Destructive testing is a type of testing used in manufacturing that ultimately destroys the sample being tested. Used to determine the soundness, safety, and lifespan of products, destructive testing is often used to test welds, but is probably most well-known as a method to test car safety. Destructive testing comes in three forms: stress, or stability; impact, or safety; and hardness, or resistance, tests.
Designed to find weaknesses that are not immediately apparent, destructive testing is usually much more decisive than non-destructive testing. When dealing with mass-produced items, this form of testing is also less expensive than other methods because only a small handful of the product will be destroyed. When dealing with other products, however, this method can be expensive. Destructive tests may be conducted on a product at any time in its development, from beginning research to production-ready stages.
Since the point of breaking often happens very rapidly, tests are generally recorded by high quality cameras, which are designed to capture every detail of the test. Tests also use a variety of measurement devices that give the exact conditions at point of breakage. Temperature, pressure, and other types of sensory data are almost always recorded for later study along with the visual log of the destructive test.
Welds, particularly, go through many types of destructive testing when used on products. A weld is a bond that connects two pieces of metal by melting the metals together. It is used on a variety of different products, including vehicles and buildings, so the strength and soundness of particular types of welds are important.
Welds go through stress, impact, and hardness tests. Free-bend, nick break, etching, and fillet weld tests are all types of stress tests that test a weld's soundness and quality. Impact tests are designed to break the weld in a single blow at various angles. Welds also are subjected to tensile strength tests, which pull the weld at both ends until it breaks apart. Recording under what conditions the weld breaks gives researchers important information about what that type of weld can be used for and what conditions would make the weld unsafe.
Destructive testing is wise for anything that might be subjected to extreme conditions. Car manufactures use crash tests to see what actually happens to a car when in a collision. These tests allow the researchers to test safety procedures in a real-time way that would be impossible if they had to kept the car intact. Destructive testing is not only useful for man-made conditions, however. For example, The International Hurricane Research Center in Florida uses destructive testing on roofs of houses to attempt to mitigate the damage hurricanes cause to homes.