A computational approach to the optimization of service properties of two-phase materials (in this case, fracture resistance of tool steels) by varying their microstructure is developed. The main points of the optimization of steels are as follows: (1) numerical simulation of crack initiation and growth in real microstructures of materials with the use of the multiphase finite elements (MPFE) a...

STATEMENT OF PROBLEM Patients' demand for tooth-colored restoratives in the posterior region is increasing. Clinicians use universal nanohybrid resin composites for both anterior and posterior regions. There are few published reports comparing fracture toughness of nonohybrids and that of hybrid composite stored wet and dry. OBJECTIVES To investigate the fracture toughness of three nanohybrid...

magnesium alloys in liquid-phase condition form surface oxide films due to their high rate of oxidation. oxide films enter the melt as a result of surface turbulence, and remain inside the workpiece after solidification. the incoherent nature of their interface causes decreases in mechanical properties and reliability of castings. the effect of critical velocity and greater velocities of enteri...

The fracture toughness and strength of ceramics can be improved with respect to monolithic ceramics by developing graded materials as laminates composed of periodic alternating layers of one material separated by layers of a second material. The second layer must contain residual compressive stresses which are induced during densification because of differential thermal contraction of the layer...

Fracture toughness of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) in both bulk and film forms after sintering at 900°C to 1200°C was measured using both single-edge V-notched beam (SEVNB) 3-point bending and Berkovich indentation. FIB/SEM slice-and-view observation after indentation revealed the presence of Palmqvist radial crack systems after indentation of the bulk materials. Based on crack length measur...

Bone tissue and geometry are constantly modified through modeling and remodeling at the periosteal, endosteal and intracortical envelopes. Results from several studies indicate that femoral bone geometry is a predictor of whole bone strength (e.g. femoral neck strength), however, it is not known whether there is a relationship between bone structural and material properties. Bone geometry can b...

The mechanical interaction between the surgical tools and the target soft tissue is mainly dictated by the fracture toughness of the tissue in several medical procedures, such as catheter insertion, robotic-guided needle placement, suturing, cutting or tearing, and biopsy. Despite the numerous experimental works on the fracture toughness of hard biomaterials, such as bone and dentin, only a ver...

Glass ionomer cements show great potential as low cost, minimally invasive dental restorative materials. However, their use is limited by relatively poor mechanical properties, especially fracture toughness. One possibility for improving their fracture toughness is through the addition of fluorhydroxyapatite nanoparticles, which resemble the crystals found in tooth enamel. Hydroxyapatite and fl...

A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength-toughness balance of the developed steels was markedly better than that of conventionall...

INTRODUCTION Polymer brackets still have some disadvantages because of decreased wear resistance and hardness. The aim of this study was to investigate the mechanical properties of alternative bracket polymers; urethane-dimethacrylate, high-density polyethylene, and an experimental bracket polymer (EBP) consisting of polyethylene and a copolymer were tested. Polycarbonate and polyoxymethylene b...