Options
2016
Book Article
Titel
Hybrid methods for materials characterization
Abstract
In nondestructive testing (NDT) a hybrid method is understood as an approach which combines two or more NDT methods. Due to the variety of NDT techniques, many combinations are possible. In the nondestructive evaluation area of fault detection, for example, several combinations of NDT methods (hybrid methods) are in use. Several combined methods are possible in order to achieve optimized materials characterization. This section will give insight into combinations of micromagnetic, eddy current, and ultrasonic methods. Combinations are presented where hybrid sensors can be used. Several NDT can therefore be applied with the help of such hybrid sensors. Due to the combination of several NDT methods, multiple measuring quantities are always used in materials characterization applications. Therefore, many hybrid methods use computational algorithms, eg, regression analyses or pattern recognition algorithms, for a connection between measuring quantities with different physical information content and reference values of the tested materials. These are relevant quality features like residual stresses, hardness, hardening depth, yield strength, etc. This section shows the potential of hybrid approaches on several industrial applications and documents the benefits for the industrial user, which are mainly in the context of safety, quality, and lifetime. This section also documents some signal processing aspects for the use of eddy current techniques and micromagnetic hybrid methods and gives insight into possible calibration procedures. A hybrid method uses the combination between micromagnetic and ultrasonic methods and has potential for texture determination in steel sheets. A known micromagnetic hybrid method is the micromechanic, multiparameter, microstructure and stress analysis, or 3MA approach. This approach combines different micro- and electromagnetic measuring quantities and uses regression analyses or pattern recognition algorithms for the quantitative determination of material properties for ferromagnetic materials. An advantage of some hybrid approaches is that different material features such as residual stresses, hardness, and hardening depth are predicted simultaneously.