Identification and validation of ductile damage parameters by the small punch test

The small punch test (SPT) is a suitable miniaturized test method to determine the actual and local material state in structural components under operating conditions. A combined experimental-numerical approach is presented to identify material parameters of plastic deformation and ductile damage behaviour from the SPT. Neural networks (NN) are generated and trained by finite element simulations to obtain the relation between a load displacement curve of the SPT and the matching material parameters. These parameters, identified from the SPT, are validated by reference values determined from smooth and notched tensile specimens. Next, the same parameters are used to simulate the ductile crack growth in fracture specimens by means of finite elements. This way, even fracture thoughness data J_Ic of the materials could be successfully predicted. These findings substantiate the feasibility to gain comprehensive material characteristics from the SPT and their transferibility to quantify the ductile failure of strucural components.