Mode II delamination toughness of z-pin reinforced composite laminates is investigated using finite element (FE) method. The z-pin pullout process is simulated by the deformation and breakage of non-linear springs. A critical shear stress criterion based on linear elastic fracture mechanics is used to simulate crack growth in an end-notched-flexure (ENF) beam made of z-pinned laminates. The mod...

Studies of bone have determined multiple toughening mechanisms slowing the propagation of a crack. These toughening mechanisms contribute to the fracture toughness of bone in life, making their activities of clinical interest. The primary standard methods for measuring bone fracture toughness use a single-notched compact type specimen (CT) or single-notched bending specimens in four-point (SN4P...

Crack propagation is a significant mechanism for quasi-brittle materials under applied loading. It can occur very suddenly and causes numerical instabilities deficiencies in some problems. This behavior manifest itself as non-convergence solutions i.e. the inability to obtain entire load-displacement curve or jumps load displacement curve. In this study, control technique implemented whole load...

In this paper, we propose a new experimental method to investigate the fatigue crack growth mechanisms of submicron-scale cracks by using freestanding single edge notched micro-beams that are fabricated on the surfaces of conventional bending specimens with the focused ion beam technique. Three dimensional FEM simulations in conjugate with LEFM fracture analysis were carried out to correlate th...

The cohesive crack model has been widely accepted as the best compromise for the analysis of fracture of concrete and other quasibrittle materials. The softening stress-separation law of this model is now believed to be best described as a bilinear curve characterized by four parameters: the initial and total fracture energies Gf and GF , the tensile strength f 0t , and the knee-point ordinate ...

A printed monopole ultra wideband (UWB) antenna with frequency band-notched characteristics is proposed and investigated. The antenna consists of a half-disk shaped structure combined with an inverted isosceles trapezoid structure. To achieve the frequency band notched characteristics, an open-ended thin slit with a length of about one quarter guided wavelength is inserted on the radiator. Mult...

Polyamide polymers have moderate mechanical properties, excellent wear resistant properties, and solvents. However, polyamides have some disadvantages such as notch sensitivity and high water absorption. Generally, polyamides are ductile in the un notched state but they show brittle behavior in the state of notched impact. Some disadvantages of polyamides can be improved by some fillers and add...

Blends of nylon-6 with polybutadiene were prepared with comparable morphology and different molecular weights of the matrix. These specimens were tested using the notched Izod impact test and the notched tensile impact test. An increase in molecular weight resulted in a shift of the brittle-to-tough transition temperature of 40°C to lower temperatures. In the notched tensile impact tests, espec...

In this research, residual strength and stress concentration factor of laminated composites with a circular open hole are studied analytically, numerically and experimentally. The numerical study was carried out using the finite element method. Moreover an analytical study was carried out with developing of point stress criterion. Mechanical testing was performed to determine the un-notched ten...

Polyamide polymers have moderate mechanical properties, excellent wear resistant properties, and solvents. However, polyamides have some disadvantages such as notch sensitivity and high water absorption. Generally, polyamides are ductile in the un notched state but they show brittle behavior in the state of notched impact. Some disadvantages of polyamides can be improved by some fillers and add...