Determination of internal stresses

Internal stresses are inseparable from materials. They are produced by lattice defects on the atomic scale, by interfaces on the naometer or micrometer scale or by manufacturing processes on macroscopic scales up to almost any length scales. They can be homogeneous on different scales from a meter down to atomic distances or heterogeneous over any distances. One of the best classification was done by the pioneering work of Macherauch. It was based on the physical properties and the measuring methods of internal stresses. The first to classes scale from macroscopic down to about a few tens of micrometers and are related to the continuum properties of materials. Third order stresses scale down to atomic distances and are related to lattice defects, especially dislocations. The different methods of determination: diffraction methods, changing of the geometry of the specimen, Barkhausen noise or magnetic acoustic emission are specific and sensitive to different classes of internal stresses.