Testing of structures by impact
AssigneeNational Research Development Corporation
InventorsPeter Cawley, Robert D. Adams
Life of this patent
Estimating the term…
Abstract
Apparatus and method for testing structures by impact. The structure is struck by an impactor associated with a force transducer the output of which is related to the force which the transducer experiences on impact and encompasses a frequency range including the lowest frequencies (typically approaching zero frequency, see FIG. 3) which that force contains to any substantial degree. A test spectrum of the force including that full range of frequencies is produced by a Fourier transformer in a form suitable for automatic comparison, and is then so compared with a reference spectrum typical of impact with a reference structure, and a signal is produced indicating fit or lack of fit between the test and reference spectra.
Claims9
A method of testing a structure by the use of an impactor attached to a force transducer comprising:
- causing the impactor to make impact with the structure;
- obtaining from the force transducer an output the magnitude of which is linearly related to the force to which the transducer is subjected by reason of the impact, the output encompassing a frequency range including the lowest frequencies which the force includes to any substantial degree;
- passing the output of the force transducer to a spectrum analyser to yield a test frequency spectrum of the output over the said frequency range in a form suitable for automatic comparison with a reference spectrum of similar form indicative of the same impactor striking a reference structure;
- so comparing the test and reference spectra automatically, and
- producing a signal indicative of a fit or lack of fit between the test and reference spectra.
Apparatus for testing structures by impact comprising:
- an impactor;
- a force transducer associated with the impactor, and adapted when the impactor makes impact with a structure to produce an output the magnitude of which is linearly related to the force to which the force transducer is subjected by reason of the impact, the output emcompassing a frequency range including the lowest frequencies which the force includes to any substantial degree;
- a spectrum analyser adapted to receive the output of the force transducer and produce a test frequency spectrum of that output;
- means to produce a reference spectrum indicative of the frequency spectrum of the impactor striking a reference structure;
- means to compare the test and reference spectra automatically, and means to produce a signal indicative of a fit or lack of fit between the test and reference spectra.
Dependencies are inferred from the claim text.