It has been said that ‘God invented plasticity, but the Devil fracture!’ Both mechanisms represent two prime modes of structural failure, respectively, plastic collapse and rupture/breaking a component, concept developing materials with enhanced resistance to fracture can be difficult. This is because invariably involves compromise—between strength ductility, between toughness—fundamentally lea...

Pangolin scales form a durable armor whose hierarchical structure offers an avenue towards high performance bio-inspired materials design. In this study, the fracture resistance of African pangolin scales is examined using single edge crack three-point bend fracture testing in order to understand toughening mechanisms arising from the structures of natural mammalian armors. In these mechanical ...

The toughening of an aromatic amine-cured diglycidyl ether of bisphenoI-A epoxy with particles of crystalline polymers was studied. The crystalline polymers were poly(butylene terephthalate), nylon 6, and poly(vinylidene fluoride). Nylon 6 and poly(vinylidene fluoride) were found to toughen the epoxy about as well as did an equivalent amount of CTBN rubber. Poly(butylene terephthalate) was foun...

In previous studies, enamel showed indications to occlude small cracks in-vivo and exhibited R-curve behaviors for bigger cracks ex-vivo. This study quantifies the crack tip's toughness (K(I0),K(III0)), the crack's closure stress and the cohesive zone size at the crack tip of enamel and investigates the toughening mechanisms near the crack tip down to the length scale of a single enamel crystal...

The present study is devoted to the problem of enhancing fracture toughness of ZrO2 ceramic materials through the formation of composite structure by addition of Al2O3 and NiO particles. In this paper, we analyzed the general and distinguished features of microstructure of both composite materials and its effect on fracture toughness of materials. In this paper, we used the XRD, SEM, and EDS me...

Inspired by the ternary structure of natural nacre, robust ternary artificial nacre is constructed through synergistic toughening of graphene oxide (GO) and molybdenum disulfide (MoS2) nanosheets via a vacuum-assisted filtration self-assembly process. The synergistic toughening effect from high mechanical properties of GO and lubrication of MoS2 nanosheets is successfully demonstrated. Meanwhil...

The aim of the present study is to investigate the stability of crack propagation in cementitious materials. Tests were conducted on bend specimens in three-point and four-point loading conditions.Three-point bend specimens showed stable crack growth for mortar, normal strength and high strength concrete specimens. Alternatively, four-point bend specimens showed catastrophic failure for mortar ...

In this study, we tailor the microstructure of hydroxyapatite/zirconia nanocrystalline composites by optimizing processing parameters, namely, introducing an atmosphere of water vapor during sintering in order to control the thermal stability of hydroxyapatite, and a modified sol-gel process that yields to an excellent intergranular distribution of zirconia phase dispersed intergranularly withi...

A numerical study on toughening laminated composite materials against delamination by initiating multiple interlaminar cracks is presented. Different configurations of interface and weakening patches, that modify the properties at selected locations, are investigated as a way to trigger delaminations. Both patches can be configured toughen material The initiation delaminations increase in tough...