Cross-linked fiberglass packs: Microstructure reconstruction and finite element analysis of the micromechanical behavior

An automated computational framework is introduced for simulating the micromechanical behavior of a fiberglass insulation pack with cross-linked fibers under compression. A new microstructure reconstruction algorithm is proposed that utilizes the NURBS representation of fiber geometries, together with statistical descriptors extracted from imaging data, to synthesize realistic microstructures by virtually packing fibers with the desired volume fraction, diameter distribution, and spatial orientations. Given the highly nonlinear micromechanical behavior of this nonwoven entangled material due to large deformations and contact-friction between fibers, a reduced-order finite element model is utilized to simulate its deformation response. In this approach, beam elements are used for modeling fibers, while a truss-shaped set of bushing-like connector elements are utilized to model binder particles that provide cross-linking between fibers. The accuracy of this model is verified through comparison with high-fidelity 3D simulations. Appropriate boundary conditions for simulating the mechanical behavior of microstructural models are then studied and the size of representative volume element (RVE) of the fiberglass pack is identified. The model is then employed to analyze the impacts of cross-linking and presence of fiber bundles in the microstructure on the deformation response of this materials system subject to a compressive load.