Miniature Specimen Tests - Problems, Comments and New Ideas

The main purpose for miniature specimen technique is to derive standard material properties with limited amount of materials, including strength/toughness, creep and fatigue behavior. In order to achieve the objective, many methods have been put forward in last three decades, however, for both strength/toughness and creep region, no common acceptable methods are available yet. This paper reviews existing methods, points out problems, gives comments, and put forward new ideas. Discussions start with determination of strengths/toughness, including Tsp-FATT-KIC method, Mao¿s empirical method and Fould's analytic method. A new type specimen with O-type notch and a new approach, based on micro-mechanics, are proposed. Discussions and suggestions are given according to recent experimental and analytic results. Finally, other miniature test techniques, such as instrumented indentation test (IIT), impression creep test (ICT), ring-type creep test (RCT) and micro-tensile test, are also addressed. As no specimens are required, thus no sample machine and process are needed, the IIT technique maybe more attractive to be applied for residual life assessment on site.JRC.DDG.F.4-Safety of future nuclear reactor