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Two different methods to obtain crack propagation curves are considered in this work. In an analytical approach, the adhesion between the plates is considered perfect. In…
Two different methods to obtain crack propagation curves are considered in this work. In an analytical approach, the adhesion between the plates is considered perfect. In such case, the interface stiffness is not taken into account and the classic beam theory is used to study the behavior of the plates during the delamination. The second approach is numerical and the bonded interface is now considered elastic. The paper aims to discuss these issues.
The propagation curves are obtained with the aid of the finite element code CAST3M by taking the structural response for a given value of initial crack length at a time.
A good fit is achieved when analytical and numerical curves are compared. Finally, mechanical tests results are presented to validate the numerical method and to identify the critical energy release rate (Gc ).
More than an easier method to obtain propagation curves, the numerical method presented in this paper is an important tool to selection of optimized test geometries.
This paper focuses on the design of a superconducting quadrupole prototype. This structure includes many frictional contact zones, and the loading conditions are complex…
This paper focuses on the design of a superconducting quadrupole prototype. This structure includes many frictional contact zones, and the loading conditions are complex (mechanical, thermal and magnetic). A dedicated computational strategy, based on both a decomposition of the structure and an iterative resolution scheme, has been applied to solve this problem. A simplified approach is used to take complex loading conditions into account. The initial set of results, which are presented herein, demonstrates the interest of this approach with respect to classical finite element methods. This study was conducted within the framework of a joint research contract between the CEA (DSM/DPANIA/STCM) and LMT‐Cachan.
Large structures (e.g. plane, bridge, etc.) often include several hundreds of assembly points. Structural computations often use over-simplistic approximations for these…
Large structures (e.g. plane, bridge, etc.) often include several hundreds of assembly points. Structural computations often use over-simplistic approximations for these points; among others, they do not take into account the thermo-mechanical history due to the assembling process. Running computations with each assembly point modelled completely would require too much time to achieve a simulation. There is thus a need to create equivalent elements for assembly points in order to: take into account the mechanical state of the assembly point in the design stage – while reducing the computational time cost at the same time. This paper aims to discuss these issues.
This paper introduces an innovative strategy based on a coupling procedure between a finite element tool for modelling the assembly process in order to access to the mechanical state of the assembly point and an optimisation algorithm, in order to identify the equivalent element parameters.
The strategy has proven to be successful. A connector model easier to use and much faster than the complete model, has been obtained. Results obtained with this element are in good agreement with experimental tests in the case of multipoint assemblies and with the simulation results of the complete numerical model. Finally the connector model appears to be easier to use and much faster than the complete model, more difficult to model properly.
The main innovative aspects of this strategy lie in the fact that the creation of this equivalent element is based on a complete numerical approach. The thermo-mechanical history due to the assembly process is considered – the element parameters are identified thanks to an evolution strategy based on the coupling between a finite element model and a zero-order minimisation algorithm.