Measuring and testing – Specimen stress or strain – or testing by stress or strain... – Specimen clamp – holder – or support
Patent
1993-04-05
1995-02-14
Williams, Hezron E.
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
Specimen clamp, holder, or support
73826, G01N 302
Patent
active
053884647
DESCRIPTION:
BRIEF SUMMARY
This application is a continuation of PCT/GB91/01386 filed Aug. 15, 1991.
TECHNICAL FIELD
This invention relates to a stressing device for use, for instance, in testing the durability of bonded joints.
BACKGROUND ART
The durability of structural adhesive bonds exposed to combinations of stress and an aggresive environment has traditionally been evaluated using large, bulky stressing devices suitable only for use in laboratory based or static outdoor test environments. These devices may typically be a meter or more in length and 5 to 10 cm in width.
DISCLOSURE OF INVENTION
The present invention aims to provide a smaller stressing device suitable for use in confined spaces, e.g. the underside of a vehicle or inside a vehicle engine compartment, to enable durability tests to be conveniently carried out in real-life environments and over extended periods of time.
According to a first aspect of the invention there is provided a stressing device for applying a stress to a specimen being tested, the device comprising a tubular body portion having a bore passing from one end of the device to the other; first and second jaws mounted within the tubular body portion and arranged to be secured to opposite ends of a specimen to be tested; securing means for securing the first jaw to the body portion; and resilient means housed in a chamber within the bore of the body portion and arranged to apply a load to the second jaw and thus to the specimen being tested, at least one cut-out being provided in the side of the body portion to provide access to a specimen held between the first and second jaws and to expose the specimen to the surrounding environment, the device being sufficiently small to enable it to be used in confined spaces, such as the underside of a vehicle or within a vehicle engine compartment, so that tests can be carried out in real-life environments.
According to a second aspect of the invention, there is provided a method of testing a specimen using a stressing device as detailed above comprising the steps of: fitting the specimen within the device and installing the device in a real-life situation, e.g. by mounting it on the body of a vehicle, so it is subject to real-life temperature changes and a real-life chemical environment.
Preferred features of the invention will be apparent from the following description and the subsidiary claims of the specification.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be further described, merely by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a cross-sectional side view of a first embodiment of a stressing device according to the invention and also shows an adaptor for mounting the device within a tensometer;
FIG. 2 is a plan view of a body portion of the device shown in FIG. 1;
FIG. 3 shows plan views of specimen jaws used in the device shown in FIG. 1 and a nut which fits into one end of the device;
FIG. 4 is a side view of a second embodiment of a stressing device according ot the invention showing two possible modifications to the first embodiment;
FIG. 5 is a schematic view of one end of a stressing device illustrating a further modification of the embodiments shown in the preceding drawings; and
FIGS. 6A and 6B are schematic diagrams of two forms of movement sensor which may be used in conjunction with the device shown in FIG. 5.
BEST MODE OF CARRYING OUT THE INVENTION
The device illustrated in FIGS. 1 to 3 comprises a substantially tubular body portion 1, a first jaw 2 for holding one end of a specimen 3, a second jaw 4 for holding the other end of the specimen 3, a compression spring 5, a nut 6 which fits into one end of the body portion 1 and a security bolt 7 which fits into the other end of the body portion 1.
In use, the components of the device are assembled as shown in FIG. 1 with the jaws 2 and 4 fitted within a bore 8 of the tubular body portion 1. The specimen 3 is secured between the jaw 2 and 4 by means of stainless steel pins (not shown) fitted through holes 2A and 4A provided in the ends
REFERENCES:
patent: 3142980 (1964-08-01), Andersen
patent: 3433061 (1969-03-01), Burr
Soviet Inventions Illustrated, Week 8710, Abstract KBAV S03 87-071828/10, 18 Mar. 1987, Derwetn Publications Ltd., (London, GB) & SU, A, 1245-926 23 Jul. 1986.
Olsen James M.
Williams Hezron E.
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