Viscoplastic fracture transition of a biopolymer gel

Soft Matter ◽  
2018 ◽  
Vol 14 (23) ◽  
pp. 4696-4701 ◽  
Author(s):  
Bradley R. Frieberg ◽  
Ray-Shimry Garatsa ◽  
Ronald L. Jones ◽  
John O. Bachert ◽  
Benjamin Crawshaw ◽  
...  
Keyword(s):  
Fracture Behavior ◽  
Critical Concentration ◽  
Fracture Mechanisms ◽  
Fracture Transition ◽  
Gelatin Gels ◽  
Chain Composition ◽  
Cavitation Rheology

We study the effects of gelatin chain composition on the fracture behavior of gelatin gels using cavitation rheology to show two fracture mechanisms exist for these materials that is determined by the whether the gel concentration is above or below the critical concentration for entanglements.

scholarly journals The Investigation of the Fracture Behavior of a Chinese 9% Cr Steel Welded Joint under Creep-Fatigue Interactive Loading

2021 ◽  
Vol 11 (21) ◽  
pp. 9983
Author(s):  
Yuebing Li ◽  
Yuxuan Song ◽  
Pan Liu ◽  
Ting Jin
Keyword(s):  
Fracture Behavior ◽  
Welded Joint ◽  
Inelastic Strain ◽  
Cyclic Softening ◽  
Fracture Mechanisms ◽  
P92 Steel ◽  
Holding Period ◽  
Creep Fatigue ◽  
Softening Stage

To understand the premature-fracture mechanisms of long-term service damage of an advanced alloy’s (Chinese P92 steel) welded joint, the creep-fatigue (CF) experiments with holding times of 30, 120, 300, 600 and 900 s were individually performed at 923 K. The cyclic softening, inelastic-strain amplitudes and stress-relaxation behaviors were compared between welded and base-metal (BM) specimens. From the results, the failure stage of the welded specimens occupies 45% of the lifetime fraction, while it only takes up 20% of the lifetime fraction in BM specimens with short holding times (30 and 120 s). Furthermore, only two softening stages were observed for both kinds of CF specimens with long holding times. The absence of a third softening stage in longer-held specimens indicates that the processes of macroscopic-crack initiation, propagation and rupture were accelerated. Based on the observation of the fracture surfaces, the fracture mechanism shifted from fatigue-dominated damage to creep-fatigue interaction when the holding period was increased.

Study on Fracture Behavior of γ-TiAl Based Alloys

2007 ◽  
Vol 546-549 ◽  
pp. 1437-1442 ◽  
Author(s):  
Rui Cao ◽  
Jian Hong Chen ◽  
J. Zhang
Keyword(s):  
Fracture Toughness ◽  
Main Crack ◽  
Fracture Behavior ◽  
Fracture Mechanisms ◽  
Narrow Strip ◽  
Tial Alloys ◽  
Notched Specimen ◽  
Crack Tips ◽  
Fully Lamellar ◽  
Crack Bifurcation

Fracture behavior of fully lamellar (FL) and duplex phase (DP) TiAl alloys is reported in this paper. It was found that the inverse behavior of coarse FL TiAl alloy showing inferior tensile properties but superior fracture toughness resulted from the different fracture mechanisms of these two types’ tests. In tensile specimens, the final fracture happened at a section that was most heavily damaged by the accumulation of large interlamellar microcracks and arbitrarily located within the gauge-limited volume. In 3PB notch specimens, the propagation of the main crack was constrained within a narrow strip nearby the centerline where the normal stress was the highest. Large lamellar grains caused serious damage in tensile tested specimens. However multi-oriented large lamellar grains formed seriously bifurcated crack tips, which made the crack propagation more difficult in 3PB notched specimen. The main mechanisms of toughening in FL specimens were the deflection of main crack, bifurcation and blunting of crack tip and formation of a diffuse zone of microcracks. These phenomena reduced the driving force for crack extending and then increased the fracture toughness.

scholarly journals Numerical Simulation of Crack Propagation in Flexible Asphalt Pavements Based on Cohesive Zone Model Developed from Asphalt Mixtures

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1278 ◽  
Author(s):  
Pengfei Liu ◽  
Jian Chen ◽  
Guoyang Lu ◽  
Dawei Wang ◽  
Markus Oeser ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Fracture Behavior ◽  
Cohesive Zone Model ◽  
Mechanical Design ◽  
Design Methods ◽  
Asphalt Mixtures ◽  
Asphalt Pavements ◽  
Fracture Mechanisms ◽  
Zone Model

To give engineers involved in planning and designing of asphalt pavements a more accurate prediction of crack initiation and propagation, theory-based models need to be developed to connect the loading conditions and fracture mechanisms present in laboratory tests and under traffic loading. The aim of this study is to develop a technical basis for the simulation of fracture behavior of asphalt pavements. The cohesive zone model (CZM) approach was applied in the commercial FE software ABAQUS to analyze crack propagation in asphalt layers. The CZM developed from the asphalt mixtures in this study can be used to simulate the fracture behavior of pavements and further optimize both the structure and the materials. The investigations demonstrated that the remaining service life of asphalt pavements under cyclic load after the initial onset of macro-cracks can be predicted. The developed CZM can, therefore, usefully supplement conventional design methods by improving the accuracy of the predicted stress states and by increasing the quality, efficiency, and safety of mechanical design methods by using this more realistic modeling approach.

CT Investigation of Fracture Mechanism of Soil-Rock Mixtures

2012 ◽  
Vol 204-208 ◽  
pp. 67-71 ◽  
Author(s):  
Hua Fei Sun ◽  
Zeng Kun Yang ◽  
Ming Xu Xing ◽  
Yang Ju ◽  
Yong Ming Yang
Keyword(s):  
Computed Tomography ◽  
Fracture Behavior ◽  
The Self ◽  
Fracture Mechanisms ◽  
Geological Material ◽  
Unique Type ◽  
Processing Program ◽  
Strength And Deformation ◽  
Loading Devices ◽  
Internal Fracture

Soil-Rock Mixture (SRM) is a unique type of geological material characterized by inhomogeneous composition and complicated structures. This paper investigated the fracture mechanisms that govern the strength and deformation of SRM subjected to uniaxial compression loads by means of computed tomography (CT) techniques. The self-designed loading devices and self-developed image processing program were applied to identify and quantify the fractures inside SRM during compressions. The results show that the internal fracture behavior of SRM greatly depends on the rock ratios of SRM.

Fracture Behavior of Cement-Based Materials

MRS Bulletin ◽  
1993 ◽  
Vol 18 (3) ◽  
pp. 55-59 ◽  
Author(s):  
S.P. Shah ◽  
C. Ouyang ◽  
D.A. Lange
Keyword(s):  
Fracture Behavior ◽  
Peak Stress ◽  
Elastic Response ◽  
Fracture Mechanisms ◽  
Stress Strain ◽  
Fracture Properties ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Cement Based Materials ◽  
Material Fracture

The characterization of fracture behavior is a continuing challenge to the cement and concrete community. The performance of a material can be evaluated by its stress-strain response. For an ideally brittle material, elastic response is terminated when stress suddenly drops to zero, as shown in Figure 1a. However, cement-based materials are considered quasi-brittle because they respond nonlinearly prior to peak stress, and their stress gradually decreases after reaching a peak, as indicated in Figure 1b.To make cement-based materials stronger and tougher, one needs to understand the fracture mechanisms associated with nonlinear stress-strain behavior and to characterize material fracture properties based on these fracture mechanisms. Three novel techniques are being used at the Center for Advanced Cement-Based Materials (ACBM) to detect the quasi-brittle nature of cement-based materials. These three techniques are laser holographic interferometry, acoustic emission, and microscopic surface analysis. This article summarizes both the fracture mechanisms in cement-based materials and the application of the three techniques to characterize and measure fracture properties.

Fracture Mechanisms in NiAlCr Eutectic Composites

1992 ◽  
Vol 273 ◽  
Author(s):  
Keh-Minn Chang
Keyword(s):  
Fracture Toughness ◽  
Fracture Resistance ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Ternary Systems ◽  
Fracture Mechanisms ◽  
Fracture Properties ◽  
Intermetallic Matrix ◽  
Binary Eutectic ◽  
Ternary Eutectics

ABSTRACTSelected eutectic compositions in Ni-Al-Cr ternary systems were processed by directional solidification (DS) with various growth rates. Fracture toughness tests were performed at room temperature and 400 °C; fracture surfaces of broken specimens were examined using SEM to investigate fracture behavior of each alloy. The alignment of eutectic phases was found to play an important role in composite toughening for the intermetallic matrix. Binary eutectic composites consisting of bcc α-Cr and B2 β-NiAl phases with a directional, well-aligned structure showed improved fracture properties over NiAl single crystals. Ternary eutectics, which contain an fcc γ-Ni phase, offered an excellent fracture resistance at room temperature.

Simulation of Ductile Crack Propagation in High-Strength Pipeline Steel Using Damage Models

2012 ◽  
Author(s):  
Aida Nonn ◽  
Christoph Kalwa
Keyword(s):  
Crack Propagation ◽  
High Strength Steel ◽  
Fracture Behavior ◽  
Damage Mechanics ◽  
Failure Prediction ◽  
High Strength ◽  
Fracture Mechanisms ◽  
Ductile Crack ◽  
Damage Models ◽  
Prediction Tools

The performance of engineering design of high-strength steel pipelines has revealed the necessity to revise current design procedures. Therefore, an improved and detailed comprehension of fracture mechanisms and development of failure prediction tools are required in order to derive new design criteria. In last decades the most successful failure prediction tools for steel structures subjected to various type of loading can be encountered in the field of damage mechanics. This paper aims to describe ductile fracture behavior of high-strength steel pipelines by applying three different damage models, Gurson-Tvergaard-Needelman (GTN), Fracture Locus Curve (FLC) and Cohesive Zone (CZ). These models are evaluated regarding their capability to estimate ductile crack propagation in laboratory specimens and linepipe components without adjusting the calibrated parameters. It can be shown that appropriate parameter sets can be identified to reproduce load-deformation and fracture resistance curves accurately. The strain rate effect on the fracture behavior is examined by dynamic tests on the BDWT specimens. Finally, the shortcomings of the applied models are pointed out with the reference to possible extensions and modifications.

Characterization of Impact Fracture Behavior of Biodegradable PLA/PCL Polymer Blend

2006 ◽  
Vol 326-328 ◽  
pp. 1569-1572 ◽  
Author(s):  
Tetsuo Takayama ◽  
Mitsugu Todo ◽  
Kazuo Arakawa
Keyword(s):  
Fracture Behavior ◽  
Impact Resistance ◽  
Impact Fracture ◽  
Fracture Mechanisms ◽  
Thermoplastic Polymer ◽  
Fracture Properties ◽  
Impact Fracture Behavior ◽  
The Impact ◽  
Scanning Electron

Attempts have been made to improve the impact resistance of biodegradable thermoplastic polymer, PLA. A ductile biodegradable polymer, PCL, has been used to improve such property of PLA by using blending technique. Details of the impact fracture properties and mechanisms of PLA/PCL blends, however, have not fully been understood yet. Recently, it was also found that LTI can improve the immiscibility between PLA and PCL. In this study, PLA/PCL and PLA/PCL/LTI blends were prepared, and their impact fracture toughness values were measuredto assess the effect of PCL content and LTI addition on the impact resistance. Fracture mechanisms of the polymer blends were also characterized by scanning electron microscopy.

Analytical and Experimental Investigation of Flow and Fracture Mechanisms Induced by Indentation in Single Crystal MgO

1982 ◽  
Vol 26 ◽  
pp. 299-306
Author(s):  
T. Larchuk ◽  
T. Kato ◽  
R. N. Pangborn ◽  
J. C. Conway
Keyword(s):  
Fracture Behavior ◽  
Large Degree ◽  
Surface Damage ◽  
Fracture Mechanisms ◽  
Flow Zone ◽  
Double Crystal ◽  
Contact Loading ◽  
X Ray ◽  
Static Contact ◽  
And Performance

The flow and fracture behavior of ceramic and other brittle materials under the influence of contact loading is important to both component fabrication and performance. The ease of machining, severity of residual surface damage and rate of wear during subsequent service are controlled to a large degree by the character and extent of the flow zone and its influence on the fracture mode. This Investigation was undertaken to provide experimental verification of the results obtained through elastic/plastic finite element modeling cf the stress distribution and deformations introduced by static contact loading. Experimentally, X-ray double-crystal diffractometry (DCD) was applied to obtain a mapping of the distortions produced beneath a Vickers indenter, and hence to evaluate the effect of material and geometric parameters on the flow and fracture mechanisms.

scholarly journals Correlation of Macroscopic Fracture Behavior with Microscopic Fracture Mechanism for AHSS Sheet

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 900 ◽  
Author(s):  
Lingyun Qian ◽  
Xiaocan Wang ◽  
Chaoyang Sun ◽  
Anyi Dai
Keyword(s):  
Fracture Mechanism ◽  
Fracture Behavior ◽  
Pure Shear ◽  
Stress Triaxiality ◽  
High Strength ◽  
Numerical Approach ◽  
Fracture Mechanisms ◽  
Macroscopic Fracture ◽  
Shear Slip ◽  
Stress States

This research aims to correlate the macroscopic fracture phenomenon with its microscopic fracture mechanism for an advanced high-strength steel (AHSS) TRIP 780 sheet by applying a combined experimental-numerical approach. Six specimens with different shapes were tensioned to fracture and the main deformation areas of specimens were subjected to stress states ranging from lower to higher stress triaxiality. The final fracture surface feature for each specimen was obtained to characterize the macroscopic fracture modes at different stress states. The scanning electron microscope (SEM) fractographies of fracture surfaces were detected to reveal the microscopic fracture mechanisms. The stress triaxiality evolution was applied to correlate of fracture mode and fracture mechanism by comparing the macroscopic fracture features as well as micro-defect changes. An increase of stress triaxiality leads to voids extension and then results in a voids-dominant fracture. The micro-shear-slip tends to appear in the stress triaxiality level lower than that of pure shear stress state. The fracture behavior of a practice deformation process was the result of interplay between shear-slip fracture and void-dominant fracture. The unified relationship between average void sizes and stress triaxiality was obtained. The void growth was predicted by the Rice–Tracey model with higher precision.

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