Strain Gauge Extensometers - Instron 4400 Series Operator's Manual

Strain Calibration

Strain Gauge Extensometers

Instron manufactures a host of different types of exten-
someters and other strain measuring devices, most of
which can be used with the Series 4400 Testing System.
In the following sections, the discussion will center on
Instron's Series 2630 Extensometers, but the calibration
procedures described apply equally well to other types
of extensometers and strain gauges.
The Instron Series 2630 Strain Gauge Extensometers are
lightweight units that are provided with clamps for at-
taching the devices to round or flat test specimens.
These extensometers are available in models covering
high and medium magnification ranges, and with initial
gauge lengths of 10, 25, or 50 mm (1/2, 1, or 2 in.). Op-
erating instructions are included with each extensometer.
The calibration procedure for an extensometer compares
the strain measuring system of a Series 4400 instrument
against a precise voltage, and sets system calibration for
the extensometer in use. The system then is able to pro-
vide an accurate strain signal which is automatically
ranged during a test over 100% (x1), 50% (
(
someter.
The calibration procedure varies depending upon the
type of extensometer installed and the method used:
1. Self identifying and electrically calibrated.
2. Self identifying and manually calibrated.
5-20
load and strain channels and reset all limits
(Load, Extension, and Strain).
5) and 10% ( 10) of the maximum range of the exten-
X X
M10-94400-1
2), 20%
X