A test panel which may be used for evaluating inspection penetrant crack detection performance, comprising essentially a soft, malleable metal substrate coated with a brittle surface layer of controlled thickness within the range of from about 5 microns to 50 microns, said brittle layer having a pattern of craze cracks which are generated by a mechanical stretching of the panel to a point where the average crack width falls within the range of values from about 0.5 micron to 20 microns.
A flaw penetrant test panel having a sheet metal surface in which are impressed tiny or microscopic flaw simulating cavities distributed over the test surface to receive one or more penetrants being tested, the mouth size of the cavities being in the range of about 1 to 10 thousandth inch and being formed by heating the metal to incipient softening temperature followed by penetration of the surface test area using a needle-like tool proportioned to the desired cavity size and depth and which upon penetration of the metal displaces it in a crater-like rim about the cavity being formed.
Nanopatterned devices are easily fabricated, over large surface areas when desired, by forming a multilayer article of deformable substrate, brittle layer, and coating layer, and deforming the multilayer film such that a plurality of cracks are formed therein. The cracks have different physicochemical properties than the non-cracked coating layer, and advantageously serve as attachment points for culturing microorganisms.
A test panel for use in evaluating fluorescent penetrants and being composed of a spring steel substrate having surfaces coated with a thin electroless nickel plating capable of producing stress induced microcracks in the plated surfaces.
A testing device for dyed liquid penetrants consisting of a glass panel grit-blasted with a grit of pre-determined mesh. The grit-blasted surface of the glass panel not only exhibits a roughness characteristic corresponding to the mesh number of the grit used, but it also contains minute fracture cracks which extend to varying depths in the glass surface, depending on the grit used and the impact energy of force of the grit particles during grit-blasting. The thus-formed fracture cracks are statistically reproducible in production of the test panels, and they may serve to simulate crack defects which are found in service parts. A dyed liquid inspection penetrant applied to a grit-blasted fractured glass panel forms entrapments in the fracture cracks, and the portion of these entrapments which remain throughout washing or solvent removal of surface penetrant may be measured and/or compared with reference to known penetrant standards.
Quantitative characterization of a crack detection analysis method is achieved by determining the detection sensitivity and background noise produced by the analysis method by suitably processing images obtained from one or more control specimens prepared by the method and subjected to appropriate and optimized conditions of illumination. In addition, the crack detection analysis method is optimized by looking for the parameters which influence the method and determining the value thereof which maximizes detection sensitivity and minimizes background noise.
