Destructive Testing Methods

It can often be practical to supplement the methods described above with destructive testing. This can afford valuable leads under laboratory conditions in particular, so that the causes of failure in the field can be analyzed in detail. In series production too, these processes are used with random sampling as a way of monitoring 

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Munns, G.A. Georgiou, Non-destructive testing methods for adhesively bonded joint nspection - a review, INSIGHT, Vol 37, No 12, Dec 1995, pp 941-952... 

Due to the outer circumference of the silo, about 25 meters, a non- or rarely destructive testing method was needed for the localization. Because the building was still in use, it was only accessable from the exterior side. We chose the ultrasonic pulse-echo-technique as an appropriate way of doing the testing. 

The use of tracers enables efficient and reliable measurements of oil, gas and water flow in industrial process units and pipe line systems under production conditions thus fundamentally being non-destructive testing methods. Typical problems which can be efficiently assessed by tracer studies include ... 

Non-Destructive Test Method for Defects in Propellant Rocket Motors (Ref 11)... 

The impact of thermal shock on the properties of a ceramic or a CMC is assessed by means of both destructive and non-destructive testing methods. Flexural or tensile (mainly for CMCs) tests of suitably-sized thermally shocked specimens are usually employed to measure retained mechanical properties as a function of the temperature difference. The temperature differential for which a significant drop in property values is observed is the A A- For monolithic ceramics and particle- or whisker-reinforced CMCs the property under investigation is usually strength, whereas in fibre-reinforced CMCs a drop in Young s modulus is usually a better indication of the onset of damage. 

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. 

Quality control of BDD electrodes is essential and is performed both by nondestructive and destructive testing methods. Nondestructive methods are either routine methods performed on each electrode (Raman spectroscopy to evaluate sp3/sp2... 

One recourse is to use low-destructive test methods that can quantify the efficacy of protective agents [27] and provide evidence of improper use or application of the silicone [4, 15, 27, 28, 32, 36, 37], High-resolution microscopy would offer the advantage of visualizing the reasons for failure of hydrophobic treatments just after application, before they became visible very much later when the weathered materials started to fail [38, 39]. Weak areas such as inadequate uptake of the treatment, poor penetration depth, and incompleteness of coating could be documented just after the masonry treatment had been applied. 

The most important methods, however, are the destructive test methods by means of special test pieces which allow for the determination of the strength of bonded joints. 

After a further 48 hr the third and last stiffener is welded in the same manner as the second but using a preheat of 100 °C. After a further 48 hr the welds are examined, firstly by non-destructive testing methods and then by selective sectioning to establish whether cracking has occurred. This examination provides the fabricator with evidence to justify his use of either no preheat at all or a level below the recommended temperature of 60 °C. The evidence might, of course, justify the original prediction of 60 °C minimum. 

Munns. 1. J.. and Georgiou. G. A. (1995). Non-destructive testing methods for adhesively bonded joint in.spection--A review. Insight. Dec. 1995. 12. 941 9.S2. 

The chosen method depends on the geometry and properties of the article. Table 2.2 lists many of the available non-destructive test methods for composites for initial quality control and for assessing damage and repair [8]. The following discussion highlights just a few of the more important techniques. 

Different from other non-destructive testing methods AE analysis does not deal with a steady state but with a procedure that basically changes the condition of the structure. Therefore AE signals are unique they cannot be reproduced and recordings cannot be repeated. 

Like for all non-destructive testing methods there is a need to depict results in graphic form. Images have a large potential to discover both repetitions and abnormalities that would not be recogiuzed in a pure numerical analysis. Imaging techniques need according special skills. 

Ceramographic methods have proven indispensable in the characterization of thermally sprayed coatings, in which non-destructive testing methods for purposes of quality assurance have only limited applicability. Characteristic properties of a coating, such as its thickness, structure, porosity, and adhesion to the base material, as well as the hardness of individual phases or the overall composite, can be accurately evaluated by applying these ceramographic methods to the polished section. 

Non-destructive evaluation of reinforced concrete structures Volume 2 Non-destructive testing methods... 

Particular attention needs to be paid to establishing an effective system of quality assurance for adhesive connections. Non-destructive test methods based on ultrasound, X-rays or the measurement of electrical or thermal conductivity are available but only of limited value in practice. Specific data on adhesion cannot always be obtained by these methods. This section examines the issue of quality assurance from a practical point of view. Many years of experience have shown that only a quality assurance system that takes into account the specific features of adhesive bonding technology can produce consistently satisfactory results over an extended production period. The information outlined here should be viewed as a general checklist to be adapted to the specific requirements of each manufacturing environment. 

More important, however, is the performance of the adhesive in an actual joint. Standard test specimens are bonded under standard conditions and subjected to destructive tests. The load values of these tests give information on the adhesive strength between two bonded substrates. Standard destructive test methods are ... 

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