Three-dimensional finite element modeling of inorganic-matrix composite materials using a mesoscale approach

Fiber reinforced cementitious matrix (FRCM) composites represent a promising alternative to the use of fiber reinforced polymer (FRP) composites for strengthening existing structures. FRCM composites are comprised of a high-strength fiber net (textile) embedded within an inorganic matrix, which is responsible of the stress-transfer between the composite and the substrate. FRCM composites comprising one layer of fiber are generally reported to fail due to debonding of the fibers from the embedding matrix. However, depending on the FRCM material employed, failure at the matrix-substrate interface, interlaminar (delamination) of the matrix, and fiber rupture may also occur. When stitch-bonded textiles are employed, i.e. textiles where longitudinal and transversal bundles are firmly connected, the interlocking between fibers and matrix plays a key role in the matrix-fiber stress-transfer mechanism and failure generally occurs due to cracking of the matrix. In this paper, the bond behavior of FRCM-masonry joints comprising one layer of a carbon stitch-bonded textile embedded within a lime-based matrix is studied by means of single-lap direct-shear tests of FRCM-masonry joints. A mesoscale three-dimensional finite element approach, which accounts for the matrix-fiber bond behavior and matrix-textile interlocking, is adopted to study the formation and propagation of the matrix cracks in the FRCM strip that eventually led to failure of the FRCM-masonry joints. The finite element analysis was carried out by using a dynamic explicit approach, which allowed for overcoming convergence difficulties associated with severe nonlinearities of the model.