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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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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Failure Modes Experienced on Spacecraft Nicd Batteries

A review was made of failures and irregularities experienced on nickel cadmium batteries for 31 spacecraft. Only rarely did batteries fail completely. In many cases, poorly performing batteries were compensated for by a reduction in loads or by continuing to operate in spite of out-of-voltage conditions. Low discharge voltage was the most common problem observed in flight spacecraft (42%). Spacecraft batteries are often designed to protect against cell shorts, but cell shorts accounted for only 16% of the failures. Other causes of problems were high charge voltage (16%), battery problems caused by other elements of the spacecraft (10%), and open circuit failures (6%). Problems of miscellaneous or unknown causes occurred in 10% of the cases.

Gross, S.↗
NASA NTRS1990

Fundamental aspects of and failure modes in high-temperature composites

Fundamental aspects of and attendant failure mechanisms for high temperature composites are summarized. These include: (1) in-situ matrix behavior; (2) load transfer; (3) limits on matrix ductility to survive a given number of cyclic loadings; (4) fundamental parameters which govern thermal stresses; (5) vibration stresses; and (6) impact resistance. The resulting guidelines are presented in terms of simple equations which are suitable for the preliminary assessment of the merits of a particular high temperature composite in a specific application.

Chamis, Christos C.↗
NASA NTRS1993

Failure modes of reduced-order orbit determination filters and their remedies

Ways in which failure can occur in reduced-order, orbit determination filter, error covariance calculations are discussed. In the context of this article, reduced-order filters denote nonoptimal filters which include fixed levels of uncertainty in some parameters of the measurement models or in the spacecraft dynamical model which are not explicitly estimated in the filter equations. Failure is defined as an increase in the orbit determination covariance with the addition of data or as an unreasonable growth in the covariance with time, i.e., nonasymptotic behavior of the covariance. Some simple, known cases of failure are discussed along with their traditional remedies. In addition, more modern remedies are discussed which are currently under development at the Jet Propulsion Laboratory. The article first describes the known problems of reduced-order filters when they are employed for orbit determination, and their traditional remedies. Then, having defined these, the relevancy and desirability of the more modern remedies are made apparent.

Scheeres, D. J.↗
NASA NTRS2011

Failure Modes in Capacitors When Tested Under a Time-Varying Stress

Power-on failure has been the prevalent failure mechanism for solid tantalum capacitors in decoupling applications. A surge step stress test (SSST) has been previously applied to identify the critical stress level of a capacitor batch to give some predictability to the power-on failure mechanism [1]. But SSST can also be viewed as an electrically destructive test under a time-varying stress (voltage). It consists of rapidly charging the capacitor with incremental voltage increases, through a low resistance in series, until the capacitor under test is electrically shorted. When the reliability of capacitors is evaluated, a highly accelerated life test (HALT) is usually adopted since it is a time-efficient method of determining the failure mechanism; however, a destructive test under a time-varying stress such as SSST is even more time efficient. It usually takes days or weeks to complete a HALT test, but it only takes minutes for a time-varying stress test to produce failures. The advantage of incorporating a specific time-varying stress profile into a statistical model is significant in providing an alternative life test method for quickly revealing the failure mechanism in capacitors. In this paper, a time-varying stress that mimics a typical SSST has been incorporated into the Weibull model to characterize the failure mechanism in different types of capacitors. The SSST circuit and transient conditions for correctly surge testing capacitors are discussed. Finally, the SSST was applied for testing Ta capacitors, polymer aluminum capacitors (PA capacitors), and multi-layer ceramic (MLC) capacitors with both precious metal electrodes (PME) and base metal electrodes (BME). The test results are found to be directly associated with the dielectric layer breakdown in Ta and PA capacitors and are independent of the capacitor values, the way the capacitors were built, and the capacitors manufacturers. The test results also show that MLC capacitors exhibit surge breakdown voltages much higher than the rated voltage and that the breakdown field is inversely proportional to the dielectric layer thickness. The SSST data can also be used to comparatively evaluate the voltage robustness of capacitors for decoupling applications.

Liu, David (Donhang)↗
NASA NTRS1979

Maximum likelihood estimation for life distributions with competing failure modes

Systems which are placed on test at time zero, function for a period and die at some random time were studied. Failure may be due to one of several causes or modes. The parameters of the life distribution may depend upon the levels of various stress variables the item is subject to. Maximum likelihood estimation methods are discussed. Specific methods are reported for the smallest extreme-value distributions of life. Monte-Carlo results indicate the methods to be promising. Under appropriate conditions, the location parameters are nearly unbiased, the scale parameter is slight biased, and the asymptotic covariances are rapidly approached.

Sidik, S. M.↗
NASA NTRS1987

Failure modes for compression loaded angle-ply plates with holes

A combined theoretical-experimental investigation of failure in notched, graphite-epoxy, angle-ply laminates subjected to far-field compression loading indicates that failure generally initiates on the hole boundary and propagates along a line parallel to the fiber orientation of the laminate. The strength of notched laminates with specimen width-to-hole diameter ratios of 5 and 10 are compared to the strength of unnotched laminates. The experimental results are complemented by a three-dimensional finite element stress analysis that includes interlaminar stresses around holes in (+/- theta)s laminates. The finite element predictions indicate that failure is initiated by shear stresses at the hole boundary.

Burns, S. W.↗
NASA NTRS1985

Characterization of mode 1 and mixed-mode failure of adhesive bonds between composite adherends

A combined experimental and analytical investigation of an adhesively bonded composite joint was conducted to characterize both the static and fatigue beyond growth mechanism under mode 1 and mixed-mode 1 and 2 loadings. Two bonded systems were studied: graphite/epoxy adherends bonded with EC 3445 and FM-300 adhesives. For each bonded system, two specimen types were tested: a double-cantilever-beam specimen for mode 1 loading and a cracked-lapshear specimen for mixed-mode 1 and 2 loading. In all specimens tested, failure occurred in the form of debond growth. Debonding always occurred in a cohesive manner with EC 3445 adhesive. The FM-300 adhesive debonded in a cohesive manner under mixed-mode 1 and 2 loading, but in a cohesive, adhesive, or combined cohesive and adhesive manner under mode 1 loading. Total strain-energy release rate appeared to be the driving parameter for debond growth under static and fatigue loadings.

Mall, S.↗
NASA NTRS1986

Characterization of mode I and mixed-mode failure of adhesive bonds between composite adherends

A combined experimental and analytical investigation of an adhesively bonded composite joint was conducted to characterize both the static and fatigue beyond growth mechanism under mode 1 and mixed-mode 1 and 2 loadings. Two bonded systems were studied: graphite/epoxy adherends bonded with EC 3445 and FM-300 adhesives. For each bonded system, two specimen types were tested: a double-cantilever-beam specimen for mode 1 loading and a cracked-lapshear specimen for mixed-mode 1 and 2 loading. In all specimens tested, failure occurred in the form of debond growth. Debonding always occurred in a cohesive manner with EC 3445 adhesive. The FM-300 adhesive debonded in a cohesive manner under mixed-mode 1 and 2 loading, but in a cohesive, adhesive, or combined cohesive and adhesive manner under mode 1 loading. Total strain-energy release rate appeared to be the driving parameter for debond growth under static and fatigue loadings.

Mall, S.↗
NASA NTRS1971

Establishment of design criteria for acceptable failure modes and fail safe considerations for the space shuttle structural system

The application of general design approaches for preventing failures due to repeated load cycles is briefly discussed. Program objective, mission requirements, and structural design criteria are summarized. Discrete structural elements and associated sections were selected for detailed strength, fatigue, and fracture mechanics investigations.

Westrup, R. W.↗
NASA NTRS2009

CSM RCS Design Considerations and Failure Modes

Objectives include: a) Define major Command and Service Module (CSM) design considerations; b) List Command Module (CM) RCS failures and lessons learned; and c) List Service Module (SM) RCS failures and lessons learned.

Interbartolo, Michael↗
DOE OSTI2020

Preseismic Fault Creep and Elastic Wave Amplitude Precursors Scale With Lab Earthquake Magnitude for the Continuum of Tectonic Failure Modes

Tectonic faults fail in a continuum of modes from slow earthquakes to elastodynamic rupture. Precursory variations in elastic wavespeed and amplitude, interpreted as indicators of imminent failure, have been observed in limited natural settings and lab experiments where they are thought to arise from contact rejuvenation and microcracking within and around the fault zone. However, the physical mechanisms and connections to fault creep are poorly understood. Here we vary loading stiffness during frictional shear to generate a range of slip modes and measure fault zone properties using transmitted elastic waves. We find that elastic wave amplitudes show clear changes before fault failure. The temporal onset of amplitude reduction scales with lab earthquake magnitude and the magnitude of this reduction varies with fault slip. Our data provide clear evidence of precursors to lab earthquakes and suggest that continuous seismic monitoring could be useful for assessing fault state and seismic hazard potential.

58 GEOSCIENCES↗
NASA NTRS1981

Analysis of the shearout failure mode in composite bolted joints

A semi-empirical shearout strength model has been formulated for the analysis of composite bolted joints with allowance for the effects of joint geometry. The model employs a polynomial stress function in conjunction with a point stress failure criterion to predict strength as a function of fastener size, edge distance, and half spacing. The stress function is obtained by two-dimensional plane-stress finite element analysis using quadrilateral elements with orthotropic material properties. Comparison of experimentally determined shearout strength data with model predicted failures has substantiated the accuracy of the model.

Wilson, D. W.↗
NASA NTRS2009

Apollo CSM Power Generation System Design Considerations, Failure Modes and Lessons Learned

The objectives of this slide presentation are to: review the basic design criteria for fuel cells (FC's), review design considerations during developmental phase that affected Block I and Block II vehicles, summarize the conditions that led to the failure of components in the FC's, and state the solution implemented for each failure. It reviews the location of the fuel cells, the fuel cell theory the design criteria going into development phase and coming from the development phase, failures and solutions of Block I and II, and the lessons learned.

Interbartolo, Michael↗
NASA NTRS1972

Establishment of design criteria for acceptable failure modes and fail safe considerations for the space shuttle structural system

Investigations of fatigue life, and safe-life and fail-safe design concepts as applied to space shuttle structure are summarized. The results are evaluated to select recommended structural design criteria to provide assurance that premature failure due to propagation of undetected crack-like defects will not occur during shuttle operational service. The space shuttle booster, GDC configuration B-9U, is selected as the reference vehicle. Structural elements used as basis of detail analyses include wing spar caps, vertical stabilizer skins, crew compartment skin, orbiter support frame, and propellant tank shell structure. Fatigue life analyses of structural elements are performed to define potential problem areas and establish upper limits of operating stresses. Flaw growth analyses are summarized in parametric form over a range of initial flaw types and sizes, operating stresses and service life requirements. Service life of 100 to 500 missions is considered.

Westrup, R. W.↗
DOE OSTI2020

Failure modes of protection layers produced by atomic layer deposition of amorphous TiO 2 on GaAs anodes

Amorphous titanium dioxide (a-TiO 2 ) films formed by atomic layer deposition can serve as protective coatings for semiconducting photoanodes in water-splitting cells using strongly alkaline aqueous electrolytes. Herein, we experimentally examine the mechanisms of failure for p + -GaAs anodes coated with a-TiO 2 films (GaAs/a-TiO 2 ). Galvanic displacement of exposed GaAs by Au allowed imaging of pinholes in the a-TiO 2 coatings, and enabled collection of quantitative and statistical data associated with pinhole defects. A combination of imaging, electrochemical measurements, and quantitative analyses of corrosion products indicated that extrinsic pinholes were present in the a-TiO 2 films before electrochemical operation. During electrochemical operation these pinholes led to pitting corrosion of the underlying GaAs substrate. The dominant source of pinholes was the presence of atmospheric particulate matter on the GaAs surface during deposition of the a-TiO 2 layer. The pinhole density decreased substantially when the thickness of the a-TiO 2 coating increased beyond 45 nm, and approached zero when the thickness of the film exceeded 112 nm. The density of pinholes in films thinner than 45 nm decreased when the a-TiO 2 coating was deposited in an environmentally controlled cleanroom. Pinhole-free GaAs/a-TiO 2 devices were also tested via chronoamperometry to quantify the rate of pinhole formation during electrochemistry. The time-to-failure increased with thickness, suggesting that the failure mechanism may involve diffusion or migration through the film. However, other mechanisms may also contribute to the degradation of thicker films (>112 nm). Nevertheless, as previously hypothesized, extrinsic pinhole defects formed during deposition and testing control the short-term protective performance of the a-TiO 2 film for GaAs anodes evolving O 2 from water.

25 ENERGY STORAGE↗
DOE OSTI2023

Unraveling kinking: A plasticity enhancing failure mode in high strength nano metallic laminates

Kinking is an important and plasticity-enhancing deformation/failure mode in numerous mechanically anisotropic materials including high-strength nano metallic laminates (NMLs). However, our current limited understanding of the mechanics of kinking and its dependence on microstructural attributes is insufficient for thoroughly comprehending and eventually being able to control failure behaviors of materials. In this study, we investigate kinking dependencies on microstructural attributes in NMLs via in situ micropillar compression, multiscale microstructure characterization, dislocation dynamic simulations, and crystal plasticity modeling. Additionally, by examining several NML systems (Cu/Fe, Ag/Fe, Al-4Mg/Fe), we demonstrate that the development of internal stresses during loading activates local layer-parallel glide triggering kinking in NMLs. Furthermore, this work reveals the effect of key microstructural features including layer thickness, layer waviness, interface barrier strength, and work hardening capacity on kink band formation in NMLs. More broadly, our efforts represent a generically applicable approach for probing large-strain deformation behavior of complex materials via synergetic modeling and experimental efforts.

36 MATERIALS SCIENCE↗