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Test of six types of Bakelite-bonded wire strain gages

Description: Report presenting results of testing of 10 gages of each of 6 types of multistrand, single-element, bakelite-bonded wire strain gages. Some of the factors investigated included the uniformity of calibration factors for individual gages of the same type, variation of calibration factor with temperature, creep, effect of current on gage resistance, and variation in gage resistance with temperature.
Date: July 1948
Creator: Campbell, William R.
Partner: UNT Libraries Government Documents Department

Performance tests of wire strain gages 1: calibration factors in tension

Description: Report presenting calibrations in axial tension over the strain range from 0 to 0.0024 are presented for 15 types of single element multistrand wire strain gages. The majority of the gages showed significant differences between the calibration factors for strain increasing and strain decreasing. Improvement in gage performance after preloading was apparent in most cases.
Date: November 1944
Creator: Campbell, William R.
Partner: UNT Libraries Government Documents Department

Errors in indicated strain for a typical wire strain gage caused by restraining, temperature changes, and weathering

Description: Report presenting testing on a wire strain gage of representative design to determine zero shift after straining at room temperature, error in indicated strains at high and low temperature, and changes in calibration factor and zero shift after exposure to heavy weathering. Results regarding the measurements of zero shift after 1 to 10 cycles of straining and testing to determine whether or not zero shift was removed by prestraining reappeared after the gages were left unstrained are provided.
Date: April 1946
Creator: Campbell, William R.
Partner: UNT Libraries Government Documents Department

Performance tests of wire strain gages 2: calibration factors in compression

Description: Report presenting the results of calibrations in axial compression over the strain range 0 to 0.0021 for 15 types of single element multistrand wire strain gages. The majority of gages showed significant differences between the calibration factors for strain increasing and strain decreasing. The majority of the gages were found to have slightly lower factors in compression than in tension.
Date: September 1945
Creator: Campbell, William R.
Partner: UNT Libraries Government Documents Department

Performance tests of wire strain gages 6: effect of temperature on calibration factor and gage resistance

Description: Report presenting results of testing to determine the variation in calibration factor and gage resistance with temperature are presented for 15 types of single-element, multistrand wire strain gage. More than half of the gages tested were relatively insensitive to changes in temperature.
Date: January 1948
Creator: Campbell, William R.
Partner: UNT Libraries Government Documents Department

Performance tests of wire strain gages 3: calibrations at high tensile strains

Description: Report presenting results of calibration in axial tension over the strain range 0 to 0.03 are presented for 15 types of single element, multistrand wire strain gages. Considerable nonlinearity was observed at strains between 0.0025 and 0.006. Fifty-eight percent of the gages failed by breaking of the strain-sensitive wire at strains less than 0.03.
Date: December 1945
Creator: Campbell, William R.
Partner: UNT Libraries Government Documents Department

Performance tests of wire strain gages 4: axial and transverse sensitivities

Description: Report presenting the results of calibrations to determine axial and transverse strain sensitivities for 15 types of single-element, multistrand wire strain gages. The gages were separated into those which had positive average ratios of transverse sensitivity and those which had negative transverse sensitivity.
Date: June 1946
Creator: Campbell, William R.
Partner: UNT Libraries Government Documents Department

The determination of effective column length from strain measurements

Description: From Summary: "A method is presented for the experimental determination of the effective length of a column for which the end conditions are unknown by establishing the points of zero curvature from readings of strain gages distributed along the length of the column. Tests of four columns of different cross sections indicated that the proposed method gives satisfactory results even when there is considerable scatter in the strain-gage readings."
Date: June 1944
Creator: Schuette, Evan H. & Roy, J. Albert
Partner: UNT Libraries Government Documents Department

Effect of misalignment of strain-gage components of strain rosettes

Description: Report presenting a mathematical analysis of the effect of misalignment among the components of rectangular and equiangular strain rosettes on the determination of the magnitudes and directions of principal strains. Misalignments of 2 degrees among individual gases introduced serious errors in the computation of principal strains from rosette data.
Date: September 1946
Creator: Manson, S. S. & Morgan, W. C.
Partner: UNT Libraries Government Documents Department

A Study of the Correlation Between Flight and Wind-Tunnel Buffeting Loads

Description: Report presenting a comparison of the buffet loads measured on wind-tunnel models with loads measured in flight, which indicate that a simple strain-gage measurement can be used in wind tunnel testing that can be used to predict the wing buffet loads on the airplane. The technique appears to be usable for both unswept and swept configurations.
Date: July 19, 1955
Creator: Huston, Wilber B.; Rainey, A. Gerald & Baker, Thomas F.
Partner: UNT Libraries Government Documents Department

Application of obliquely mounted strain gage to measurement of residual stresses in disks

Description: Report presenting a method by which the residual stress distribution in a disk can be determined with the aid of the obliquely mounted strain gage when the directions of the principal stresses are radial and tangential. The strain gages are mounted in such a way as to make them sensitive only to the tangential stresses in the disk. Results regarding cutting procedure, accuracy of the method, and an independent check of the method are required.
Date: September 1957
Creator: Hirschberg, M. H.; Kemp, R. H. & Manson, S. S.
Partner: UNT Libraries Government Documents Department

A portable calibrator for dynamic strain gages

Description: From Summary: "A portable device for calibrating dynamic strain gages is described. The device contains a motor-driven cam, which applies alternating tensile loads to a metal strip 5/8 inch wide and 6 1/4 inches long. The cam is designed to produce a nearly sinusoidal variation of strain with time. Dynamic strain gages with gage lengths up to 5 inches may be calibrated by mounting them on the strip and by changing the frequency and the amplitude of the tensile load. The frequency may be varied from 15 to 30 cycles per second and the strain amplitude from 0 to 10x10-4 in steps of 2x10-4."
Date: February 1943
Creator: McPherson, Albert E.
Partner: UNT Libraries Government Documents Department

The Development of Electrical Strain Gages

Description: "The design, construction, and properties of an electrical-resistance strain gage consisting of fine wires molded in a laminated plastic are described. The properties of such gages are discussed and also the problems of molding of wires in plastic materials, temperature compensation, and cementing and removal of the gages. Further work to be carried out on the strain gage, together with instrument problems, is discussed" (p. 1).
Date: January 1940
Creator: de Forest, A. V. & Leaderman, H.
Partner: UNT Libraries Government Documents Department

Determination of the Stress Concentration Factor of a Stepped Shaft Stressed in Torsion by Means of Precision Strain Gages

Description: The stress distribution in stepped shafts stressed in torsion is determined by means of the electric precision strain gage the stress concentration factor is ascertained from the measurements. It is shown that the test values always are slightly lower than the values resulting from an approximate formula.
Date: September 1947
Creator: Weigand, A.
Partner: UNT Libraries Government Documents Department

Application of Pulse Techniques to Strain Gages

Description: Memorandum presenting pulse techniques applied to strain gages for increasing the output level and extending the usable range. Bonded and unbonded strain gages which normally operate with exciting potentials between 3.5 and 14 volts operated satisfactorily with 200-volt pulses of 1-microsecond duration and a repetition rate of 350 per second. Results regarding maximum allowable voltages, effective pulse duration, sensitivity, minimum readable signal, effects of cable capacitance and inductance, sensitivity to external noise, and linearity are provided.
Date: May 4, 1954
Creator: Sanders, Newell D. & Brodie, George H.
Partner: UNT Libraries Government Documents Department

Adaptor for Measuring Principal Strains With Tuckerman Strain Gage

Description: Report discussing an adapter which uses three Tuckerman optical strain gages to measure the displacement of the three vortices of an equilateral triangle along lines 120 degrees apart. These displacements are substituted in well-known equations in order to compute the magnitude and direction of the principal strains. Tests of the adaptor indicate that principal strains over a gage length of 1.42 inch may be measured with a systematic error not exceeding 4 percent and a mean observational error of the order of + or minus 0.000006. The maximum observed error in strain was of the order of 0.00006. The directions of principal strains for unidirectional stress were measured with the adaptor with an average error of the order of 1 degree.
Date: June 1943
Creator: McPherson, A. E.
Partner: UNT Libraries Government Documents Department

A Multiple Bridge for Elimination of Contact-Resistance Errors in Resistance Strain-Gauge Measurements

Description: Note presenting a multiple-bridge circuit that eliminates contact-resistance errors of the first order between the arms of the ordinary Wheatstone bridge. The circuit is applied to the elimination of the effects of contact-resistance variations that may occur in resistance strain-gage measurements made through switch contacts or slip rings. The general theory is derived and correct circuits and constructions are described.
Date: March 1946
Creator: Warshawsky, Isidoro
Partner: UNT Libraries Government Documents Department

Construction of Wire Strain Gages for Engine Application

Description: Report presenting instructions for winding, baking, and mounting a phanolic resin-impregnated, bobbin-type wire strain gage that consists of Advance wire wound around a paper form. A description of some test equipment useful for establishing the merits of the techniques used in gage construction has been included.
Date: December 1943
Creator: Nettles, J. Cary & Tucker, Maurice
Partner: UNT Libraries Government Documents Department

Performance Tests of Wire Strain Gages 5: Error in Indicated Bending Strains in Thin Sheet Metal Due to Thickness and Rigidity of Gage

Description: Note presenting the results of tests to determine the combined effects of rigidity and thickness of wire strain gages on indicated bending strains in thin sheet metal for 15 types of single-element multistrand wire strain gages. In most cases, the indicated extreme-fiber bending strain was greater than the actual strain. The positive error caused by the finite thickness of the gage predominated over the negative error caused by the rigidity of the gage.
Date: July 1947
Creator: Campbell, W. R. & Medbery, A. F.
Partner: UNT Libraries Government Documents Department

Test Results on Nb3Sn Dipole Magnets

Description: A cosine theta type dipole magnet using Nb{sub 3}Sn conductor have been designed, built and tested. D19H is a two-layer dipole magnet with a Nb{sub 3}Sn inner layer and a NbTi outer layer. Coil-pairs are connected with two of the four Nb{sub 3}Sn splices in a high field region, and compressed by a ring and collet system. It trained well at 4.4K, but poorly at 1.8K. Strain gages revealed that the coil-ends were not loaded well enough for high field operation (after cool-down), so another thermal cycle is planned. The low end-load is believed to be the cause of several mysteries observed during operation. Except for the outer-layer 1.8 K training difficulty, the magnet's operation was encouraging.
Date: December 12, 1996
Creator: Lietzke, A.F.; Benjegerdes, R.; Caspi, S.; Dell'Orco, D.; Harnden, W.; McInturff, A.D. et al.
Partner: UNT Libraries Government Documents Department

Strain gauge installation tool

Description: A tool and a method for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.
Date: December 1, 1997
Creator: Conard, Lisa Marie
Partner: UNT Libraries Government Documents Department