Showing 4 results for Fracture Toughness
Hadian A.m., Abu Fanas S.h.,
Volume 2, Issue 4 (12-2005)
Abstract
Enhancing the properties of dental resin composites is of interest to researchers. The objective of the present investigation was to improve the strength and fracture toughness of dental composites via addition of silicon carbide whiskers and substitution of commonly used filler materials with stabilized zirconia ceramic powder. It was also intended to study the effect of powder- to- whisker ratio on mechanical properties of the resultant composites. The flexural strength and fracture toughness of composite samples with different whiskers loadings were measured. It was found that addition of whiskers to the composites enhances the mechanical properties of the composites. The strength and fracture toughness increased by increasing the amount of whiskers. The flexural strength of a composite having 60wt% whisker and 10wt% zirconia powder was about 210 MPa while that of the composite having only 60wt% ceramic powder was about 110 MPa. The microstructural examinations revealed that reinforcing mechanism was whiskers pull-out as well as crack deflection.
A. Hassani, R. Ravaee,
Volume 5, Issue 2 (6-2008)
Abstract
Abstract: To ensure the rail transportations safety, evaluation of fatigue behavior of the rail steel
is necessary. High cycle fatigue behaviour of a rail steel was the subject of investigation in this
research using fracture mechanics. Finite element method (FEM) was used for analyzing the
distribution of the stresses on the rail, exerted by the external load. FEM analysis showed that the
maximum longitudinal stresses occurred on the railhead. To find out about the relation of crack
growth with its critical size, and to estimate its lifetime, the behaviour of transverse cracks to rail
direction was studied using damage tolerance concept. It revealed that transverse crack growth
initially occurred slowly, but it accelerated once the crack size became larger. Residual service
life was calculated for defective segments of the rails. In addition, allowable crack size for
different non-destructive testing intervals was determined the allowable crack size decreased as
the NDT intervals increased.
A. Mohassel, A. H. Kokabi, P. Davami,
Volume 8, Issue 4 (12-2011)
Abstract
The wide-gap aluminothermic rail welds with root opening of 50-70 mm were produced using plain carbon steel rail and non-alloy aluminothermic charge. Mechanical properties and micro-structure of the weld metal and HAZ as well as the impact energy and the fracture toughness of the welds were investigated. The yield and tensile strength of wide-gap welds were about 98% and 95% of the base metal, respectively. Both minimum and maximum hardnesses of the joint were seen in HAZ which were related to the grain coarsening and normalizing, respectively. The mean value of wide-gap weld fracture toughness is more than narrow-gap weld. Moreover, trans-granular cleavage indicated the brittle fracture mode of the weld metal.
Umarfarooq Maktedar Abdulkhadar, Patil Somalingana Shivakumar Gouda, Anil Shirahatti, Gonal Basavaraja Veeresh Kumar, Nagaraj Ramalingyya Banapurmath,
Volume 18, Issue 4 (12-2021)
Abstract
The energy release rate for delamination in a laminated composite is supposed to be the material property being considered as independent of non-material property variables. However, Mode I fracture toughness(GI) is found to vary with lamina arrangement, geometrical dimensions, and process-induced stresses. In this investigation, the influence of lamina stacking arrangement on process-induced stresses and their effects on GI of laminated composites are studied. Unidirectional (UD) ([0]16) and cross-ply ([902/06]s, [904/04]s and [906/02]s) Glass/ epoxy (GE) composites with the delamination plane at 0◦//0◦ were prepared by manual layup method and post-cured at 120 °C for 4 hours. GI of composite laminates were experimentally determined using a double cantilever beam(DCB) specimen as per ASTM D 5528. The slitting method was applied to determine the Process-induced stresses in GE laminates. The stacking sequence of laminas was found to have a noticeable effect on the state of residual stresses and GI of GE laminates. Residual stresses do not have much influence on the GI for delamination initiation, whereas GI for the crack propagation was found to increase with a gradual increase in compressive residual stresses in GE laminates.
