Non-Destructive Analysis: A Secret Peek Inside the Box

Non-Destructive Analysis (NDA) is a big term for figuring out what is inside of all the boxes beneath the Christmas tree on Christmas eve without anybody knowing that you did. Some simple methods include: shaking, thumping, bending and "feeling the weight" of the present or sample.

In the world(s) of Science, Engineering and Medicine, this can be done using some of the same techniques. There are the added tools of x-rays, ultrasound, microwaves, magnetic fields, radio waves and things yet-recognized. Each of these has its own specialties, for example:

x-rays CAT Scan Laminography Flat-Plane Diffraction
Ultrasound Echograms 3-D reconstructions    
Magnetic Densitometry Magnetic Resonance Imaging



Imagining Scanning Electron Microscopy (SEM) Transmission Electron Microscopy (TEM) Light Microscopy Fluorescence

These are active techniques; called so because they use a probe energy.

There are other techniques, which only listen to the specimen and are called passive. For example Infra-Red Imaging (temperature), as used by fire departments to locate "hot-spots"; where to put the water without hacking into any more walls.

Another aspect of NDA is Forensic Analysis. This is the "why things failed." We are used to hearing this term in relation to people; a forensic exam is done to determine the cause of death. In the non-medical community, we use these techniques to discover why a machine, device or system failed or died.

This is usually accomplished by first looking at the big-picture. What are the obvious things that caused a machine to fail: did someone drop a pipe wrench into the gears? (A Dutch shoe is called a sabot; the Dutch during a labor dispute threw their shoes into their machines to make them fail. Thus evolved the term: sabotage.) Or did a gear fracture and fall into the works? If the latter, the gear would be analyzed and discovered if it failed because the machine was not oiled or the gear was a product of shoddy work. Another example is of Fire Investigation; what caused the fire, where did it start, how could it have been prevented?