Delphine Brancherie

Novel anisotropic continuum‐discrete damage model capable of representing localized failure of massive structures: Part II: identification from tests under heterogeneous stress field

Purpose n n n n– The purpose of this paper is to discuss the identification of the model parameters for constitutive model capable of representing the failure of massive structures, from two kinds of experiments: a uniaxial tensile test and a three‐point bending test. n n n n nDesign/methodology/approach n n n n– A detailed development of the ingredients for constitutive model for failure of massive structures are presented in Part I of this paper. The salient feature of the model is in its ability to correctly represent two different failure mechanisms for massive structures, the diffuse damage in so‐called fracture process zone with microcracks and localized damage in a macrocrack. The identification of such model parameters is best performed from the tests under heterogeneous stress field. Two kinds of tests are used: the simple tension test and the three‐point bending test. The former allows us illustrate the non‐homogeneity of the strain field at failure even under homogeneous stress, whereas the latter provides a very good illustration for the proposed inverse optimization problem for which the specimen is subjected to a heterogeneous stress field. n n n n nFindings n n n n– Several numerical examples are presented in order to illustrate a very satisfying performance of the proposed methodology for identifying the corresponding material parameters of the constitutive model for failure of massive structures. n n n n nOriginality/value n n n n– The paper confirms that one can make a very good use of the proposed identification procedure for estimating the corresponding parameters of damage model for localized failure of massive structure, and the advantages to using the experimental results obtained by testing under heterogeneous stress field.

NONLINEAR TRANSIENT ANALYSIS AND DESIGN OF COMPLEX ENGINEERING STRUCTURES FOR WORST CASE ACCIDENTS : EXPERIENCE FROM INDUSTRIAL AND MILITARY APPLICATIONS

In this work we address some of the present threats posed to engineering structures in placing them under extreme loading conditions. The common ground for the problems studied herein from the viewpoint of structural integrity is their transient nature characterized by different time scales and the need to evaluate the consequence for a high level of uncertainty in quantifying the cause. The pertinent issues are studied in detail for three different model problems: i) the worstcase scenario of system functioning failure accident in a nuclear power plant causing the loss of cooling liquid, ii) the terrorist attacks brought explosion and impact of large aeroplane on a massive structure, iii) devastating fire and sustained high temperatures effects on massive cellular structures. By using these case studies, we discuss the issues related to multi-scale modelling of inelastic damage mechanisms for massive structures, as well as the issues pertaining to the time integration schemes in presence of different scales in time variation of different sub-problems brought by a particular nature of loading (both for a very short and a very long loading duration) and finally the issues related to model reduction seeking to provide an efficient and yet sufficiently reliable basis for parametric studies employed within the framework of a design procedure. Several numerical simulations are presented in order to further illustrate the approaches proposed herein. Concluding remarks are stated regarding the current and future research in this domain.