讲座题目：Determination of ductile and brittle damage parameters by means of the small punch test 

报告人：Professor Meinhard Kuna 

时 间：9月1日（周四）下午3:00-4:30
地 点：力学楼434会议室
主持人：方岱宁（教授）

报告内容摘要：
     In recent years the small punch test method (SPT) has become an attractive miniaturized material testing procedures, especially in cases where only small amounts of material are available. In contrast to standard test methods, the relevant material parameters cannot be as simply obtained from the experimental measurements of SPT because of its non-uniform stress and deformation state. However this can be achieved by comparing the experimental SPT results with those obtained by finite element computations of SPT using advanced material models. Then the task is to determine the parameters of the material models using special optimization techniques.
      The presentation will give an overview about the experimental and theoretical work done at the IMFD Freiberg in the last years to characterize ductile, brittle and nil-ductile fracture behaviour of metals. In order to describe the failure behaviour, the Gurson-Tvergaard-Needleman model is used for ductile damage and the Beremin-Weibull-model for brittle damage. All material parameters relevant for elastic-plastic deformation, ductile and brittle damage behaviour could be determined from SPT experiments. The SPT testing techniques are extended to low temperatures and highly irradiated materials. The obtained results are verified by data from standard test specimens. Moreover, the fracture toughness of the materials will be predicted only from SPT parameters using virtual simulation of fracture testing experiments.