DESTRUCTIVE TESTING
In destructive testing (or destructive physical analysis, DPA) tests are carried out to the specimen's failure, in order to understand a specimen's performance or material behavior under different loads.
These tests are generally much easier to carry out, yield more information.
Destructive testing is most suitable, and economic, for objects which will be mass-produced, as the cost of destroying a small number of specimens is negligible.
BREAK LOAD TEST
•DC Machines can be tested by three different methods namely Direct Method, Indirect Method and Regenerative Method.
•Direct Method of testing of DC Machine, also known as Brake Test (if carried out for a DC Motor) Direct method is suitable for small DC machines.
•In-Direct Method, the DC machine is subjected to rated load and the entire output power is wasted.
TENSILE STRESS LOAD TESTING
•Tensile strength, also known as Ultimate Tensile Strength (UTS), is the maximum tensile stress carried by the specimen.
•It is defined as the maximum load divided by the original cross-sectional area of the test sample.
NON-DESTRUCTIVE TESTING (NDT)
•Non-destructive testing (NDT) as the name implies, does not damage or reduce the service life of the component.
•Usually, these tests do not directly measures the mechanical properties such as tensile strength or hardness, but they are used to locate the defects or flows in the component, which may reduce the useful life of component, resulting in the premature failure even with good design and proper material selection.
•Various techniques are available for finding the internal soundness of components without sectioning or other destructive tests.
•Although NDT tests do not provide direct measurement of mechanical properties, yet they are extremely useful in revealing defects in components that could impair their performance when put in service.
•NDT make components more reliable, safe and economical.
SOME OF THE IMPORTANT NON-DESTRUCTIVE TESTING METHODS
•Radiographic testing,
•Ultrasonic testing,
•Liquid penetrant or dye penetrant testing,
•Magnetic particle testing,
•Eddy current testing,
•Visual testing.
