FIELD OF THE INVENTION
The present invention relates to development of a method and device for
measurement of residual stresses of metallic components in inclined position.
More specifically the invention relates to development of methodology for
installing the tripod arrangement over the installed strain gauge in Tee-cross
Section position of a component in which field of approach for the conventional
standard tripod arrangement fails.
BACKGROUND OF THE INVENTION
There are instances in manufacturing industry to measure residual stress on the
weld / base metal regions of the components to ensure their smooth operation.
Residual stress in engineering is defined as the stresses remaining within a
material after processing and removal of all external loads.

Residual stress of metallic material is measured according to the relevant
standards of ASTM. It involves installing a strain gauge on the surface of the
component. A standard tripod is then placed over the strain gauge. After fixing
the tripod arrangement a precise hole of 1.6 mm diameter is drilled on the strain
gauge through the tripod to relax the strain and stresses are computed from the
relaxed strain.
The tripod has a base at its top, over which a provision for inserting a mandrel
for drilling is available.
At the bottom of the tripod screws are provided for fixing the tripod to the
surface of a component. In this procedure Tripod can be fixed on the flat
surfaces of stressed components and through this arrangement tripod can be
fixed on the components only in vertical, horizontal, and overhead positions.
But with this conventional tripod arrangement it is not possible to measure
residual stresses of components in Tee cross sections.
To solve this practical difficulty in the existing practice, there has been a long
felt requirement to develop a testing facility in this field of approach.
No prior art reference has been found in this specific field of technology
development.

OBJECTS OF THE INVENTION
One object of the invention is to propose an improved method for measurement
of residual stresses in metallic components at inclined position.
Another object of the invention is to propose a device for measurement of
residual stresses in metallic components in inclined positions, by providing a
fabricated aluminum plate with a hole at the center.
A still another object of the invention is to propose a device for measurement of
residual stresses in metallic components in inclined positions, in which a bolting
means in the device is provided so that the tripod can be mounted.
A further object of the invention is to propose a device for measurement of
residual stresses in metallic components in inclined positions, in which a strain
gauge is mounted on the inclined surface of the component.
SUMMARY OF THE INVENTION
In the proposed invention an aluminum plate is fabricated with optimized
thickness and shape having bevelled edges, and is drilled at its centre to provide
a circular hole. The drilled and bevelled aluminum plate when fixed at the base
of the tripod by bolting constitutes a device for residual stress measurement in
tee cross-sectional component in inclined position. The improved device is

maintained in an inclined position of the component by means of an adhesive
and the tripod is installed over the device by bolting on its base on removing the
three out of the four feet of the tripod support.
According to the invention there is provided a device for residual stress
measurement of a component at inclined position in particular a tee cross
sectional position comprising :a bevelled and holed aluminium plate mounted on
the tee cross section of the component by adhesive; a tripod equipment
consisting of a base, a circular hole for inserting a mandrel for drilling, a screw
of adjusting the mandrel to get aligned with the centre of a strain gauge hole, a
support consisting of a holed cylindrical piece embedded inside on another holed
cylindrical support, the tripod equipment being installed over an aluminium plate
mounted on the component; a mandrel being guided through the hole of the
tripod to extend through the hole in the aluminium plate so that a precise hole
is drilled on the strain gauge to relax the strains at the inclined position.
According to the invention there is also provided a method of forming a device
for residual stress measurement of a component comprising the steps of:
fabricating a bevelled and holed aluminium plate of desired thickness and shape
corresponding to that of the component for its measurement of residual stress;
mounting said aluminium plate on the surface of the component at inclined

position by adhesive; positioning the tripod equipment consisting of a base;(
after removing the three legs), a support consisting of a holed cylindrical piece
embedded inside another holed cylindrical support; installing said tripod
equipment on the mounted aluminium plate to enable the tripod equipment to
be aligned in the same inclination of the aluminium plate; and drilling a precise
hole on the strain gauge by inserting a mandrel through the tripod arrangement.
The proposed invention will be better understood by the following description
with reference to the accompanying drawings in which
Figure 1 shows a conventional tripod arrangement for measurement
of residual stress of a component in vertical position.
Figure 2 shows an improved device for measurement
of residual stress of a component at an inclined
position, in particular at tee-cross sectional position,
according to the present invention.
Figure 3 shows a process of measurement including positioning of the
device on the component.

In Figure 1 the tripod arrangement consists of three legs (1) on which the tripod
equipment rests, a base (2) which is fixed with the legs (1) through screws (3).
On the base of the tripod, a holed support (4) is provided and a smaller holed
diameter piece (6) is mounted on the support (4) by means of screws (5). The
tripod arrangement when set-up, allows a strain gauge (not shown) at the
bottom of the tripod arrangement to be drilled by a mandrel inserted through the
hole of the piece (6).
There exists a circular hole (4) over which another hole (6) is provided for
inserting the mandrel for drilling. A screw (5) is provided for adjusting the
mandrel to get aligned with the center of the strain gauge hole.
The strain gauge is fixed at the surface of the component. A mandrel is inserted
through this hole to drill a precise hole of 1.6 mm diameter on the installed strain
gauge.
By the said conventional tripod arrangement it is possible to measure residual
stress of a component in vertical and horizontal position but it is impossible to
measure residual stresses in tee cross sectional position.

Figure 2 shows the developed device for measurement of residual stresses in
inclined positions by strain relaxation principle.
An aluminium plate (8) is fabricated having thickness and shape corresponding
to the shape and size to suit the tripod.
The aluminum plate (8) is drilled at its center such that the drilled hole and the
hole in the tripod match, when the tripod is placed on the aluminium plate. The
said drilled aluminum plate (8) when mounted on the inclined surface of a
component (9) by adhesive, constitute a device for measuring residual stress of
a stressed component (9) in the inclined position.
Figure 3 shows the positioning of fabricated beveled aluminum plate (8) in the
tee cross sectional component (9).
The drilling of required precise hole on the strain gauge is then carried out by
inserting the mandrel through this arrangement.
The developed device constructed through this methodology make it possible to
drill the strain gauge without any difficulty in inclined position so that residual

stress of a strained component in inclined position can be determined through
strain relaxation of the strain gauge.
The proposed invention as narrated herein above should not be read and
construed in a restrictive manner as some modifications, adaptations and
alterations are possible within the scope and limit of the invention as defined in
the encompassed appended claims.

WE CLAIM
1. A device for residual stress measurement of a component at inclined
position in particular a tee-cross sectional position, comprising:
- mounting a fabricated holed aluminum plate (8) on a Tee cross
section of the component by an adhesive (10);
- setting up a tripod arrangement fixing the tripod with the
aluminum plate (8) by a plurality of screws (7);
- the tripod equipment consisting of a base (2), a circular hole (4)
over which another hole (6) for inserting a mandrel for drilling, a
screw (5) for adjusting the mandrel to get aligned with the center
of the strain gauge hole, a cylindrical support consisting of a holed
cylindrical piece (6) embedded on another holed cylindrical support
(4) by screws (5) being fixed to the base (2), said tripod
equipment being installed over the aluminium plate(8) mounted on
the component(9);
- a mandrel guidable through the hole of the tripod and extending
via the hole in the aluminium plate (8) so that a precise hole is
drilled on a strain gauge disposed in inclined position.

2. The device for residual stress measurement of component as claimed in
claim 1, wherein the device is enabled to drill the strain gauge in inclined
position of a tripod equipment through removal of the legs of the tripod
equipment on withdrawal of a second plurality of screws (3) at the base
of the tripod and fixing the tripod equipment on the bevelled aluminum
plate (8) through at least three bolts , the aluminum plate (8) being
positioned on the component (9) by the adhesive (10), and allowing
drilling of the precise hole on the strain gauge in inclined position.

ABSTRACT

TITLE: A DEVICE FOR RESIDUAL STRESS MEASUREMENT OF A COMPONENT
AT INCLINED POSITION IN PARTICULAR A TEE-CROSS SECTIONAL POSITION
The invention relates to a device for residual stress measurement of a
component at inclined position in particular a tee-cross sectional position,
comprising mounting a fabricated holed aluminum plate (8) on a Tee cross
section of the component by an adhesive (10); setting up a tripod arrangement
fixing the tripod with the aluminum plate (8) by a plurality of screws (7); the
tripod equipment consisting of a base (2), a circular hole (4) over which another
hole (6) for inserting a mandrel for drilling, a screw (5) for adjusting the mandrel
to get aligned with the center of the strain gauge hole, a cylindrical support
consisting of a holed cylindrical piece (6) embedded on another holed cylindrical
support (4) by screws (5) being fixed to the base (2), said tripod equipment
being installed over the aluminium plate(8) mounted on the component(9); a
mandrel guidable through the hole of the tripod and extending via the hole in the
aluminium plate (8) so that a precise hole is drilled on a strain gauge disposed in
inclined position.