TESTING OF MATERIALS
Material tests are used to determine the properties of a material. These fall into two main categories - destructive testing and non-destructive testing.
DESTRUCTIVE TESTING: (DT)
PDF Notes: J.J.Byrnes
Also called Mechanical Testing. This is when we damage something in order to measure it. For example: The ultimate tensile strength is measured by pulling a specimen until it breaks.
To be a little more accurate, we do not always destroy the part. Here are two examples:
Hardness testing is often carried out on a production item since the tiny indent goes unnoticed and does no harm to the part.
'Destructive' tests can also be carried out by flexing or stretching the part within limits (e.g. MSG - Machine Stress Graded timber, where the timber bends as it runs through rollers and the stiffness is measured - which is an indicator of bending strength, which translates to tensile strength). This applies to machine graded timber that gets sold.
- Hounsfield tester.
- Bending Test:
- Torsion Test:
- Impact Test: (Toughness) This measures the energy to break the material. The Charpy test breaks the specimen in the middle and the Izod test hits the end. Both have a groove machined into the specimen to initiate and control the fracture.
NON-DESTRUCTIVE TESTING: (NDT)
PDF Notes: J.J.Byrnes
These methods are used to find out about the material without wrecking it, bending it, flexing it or denting it. Most often it is used to search for voids, cracks or porosity inside the part.
It is useful in the casting processes, to ensure integrity inside the part. (e.g. checking for porosity in a casting)
It is also commonly used in the maintenance industry to check for deterioration of the components and assemblies (e.g. aircraft - checking crack propagation, delamination of composites, corrosion etc)
- Dye penetrant
- Magnetic Particle
- Radiography - X rays
VIDEO (From college library)
Non-Destructive Testing [videorecording] Scutt, Don.
Publication info: [Chadstone, Vic.] : Double D Technical Productions, c2002.
Physical descrip: 1 videodisc (29 min.) : sd., col. ; 4 3/4 in.
Mt Druitt College Library: DVD 620.1127/NOND
Dye penetrant, Magnetic Particle, Ultrasound, Eddy current, Radiography: X rays and Gamma rays,
Quality: High quality video with excellent footage of processes in all the above areas.
Recommended Viewing: All sections.
Dye penetrant, Magnetic Particle.
Assignment: Read pdf notes and do tester.