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In this work, the properties of microcellular ABS were studied. Foamed samples exhibited a solid skin/foamed core structure, with some elongated cells in the flow direction, while spherical cells were mostly observed in the transversal direction. The flexural modulus, flexural strength, and fracture toughness K Ic decreased with the density. However, the crack tip opening displacement (CTOD) was found to increase with the foaming ratio. The evolution of the mechanical properties and fracture toughness was well described by prediction models considering the skin/core morphology of these microcellular materials. Foaming increased the anisotropic behavior of the material, due to the cell elongation caused by the fountain flow during injection. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43010.

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This report deals with the testing problems of thin sheet steels subjected to cyclic load and introduces at the same time the appropriate techniques to procure the reliable and significant testing results. Practically, a proper judgement of cyclic fatigue behaviours of such conventional deep drawing steels is only possible, if the specimens were to be tested either under strain control mode in elastic‐plastic range with sufficient plastic deformations or load controlled in elastic range by using the notched specimens with adequate local strain concentration. Besides the study of specific material properties, as absolutely determined by using the unnotched specimens, the influence of notch geometry can also be investigated by means of the notched specimens. For a promising performance of elastic‐plastic cyclic tests on thin sheets the use of a particular specimen shape with uncritical length of high buckling resistance is most essential. Moreover, a special grip with great precision is necessary to ensure an axial and rigid alignment of specimens. In the course of a development an optimal specimen shape and its gripping device has been designed. The cyclic properties of some thin sheet steels, obtained in this way, are also illustrated.

In this report a non‐contact gauging system based on eddy current technology is presented which permits unproblematic detection and tracking of cracks initiated by cyclic loading in sheet steel specimens. In comparison with other measuring methods the automatic pilot unit developed displays distinct advantages thanks to its highly accurate measuring results. This measuring unit is suitable for the examination of thin sheet steels (< 2 mm) and has been successfully used for studying ductile materials. Some results of such investigations are therefore illustrated.