Fracture Resistance of Bended Glued Timber Elements with Flaws

2014 ◽  
Vol 988 ◽  
pp. 363-366 ◽  
Author(s):  
Leonid Stupishin ◽  
Victor Kabanov ◽  
Aleksander Masalov
Keyword(s):  
Stress Intensity ◽  
Moisture Content ◽  
Stress Intensity Factors ◽  
Critical Stress ◽  
Critical Stress Intensity Factor ◽  
Intensity Factors ◽  
Front Width ◽  
Glue Joint ◽  
Glued Laminated Timber ◽  
Second Fracture

The test results for deriving of the dependencies of critical stress intensity factors on significant agents are presented for glued laminated timber. The dependencies of critical stress intensity factors on moisture content, width of cross section for I and II forms of fracture are investigated. For the second fracture form the influence of glue joint thickness within the limits of 0.07 - 0.35 mm was estimated. The influence on critical stress intensity factor was estimated also for the moisture content of wood within the limits of 12-35%, for crack front width within the limits of 30 - 140 mm, for loading velocity within the limits of 16 - 32 kN/min, for the form of crack tip, and the location of crack - in glue joint or in wood.

Evolution of Tenacity in Mixed Mode Fracture – Volumetric Approach

2020 ◽  
Vol 22 (4) ◽  
pp. 931-938
Author(s):  
O. Zebri ◽  
H. El Minor ◽  
A. Bendarma
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Mixed Mode ◽  
Local Stress ◽  
Critical Stress Intensity Factor ◽  
Mixed Mode Fracture ◽  
Intensity Factors ◽  
Singular Stress

AbstractIn fracture mechanics most interest is focused on stress intensity factors, which describe the singular stress field ahead of a crack tip and govern fracture of a specimen when a critical stress intensity factor is reached. In this paper, stress intensity factors which represents fracture toughness of material, caused by a notch in a volumetric approach has been examined, taking into account the specific conditions of loading by examining various U-notched circular ring specimens, with various geometries and boundary conditions, under a mixed mode I+II. The bend specimens are computed by finite element method (FEM) and the local stress distribution was calculated by the Abaqus/CAE. The results are assessed to determine the evolution of the stress intensity factor of different notches and loading distances from the root of notch. This study shows that the tenacity is not intrinsic to the material for all different geometries notches.

Fracture Toughness and Subcritical Crack Growth in Polycrystalline Silicon

2005 ◽  
Vol 73 (5) ◽  
pp. 714-722 ◽  
Author(s):  
I. Chasiotis ◽  
S. W. Cho ◽  
K. Jonnalagadda
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Crack Growth ◽  
Critical Stress ◽  
Polycrystalline Silicon ◽  
Subcritical Crack Growth ◽  
Crack Tip ◽  
Critical Stress Intensity Factor ◽  
Mode I ◽  
Intensity Factors

The fracture behavior of polycrystalline silicon in the presence of atomically sharp cracks is important in the determination of the mechanical reliability of microelectromechanical system (MEMS) components. The mode-I critical stress intensity factor and crack tip displacements in the vicinity of atomically sharp edge cracks in polycrystalline silicon MEMS scale specimens were measured via an in situ atomic force microscopy/digital image correlation method. The effective (macroscopic) mode-I critical stress intensity factor for specimens from different fabrication runs was 1.00±0.1MPa√m, where 0.1MPa√m is the standard deviation that was attributed to local cleavage anisotropy and grain boundary effects. The experimental near crack tip displacements were in good agreement with the linearly elastic fracture mechanics solution, which supports K dominance in polysilicon at the scale of a few microns. The mechanical characterization method implemented in this work allowed for direct experimental evidence of incremental (subcritical) crack growth in polycrystalline silicon that occurred with crack increments of 1-2μm. The variation in experimental effective critical stress intensity factors and the incremental crack growth in brittle polysilicon were attributed to local cleavage anisotropy in individual silicon grains where the crack tip resided and whose fracture characteristics controlled the overall fracture process resulting in different local and macroscopic stress intensity factors.

Simple estimation of critical stress intensity factors of wood by tests with double cantilever beam and three-point end-notched flexure

Holzforschung ◽  
2007 ◽  
Vol 61 (2) ◽  
pp. 182-189 ◽  
Author(s):  
Hiroshi Yoshihara
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Cantilever Beam ◽  
Stress Intensity Factors ◽  
Critical Stress ◽  
Double Cantilever Beam ◽  
Western Hemlock ◽  
Mode I ◽  
Intensity Factors

Abstract Simple equations are proposed for calculation of critical stress intensity factors by tests using double cantilever beam (DCB) and three-point end-notched flexure (3ENF). The calculation modes are named here as modes I and II and are based on the beam theory and 95 previously published data on the elasticity properties of woods. The validity of the data was examined on specimens of western hemlock wood with various crack lengths. The influence of the elastic properties is more significant on the stress intensity factor calculated in mode I than that calculated in mode II. Further work is needed, particularly for measuring the mode I stress intensity factor. However, it is obvious from the experiments with western hemlock that the critical stress intensity factors can be determined by the equations proposed here.

Critical stress intensity factors in steel cracked wires

2011 ◽  
Vol 32 (8-9) ◽  
pp. 4424-4429 ◽  
Author(s):  
J. Toribio ◽  
F.J. Ayaso ◽  
B. González ◽  
J.C. Matos ◽  
D. Vergara ◽  
...  
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Critical Stress ◽  
Intensity Factors
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