RESIDUAL STRESS PATTERNS - Vishay

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Residual Stress Patterns

Vishay Micro-Measurements

Document Number: 11516

Revision 21-Aug-03

www.vishaymg.com

Special Purpose Sensors - Residual Stress Patterns

The most widely used practical technique for determining

residual stresses is the hole-drilling strain gage method

described in ASTM Standard E837. With this method, a

specially configured strain gage rosette is bonded to the

surface of the test object; and a small, shallow hole is

introduced into the structure, through the center of the gage,

with a precision drilling apparatus. Strains in the immediate

vicinity of the hole are measured, and the relaxed residual

stresses are computed from these measurements. The

general theory of making residual stress measurements is

covered in Vishay Micro-Measurements Tech Note TN-503,

Measurement of Residual Stresses by the Hole-Drilling

Strain Gage Method and the requisite hardware is described

in Bulletin 304.

CONSTRUCTION

All gages are constructed of self-temperature-compensated

foil (06 and 13 S-T-C) on a flexible polyimide carrier, and

incorporate a centering target for use with a precision milling

guide. EA-Series (A-Alloy) gages are available “open-faced”

or with solder dots and encapsulation (Option SE); CEA-

Series (A-Alloy) gages have encapsulated grids, and

rugged, copper-coated solder tabs. Construction of the N2K

Series (K-alloy) is similar to the N2A Series and includes

copper pads (DP) on the solder tabs. The 062UM gage

permits installation adjacent to weldments and intersecting

surfaces.

GAGE PATTERN RES. DIMENSIONS

AND DESIGNATION IN

Actual Size Shown. OHMS GAGE GRID

Insert Desired S-T-C No. in Spaces Marked XX. LENGTH CTR’LINE Min. Max. Length Width

DIA.

EA-XX-031RE-120 120 ±0.2% 0.031 0.101 0.03 0.04 0.29 0.29

EA-XX-031RE-120/SE 120 ±0.4% 0.79 2.56 0.8 1.0 7.4 7.4

N2K-XX-030RR-350/DP 350 ±0.4% 0.030 0.170 0.090 0.100 0.37 0.37

0.76 4.32 2.3 2.5 9.4 9.4

EA-XX-062RE-120 120 ±0.2% 0.062 0.202 0.06 0.08 0.42 0.42

EA-XX-062RE-120/SE 120 ±0.4% 1.57 5.13 1.5 2.0 10.7 10.7

EA-XX-125RE-120 120 ±0.2% 0.125 0.404 0.12 0.16 0.78 0.78

EA-XX-125RE-120/SE 120 ±0.4% 3.18 10.26 3.0 4.1 19.8 19.8

CEA-XX-062UL-120 120 ±0.4% 0.062 0.202 0.06 0.08 0.50 0.62

1.57 5.13 1.5 2.0 12.7 15.7

CEA-XX-062UM-120

120 ±0.4% 0.062 0.202 0.06 0.08 0.38 0.48

1.57 5.13 1.5 2.0 9.6 12.2

Due to small pattern size, measurement error can be magnified by

slight mislocation of drill hole. Pattern not recommended for general-

purpose applications.

Special six-element configuration that provides somewhat higher

output than three-element designs.

Most widely used RE pattern for general-purpose residual stress

measurement applications.

Larger version of the 062RE pattern.

Fully encapsulated with large copper-coated soldering tabs. Same

pattern geometry as 062RE pattern.

Fully encapsulated with large copper-coated soldering tabs and

special trim alignment marks. Trim line spaced 0.068 in (1.73 mm)

from hole center. Limitations may exist in data reduction equations.

TYPICAL HOLE DIA.

MATRIX