Development and Application of High-Temperature Strain Gages for Stress Measurements in Jet Engines PDF Download

Author: B. R. Anderson
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 9

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Book Description
This paper covers recent advancements in the development and application of high-temperature strain gages for stress measurements in jet engines. Development of high-temperature strain gages can be divided into three areas: (1) alloys, (2) cements, and (3) fabrication and application techniques. In the Aircraft Gas Turbine Division, the measurement of vibratory stress and static stress are both of primary importance. For vibratory stress measurement, a high-temperature strain gage has been developed which will operate at temperatures up to 1500 F continuously and up to 1800 F for short periods of time. For static stress measurement, a self-temperature -- compensating, high -- temperature strain gage has been developed for application on specific alloys up to 850 F. Developments to increase the temperature range of both of these gages are under way.

Author: Naval Air Material Center, Philadelphia. Aeronautical Structures Laboratory
Publisher: ASTM International
ISBN:
Category :
Languages : en
Pages : 170

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Author: R. H. Kemp
Publisher:
ISBN:
Category : Turbines
Languages : en
Pages : 36

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Book Description
The thermal stresses in a turbine stator vane of a turbojet engine were measured by means of static high-temperature resistance-wire strain gages. The temperature variations existing in the engine were duplicated in the vane in a test setup at a reduced average temperature. Stress measurements at the leading and trailing edges indicated maximum principal values in compression of 18,100 and 27,200 psi, respectively. In the midchord region on the suction surface, the maximum principal stress was 19,600 psi in compression and in the midchord region on the pressure surface, 26,200 psi in tension.

Author: Society for Experimental Stress Analysis. Technical Committee on Strain Gages
Publisher:
ISBN:
Category : Strain gages
Languages : en
Pages : 36

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Book Description

Author: J. W. Pitts
Publisher:
ISBN:
Category : Cement
Languages : en
Pages : 318

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Book Description
A summary is presented of a research program aimed at the improvement of high-temperature strain gages of the electrical resistance type. Potential ceramic and metal components were evaluated and a gage was devised that was based on these evaluations. This gage (NBS 5B) was flexible and easy to install; however, it lacked resistance stability at higher temperatures. In an attempt to minimize this deficiency, ceramic cements were developed that showed greater electrical resistivity than had been previously observed in the range 800 to 1800 degrees Fahrenheit; also, a technique was devised for increasing the resistance to ground by applying a fired-on ceramic coating to the grid of a specifically developed unbacked gage. A study was made of the cause of the erratic response of cemented gages that had not been preheated prior to use. There were strong indications that the erratic response was caused mostly by the rapid decrease in resistance that accompanied structural changes in the cement.

Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723145841
Category :
Languages : en
Pages : 146

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Final results are presented from a program to develop a thin film static strain gage for use on the blades and vanes of running, test stand gas turbine engines with goals of an 3 x 3 mm gage area and total errors of less than 10 pct. of + or - 2,000 microstrain after 50 hrs at 1250 K. Pd containing 13 Wt. pct. Cr was previously identified as a new strain sensor alloy that appeared to be potentially usable to 1250 K. Subsequently, it was discovered, in contrast with its behavior in bulk, that Pd-13Cr suffered from oxidation attack when prepared as a 4.5 micron thick thin film. Continuing problems with electrical leakage to the substrate and the inability of sputtered alumina overcoats to prevent oxidation led to the discovery that sputtered alumina contains appreciable amounts of entrapped argon. After the argon has been exsolved by heating to elevated temperatures, the alumina films undergo a linear shrinkage of about 2 pct. resulting in formation of cracks. These problems can be largely overcome by sputtering the alumina with the substrate heated to 870 K. With 2 micron thick hot sputtered alumina insulation and overcoat films, total 50 hr drifts of about 100 microstrain (2 tests) and about 500 microstrain (1 test) were observed at 1000 and 1100 K, respectively. Results of tests on complete strain gage systems on constant moment bend bars with Pd temperature compensation grids revealed that oxidation of the Pd grid was a major problem even when the grid was overcoated with a hot or cold sputtered alumina overcoat. Hulse, C. O. and Bailey, R. S. and Grant, H. P. and Anderson, W. L. and Przybyszewski, J. S. Unspecified Center GAS TURBINE ENGINES; HIGH TEMPERATURE; SPUTTERING; STRAIN GAGES; THIN FILMS; VANES; ALUMINUM OXIDES; ARGON; CRACKS; LEAKAGE; OXIDATION; SHRINKAGE; SUBSTRATES; TEST STANDS; THICK FILMS...

Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722434427
Category :
Languages : en
Pages : 54

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An experimental evaluation of Pd 13 percent Cr and of BCL-3 alloy wire strain gages was conducted on IN100 and Cu 0.15 percent Zr alloy substrates. Testing included apparent strain, drift, gage factor, and creep. Maximum test temperature was 1144 K (1600 F). The PdCr gages incorporated Pt temperature compensation elements. The PdCr gages were found to have good resistance stability below 866 K (1100 F). The BCL 3 gages were found to have good resistance stability above 800 K (981 F), but high drift around 700 K (800 F). Anderson, W. L. and Grant, H. P. Unspecified Center...

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 54

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Author: G. STEVENS
Publisher:
ISBN:
Category :
Languages : en
Pages : 1

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To measure stresses produced in aircraft structures by aerodynamic heating, a quasi-static high temperature strain gage is required which exhibits good stability characteristics. In the present application it was desired to measure large strains in the temperature range 1000 to 1600 F. Refractory single phase alloys with Fe, Co, and Ni bases were selected for exploration as strain gage wires. Besides good oxidation resistance it was aimed to achieve a low temperature coefficient of resistance and matching expansivity with the chosen base material. The solid solution alloys of the Fe-Cr-Al composition approached most closely the ideal requirements for high temperature strain gage wires. Several alloys in this group were vacuum melted and the hot and cold forming properties were determined. Fe25 Cr-5 Al, Fe-25 Cr-7.5 Al, and Fe-20 Cr-10 Al alloys ultimately were drawn into 0.001 to 0.002in.-diam wires. Strain gages fabricated from these wires were cemented to Inconel test bars and preliminary gage calibrations were made at elevated temperatures. (Author).

Author: R.L. Hannah
Publisher: Springer Science & Business Media
ISBN: 9780412537202
Category : Technology & Engineering
Languages : en
Pages : 508

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Book Description
This highly detailed handbook is a resource for those entering the field of stress analysis and instrumentation. The authors were brought together to provide their expert experience and have presented many practical solutions.