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Author: H. Conrad Publisher: ISBN: Category : Languages : en Pages : 50
Book Description
Data available in the literature on the mechanical behavior of beryllium were evaluated to ascertain the operative dislocation mechanisms. These suggest that the deformation dynamics of polycrystalline beryllium in the range of 78 K to 800 K is related to the motion of dislocation on the first order prism planes. Above 800 K, the yield stress exhibits a stronger temperature dependence than that for prism slip and the deformation dynamics may be associated with either the operation of C + a pyramidal slip or perhaps some diffusion-controlled mechanism. Insufficient data are presently available to positively identify the rate controlling dislocation mechanisms. The effect of hydrostatic pressure on the ductile-to-brittle transition temperature is in accord with the concept that the transition is associated with the operation of c + a pyramidal slip. As a first step in the study of the anisotropy of bonding in beryllium the elastic shear constant C = C(11) + C(12) + 2 C(33) - 4 C(13) has been calculated for beryllium using Jones' model and was found to be in good accord with the experimental value. Using this model, the effect of the addition of monovalent and polyvalent alloying elements on the elastic constant was calculated and found to be significant. (Author).
Author: H. Conrad Publisher: ISBN: Category : Languages : en Pages : 50
Book Description
Data available in the literature on the mechanical behavior of beryllium were evaluated to ascertain the operative dislocation mechanisms. These suggest that the deformation dynamics of polycrystalline beryllium in the range of 78 K to 800 K is related to the motion of dislocation on the first order prism planes. Above 800 K, the yield stress exhibits a stronger temperature dependence than that for prism slip and the deformation dynamics may be associated with either the operation of C + a pyramidal slip or perhaps some diffusion-controlled mechanism. Insufficient data are presently available to positively identify the rate controlling dislocation mechanisms. The effect of hydrostatic pressure on the ductile-to-brittle transition temperature is in accord with the concept that the transition is associated with the operation of c + a pyramidal slip. As a first step in the study of the anisotropy of bonding in beryllium the elastic shear constant C = C(11) + C(12) + 2 C(33) - 4 C(13) has been calculated for beryllium using Jones' model and was found to be in good accord with the experimental value. Using this model, the effect of the addition of monovalent and polyvalent alloying elements on the elastic constant was calculated and found to be significant. (Author).
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722817046 Category : Languages : en Pages : 62
Book Description
In response to the failure of a conical section of the Insat C satellite during certification testing, the use of beryllium for payload structures, particularly in sheet product form, is being reevaluated. A test program was initiated to study the tensile, shear, and out-of-plane failure modes of beryllium cross-rolled sheet and to apply data to the development of an appropriate failure criterion. Tensile test results indicated that sanding the surface of beryllium sheet has no significant effect on yield strength but can produce a profound reduction in ultimate strength and results obtained by finite element analysis. Critical examination of these test results may contribute to the modification of a JSC policy for the use of beryllium in orbiter and payload structures. Henkener, J. A. and Spiker, I. K. and Castner, W. L. Johnson Space Center...
Author: Webster Hodge Publisher: ISBN: Category : Beryllium Languages : en Pages : 230
Book Description
Reports of Government-supported research on the physical and process metallurgy of beryllium that were received at DMIC during the period 1958-1960, inclusive, are summarized, together with some reports and publications of foreign authors. No proprietary or classified information is included. In addition, reference is made to some of the more importa t writings on health hazards and safety procedures that appeared during the period covered. (Author).
Author: Publisher: ISBN: Category : Defense contracts Languages : en Pages : 366
Book Description
Abstracts of Air Force Materials Laboratory contracts that were active on 15 August 1966 are reported. The abstracts are ordered by Divisions of laboratory and are indexed by contract number. Each abstract entry provides the title of the contract, contractor, duration, project engineer, objective and progress.
Author: D. B. King Publisher: ISBN: Category : Beryllium Languages : en Pages : 114
Book Description
Samples of hot pressed and hot isostatically pressed S-65 beryllium were prepared from billets salted with iron base and graphite particles. Quasistatic tension, biaxial disc, and interally pressurized ring tests were performed to evaluate the effects of the resultant inclusions on the mechanical properties of beryllium. Inclusions in salted billets were characterized and compared with those found in production pressings. Fracture surfaces at inclusions were examined. Results indicate that inclusions degrade the mechanical properties of beryllium but not catastrophically. Surface inclusions were found to be more deleterious than internal inclusions. The salting technique was found to provide a convenient method for producing material for test specimens having inclusions of a predetermined type, size range, and number, which are representative of those found in production pressings. (Author).
Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
The compressive stress-strain response of three grades of beryllium were studied as a function of strain rate and temperature. Grades S2OOD, E, and F represent a historical perspective of beryllium processing from the 1960's through 1990's technology. The purpose of this study was to measure the mechanical behavior of beryllium over a range of deformation conditions for constitutive model development and to obtain microstructural evidence for deformation mechanisms. The compressive stress-strain response was found to be independent of grade and strongly dependent on the applied strain rate between 0.001 and 8000. The strain-hardening response displayed a moderate temperature dependence between 77 K and 873 K Because distinct yield was not observed, the intercept-stress from linear strain-hardening fits was analyzed and was found to be only weakly dependent on strain rate and temperature above ambient. Microstructural examination of SHPB specimens revealed that twinning was extensive at strains between 7-22%. A SHPB sample deformed to over 20% strain contained both extensive twinning and grain boundary microcracking.
Author: H. Conrad
Author: H. Conrad
Author: J. A. Henkener
Author: National Aeronautics and Space Administration (NASA)
Author: Defense Documentation Center (U.S.)
Author: Webster Hodge
Author: 
Author: D. B. King
Author: E. E. Baldwin
Author: S. H. Gelles
Author: