NDE of Bond Strength
Publication Date: 2013-Nov-07
The IP.com Prior Art Database
Described is a method of using ultrasonic waves to calculate variable de-bonded area in a composite material. The process involves calculating a baseline measurement of various de-bonded length and then comparing it with the test sample.
Page 01 of 3
NDE of Bond Strength
The following disclosure uses a nondestructive method to calculate the bond strength of an interface. Currently there exists various destructive methods to evaluate the same.
Destructive tests are standard in quality control - taking a statistically-defined sample of products from a production batch and testing those products in a way that means they may no longer be used. But destructive tests extrapolate the results of the sample to the entire production batch, and this can be unacceptable for very high-value products or products where failure to meet quality control criteria can have high impact, e.g., an airplane engine part.
The Seeker requires a nondestructive and predictive test method for a structure comprising a steel part and a plastic layer. The steel and plastic are bonded by adhesive. The Seeker has explored several cutting-edge technologies but has not found a nondestructive method that is predictive of bond strength. The Seeker produces structural parts composed of a steel component and a porous composite layer.
Steel component (planar, conical and cylindrical surfaces) - 1-2 cm thick sintered or compact steel with a smooth surface
Adhesive layer - 10 micrometers of epoxy-based adhesive
Plastic layer - 700 micrometers of a porous epoxy-based composite (20-50% porous with 200
m mean pore size)
Endurable surface pressure of 15 N/mm² and 15 N/mm² (approximately 2500 psi) shear
The glued structure is not highly flexible and the Seeker will not disclose additional details of its geometry. The Seeker is well aware of nondestructive methods to test adhesive bonds - none of the following technologies has been able to predict bond strength:
Shearography- coherent light is used to analyze structures in unloaded and loaded states to identify areas of non-uniform deformation.
Thermography- infrared cameras are used to detect differences in heat profiles of the part as
it is subjected to a load, heat source or ultrasonic excitation.
Ultrasonic testing- analyzing the reflected or transmitted amplitude
The above technologies may form part of the desired solution but careful attention should be paid to indicating how the proposed technology is able to predict bond strength under application load, which is a combination of pressure and shear force.
The Seeker is open to a wide range of approaches, including, for example, using destructive methods to create a 'standard curve' of bond strength and correlating it to markers of bond stress that could be quantified in a nondestructive test. The most important criteria are that the solution enables nondestructive and space-resolved quantification of bond strength in each part produced in a production environment.
The Seeker is NOT interested in proposals describing HACCP (Hazard Analysis...