A new thermomechanical fracture analysis approach for 3D integration technology
In this study, the peridynamic framework is applied to model heat diffusion to derive peridynamic heat diffusion equations. A numerical scheme is put forward and implemented in order to establish the validity of these equations. Finally, an approach is developed for coupled solution of heat conduction and solid mechanics equations in the realm of peridynamics.
A Peridynamics-FEM Approach for Crack Path Prediction in Fiber-Reinforced Composites
Peridynamics (PD) theory provides a means to investigate crack propagation behavior in solids, without the need for re-meshing the domain or other special treatments necessitated by conventional FEM approaches. As such, it has been increasing applied for modeling failure in different applications. In this work, we investigate crack propagation behavior in fiberreinforced composite (FRC) structures using a Peridynamics approach that builds on finite element method (FEM) solution kernels. The PD bonds representative of the composite are modeled as truss elements which takes into account the corresponding fiber/matrix micromechanics in definition of its constitutive behavior. The PD-FEM framework is implemented using a commercial FEA package ABAQUS, via custom defined application programming interface (API). Subsequently, we employ it to investigate crack propagation behavior in 3D composite structures subject to various types of loading conditions. Crack propagation simulations are performed on 3-D composites with fibers oriented in different directions per ply (unidirectional fiber lay-up within each ply) and multidirectional composite (woven, multi-ply). The developed framework is able to predict crack propagation behavior based on applied loading conditions and nature of pre-existing defects. A comparison between simulated results and available literature data is also undertaken.
In-House Industrial Production of the Superconducting Conductor for the 43 T Hybrid Magnet of LNCMI-Grenoble
The hybrid magnet being built at LNCMI-Grenoble is based on the combination of resistive inserts, made up of Bitter and polyhelix coils, with a large bore superconducting outsert. It will produce, in the first step, an overall continuous magnetic field of 43 T in a 34 mm warm bore aperture. The superconducting coil will provide a nominal magnetic field of 8.5 T in a 1.1 m cold bore diameter. It relies on the novel development of an Nb-Ti/Cu Rutherford Cable On Conduit Conductor (RCOCC) cooled down to 1.8 K by a bath of superfluid helium pressurized at 1200 mbar. After a brief reminder of the specificity of hybrid magnets, namely the strong electromechanical coupling between resistive and superconducting coils, the main requirements of the RCOCC for efficient and reliable magnet operation are given. The test and validation phases prior to the industrial production of the RCOCC are reported, including the trial production of the ½ hard-drawn (H02 cold-worked) Cu-Ag 0.05% hollow stabilizer in continuous lengths of 325 m. The novelty of the RCOCC development concerns the assembly and the induction soft-soldering of the Rutherford cable on the Cu-Ag hollow stabilizer allowing a strict control of the interstrand contact resistance. Studies, developments, and the integration of the industrial production line at LNCMI-Grenoble are presented together with the result of the production of all RCOCC unit lengths.