What Is a Bending Stiffness Tester?
A bending stiffness tester is a device used to perform bending tests, in which a load is applied to a test specimen to measure its strength against bending force.
It consists of a jig to support the test piece, an indenter to apply load to the test piece, and a detector to measure the amount of deflection. In addition to bending tests, strength tests include tensile tests, which measure the strength of a material when it is pulled outward on both sides, and hardness tests, which measure the depth and area of an indentation by pressing a hard sphere against it.
Uses of Bending Stiffness Testers
Bending stiffness testers are used in a wide variety of industrial fields.
Some bend testers are small enough to fit on a tabletop and are used for electronic components such as semiconductor products and substrates, and medical devices such as dental implants and bone fracture treatment devices. On the other hand, there are also large bending stiffness testers for construction materials such as railroad rails, concrete, and reinforcing bars, etc., and various sizes of bending testers are used depending on the subject under test.
Principle of Bending Stiffness Testers
There are two types of bending tests: the 3-point bending test, in which a load is applied to the center of the test specimen by supporting both ends of the specimen, and the 4-point bending test, in which the same load is applied at equidistant positions from the fulcrums at both ends.
Bending stiffness testers are usually available for both 3-point and 4-point bending.
The 3-point bending test is not suitable for safety tests to determine the basic strength of a material because the load applied to the specimen is not uniform, but industrial tests to determine the ease of bending a material are performed with the 3-point bending test.
The four-point bend test applies a load at two points, but the force applied between the two indentors of the specimen is uniform. This makes it suitable for examining the basic flexural strength of materials.
In a bending stiffness test, the deflection (in mm) of a specimen is measured when a bending load (in newtons) is applied to the specimen. This curve plotting load versus deflection is converted into a bending stress (unit: MPa) and bending strain (unit: %) diagram by analysis software. From this stress-strain diagram, the maximum stress is determined, which is the bending strength of the specimen.