Nondestructive testing damage

As well as being a good way of measuring the yield strengths of materials like ceramics, as we mentioned above, the hardness test is also a very simple and cheap nondestructive test for (Ty. There is no need to go to the expense of making tensile specimens, and the hardness indenter is so small that it scarcely damages the material. So it can be used for routine batch tests on materials to see if they are up to specification on without damaging them. 

When a scheduled repair to a facility is made by cutting out the damaged portion of the pipe as a cylinder and replacing it with another section of pipe, the replacement section of pipe shall be subjected to a pressure test. The replacement section of pipe shall be tested to the pressure required for a new facility installed in the same location. The tests may be made on the pipe prior to installation, provided nondestructive tests meeting the requirements of the applicable Part of this Code are made on all field girth butt welds after installation. If the replacement is made under controlled fire conditions (hydrogen in the facility), full encirclement welded split sleeves may be used to join the pipe sections instead of butt welds. 

Nondestructive testing (qv) can include any test that does not damage the plastic piece beyond its intended use, such as visual and, in some cases, mechanical tests. However, the term is normally used to describe x-ray, nuclear source, ultrasonics, atomic emission, as well as some optical and infrared techniques for polymers. Nondestructive testing is used to determine cracks, voids, inclusions, delamination, contamination, lack of cure, anisotropy, residual stresses, and defective bonds or welds in materials. 

A statistical study of mine-hoist wire ropes showed that 66% of the ropes exhibited greatest loss in strength in the portion of the rope in contact with the shaft environment during its service life (26). The Mine Safety and Health Administration (MSHA) of the US Department of Labor requires that wire ropes in service be visually examined for structural damage, corrosion, and improper lubrication or dressing (27). MSHA also requires performance of careful nondestructive testing (NDT) every 6 months and cites one instance where a contractor reported that four ropes were in acceptable condition for use in an elevator shaft. However, less than 6 weeks later, one of the four 12.7 mm (0.5 in.) diameter ropes broke and another was severely corroded with several broken wires (28). 

FAA. Impact damage characterization and damage tolerance of composite sandwich airframe structures — phase II. DOT/FAA/AR-02/80 Final Report October 2002. Workman GL, Kishoni D. Ultrasonic testing. 3rd ed. American Society for Nondestructive Testing 2007. 

Quantitative nondestructive testing (NDT) inspection to measure extent and rate of damage accumulation... 

The Mohs hardness test (the word scratch is assumed) is almost a nondestructive test. The hardness of a gemstone is usually referred to as its Mohs hardness. Since this hardness value is determined by a scratch test, it is not actually a hardness. The scale has many drawbacks including the fact that it is not linear, it does not necessarily relate to wear resistance, and it damages the specimen so it is not ideal for polished stones. 

Figure 17.94 Ultrasonic C-scan of cfrp laminate showing an area of impact induced delamination white indicates negligible damage and black bad damage. Source Reprinted from Cawley P, The sensitivity of the mechanical impedance method of nondestructive testing, NDT Int, 30(4), 209-215, Aug 1987.

Acoustic emission can be used for testing pressure vessels and is not strictly a nondestructive test as it involves listening to the propagation of damage when subjected to an applied stress. 

Ohtsu M, Okamoto T, Yuyama S (1998) Moment tensor analysis of acoustic emission for cracking mechanisms in concrete. ACI Stracmral Journal 95(2) 87-95 Ohtsu M, Ohtsuka M (1998) Damage evolution by AE in the fracture process zone of concrete. J Materials, Cone. Struct. Pavement, JSCE, 599/V-40 177-184 Ohtsu M (2000) Moment tensor analysis of AE and SiGMA code. Acoustic Emis-sion-Beyond the Millennium. Elsevier, pp 19-34 Ouyang C, Landis E, Shah SP (1992) Damage assessment in concrete using acoustic emission. Nondestructive Testing of Concrete Elements and Structures, ASCE, pp 13-24... 

Nondestructive Testing, ACI SP-112 63-82 Ohtsu M, Murakami Y, Yuyama S (1995) AE generating behavior under Concrete Ppacement and application to process control. ASNT, Proc. AECM-5 332-339 Ohtsu M (1995) The history and development of acoustic emission in concrete engineering. Concrete Library of JSCE 25 121-134 Ohtsu M, Watanabe H (2001) Quantitative damage estimation of concrete by AE. 

Tests of a different nature and purpose are used to examine manufactured components and assemblies for internal flaws and faults and surface cracks and defects without destroying the component. These tests are known as nondestructive tests (NDT), since the component is not physically damaged as a result of the test and therefore remains fit for purpose. These tests are carried out to check possible defects produced during machining, welding, casting and heat treatment and are also carried out on in-service component s, e.g. jet engine turbine blades and aircraft components. 

Nondestructive testing/examination (NDT/NDE) Evaluation of an equipment item with the intention of measuring an equipment parameter without damaging or... 

The use of probability-density-function analysis, an important topic in statistical analysis, is mentioned with respect to its utility in nondestructive testing for inspectability, damage analysis, and F-map generation. In addition to the mathematical concepts, several sample problems in composite material and adhesive bond inspection are discussed. A feature map (or F map) is introduced as a new procedure that gives us a new way to examine composite materials and bonded structures. Results of several feasibility studies on aluminum-to-alumi-num bond inspection, along with results of color graphics display samples will be presented. 

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