Effects of grain boundary heterogeneities on creep fracture studied by rate-dependent cohesive model

2012 ◽  
Vol 93 ◽  
pp. 48-64 ◽  
Author(s):  
Chi-Hua Yu ◽  
Chang-Wei Huang ◽  
Chuin-Shan Chen ◽  
Yanfei Gao ◽  
Chun-Hway Hsueh
Keyword(s):  
Grain Boundary ◽  
Cohesive Model ◽  
Creep Fracture ◽  
Rate Dependent

scholarly journals CHARACTERIZATIONS OF SIZE EFFECT AND OVERALL MECHANICAL BEHAVIOR OF NANOCRYSTALLINE METALS

2013 ◽  
Vol 05 (01) ◽  
pp. 1350004 ◽  
Author(s):  
LI CHEN ◽  
YUEGUANG WEI
Keyword(s):  
Grain Boundary ◽  
Energy Release Rate ◽  
Mechanical Behavior ◽  
Energy Release ◽  
Release Rate ◽  
Mixed Mode ◽  
Gradient Plasticity ◽  
Cohesive Model ◽  
Critical Separation ◽  
Boundary Fracture

A systematical study of size effects and mechanical behaviors for the nanocrystalline (nc) metals is performed. The grain boundary fracture process is considered and described by the mixed-mode interface cohesive model. The grain material is characterized by the conventional theory of strain gradient plasticity. In the present investigation, the effects of five important parameters on the overall mechanical behavior are studied systematically, which include the grain size, critical separation strength, energy release rate of interface separation, mixity of separation strength, as well as the mixity of separation energy release rate. A finite element method (FEM) covering the above characteristics within the grain and on the grain boundary is developed. The present results show that the overall strength and ductility of the nc metals strongly depend on the grain boundary features described by the mixed-mode cohesive interface model, and there is a competition of deformation of grain boundary with that of grain interior.

GROWTH AND LINKAGE OF CRACKS AND FORMATION OF CREEP FRACTURE PATTERN SIMULATED BY A MULTICRACK GROWTH MODEL

Fractals ◽  
2001 ◽  
Vol 09 (02) ◽  
pp. 223-230 ◽  
Author(s):  
MANABU TANAKA ◽  
RYUICHI KATO ◽  
ATSUSHI KAYAMA
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Growth Model ◽  
Size Dependence ◽  
Grain Boundary Sliding ◽  
Fracture Pattern ◽  
Square Lattice ◽  
Creep Fracture ◽  
Lattice Effects ◽  
Boundary Sliding

A computer simulation using a multicrack growth model was carried out on the growth and linkage of cracks and the formation of creep fracture pattern resulting from the initial defects. The percolated crack patterns and the number of steps to percolation were examined by Monte Carlo simulation on a square lattice. Effects of stress and grain size on creep fracture process are then discussed. The stress and grain size dependence of the number of steps to percolation in the simulation was similar to that of grain-boundary sliding in the austenitic 21Cr-4Ni-9Mn heat-resisting steel, which controlled the growth of grain-boundary cracks. The fractal dimension of the percolation crack was also correlated with that of the creep fracture pattern in the 21Cr-4Ni-9Mn steel.

scholarly journals Calibration of a Cohesive Model for Fracture in Low Cross-Linked Epoxy Resins

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1321 ◽  
Author(s):  
Dery Torres ◽  
Shu Guo ◽  
Maria-Pilar Villar ◽  
Daniel Araujo ◽  
Rafael Estevez
Keyword(s):  
Epoxy Resin ◽  
Epoxy Resins ◽  
Glassy Polymer ◽  
Failure Process ◽  
Shear Bands ◽  
Glassy Polymers ◽  
Constitutive Law ◽  
Cohesive Model ◽  
Rate Dependent ◽  
Structural Applications

Polymer-based composites are becoming widely used for structural applications, in particular in the aeronautic industry. The present investigation focuses on the mechanical integrity of an epoxy resin of which possible damage results in limitation or early stages of dramatic failure. Therefore, a coupled experimental and numerical investigation of failure in an epoxy resin thermoset is carried out that opens the route to an overall micromechanical analysis of thermoset-based composites. In the present case, failure is preceded by noticeable plasticity in the form of shear bands similar to observations in ductile glassy polymers. Thus, an elastic-visco-plastic constitutive law initially devoted to glassy polymer is adopted that captures the rate- dependent yield stress followed by softening and progressive hardening at continued deformation. A general rate-dependent cohesive model is used to describe the failure process. The parameters involved in the description are carefully identified and used in a finite element calculation to predict the material’s toughness for different configurations. Furthermore, the present work allows investigation of nucleation and crack growth in such resins. In particular, a minimum toughness can be derived from the model which is difficult to evaluate experimentally and allows accounting for the notch effect on the onset of failure. This is thought to help in designing polymer-based composites.

DEPENDENCE OF CREEP FRACTURE OF INCONEL 718 ON GRAIN BOUNDARY PRECIPITATES

1997 ◽  
Vol 45 (7) ◽  
pp. 2735-2746 ◽  
Author(s):  
W. CHEN ◽  
M.C. CHATURVEDI
Keyword(s):  
Grain Boundary ◽  
Inconel 718 ◽  
Creep Fracture

Analysis of a rate-dependent cohesive model for dynamic crack propagation

2002 ◽  
Vol 70 (5) ◽  
pp. 685-704 ◽  
Author(s):  
Dhirendra V. Kubair ◽  
Philippe H. Geubelle ◽  
Yonggang Y. Huang
Keyword(s):  
Crack Propagation ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Cohesive Model ◽  
Rate Dependent
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