum training. Functional and hardware descriptions, operational evaluation and failure modes effects analysis are included.
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Analysis of strain gage reliability in F-100 jet engine testing at NASA Lewis Research Center
A reliability analysis was performed on 64 strain gage systems mounted on the 3 rotor stages of the fan of a YF-100 engine. The strain gages were used in a 65 hour fan flutter research program which included about 5 hours of blade flutter. The analysis was part of a reliability improvement program. Eighty-four percent of the strain gages survived the test and performed satisfactorily. A post test analysis determined most failure causes. Five failures were caused by open circuits, three failed gages showed elevated circuit resistance, and one gage circuit was grounded. One failure was undetermined.
Holanda, R.↗
Scanning beam antenna conceptual design for 20/30 GHz satellite systems
The configuration described is one of four antenna system configurations developed using a variety of monolithic microwave integrated circuit module arrangements and optical systems. A parametric analysis is expected to produce a data base for the selection of design points for a variety of applications. Soon to be accomplished is the design concept of the active (lens) array, which will take into consideration such factors as, coupling effects, the space-fed power divider network design, input bias and control layout, investigation of thermal distribution, and analysis of module failure (graceful degradation).
Smetana, J.↗
Advances and trends in computational structural mechanics
Recent developments in computational structural mechanics are reviewed with reference to computational needs for future structures technology, advances in computational models for material behavior, discrete element technology, assessment and control of numerical simulations of structural response, hybrid analysis, and techniques for large-scale optimization. Research areas in computational structural mechanics which have high potential for meeting future technological needs are identified. These include prediction and analysis of the failure of structural components made of new materials, development of computational strategies and solution methodologies for large-scale structural calculations, and assessment of reliability and adaptive improvement of response predictions.
Noor, A. K.↗
Traveling-wave maser closed-cycle refrigerator data acquisition and display system
A data acquisition and display system that automatically monitors the performance of the 4.5-K closed-cycle refrigerators used to cryogenically cool traveling-wave masers is described. The system displays and stores operating parameters for the purpose of providing status information, failure prediction, and analysis. A prototype of this system will be installed at Deep Space Network 12 in the near future. The advantages of using commercial data acquisition hardware with installed operating systems and BASIC programs for this application are discussed.
Fowler, L.↗
Framework for a space shuttle main engine health monitoring system
A framework developed for a health management system (HMS) which is directed at improving the safety of operation of the Space Shuttle Main Engine (SSME) is summarized. An emphasis was placed on near term technology through requirements to use existing SSME instrumentation and to demonstrate the HMS during SSME ground tests within five years. The HMS framework was developed through an analysis of SSME failure modes, fault detection algorithms, sensor technologies, and hardware architectures. A key feature of the HMS framework design is that a clear path from the ground test system to a flight HMS was maintained. Fault detection techniques based on time series, nonlinear regression, and clustering algorithms were developed and demonstrated on data from SSME ground test failures. The fault detection algorithms exhibited 100 percent detection of faults, had an extremely low false alarm rate, and were robust to sensor loss. These algorithms were incorporated into a hierarchical decision making strategy for overall assessment of SSME health. A preliminary design for a hardware architecture capable of supporting real time operation of the HMS functions was developed. Utilizing modular, commercial off-the-shelf components produced a reliable low cost design with the flexibility to incorporate advances in algorithm and sensor technology as they become available.
Hawman, Michael W.↗
Materials for a Stirling engine heater head
Work done on the 25-kW advanced Stirling conversion system (ASCS) terrestrial solar program in establishing criteria and selecting materials for the engine heater head and heater tubes is described. Various mechanisms contributing to incompatibility between materials are identified and discussed. Large thermal gradients, coupled with requirements for long life (60,000 h at temperature) and a large number of heatup and cooldown cycles (20,000) drive the design from a structural standpoint. The pressurized cylinder is checked for creep rupture, localized yielding, reverse plasticity, creep and fatigue damage, and creep ratcheting, in addition to the basic requirements for bust and proof pressure. In general, creep rupture and creep and fatigue interaction are the dominant factors in the design. A wide range of materials for the heater head and tubes was evaluated. Factors involved in the assessment were strength and effect on engine efficiency, reliability, and cost. A preliminary selection of Inconel 713LC for the heater head is based on acceptable structural properties but driven mainly by low cost. The criteria for failure, the structural analysis, and the material characteristics with basis for selection are discussed.
Noble, J. E.↗
Integrated failure detection and management for the Space Station Freedom external active thermal control system
This paper presents the integrated approach toward failure detection, isolation, and recovery/reconfiguration to be used for the Space Station Freedom External Active Thermal Control System (EATCS). The on-board and on-ground diagnostic capabilities of the EATCS are discussed. Time and safety critical features, as well as noncritical failures, and the detection coverage for each provided by existing capabilities are reviewed. The allocation of responsibility between on-board software and ground-based systems, to be shown during ground testing at the Johnson Space Center, is described. Failure isolation capabilities allocated to the ground include some functionality originally found on orbit but moved to the ground to reduce on-board resource requirements. Complex failures requiring the analysis of multiple external variables, such as environmental conditions, heat loads, or station attitude, are also allocated to ground personnel.
Mesloh, Nick↗
Study Of Corrosion Of Lead-Sheathed Cables
Report presents statistical analysis of corrosion failures of lead-sheathed cables that serve as primary communication links at Kennedy Space Center. In study, corrosion-failure data analyzed by use of Weibull distribution in effort to assess effectiveness of cathodic protection and to predict future failures.
Lee, Rupert U.↗
NASA GRC Technology Development Project for a Stirling Radioisotope Power System
NASA Glenn Research Center (GRC), the Department of Energy (DOE), and Stirling Technology Company (STC) are developing a Stirling convertor for an advanced radioisotope power system to provide spacecraft on-board electric power for NASA deep space missions. NASA GRC is conducting an in-house project to provide convertor, component, and materials testing and evaluation in support of the overall power system development. A first characterization of the DOE/STC 55-We Stirling Technology Demonstration Convertor (TDC) under the expected launch random vibration environment was recently completed in the NASA GRC Structural Dynamics Laboratory. Two TDCs also completed an initial electromagnetic interference (EMI) characterization at NASA GRC while being tested in a synchronized, opposed configuration. Materials testing is underway to support a life assessment of the heater head, and magnet characterization and aging tests have been initiated. Test facilities are now being established for an independent convertor performance verification and technology development. A preliminary Failure Mode Effect Analysis (FMEA), initial finite element analysis (FEA) for the linear alternator, ionizing radiation survivability assessment, and radiator parametric study have also been completed. This paper will discuss the status, plans, and results to date for these efforts.
Thieme, Lanny G.↗
Quality Assurance
General Electric Company requested a report from Jet Propulsion Laboratory which provides detailed information on failure modes, stress analysis and other reliability considerations was requested. General Electric Company's Nuclear Energy Division incorporated its information with that of the report. Routinely used, the report enables personnel time savings in establishing applicable screening test data.
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