In‐Plane Fracture Resistance of a Crossply Fibrous Monolith

Abstract

The in-plane fracture resistance of a crossply Si 3 N 4 /BN fibrous monolith in the 0°/90°and ؎45°orientations is examined through tests on notched flexure specimens. The measurements and observations demonstrate the importance of fiber pullout following fiber fracture. The mechanical response is modeled using a crack-bridging approach. Two complementary approaches to evaluating the bridging law are developed: one based on a micromechanical model of fiber pullout and the other based on the load versus crack mouth opening displacement response of the flexure specimens following fracture of all fibers. Both approaches indicate that the bridging law follows an exponential form, characterized by a bridging strength and an effective pullout length. An assessment of the bridging model is made through comparisons of simulations of the load-displacement response with those measured experimentally.

Advanced Structural Materials by Bioinspiration

“…It involves the use of an extruder to create the outer envelope and an auxiliary system for injecting a filling (Figure a). Coextrusion provides a method of forming fibrous ceramic/ceramic or ceramic/metal composites, with distinct cells and cell boundaries, acting as the fiber and the matrix, respectively, and leading to improved toughness and non‐catastrophic fracture behavior …”

A Novel Approach to Developing Biomimetic (“Nacre‐Like”) Metal‐Compliant‐Phase (Nickel–Alumina) Ceramics through Coextrusion

“…Coextrusion provides a method of forming fibrous monoliths, i.e., ceramic–ceramic or ceramic–metal composites with distinct cell and cell boundaries made, respectively, of each material; the cell acts as the fiber while the cell boundary acts as the matrix phase between the fibers, leading to improved toughness and non‐catastrophic fracture behavior . Coincidentally, the cross sections of these materials normal to the fiber direction are similar to that of brick‐and‐mortar composites.…”

Thermal Shock Resistance and Fracture Behavior of ZrB2–Based Fibrous Monolith Ceramics

“…Based on the HH theory, crack deflection was not expected for the FM with 30% ZrB 2 in the cell boundary. FMs typically exhibit flexure strengths of ∼50% of the cell material when the cells are aligned unidirectionally 25 . The ZS/CZ FM could support loads between 50% and 85% of the load from the initial fracture event, which is also typical of FMs that exhibit extensive delamination with numerous fracture events following the initial event.…”