Rolls-Royce is sponsoring the development of probabilistic multiscale Ceramic Matrix Composite (CMC) design tool and lifing capabilities that can model a variety of CMC architectures and various types of damage including monotonic, cyclic, and time (creep) dependent damage.
The ferroelectric thin film and bulk materials envisioned and conceptualized for future Army devices exist at scales for which current modeling techniques are ill-suited. Classical and quantum mechanical modeling methods are too computation intensive to handle the polymorphic polycrystalline structure that give ferroelectric materials their desirable as well as undesirable properties. Multiscale atomistic-to-continuum computations have experienced significant growth in recent years.
A Generalized Mathematical Homogenization (GMH) theory aimed at describing thermo-mechanical continuum equations based on atomistic description. GMH gives rise to the constitutive law-free continuum equations where coupled continuum thermo-mechanical equations are directly derived from molecular dynamics equations. An integrated computational approach, which seamlessly integrates ABAQUS for coarse scale (finite element method) computations with a molecular dynamics code, has been developed. The accuracy and efficiency of the method has been studied for crystal silicon structures including failure predictions of nanowires.
Develop new approaches for fuel development by conducting mesoscale modeling.
Novel nondestructivestructural health monitoring algorithms are investigated and validated experimentally. The detection scheme is based on extended finite element methods (XFEM) and Genetic Algorithms (GA). The main advantage of the approach is that XFEM alleviates the need for re-meshing the domain at every new iteration of the inverse solution process and GAs have proven to be robust and efficient optimization techniques in particular for this type of problems. The results show convergence robustness and accuracy provided that sufficient number of sensors are employed and sufficiently large flaws are considered.
A simplified contact model, validated by experimental data, is proposed to model the load transfer and recovery length due to frictional contact in parallel steel wires commonly used in main cables of suspension bridges. The proposed numerical model is based on nonlinear elasto-perfectly plastic springs that are placed at the contact points between the inner and the outer wires. The numerical results indicate that these models predict well the experimental observations and provide a simple way to model the transfer of loads in wires of suspension bridge cable.
Multiscale, multirate simulation campaigns often require nonlinearly implicit solution algorithms that scale to thousands of processors and beyond, to the limit of the computational storage and power available. We develop, demonstrate in applications, and disseminate in open source form solution methods that users may access at levels ranging from mathematically abstract, without concern for algorithmic choices or implementation details, to algorithm- and architecture-specific.