scholarly journals Discussion: “Measurement of the Damping of Engineering Materials During Flexural Vibration at Elevated Temperatures” (Schabtach, Carl, and Fehr, R. O., 1944, ASME J. Appl. Mech., 11, pp. A86–A92)

1945 ◽  
Vol 12 (3) ◽  
pp. A180
Author(s):  
E. W. Pike
Keyword(s):  
Elevated Temperatures ◽  
Flexural Vibration ◽  
Engineering Materials

Measurement of the Damping of Engineering Materials During Flexural Vibration at Elevated Temperatures

1944 ◽  
Vol 11 (2) ◽  
pp. A86-A92
Author(s):  
Carl Schabtach ◽  
R. O. Fehr
Keyword(s):  
Strain Gage ◽  
Modulus Of Elasticity ◽  
Tuning Fork ◽  
Elevated Temperatures ◽  
Flexural Vibration ◽  
Logarithmic Decrement ◽  
Vibration Frequencies ◽  
Bending Stresses ◽  
Engineering Materials

Abstract The method and equipment developed and used by the authors for measuring the damping of materials are described. A tuning-fork specimen is set into vibration by jerking a spreader from the gap between the ends of the tines. The damping is expressed in terms of the logarithmic decrement of the decaying vibration, which is measured and recorded by means of a magnetic oscillograph, amplifiers, and a resistance-type electric strain gage cemented to the specimen. The results include (1) the damping of a number of materials during flexural vibration at approximately 1000 cycles per sec, at maximum bending stresses up to 40,000 psi, and at temperatures up to 1400 F; (2) the variation in modulus of elasticity with temperature, as determined from the specimen vibration frequencies.

Paper 10: Titanium, Beryllium, and the Refractory Metals in the Aircraft Industry

1965 ◽  
Vol 180 (4) ◽  
pp. 75-89
Author(s):  
A. R. G. Brown ◽  
K. S. Jepson
Keyword(s):  
Elevated Temperatures ◽  
Refractory Metals ◽  
Aircraft Industry ◽  
New Materials ◽  
Engineering Materials

The need for new materials capable of operating at elevated temperatures often while severely stressed is outlined, and the properties of titanium, beryllium and the refractory metals which give them importance for such application are described. These are ‘new’ metals in that their application as engineering materials is in its infancy and, as yet, generally accepted alloys have not been developed. The difficulties in forming and joining the metals are discussed, and their characteristic properties which make utilization difficult are outlined. Finally, a brief survey is made of the properties obtainable in alloys of the metals described and potential and actual fields of application are discussed.

Analysis and Testing of Dynamic Micromechanical Behavior of Composite Materials at Elevated Temperatures

1996 ◽  
Vol 118 (4) ◽  
pp. 554-560 ◽  
Author(s):  
R. H. Pant ◽  
R. F. Gibson
Keyword(s):  
High Temperature ◽  
Composite Materials ◽  
Elevated Temperatures ◽  
Flexural Modulus ◽  
Flexural Vibration ◽  
Unidirectional Composite ◽  
Vibration Test ◽  
Impulse Frequency ◽  
Composite Moduli

This paper describes the use of a recently developed high temperature impulse-frequency response apparatus to directly measure dynamic modulus and internal damping of high temperature composite materials, matrix materials, and reinforcing fibers as a function of temperature. An extensional vibration test was used for determination of the complex Young’s modulus of fiber specimens as a function of temperature. A flexural vibration test was used for determination of the complex flexural modulus of matrix and unidirectional composite specimens (0 and 90 deg fiber orientations) as a function of temperature. These results were obtained from tests done on two different fiber reinforced composite materials: boron/epoxy (B/E) and Silicon Carbide/Ti-6Al-4V (SiC/Ti). The results from these tests were then used to assess the validity of micromechanics predictions of composite properties at elevated temperatures. Micromechanics predictions of composite moduli and damping at elevated temperatures show good agreement with measured values for the 0 deg case (longitudinal) but only fair agreement for the 90 deg case (transverse). In both cases, the predictions indicate the correct trends in the properties.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

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