Mechanical joining. Destructive testing of joints. Specimen dimensions and test procedure for cross-tension testing of single joints

Acoustic emission testing (AT) is in Europe an already well established non-destructive testing (NDT) method. Qualification requirements as well as certification of testing personnel are laid down in European standard EN 473. A widespread application of AT deals with testing of unfired pressure vessels for re-qualification after a certain period of service (repetition test). The advantages of applying AT compared to the traditional procedure of hydrostatic test plus visual inside inspection are numerous. Just to name the most important: reduction of downtime, omitting of residual humidity and no risk of product contamination with water. It is a fact that AT provides much more useful information concerning the condition of the pressure vessel under test than a simple ‘passed’ or ‘not passed’ obtained usually by a hydrostatic test. This contribution gives two examples of practical experience, where severe corrosion defects have been detected by AT. The defects have been found in both cases on the vessel’s shell under the thermal insulation, where they have been hidden undetected for years. It can be assumed that even the vessel with the most severe damage (loss of more than 50% of the nominal wall thickness) would have passed the traditional repetition test procedure and that failure within the following service period would have occurred. In contrary to this scenario, AT enabled the vessel operator to perform appropriate repair in time.

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Prediction of bursting strength of the nylon parachute fabrics

International Journal of Clothing Science and Technology ◽

10.1108/ijcst-06-2020-0088 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Vijay Kirubakar Raj ◽

Renuka Devi

Keyword(s):

Test Procedure ◽

Field Evaluation ◽

Air Permeability ◽

Regression Equations ◽

Statistical Regression ◽

Destructive Testing ◽

Content Type ◽

Bursting Strength ◽

Textile Materials ◽

Practical Implications

PurposeParachutes are equipment that is repeatedly used as and when needed. Some of them are used for as many as 60 jumps. The property of the canopy fabric gets deteriorated with use. It is evaluated by destructive tensile and bursting strength. This study aims to focus on the nondestructive evaluation of the canopy fabric's fitness by testing air permeability and relating it with bursting strength. Predictor equations were developed to determine bursting strength from air permeability values.Design/methodology/approachANOVA techniques and statistical regression equations were formed.FindingsA series of samples containing five parachutes fabrics was used seven times, and their air permeability and bursting strength were determined to find the extent to the effect of reuse of parachute fabrics on their bursting strength and air permeability determination. It was found that there was a progressive drop in bursting strength and an increase in air permeability. An investigation of the extent of determination in terms of bursting strength and an increase in air permeability following the sense of five different types of parachute fabrics is reported.Research limitations/implicationsThe work focuses on the prediction of bursting strength to textile materials only and may not apply to other materials like membranes and sheets. The process of determining air permeability is relatively simpler and faster.Practical implicationsThe bursting strength can be predicted for used parachutes, which are otherwise subjected to destructive testing.Social implicationsThe men using the parachutes can be assured of the superior flawless performance of the parachute as equipment and also contribute to the saving of resources due to nondestructive testing, 100% evaluation of all parachutes is possible.Originality/valueThis article describes the nature of the test procedure and discusses the means of introducing it to users of parachutes. It is accepted that the method must undergo field evaluation and possible modification before it can become a routine tool of parachute using organizations.

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Investigation of Interaction of Laser Generated Lamb Waves With Structures of Interest

Volume 3: Design and Manufacturing ◽

10.1115/imece2011-62972 ◽

2011 ◽

Author(s):

Lei Yang ◽

I. Charles Ume

Keyword(s):

Lamb Waves ◽

Test Procedure ◽

Ultrasonic Inspection ◽

Wave Number ◽

Laser Generation ◽

Great Promise ◽

Non Destructive Testing ◽

Electromagnetic Acoustic Transducer ◽

Destructive Testing ◽

Non Destructive

Laser generation/EMAT (electromagnetic acoustic transducer) reception ultrasonic inspection technique shows a great promise in the field of Non-Destructive Testing of welds due to its non-contact nature. However, the broadband nature of laser generation and the dispersive characteristic of Lamb waves make the laser generated ultrasonic signals in thin structures extremely complicated. In order to ease the interpretation of received signals, it is desirable to investigate the interactions of different structural features with Lamb waves and find their related signatures in signal, which offers the potential to detect different types of weld defects using a single test procedure. This work proposed a technique based on 2-D Fourier Transformation to investigate the laser generated Lamb waves experimentally and to find the most sensitive predictors in EMAT received signals corresponding to a specific structural feature of interest. The amplitudes of different Lamb wave modes in the wave-number/frequency domain provide a wealth of information. The demonstration of the technique was carried out on aluminum plates with isolated rectangular notches of different depths. The procedure introduced here is general which can be employed in other applications of Non-Destructive Testing.

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