Crack detection in bolt holes through detection of a pressure change across a membrane
Publication Date: 2017-Jul-25
The IP.com Prior Art Database
CRACK DETECTION IN BOLT HOLES THROUGH
DETECTION OF A PRESSURE CHANGE ACROSS A MEMBRANE
Technology is related to the methods of non-destructive testing to detect cracks and
damage within holes. It would be applicable to a hole in most materials used in industry.
It was invented with the specific aim of reducing the size of detectible cracks within high
Cracks are currently detected within holes using eddy current methods which are in
general use in industry. These can detect small damages (of the order of 1mm) in
Aluminium but are only able to detect cracks larger than 3mm in high strength steels
due to high levels of noise. A 3mm crack size is considered too large in order to use this
method to confirm the presence of flaws induced during manufacture. Consequently,
this method cannot be used to determine that the hole is defect free. This technology
aims to enable very small defects to be found and thus greatly reduce the size of
detectible cracks in steels and possibly also in aluminium.
Another existing method of crack detection is the comparative vacuum monitoring
sensor (see above), this is attached to a surface and any changes in pressure (through
loss of vacuum) can be attributed to the presence of a crack. These can only be used
on plain surfaces. This technology uses a similar concept to enable it to be used within
the bore of a hole.
The purpose of this technology is to detect small cracks (<1mm long) within the bore
hole of a fastener with the fastener removed. It is intended for use in both aluminium
and steel but could also be used in other engineering materials. It would:
• Enable holes in difficult to machine high strength materials to be declared free of
damage after manufacture.
• Current manufacturing methods require a complex testin...