Extension of HybriDFEM for coupling with two-dimensional finite elements: Surface elements, coupling methods and code refactoring
Files
LEGROS_40871900_2026.pdf
Embargoed access from 2027-01-23 - Adobe PDF
- 93.34 MB
Details
- Supervisors
- Faculty
- Degree label
- Abstract
- HybriDFEM is a computational framework that combines rigid block discrete element methods with finite element analysis for modelling structures exhibiting both continuous and discontinuous behavior. Originally developed for coupling rigid blocks with one-dimensional beam elements, the framework was limited by the shared degree-of-freedom structure between these element types. This thesis extends HybriDFEM to support two-dimensional finite elements and develops multiple coupling strategies for Block-FE interfaces. Five element types are implemented: three-node and six-node triangular elements (T3, T6), and four-node, eight-node, and nine-node quadrilateral elements (Q4, Q8, Q9). The implementations are validated through cantilever beam benchmarks, comparison with Timoshenko beam theory, verification against Abaqus, and stress analysis of square domains. Four coupling methods are developed to connect rigid blocks with 2D surface elements: constraint coupling through DOF elimination, penalty coupling, Lagrange multiplier coupling, and mortar coupling for non-matching meshes. Each method addresses the fundamental challenge that blocks have three degrees of freedom per node (two translations, one rotation) while surface elements have only two (translations). Validation on hybrid cantilever configurations demonstrates that all methods produce stable, convergent solutions, with the mortar method exhibiting the most consistent behavior across element types. This extension led to a refactoring of the codebase from a monolithic architecture to a modular object-oriented design, introducing variable DOF management and extensible class hierarchies. This restructuring enables collaborative development and facilitates future extensions.