MATERIALS ENGINEERING CONCEPTS - Materials for Civil and Construction Engineers - page 38

(a)

FIGURE 1.30 Strain gauges:
(a) strain gauges with different sizes
and (b) typical foil strain gauge.

(b)

base. When the strain gauge is bonded to the object, it is cemented firmly with
the foil or wire side out. Foil-plastic gauges are more commonly used than
wire gauges.
When using strain gauges, it is very important to have a tight bond be-
tween the gauge and the member. The surface must be carefully cleaned and
prepared and the adhesive must be properly applied and cured. The adhe-
sive must be compatible with the material being tested.

1.7.4 Proving Ring
Proving rings are used to measure forces in many laboratory tests. The prov-
ing ring consists of a steel ring with a dial gauge attached, as shown in
Figure 1.31. When a force is applied on the proving ring, the ring deforms,
as measured with the dial gauge. If the relation between the force and dial