scholarly journals Relationship Between Apparent (Total) Charpy Vee-Notch Toughness and the Corresponding Dynamic Crack-Propagation Resistance

1998 ◽  
Author(s):  
Brian N. Leis ◽  
Robert J. Eiber ◽  
L. Carlson ◽  
A. Gilroy-Scott
Keyword(s):  
Crack Propagation ◽  
Ductile Fracture ◽  
Dynamic Fracture ◽  
Empirical Models ◽  
Full Scale ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Arrest Toughness

The consequences of a dynamic fracture in a gas-transmission pipeline require that pipelines be designed to avoid such incidents at a high level of certainty. For this reason, the related phenomonology has been studied since the early 1970s when the possibility of a dynamic ductile fracture was recognized. Full-scale experiments were done to characterize the fracture and gas dynamics associated with this process and empirical models were developed as a means to represent these experiments in a design or analysis setting. Such experiments focused on pure methane gas, and in the early days used steels with toughnesses less than 100 J, consistent with the steel making capabilities of the 1970s. Subsequently, interest shifted to larger diameter, higher pressure, higher BTU “rich” gases requiring higher toughness steels. The full-scale tests conducted to validate the arrest toughness levels determined that these empirical models were non-conservative. This paper presents a relationship between the dynamic crack propagation resistance and the apparent crack propagation resistance as measured by Charpy vee-notch (CVN) test specimens. This relationship is used in conjunction with the existing Battelle empirical criterion for dynamic-fracture arrest to determine the apparent toughness required to arrest a propagating ductile fracture in gas-transmission pipelines. The validity of this relationship is illustrated by successful predictions of arrest toughness in pipelines under a range of conditions including rich gases and high-toughness steels, including those showing a rising upper-shelf behavior.

scholarly journals Dynamic Fracture Analysis of Functional Gradient Material Coating Based on the Peridynamic Method

Coatings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 62 ◽  
Author(s):  
Yu Zhang ◽  
Zhanqi Cheng ◽  
Hu Feng
Keyword(s):  
Elastic Modulus ◽  
Crack Propagation ◽  
Dynamic Fracture ◽  
Gradient Material ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Functional Gradient ◽  
Damage And Failure ◽  
Functional Gradient Material ◽  
Graded Material

Functional gradient materials (FGMs) have tremendous potential due to their characteristic advantage of asymptotic continuous variation of their properties. When an FGM is used as a coating material, damage and failure of the interface with the substrate component can be effectively inhibited. In order to study the dynamic crack propagation in FGM coatings, a new method, peridynamics (PD), was used in the present study to simulate dynamic fractures of FGM coatings bonded to a homogeneous substrate under dynamic loading. The bond-based PD theory was employed to study crack propagation and branching in the FGM coating. The influences of the coating gradient pattern, loading, and the geometry and size of the structure on crack curving and propagation under impact loading were investigated. The numerical results show that different forms of the elastic modulus of graded material, the geometry of the structure, and the loading conditions have considerate effects on crack propagation in FGM coatings, but a specific form of elastic modulus had a limited effect on the dynamic fracture of FGM coating.

Theoretical Research on the Dynamic Crack Propagation Velocity Based on Nonlocal Field Theories

2009 ◽  
Vol 417-418 ◽  
pp. 953-956
Author(s):  
Cai Ping Liu ◽  
Qing Quan Duan ◽  
Jian Ping Zuo
Keyword(s):  
Crack Propagation ◽  
Dynamic Fracture ◽  
Propagation Velocity ◽  
Characteristic Length ◽  
Theoretical Research ◽  
Field Theories ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Crack Propagation Velocity ◽  
Nonlocal Field

The purpose of this paper is to discuss the nonlocal effect on dynamic crack propagation velocity. Some experimental phenomena in dynamic fracture and simulative results using molecular & atom dynamics were analyzed and discussed in this paper. The authors found that there were still some disagreements on the dynamic crack propagation velocity. Based on these researches, we introduced nonlocal field theories into the estimation of dynamic crack propagation velocity. The dynamic crack propagation velocity is affected not only by the crack instability, but by characteristic length of material. A nonlocal characteristic length parameter M is defined through a double pile-up dislocation model. According to the Mott’s research method for crack velocity in dynamic fracture and the nonlocal field theories, an approximate theoretical dynamic propagation velocity is obtained. And we conclude that the velocity is related to the combined activity of the nonlocal characteristic length parameter M, the velocity of longitudinal wave, constant k, crack length and Poisson’s ratio.

scholarly journals Uncovering the dynamic fracture behavior of PMMA

2019 ◽  
Author(s):  
Javad Mehrmashhadi ◽  
Longzhen Wang ◽  
Florin Bobaru
Keyword(s):  
Crack Propagation ◽  
Dynamic Fracture ◽  
Fracture Behavior ◽  
Numerical Models ◽  
Process Zone ◽  
Crack Tip ◽  
Dynamic Crack Propagation ◽  
Experimental Investigations ◽  
Dynamic Crack ◽  
Strain Rates

Experimental investigations of dynamic crack propagation in PMMA induced by impact show single cracks running at around 300-400 m/s. Existing numerical models for simulating dynamic fracture in PMMA consistently produce crack propagation speeds significantly higher than those measured experimentally. Here we uncover the reason for this puzzle by showing that localized softening in the fracture process zone (caused by heating due to high strain rates in front of the crack tip), leads to crack propagation speeds that match the observed ones. We introduce a new constitutive model in our peridynamic formulation for PMMA to account for material softening in the crack tip region. With the new model, the computed crack speed and crack length evolution match very closely those found experimentally.

scholarly journals Variable-order fracture mechanics and its application to dynamic fracture

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Sansit Patnaik ◽  
Fabio Semperlotti
Keyword(s):  
Dynamic Fracture ◽  
Crack Surface ◽  
A Priori ◽  
Computational Cost ◽  
Dynamic Crack Propagation ◽  
Benchmark Problems ◽  
Variable Order ◽  
Dynamic Crack ◽  
Brittle Solids ◽  
Complex Crack

AbstractThis study presents the formulation, the numerical solution, and the validation of a theoretical framework based on the concept of variable-order mechanics and capable of modeling dynamic fracture in brittle and quasi-brittle solids. More specifically, the reformulation of the elastodynamic problem via variable and fractional-order operators enables a unique and extremely powerful approach to model nucleation and propagation of cracks in solids under dynamic loading. The resulting dynamic fracture formulation is fully evolutionary, hence enabling the analysis of complex crack patterns without requiring any a priori assumption on the damage location and the growth path, and without using any algorithm to numerically track the evolving crack surface. The evolutionary nature of the variable-order formalism also prevents the need for additional partial differential equations to predict the evolution of the damage field, hence suggesting a conspicuous reduction in complexity and computational cost. Remarkably, the variable-order formulation is naturally capable of capturing extremely detailed features characteristic of dynamic crack propagation such as crack surface roughening as well as single and multiple branching. The accuracy and robustness of the proposed variable-order formulation are validated by comparing the results of direct numerical simulations with experimental data of typical benchmark problems available in the literature.

Dynamic crack propagation in matrix involving inclusions by a time-domain BEM

2012 ◽  
Vol 36 (5) ◽  
pp. 651-657 ◽  
Author(s):  
Jun Lei ◽  
Yue-Sheng Wang ◽  
Yifeng Huang ◽  
Qingsheng Yang ◽  
Chuanzeng Zhang
Keyword(s):  
Crack Propagation ◽  
Time Domain ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack

Dynamic Crack Propagation in Single-Crystalline Silicon

1998 ◽  
Vol 539 ◽  
Author(s):  
T. Cramer ◽  
A. Wanner ◽  
P. Gumbsch
Keyword(s):  
Crack Propagation ◽  
Crystalline Silicon ◽  
Potential Drop ◽  
Tensile Tests ◽  
Terminal Velocity ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Single Crystalline Silicon ◽  
Single Crystalline ◽  
Crack Propagation Velocity

AbstractTensile tests on notched plates of single-crystalline silicon were carried out at high overloads. Cracks were forced to propagate on {110} planes in a <110> direction. The dynamics of the fracture process was measured using the potential drop technique and correlated with the fracture surface morphology. Crack propagation velocity did not exceed a terminal velocity of v = 3800 m/s, which corresponds to 83%7 of the Rayleigh wave velocity vR. Specimens fractured at low stresses exhibited crystallographic cleavage whereas a transition from mirror-like smooth regions to rougher hackle zones was observed in case of the specimens fractured at high stresses. Inspection of the mirror zone at high magnification revealed a deviation of the {110} plane onto {111} crystallographic facets.

scholarly journals Dynamic crack propagation in a 2D elastic body. The out-of plane case

PAMM ◽  
2007 ◽  
Vol 7 (1) ◽  
pp. 1090801-1090802
Author(s):  
A.-M. Sändig ◽  
A. Lalegname ◽  
S. Nicaise
Keyword(s):  
Crack Propagation ◽  
Elastic Body ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Plane Case ◽  
Out Of Plane
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