Nondestructive Testing method

Test methods are used to detect flaws. As an example when flaws or cracks grow in plastic, minute amounts of elastic energy are released and propagated in the material as an acoustic wave. A nondestructive acoustic emission test has sensors placed on the surface that can detect these waves providing information about location and rate of flaw growth. These principles form the basis for nondestructive test methods such as sonic testing. 

Selection of visible light reflectance as a candidate nondestructive test method was based on results from probing experiments. It was observed that as cotton was mechanically cleaned, its visible light reflectance increased. Conversely, addition of trace amounts of particulate (trash and dust) to extensively cleaned cotton resulted in a decrease in visible light reflectance. Finally, it was noted that off-colored cotton was rendered whiter with repetitive mechanical cleaning. 

Corrosion detection plays an important role in any corrosion control program. Most of the methods employ nondestructive test methods and include hydrogen evaluation, radiography, dynamic pressure, corrosion probes, strain gauges and eddy current measurements. Of these, the methods employed in cooling tower practice are hydrogen evaluation and corrosion probes. 

This ref pertains to a US patent for a nondestructive testing method and app for determining the presence of voids, cracks or discontinuities in solid substances by the use of radioactive gases as a tracer. Although developed specifically for use with large solid proplnt rocket motors, composed mainly of active ingredients such as ammonium perchlorate imbedded in an inert binder, the method is claimed to be applicable to other solids as well... 

Nondestructive Testing. Nondestructive testing (NDT) is far more economical than destructive test methods, and every assembly can be tested if desired. Several nondestructive test methods are used to check the appearance and quality of structures made with adhesives or sealants. The main methods are simple ones such as visual inspection, tap, proof, and more advanced physical monitoring such as ultrasonic or radiographic inspection. The most difficult defects to find are those related to improper curing and surface treatments. Therefore, great care and control must be exercised in surface preparation procedures and shop cleanliness. 

A possible use for the Russell effect is to detect areas of repair on museum objects. Epoxy and polyester resins produce strong images on a Russellgraph and can be easily detected against completely inert stone, ceramic, or metal. Used in this way, the technique is one of the few truly nondestructive testing methods as no incident energy is necessary to obtain the desired information. 

Production Test methods and sensors Increased applications for robotics and automation Improved sensing technologies and portability Technologies to insure performance requirements Nondestructive test methods... 

Report on Nondestructive Test Methods for Evaluation of Concrete in Structures, ACI 228.2R-98, American Concrete Institute, Detroit, Michigan. 

The availability of nondestructive test methods is rather limited. 

Preliminary testing is done next to uncover flaws in joining, and sometimes in the metal itself. Nondestructive test methods, such as ultrasonics and X- or gamma-ray inspection, are used on main welding seams Dye penetration, hydrostatic, or air-soap tests are also used to locals leaks and cracks. Helium or Freon leak detectors are necessary fok more critical leak testing, particularly on high-vacuum equipment. 

There are three common imperfections encountered in friction stirring voids, joint line remnants, and root flaws (or incomplete root penetration). The presence of voids is easily detectable by current nondestructive testing methods, but joint line remnants and root flaws... 

EDDY CURRENT TESTING - An electromagnetic nondestructive testing method in which eddy-current flow is induced in the test object. Changes in flow caused by variations in the object are deflected into a nearby coil or coils where they are measured. 

Wegman. R. F. (1989). Nondestructive test methods for structural compo.sites. Sampe Handbook 1. 

ASNT. Laser based nondestructive testing methods. In Special nondestructive testing methods. Vol. 9 of nondestructive testing handbook. 2nd ed., vol. 9. American Society for Nondestructive Testing 2003. 

The use of fiber composite elements in the load-bearing structure of automobiles (light construction) will mean practical, nondestructive testing methods for repair workshops. Considerable research remains to be done in this field. 

Radiography is the most frequently used nondestructive test method. X rays and gamma rays passing through a structure are absorbed distinctively by flaws or inconsistencies in the material, so that cracks, voids, porosity, dimensional changes, and inclusions can be viewed on the resulting radiograph. 

Plastics are susceptible to flaws that cannot always be seen thus premature failure can only be prevented if methods are available that will disclose the presence and extent of such flaws without destroying the part. Three of the more common nondestructive testing methods are ultrasonic, -radiometric, and holographic testing. 

One problem, always present in the use of structural adhesives, is how to determine the reliability of the bonded structure. This may be at the time of manufacture, to ensure that a good joint has been produced, or during service, to monitor behavior under operating conditions. It is often impractical, or impossible, to use the types of test methods employed to determine mechanical properties and interest has centered on nondestructive test methods."" " ... 

Table 3. Nondestructive Test Methods for Wound Filaments... 

Detection, Sizing, and Evaluation of Indications with Nondestructive Test Methods... 

---