Technical Diagnostics and NDT

The development of a new imaging technique  by researchers from the University of Bristol’s Ultrasonics and Non-destructive Testing (NDT) research group promises to be able to detect damage previously invisible to acoustic imaging systems which could lead to aircraft off the future being thinner and lighter.  Acoustic nonlinearity is sensitive to many physical properties including material microstructure and mechanical damage. The lack of effective imaging has, however, held back the use of this important method.  Engineers are currently able to produce images of the interior of components using ultrasound, but can only detect large problems such as cracks.  Imaging of acoustic nonlinearity is achieved by exploiting differences in the propagation of fields produced by the parallel and sequential transmission of elements in ultrasonic arrays. Commenting on the project, study lead, Dr Jack Potter, research assistant in the Department of Mecha...

LUCIE, a noncontact, non-destructive, laser-ultrasound machine, will be tested on a composite fuselage section at Technocampus in France to determine its production feasibility. On Oct. 20, Technocampus (Pays de la Loir region, France), the R&D teams of Airbus Nantes, EADS Innovation Works (IW) and Ecole des Mines, took delivery of LUCIE, a noncontact, non-destructive, laser-ultrasound machine that will be used to detect sub-surface flaws in composite aerostructures.

Enhanced NDT Tube Inspection System is Fast, Easy, and Reliable AcousticEye, the leader in non-invasive tube inspection solutions for the heat exchanger market, has unveiled the Dolphin™ G3 tube inspection system. The G3 is based on the same breakthrough Acoustic Pulse Reflectometry (APR) technology used in the original Dolphin, which has been successfully utilized by customers worldwide since it was first introduced last year. The Dolphin G3 is ideally suited for testing heat exchanger systems across industries such as oil and gas, chemical, and power-generation markets. 

Eddy Current Crack Testing by Criterion NDT  EloScan Robotic Eddy Current Test System by Rohmann GmbH  

"The aerospace industry is leading the way in the application of non-destructive testing techniques" The simplest way to find out about a component’s structural or material properties is to quite literally push it to breaking point. But while destructive testing can be an effective and economical solution for high-volume, low-cost components, it’s clearly undesirable for larger, more expensive systems. If you want to test the limits of a multi-million-pound jet engine, destroying it is a pretty drastic way to advance your knowledge.   NDT is an essential tool in the aerospace industry  Fortunately, there is an alternative. And a range of so-called non-destructive testing (NDT) techniques - which can be used to probe structures and materials either before they enter use or as part of a maintenance programme - are now widely used across a range of engineering sectors.

"Through the adoption of new leak testing approaches that provide comprehensive data about the entire leak test cycle, manufacturers can get more out of their leak test" Leak testing is used in many industries, from engine assembly to medical device manufacturing. Source: Sciemetric Instruments  Leak testing is an important and widely deployed nondestructive test methodology used by many manufacturers to assess the quality of fabricated parts. The fact is that nothing is 100% sealed; everything leaks, whether it is supposed to or not. The challenge for manufacturers is to determine whether the leakage is acceptable from product quality and regulatory compliance perspectives. The majority of leak testing systems that are available today focus primarily on determining a single value that characterizes whether the leak rate is acceptable under internal standards and regulatory directives. While this traditional method may detect 80% of the typical defects, the other 20% wil...

"Automated fiber placement to replace established tape laying/drape forming process for the composite rear spars on the new midsize commercial passenger jet" Headquartered in Redditch, Worcestershire, U.K., GKN Plc’s Aerospace Division continues its strong growth, based to a large extent on its expertise in the production of composite structures. Even the 50 percent of the business that is not focused on composites is based primarily on materials technologies, such as complex titanium aero-engine components and cockpit canopies with vacuum-deposited surfaces to enhance stealth performance. This should not come as a surprise, because GKN’s first use of materials technology to gain market share was in the 1860s, when it dominated the railroad supply business by being the first company in the U.K. to make steel by the cost-effective Bessemer process. The company produced more than 56 million lb (25,400 metric tonnes) of steel per year by 1871. Fig. 1: The inner rear spar demo...

"ITT Corp. reported on Nov. 19 that it delivered its first major composite structural sponson subassemblies for the CH-53K heavy-lift helicopter to Sikorsky Aircraft Corp.; Spirit AeroSystems has completed a mold/cure cycle for one the panels that make up the longest section of the Airbus A350 XWB’s all-carbon fiber fuselage" ITT Corp. (Salt Lake City, Utah) reported on Nov. 19 that it delivered its first major composite structural sponson subassemblies for the CH-53K heavy-lift helicopter to Sikorsky Aircraft Corp. (a subsidiary of United Technologies Corp., Stratford, Conn.). The delivery is the culmination of nearly three years of advanced design, development, testing and manufacturing activities, according to ITT. The CH-53K is the latest iteration of Sikorsky’s legacy helicopters, used by the U.S. Marine Corps since 1963. The K model, also known as Super Stallion, will offer significantly greater payload capacity than its predecessor and is currently the largest mariti...

Eddy current theory is based on electromagnetic induction. That means, a variable magnetic field can induce an electric current on a conductor which is separate to the source of the magnetic field, and also vice versa, which is an electric current generates a magnetic field. Similar theory is used for the magnetic particles inspection as well. Electromagnetic induction is used in many applications such as, Transformers, Electric motors, Generators, etc...   In the field of Non destructive testing (NDT), we manipulate with this theory which I mentioned above, and try to find surface defects or/and shallow internal defects of ferromagnetic materials.

Short research about the history of eddy current The first person to observe current eddies was François Arago (1786-1853), the 25 th president of France, Who was also a mathematician, physicist and astronomer.1824 He discovered what has been called rotatory magnetism, and the fact that most bodies could be magnetized; these discoveries were completed and explained by Michael Faraday (1791-1867). In 1834, Heinrich Lenz stated the principle that defines how the properties of the test objects are communicated back to the test system. Lenz's law states that the direction of current flow in the test object will be such that its magnetic field will oppose the magnetic field that caused the current flow in the test object. This means, in practice, the eddy currents communicate with the test coil by developing secondary flux that cancels a portion of the coil's flux equivalent to the magnitude and phase of the flux developed by the eddy currents.   Léon Foucault (1819-1868) However,...

Global leader in digital imaging to exhibit new offerings for NDT at ASNT conference, booth 725, in Houston   WALTHAM, Mass., Nov 15, 2010 (BUSINESS WIRE) -- PerkinElmer, Inc., a global leader focused on the health and safety of people and the environment, today announced it will launch two new Digital X-Ray Flat Panel Detectors (FPDs) for Non Destructive Testing (NDT) applications at the ASNT Fall Conference and Quality Testing Show in Houston, Texas, from November 15-17 at booth 725.

Computed Tomography (CT) has come a long way since its public inception in 1972. The rapid improvement of CT and the increasing capabilities of CT scans have definitely gone hand in hand. CT scans that used to take hours, now take seconds. This increase in capabilities has led to the use of CT scans more often and in more ways than ever before. The use of CT in the industrial nondestructive testing (NDT) field is one segment that has grown tremendously in the past few years. Industrial CT uses a series of 2D images taken at specific intervals around the entire sample. Any type of industrial CT system uses three principal components: an X-ray tube, an X-ray detector, and a rotational stage. Everything is enclosed in a radiation,

Olympus, a world leader in nondestructive testing technologies and pioneer in industrial phased array ultrasound, is pleased to introduce a comprehensive inspection solution for circumferential welds in pipes with a diameter as small as 21.3 mm OD. A key component of the solution is the COBRA, a new manual scanner specifically designed to

From my article "Technical diagnostics for a safer journey" for the journal Spectrum One of the most important properties of a transport system is safety. It’s said that the human factor is the main reason for many transport accidents, from aircraft to bicycle. That means there is more chance of an accident occurring because of a simple mistake of the operator (driver or a pilot), or because of the engineer who maintains or repairs the vehicle, or the other people who involved such as the air traffic controller or the policeman on roads. This article is focused on the engineering side, more precisely about identifying problems in mechanical part or a structure. What do engineers do to minimise the probability of having a failure?

WHEN they were built, no one thought they would fly for so long. But fitted with new engines and avionics, aircraft can be kept going for a very long time. The average age of the world’s airliners is more than ten years, with some passenger jets 25 years old or more. Military planes are more geriatric: the Sikorsky Black Hawk helicopter entered service 31 years ago and the Lockheed C-5 Galaxy 40 years back. Both are still going strong. Some Boeing KC-135 aerial-refuelling planes, which are based on the venerable 707, have been flying for over 50 years. Engineers reckon they could still be in the air when they are 80.  Figure 1: C-5 Galexy One thing that does ground old aircraft is the impending failure of their aluminium structure from metal fatigue. This begins in parts that are subjected to repeated strains, such as where the wings join the fuselage. Constant flexing of the structure concentrates stress, which leads to microscopic cracks. These cracks become more numerous and eve...

There are several steps in a magnetic particle inspection. Clean the surface of the ferromagnetic material Magnetize the material Spray or pour the magnetic particles   Visual inspection   Demagnetization   Cleaning Demagnetization is done to disorganize the micro atomic arrangement which produce a magnetic field. After demagnetization the material will act as a normal metal. The magnetized components can cause problems such as,

One of the most important things an inspector should do while MPI is to check for defects at least twice in separate 90 degree angles. Let’s understand this by using a small example.  I have a piece of steel, where there suppose to be a defect. Let’s assume that there is a surface crack, which is quite straight and continues parallel to one of the edges. Then we apply a magnetic field as in the picture below. We clearly see that, no change happens to the magnetic flux.   Accordingly there is no change happens to the magnetic particles we are adding. Therefore the crack will be invisible via magnetic particles method.

First, lets check out how this magnetic particles inspection carries out :). It's always easy to understand something practical by watching a youtube video. Theory can be found in the last article . Another video with a more advanced MPI This one is in Spanish, though the MPI shown very well, and the crack is well visible. MPI usually find cracks which are perpendicular to the direction of the flux, so It's necessary to search for defects twice. I'll explain more about that in a future article, but first it's important to see and understand the basic chemistry of this method.

Magnetic particle test is one of the common NDT methods. As you can see, this has to do something with magnets. For a starter, it is better to remember little bit about magnets before understanding this method. Magnet is a material produces a magnetic field. They have two poles which are known as North, and South.   Opposite poles (N+S) attracts but same poles such as N+N or S+S repels. Figure: A magnetic field, created by iron dust Magnetic field is invisible. Any ferromagnetic material or another magnet responds to a magnetic field. Ferromagnetic materials are materials which magnetized either by another magnet or an electric field.

Sometimes, smallest of the defects can be hardly visible for human eyes. That is when engineers use the Liquid Penetrant (PT) or Dye Penetrant test. Liquid Penetrant Examination is a Non-Destructive Testing method used to detect surface breaking defects, such as cracks, laps, porosity etc., which are unperceivable with the bare eye. The method is rest upon the ability of a fluid to be drawn into a "clean" surface-breaking flaw by smooth action. After a certain time period, unnecessary surface penetrant is displaced and a developer is applied that functions as a "blotter". Color contrast penetrants demand adequate white light whereas fluorescent penetrants are suggested to be used in dark environment and require ultraviolet "black light" where penetrant glows with a luminous color which can be easily seen from our eyes.