Nondestructive testing
Materials testing is comprised of various test methods, with which the behavioral and material characteristics of normalized samples of material ( material analysis ) or finished components ( component testing ) are determined using mechanical, thermal or chemical stresses.
A material is thereby checked for its purity, accuracy or resilience. After the way the current testing methods are divided into two main areas: destructive and nondestructive testing of materials. The on the estimation of life -related products and materials tests fall into the field of environmental simulation.
History
The test gun shown in the picture shows a very early and pragmatic form of material testing. The material has been tested on the finished product. The test tube was placed over a gun lying on a pile ball. The tube had survived the firing of the powder charge, it could still be used. In this test had a mass to be accelerated, which is substantially greater than the later to be accelerated ball.
Destructive material testing
When destructive materials testing selected materials to chemical and physical properties are examined and this destroys or ( superficial ) changes; the component to be tested can then no longer be used. The main methods of this type of examination are:
- Mechanical: Weld modern biaxial servo- hydraulic testing machine
- Bending test and bend test sheets
- Blue rupture test for the evaluation of steels to macroscopic, non-metallic inclusions
- Bulgeversuch
- Fatigue test after Wöhler
- Compression test
- Charpy impact test Charpy, Izod and tensile impact
- Shear test
- Erichsen cupping test
- Torsion
- Creep test
- Tensile testing for the tensile strength, in particular the limit of elasticity
- Chemically and thermally: Brennprobe
- Differential thermal analysis
- Gas chromatography
- Crystallography / Metallography
- End-quench
Due to non-destructive testing of materials
Thus, a component can be non-destructively tested, it must have a certain minimum size and space provided surfaces. If the interior of a component to be tested, the test area must first be milled, which may be associated with destruction of the component.
- Mechanical: Drilling Resistance
- Hardness test, for example, Vickers, Brinell, Rockwell, Shore, Knoop
Non-destructive testing of materials
Non-destructive material testing, NDT short ( EN 1330, engl. Non-destructive testing / non-destructive inspection, NDT short or NDI), the quality of a workpiece is tested without damaging the material itself. To this end, various physical effects are used, which one divides into two groups: Flaw detection and Qualimetrie. The dynamic tests are based on the reflection of the elastic or electromagnetic waves at an interface, which are defined by the acoustic impedance and the dielectric contrast.
One of the first nondestructive tests were probably the determination of the density by the displacement method according to Archimedes and the visual inspection, ie viewing a component for visible defects. But most often be understood including tests on component failure.
The non-destructive testing can be sorted according to various criteria. The following table gives an overview of the most common procedures in engineering, aviation and aerospace engineering and construction. There are the common abbreviations, or abbreviations according to ISO 9712 and EN 4179 specified. The dynamics indicates the nature of the measurement, where " static" usually measuring a static electric or magnetic field means, "dynamic" measurements of wave amplitude. In principle, the physical measurement principle is to understand (mechanical, electrical, magnetic, thermal, optical, chemical ). The space of interaction with the object of investigation and the general normative basis are given in the corresponding columns.
Other known methods can be classified as subgroups of the above methods.
Testing organizations
Material tests are carried out by different institutions. These include in Germany at the federal level, the Federal Institute for Materials Research and Testing, and at the country level, the individual material testing. In addition, offer different testing organizations and scientific institutions, such as the Fraunhofer Institute for Nondestructive Testing, material testing as a service.