The Role of Transient Spectrum and Damping Analysis in Assessing the Strength of Polymeric Adhesive Metal Bonding.
Final scientific rept. 1 Jul-30 Jun 74,
ATOMIC ENERGY RESEARCH ESTABLISHMENT HARWELL (ENGLAND) NON-DESTRUCTIVE TESTING CENTRE
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This report describes the derivation of an acoustic impact testing facility and some results that have been obtained using it. The primary task has been to examine what acoustic phenomena associated with the response to impact of an adhesively bonded joint relate to the strength of the joint. A first look system employing a 40 microsec. contact time impactor, a broadband polymeric foil transducer and a PDP8I on-line computer has been used to identify the parameters of interest and the most efficient analysis scheme. This system accesses data at rates up to 4MHz with a data block size of 256, 10 bit words thus specifying the frequency interval between points in the computed frequency spectrum as sampling frequency256. The analysis has centered around the computation of the fast Fourier transform of the impact response to obtain frequency response spectra and damping information. Initial results using the first look system have shown that the presence of artificial defects in rectangular bars can be detected. For adhesively bonded joints, results suggest that damping analysis may be useful in assessing glue line porosity, whereas modal frequency shift is sensitive to cohesive strength.
- Adhesives, Seals and Binders
- Metallurgy and Metallography
- Test Facilities, Equipment and Methods