Material characteristics in table 1 are further

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(8) abnormal sources of heat. Material characteristics in Table 1 are further defined in Table 2 with respect to specific objectives and specific attributes to be measured, detected and defined. The limitations of a method include conditions to be met for method application (access, physical contact, preparation and others) and requirements to adapt the probe or probe medium to the object examined. Other factors limit the detection or characterization of discontinuities, properties and other attributes and limit interpretation of signals or images generated. Classification Relative to Test Object Nondestructive testing techniques may be classified according to how they detect indications relative to the surface of a test object. Surface methods include liquid penetrant testing, visual testing, grid testing and moiré testing. Surface/near-surface methods include tap, holographic, shearographic, magnetic particle and electromagnetic testing. When surface or near-surface methods are applied during intermediate manufacturing processes, they provide preliminary assurance that volumetric methods performed on the completed object or component will reveal few rejectable discontinuities. Volumetric methods include radiography, ultrasonic testing, acoustic emission testing and less widely used methods such as acoustoultrasonic testing and magnetic resonance imaging. Through-boundary techniques include leak testing, some infrared thermographic techniques, airborne ultrasonic testing and certain techniques of acoustic emission testing. Other less easily classified methods are material identification, vibration analysis and strain gaging. 5 Introduction to Acoustic Emission Testing T ABLE 1. Nondestructive test method categories. Categories Detection Objectives Basic Categories Mechanical and optical color, cracks, dimensions, film thickness, gaging, reflectivity, strain distribution and magnitude, surface finish, surface flaws, through-cracks Penetrating radiation cracks; density and chemistry variations; elemental distribution; foreign objects; inclusions; microporosity; misalignment; missing parts; segregation; service degradation; shrinkage; thickness; voids Electromagnetic and electronic alloy content; anisotropy; cavities; cold work; local strain, hardness; composition; contamination; corrosion; cracks; crack depth; crystal structure; electrical conductivities; flakes; heat treatment; hot tears; inclusions; ion concentrations; laps; lattice strain; layer thickness; moisture content; polarization; seams; segregation; shrinkage; state of cure; tensile strength; thickness; disbonds; voids Sonic and ultrasonic crack initiation and propagation; cracks, voids; damping factor; degree of cure; degree of impregnation; degree of sintering; delaminations; density; dimensions; elastic moduli; grain size; inclusions; mechanical degradation; misalignment; porosity; radiation degradation; structure of composites; surface stress; tensile, shear and compressive strength; disbonds; wear Infrared and thermal
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  • Fall '19
  • Nondestructive testing, Acoustic Emission

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