scholarly journals The stress field near the tip of a plane stress crack in a gel consisting of chemical and physical cross-links

2019 ◽  
Vol 475 (2227) ◽  
pp. 20180863 ◽  
Author(s):  
Jingyi Guo ◽  
Chung-Yuen Hui ◽  
Mincong Liu ◽  
Alan T. Zehnder
Keyword(s):  
Plane Stress ◽  
Crack Opening ◽  
Three Dimensional ◽  
Crack Tip ◽  
Stress Fields ◽  
Asymptotic Results ◽  
Constant Stretch ◽  
Cross Links ◽  
Theoretical Results ◽  
Gel Network

We study the time-dependent asymptotic stress fields near the tip of a mode I plane stress crack in a hydrogel. The analysis is based on a three-dimensional continuum model which describes the viscoelastic behaviour of a hydrogel gel with permanent and transient cross-links. The viscoelasticity results from the breaking and healing of the transient cross-links in the gel network. We show that the crack tip fields satisfy a local correspondence principle—that is, the spatial singularities of these fields are identical to a hyperelastic cracked body with the same but undamaged networks. Asymptotic results compare very well with finite-element simulations on a single-edge crack specimen loaded under constant stretch rate. We also compare the theoretical results (crack opening profile and crack tip strain field) with experiments and find excellent agreement.

Hybrid Measurement of CT and Strain Distribution of Internal Crack Using Synchrotron High-Energy Monochromatic X-Rays

2010 ◽  
Vol 652 ◽  
pp. 202-209
Author(s):  
Keisuke Tanaka ◽  
Takahisa Shobu ◽  
Hiroshi Kimachi
Keyword(s):  
Strain Distribution ◽  
Crack Opening ◽  
Three Dimensional ◽  
Crack Tip ◽  
High Energy ◽  
Internal Crack ◽  
X Rays ◽  
Crack Face ◽  
Dimensional Shape ◽  
Three Dimensional Shape

Using high-energy monochromatic X-rays of energy 66.4keV from the synchrotron radiation source, SPring-8, we have developed a system to perform a hybrid measurement of imaging of cracks and strain distribution around cracks. This system was applied to a fatigue crack made in a round bar made of carbon steel with a diameter of 4 mm. Computed tomography of the specimen gave the three-dimensional shape of a thumb-nail crack. High tensile strain ahead of the crack was measured at the applied maximum stress, while the strain on the crack face was low because of stress relief due to crack opening. The full width at half maximum (FWHM) increased near the crack tip under loading, and then decreased after unloading. The recoverable part of FWHM by unloading was caused by the steep distribution of the applied stress in the vicinity of the crack tip. The FWHM increased by plastic deformation does not change when unloaded. The measured distributions of the lattice strain and FWHM agreed well with those of the elastic and plastic strains calculated by the finite element method, respectively.

Growth Mechanism of Subsurface Crack Due to Hertzian Contact

1986 ◽  
Vol 108 (1) ◽  
pp. 134-139 ◽  
Author(s):  
M. Kaneta ◽  
Y. Murakami ◽  
T. Okazaki
Keyword(s):  
Crack Opening ◽  
High Surface ◽  
Three Dimensional ◽  
Crack Tip ◽  
Circular Crack ◽  
Hertzian Contact ◽  
Contact Load ◽  
Surface Traction ◽  
Penny Shaped Crack ◽  
Side Crack

The variations of three-dimensional mixed mode stress intensity factors for a circular crack under a Hertzian contact pressure moving over the surface are calculated by taking into account both the frictional forces between the crack faces and between the contact surfaces. The circular (penny shaped) crack is assumed to be embeded parallel to the surface. The crack opening occurs near the leading crack tip as well as near the trailing crack tip depending on the pass of the contact load. The crack propagates mainly Mode II, though application of a high surface traction or a heavy contact load can induce the tensile mode crack growth. When the surface traction is directed from left to right, the left side crack tip propagates parallel to the surface and the right side crack tip extends toward the surface.

Different Delamination Cracks during Fracture and Their Influences on the Fracture of X70 Pipeline Steel

2008 ◽  
Vol 33-37 ◽  
pp. 91-96
Author(s):  
Zheng Yang ◽  
Hyeon Gyu Beom ◽  
Chang Boo Kim ◽  
Chong Du Cho
Keyword(s):  
Pipeline Steel ◽  
Notch Root ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Crack Tip ◽  
Strength Distribution ◽  
Stress Fields ◽  
X70 Pipeline Steel ◽  
Delamination Crack ◽  
Delamination Cracks

Single or multiple of delaminations have been found frequently on the fracture surface of X70 pipeline steel. In this study, the delamination cracks and their influence on the fracture of pipeline are investigated by both experiment and three-dimensional fracture analyses. It is shown that the three-dimensional stress state is prerequisite for delamination crack and the strength distribution of material influences the form and direction of delamination crack. The delamination cracks are produced on the weak interfaces among the material by the tensile stress perpendicular to them before the fracture passes. The direction of delamination crack depends on the three-dimensional stress fields and strength distribution of material near the crack tip or notch root. The delamination cracks of the fracture through thickness of pipe wall make the effective thickness decrease and the delamination cracks of surface crack are perpendicular to the direction of fracture propagation direction. The delamination cracks reduce the stress triaxiality near crack tip and in turn, improve the fracture toughness of X70 pipeline steel.

Three-Dimensional Effects Near a Crack Tip in a Ductile Three-Point Bend Specimen: Part I—A Numerical Investigation

1990 ◽  
Vol 57 (3) ◽  
pp. 607-617 ◽  
Author(s):  
R. Narasimhan ◽  
A. J. Rosakis
Keyword(s):  
Plane Strain ◽  
Plane Stress ◽  
Crack Front ◽  
Three Dimensional ◽  
Crack Tip ◽  
Upper And Lower Bounds ◽  
Thickness Variation ◽  
Bend Specimen ◽  
Dimensional Effects ◽  
Point Bend

A simultaneous numerical and experimental investigation is undertaken to assess three-dimensional effects and HRR dominance near a crack front in a ductile 3-point bend specimen. In parallel to the three-dimensional calculations, a plane-strain and a plane-stress analysis of the same in-plane specimen geometry is performed to obtain upper and lower bounds for the three-dimensional calculation. The radial, angular, and thickness variation of the stresses and displacements are studied in great detail from contained yielding to fully plastic conditions. The results indicate that the plane-strain HRR field prevails in the interior of the specimen very near the crack front even for moderate extents of yielding. On the other hand, for distances from the crack tip exceeding about half a specimen thickness, plane-stress conditions are approached. The calculations presented here model a series of laboratory experiments involving three independent experimental techniques. Details regarding the experiments and comparisons of the experimental measurements with numerical calculations and theory are emphasized in Part II of this work.

Analysis of the Three-Dimensional Zone around the Interfacial Crack Tip: The K-Influence Domain Range in the Plane Stress State

2017 ◽  
Vol 754 ◽  
pp. 119-122
Author(s):  
Jelena M. Djoković ◽  
Snežana D. Vulović ◽  
Ružica R. Nikolić ◽  
Miroslav M. Živković ◽  
Branislav Hadzima
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress State ◽  
Intensity Factor ◽  
Plane Strain ◽  
Plane Stress ◽  
Three Dimensional ◽  
Crack Tip ◽  
Plane Stress State ◽  
Relevant Parameter

The bimaterial sample was analyzed to determine the three-dimensional zone at the interface crack tip and the field in the plane stress state. The solutions for the complete 3D field in different zones around the crack tip were approximated by the plane stress and plane strain states' asymptotic solutions. The difference between the solutions for the plane stress and plane strain states is defined by the three variables. The established relationship between the far field and the field around the crack tip in the plane strain conditions, enables relating the measured experimental results of the stress intensity factor to results for the stress intensity factor for the field around the crack tip, which represent the more relevant parameter for formulating the fracture criterion.

scholarly journals Effects of Micron Fish Bone with Different Particle Size on the Properties of Silver Carp(Hypophthalmichthys molitrix)Surimi Gels

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Tao Yin ◽  
Jae W. Park ◽  
Shanbai Xiong
Keyword(s):  
Particle Size ◽  
Calcium Ion ◽  
Silver Carp ◽  
Three Dimensional ◽  
Fish Bone ◽  
Hypophthalmichthys Molitrix ◽  
Bone Particle ◽  
Cross Links ◽  
Water Holding ◽  
Gel Network

Qualities of silver carp surimi (SCS) gels incorporated with micron fish bone of different particle size (22 to 0.12 μm) were evaluated. Textural values, whiteness, and water holding capacity of the SCS gels with setting significantly increased (P<0.05) as the micron fish bone particle size decreased. As the particle size decreased, more calcium ion was apparently released from the fish bone (P<0.05). Consequently the released calcium ion increased the activity of endogenous transglutaminase (TGase) and resulted in the formation of more myosin heavy chain (MHC) cross-links in the SCS gel with setting. Fish bone with particle size below 0.48 μm was steadily trapped in the three-dimensional SCS gel network without disrupting the matrices. Results indicated that size reduction of the incorporated micron fish bone improved qualities of the SCS gel with setting by the means of releasing more calcium ion and maintaining better gel matrices.

Sign in / Sign up

Export Citation Format

Share Document