Delayed fracture in viscoelastic-plastic solids
Delayed fracture in viscoelastic-plastic solids - assessment of load carrying ability of glass-like polymers having potential applications as structural materials
Knauss, W. G.↗
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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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Effects of decontamination, sterilization, and thermal vacuum on polymeric products
Adhesives, coatings, coated fabrics, elastomers, encapsulants, films, hardware and structural materials, and tapes are tested in a series of physical, mechanical, and electrical tests. Material properties are measured before and after exposure to the three environments.
Roper, W. D.↗
Optimum structural design based on reliability analysis
Proof-load test improves statistical confidence in the estimate of reliability, numerical examples indicate a definite advantage of the proof-load approach in terms of savings in structural weight. The cost of establishing the statistical distribution of strength of the structural material is also introduced into the cost formulation
Heer, E.↗
Research and Advanced Development, Volume 2 Semiannual Review, 1 Jul. - 31 Dec. 1968
Advanced research on electronic and power systems, design criteria, and structural materials for space application
Source record↗
Developing the structure to carry man to the planets
Spacecraft design for manned interplanetary missions, considering structural materials and weights, cryogenic insulation, meteoroid protection, landing gear, etc
Anderson, R. A.↗
Fatigue damage under creep effect
Creep rupture effect on fatigue damage of structural material, constructing nondimensional stress range diagrams
Shewchuk, J.↗
Nondestructive testing of adhesive bonds by nuclear quadrupole resonance method
Inert, strain sensitive tracer, cuprous oxide, added to polymeric adhesive ensures sufficiently large signal to noise ratio in NQR system output. Method is successful, provided that RF-transparent structural materials are used between modified adhesive and probe of NQR spectrometer.
Hewitt, R. R.↗
Graphite-reinforced aluminum composite
Metallic composite prepared for utilization which remains intact without aluminum/carbon reactions, is less expensive than other structural materials, and yields a flexible composite material.
Lalacona, F. P.↗
Application of beryllium to orbiter primary structure
Reduction of overall program costs for reusable space shuttle by use of beryllium as primary structural material
Harvey, T. J.↗
Design of experiments as multiply telescoping sequences of blocks
Measuring elevated-temperature time-dependent corrosion effects of liquid metal on immersed structural materials
Holms, A. G.↗
Design of experiments as multiply telescoping sequences of blocks with application to corrosion by liquid metals
Measurement of elevated temperature, time dependent corrosion effects of liquid metals on immersed structural materials by blocked two-level factorial experiment
Holms, A. G.↗
Design of experiments as 'multiply telescoping' sequences of blocks
Liquid metal elevated temperature time dependent corrosion effects on immersed structural materials, discussing blocked two level factorial experiment design for multiply telescoping sequences
Holms, A. G.↗
An investigation of strain cycling behavior of 7075-T6 aluminum under combined state of strain: The effects of out-of-phase, biaxial strain cycling on low cycle fatigue
The effect of out-of-phase strain cycling on the low cycle fatigue of biaxially loaded specimens is discussed. A method to apply phase angles between two strains imposed in two different directions was developed. The data and the proposed theoretical analysis are part of a research program on biaxial strain cycling effect on fatigue life of structural materials.
Zamrik, S. Y.↗
Neutronics analysis of an open-cycle high-impulse gas core reactor concept
A procedure was developed to calculate the critical fuel mass, including the effects of propellant pressure, for coaxial-flow gas-core reactors operating at 196,600 newtons thrust and 4400 seconds specific impulse. Data were generated for a range of cavity diameter, reflector-moderator thickness, and quantity of structural material. Also presented are such core characteristics as upper limits on cavity pressure, spectral hardening in very-high-temperature hydrogen, and reactivity coefficients.
Whitmarsh, C. L., Jr.↗
A mixed optimization method for automated design of fuselage structures.
A procedure for automating the design of transport aircraft fuselage structures has been developed and implemented in the form of an operational program. The structure is designed in two stages. First, an overall distribution of structural material is obtained by means of optimality criteria to meet strength and displacement constraints. Subsequently, the detailed design of selected rings and panels consisting of skin and stringers is performed by mathematical optimization accounting for a set of realistic design constraints. The practicality and computer efficiency of the procedure is demonstrated on cylindrical and area-ruled large transport fuselages.
Sobieszczanski, J.↗
Scatter factor and reliability of aircraft structures
The concept of time to first failure is utilized to perform a parameter study of scatter factors of aircraft structures. The Weibull distribution is used for estimation of characteristic and certifiable lives. Scatter factors for various Weibull-shaped parameters, fleet sizes and level of reliabilities are calculated. It is concluded that the currently used range of scatter factors (2 through 4) is too narrow for the estimation of a safe life and that a safe and economical design for structural materials with shape parameters less than 2 does not seem feasible except for very small fleet sizes and low levels of reliability.
Schueller, G. I.↗
Apollo experience report: The problem of stress-corrosion cracking
Stress-corrosion cracking has been the most common cause of structural-material failures in the Apollo Program. The frequency of stress-corrosion cracking has been high and the magnitude of the problem, in terms of hardware lost and time and money expended, has been significant. In this report, the significant Apollo Program experiences with stress-corrosion cracking are discussed. The causes of stress-corrosion cracking and the corrective actions are discussed, in terminology familiar to design engineers and management personnel, to show how stress-corrosion cracking can be prevented.
Johnson, R. E.↗
Study of design and control of remote manipulators. Part 2: Vibration considerations in manipulator design
An investigation is reported involving a mathematical procedure using 4 x 4 transformation matrices for analyzing the vibrations of flexible manipulators. Previous studies with the procedure are summarized and the method is extended to include flexible joints as well as links, and to account for the effects of various power transmission schemes. A systematic study of the allocation of structural material and the placement of components such as motors and gearboxes was undertaken using the analytical tools developed. As one step in this direction the variables which relate the vibration parameters of the arm to the task and environment of the arm were isolated and nondimensionalized. The 4 x 4 transformation matrices were also used to develop analytical expressions for the terms of the complete 6 x 6 compliance matrix for the case of two flexible links joined by a rotating joint, flexible about its axis of rotation.
Book, W. J.↗