A bending test, also known as a bend test, is used to determine the strength of a material by applying force to the item in question and seeing how it reacts under pressure. Typically the bend test measures ductility, the ability of a material to change form under pressure and keep that form permanently. In certain cases the bending test can determine tensile strength. When using the bend test for this purpose, testers examine which side of the material breaks first to see what type of strength the material has. It also lets them know what kinds of pressure it holds up against and what kinds it doesn't.
Ductility describes how well a material, usually metal, can be stretched and keep its new shape. Steel, for example, is highly ductile. If pressure is applied that stretches the steel into a new shape, it will keep this shape even after the pressure has been removed. This characteristic is referred to as ductility and is a desirable characteristic for metals and other building materials.
To determine how ductile a material is, a bending test is used. Force is applied to a piece of the material at a specific angle and for a specific amount of time. The material is then bent to a certain diameter using force. After the bending test is over, the material is examined to see how well it held its shape once the pressure was removed, and whether or not the material cracked when pressure was applied.
This test can also determine tensile strength. The test may be used when more brittle materials need to be tested. These brittle materials may not hold up well under a normal test for tensile strength, therefore a bending test is used. It is applied the same way as normal, by bending the material while applying force, and then the results are examined. If the material shows cracks on the bent side, this shows the material holds up better against compression than tension.
Welding is an area where the bend test is popular. A guided bend test is used to determine how strong a weld is after it has been created. A special machine is used to perform the guided bend test. The material must be able to bend up to a specific angle, such as 180 degrees for example, without any cracks appearing. If this happens, the weld has passed the test.