Yapı mühendisliği için genişletilebilir parelel sonlu elemanlar çözümleme platformu

TÜBİTAK MAG Proje01.09.2012The parallel computing systems became more affordable and available in consequence of the recent development in computer technology. Many institutions and engineers, however, can not utilize already available parallel computer hardwares due to the insufficiencies of the structural analysis softwares that they were using. Thus, one of the main objectives of this project is presenting a way to utilize the existing parallel computing hardwares without the need of additional cost and creating a considerable reduction in the analysis times by parallelizing the most frequently utilized finite element analysis techniques in structural engineering. In this project, a sigficant effort was spent on the main analysis methods of finite element method such as linear static, non-linear static, linear and non-linear time history analysis. As paralel solution techniques of linear systems of equations, two different solution approach, i.e. globnal and substructure based were implemented and their performances are tested with several structural models. Likewise, for time history analysis of structures, both implicit and explicit time integration techniques were implemented and their parallel efficiency were tested. Parallel non-linear time history analysis algoritms were also implemented utilizing the explicit integration technique. One of the main problems of developing a computational mechanics software is the difficulty of having the third parties other than the developers to use and further develop such softwares. Because of this reason, most of the academical softwares were being utilized only by a few researchers. Thus, the other important target of this project is to create an expandable software structure so that the framework can easily be utilized and further developed by other researchers. For this reason, an objectoriented data structure was carefully designed for such an analysis software and with the help of the state of the art ‘plug-in’ technolgy, external programs can be easily added to the analysis engine and utilized without any problems. In order to validate the extensibility of the developed analysis framework, finite elements and analysis methods for the heat transfer problems were developed and added to the framework as plug-ins. As a final step, the use of GP-GPU’s in finite element analysis were examined by developing several analysis methods. Even though fast solution times for direct sparse matrix solvers were not obtained when compared to the performance of multi-core CPUs, significant reduction in solution times for dense matrix operations and explicit time integration methods were obtained

High-performance computing for impact-induced fracture analysis exploiting octree mesh patterns

The impact-induced fracture analysis has a wide range of engineering and defence applications, including aerospace, manufacturing and construction. An accurate simulation of impact events often requires modelling large-scale complex geometries along with dynamic stress waves and damage propagation. To perform such simulations in a timely manner, a highly efficient and scalable computational framework is necessary. This thesis aims to develop a high-performance computational framework for analysing large-scale structural problems pertaining to impact-induced fracture events. A hierarchical grid-based mesh containing octree cells is utilised for discretising the problem domain. The scaled boundary finite element method (SBFEM) is employed, which can efficiently handle the octree cells by eliminating the hanging node issues. The octree-mesh is used in balanced form with a limited number of octree cell patterns. The master element matrices of each pattern are pre-computed while the storage of the individual element matrices is avoided leading to a significant reduction in memory requirements, especially for large-scale models. Further, the advantages of octree cells are leveraged by automatic mesh generation and local refinement process, which enables efficient pre-processing of models with complex geometries. To handle the matrix operations associated with large-scale simulation, a pattern-by-pattern (PBP) approach is proposed. In this technique, the octree-patterns are exploited to recast a majority of the computational work into pattern-level dense matrix operations. This avoids global matrix assembly, allows better cache utilisation, and aids the associated memory-bandwidth limited computations, resulting in significant performance gains in matrix operations. The PBP approach also supports large-scale parallelism. In this work, the parallel computation is carried out using the mesh-partitioning strategy and implemented using the message passing technique. It is shown that the developed solvers can simulate large-scale and complex structural problems, e.g. delamination/fracture in sandwich panels with approximately a billion unknowns (or DOFs). A massive scaling can be achieved with more than ten thousand cores in a distributed computing environment, which reduces the computation time from months (on a single core) to a few minutes