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Crack detection in bolt holes through detection of a pressure change across a membrane

IP.com Disclosure Number: IPCOM000250480D
Publication Date: 2017-Jul-25
Document File: 4 page(s) / 2M

Publishing Venue

The IP.com Prior Art Database

Abstract

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 55% of the total text.

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

strength steels.

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...