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At present, hot stamping represents an innovative manufacturing process for forming of high strength steels, implying a sheet at austenite temperature being rapidly cooled down and formed into a die at the same time (quenching). This forming process is used for the manufacturing of automobile structural components with a strength of up to 1,500 MPa, thus enabling extensive cost savings and good crash performance. Better formability at elevated temperatures and lower springback are further advantages of parts formed by hot stamping. The Finite Element Analysis is an essential precondition for a good process design including all process parameters. This paper presents the finite element simulation of a hot stamping process by means of experimentally calculated material data and describes a number of procedures for the simulation of hot stamping, aiming at a notable decrease in computation time. For a faster calculation thermal and mechanical phenomena are decoupled in two simulation programs.

This paper presents details on the load bearing capacity of pipelines subjected to combined loading (internal pressure, axial and bending load) based on the findings of a recent research project of the European Pipeline Research Group (EPRG). Firstly, the failure mechanisms of line pipe under combined loading, which depend on local geometry, material characteristics as well as local and global applied loading, are characterized. Afterwards, differences between laboratory testing and the real-life situation of pipelines subjected to combined loading are described. Here, optimal boundary conditions for realistic testing are defined. Finally, a large variety of modelling approaches, specifically dedicated to combined loading experimental data from 59 full-scale tests on line pipe joints have been analysed. The relevant parameters in the analysis of buckling behavior of the pipes were: actual material properties, boundary conditions, failure phenomena and strain at failure, with the final aim to issue recommendations with regard to the selection of modelling approaches, sensitivity towards input parameters as well as strain threshold values. For the prediction of the limit pipe deformation a large selection of equations suggested by various authors in terms of critical bending moment, critical strain and critical stress for various loading conditions were considered. The methods differ in solution methodology (analytical vs. numerical), in the definition of material behavior (elastic, elastic-plastic) and in the definition of critical conditions and critical points. Then, the different types of buckling as a function of pipe geometry were characterized. Finally, the buckling behavior of an actual bending test was simulated using measured input data.

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