A Full-Field Calibration Approach on Material Parameter Identification

In the recent years, the usage of HS-steels has risen significantly in the automotive field. Their characteristics, such as hardness and favorable weight to strength ratio, can increase safety, fuel efficiency and overall product profitability. In this context, for the design with this material it has become crucial to be able to characterize precisely HS-steels and accurately predict their failure in many complex conditions, to fully exploit their capabilities. One of the most accredited ways to approach the prediction of failure for a wide range of materials is the generalized incremental stress-state dependent damage model GISSMO. The model is highly flexible and provides a framework inside LS-DYNA in which failure parameters can be tuned to reproduce experimental data. The definition of the optimal parameters is an inverse problem, therefore it was implemented using LS-OPT. In this work, the experimental evaluation of the MS1500 was carried out using the digital image correlation (DIC). With such technology, the displacements’ field of the test specimen is recorded.The evalueted field was processed as a family of stress-strain curves (hyper-curves) and became the objective of the optimization. This approach is named full field calibration and in this work was split in two phases. First, the stress-strain curve of the material was defined, then the tuning of the GISSMO parameters was performed. To evaluate the effectiveness of the full field approach a parallel study was implemented. The same routine of optimization run with a single stress-strain curve, which was measured with an extensometer. The comparison between the results obtained with the traditional approach and the results obtained with the full field approach highlighted the strenghts and the limitations of the two methods

in keeping with the spirit of the albertine statute constitutionalisation of the national unification

This chapter deals with the difficult process of constitutionalisation which characterised Italian Unification. Constitutionalisation is a long-term phenomenon which had the purpose of giving constitutional forms to the Nation. The promulgation of the Albertine Statute is more the start than the arrival of this phenomenon. The focus of this investigation is, therefore, to study the Constitution through its evolution paying particular attention to the process of legal integration within the structures of the Albertine Statute and to the amendment mechanisms of the constitutional text. The preamble of the Albertine Statute speaks of «perpetual and irrevocable fundamental law». The word «perpetual» meant the prohibition of revoking constitutional concession, while the word «irrevocable» was intended as a pact between the Sovereign and the Nation. Over the years, very few were the changes to the letter of the Albertine Statute. The interpretation and the practice represented the most important mechanisms of constitutional change (implicit constitutional changes). A primary role was acknowledged to non-written norms. In this perspective, it may well be said that the Italian Constitution consisted in something more than the written text and dwelt in the spirit and not in the letter of the Albertine Statute