Rate-Dependent Cohesive Zone Modeling of Unstable Crack Growth in an Epoxy Adhesive

2005 ◽  
Author(s):  
Dhaval P. Makhecha ◽  
Rakesh K. Kapania ◽  
Eric R. Johnson ◽  
David A. Dillard ◽  
George C. Jacob ◽  
...  
Keyword(s):  
Energy Release Rate ◽  
Crack Growth ◽  
Release Rate ◽  
Cohesive Zone ◽  
Compact Tension ◽  
Epoxy Adhesive ◽  
Mode I ◽  
Unstable Crack ◽  
Rate Dependent ◽  
Fracture Tests

This paper presents the development and numerical implementation of a rate dependent fracture model of an epoxy adhesive. Previous mode I fracture tests conducted under quasistatic, displacement controlled loading of an aluminum double cantilever beam (DCB) bonded with the epoxy exhibited unstable crack growth in the adhesive. Results from mode I fracture tests of compact tension specimens made from bulk adhesive at increasing cross head opening speeds are reported in this paper. The compact tension tests results showed a decreasing critical strain energy release rate with increasing cross head speed, with the critical energy release rate at 1 m/s cross head speed equal to about 20% of its quasi-static value. Two rate dependent cohesive zone models are formulated based on the compact tension test data. A cohesive de-cohesive relationship was postulated between the tractions acting across the crack faces and the opening displacement and opening velocity. These rate dependent cohesive zone models are implemented in a interface finite element to model discrete crack growth in the adhesive. The reaction force history from simulation of the DCB test is in good agreement with the test data using only the rate dependent interface element to model the adhesive.

Rate-Dependent Cohesive Zone Modeling of Unstable Crack Growth in an Epoxy Adhesive

2009 ◽  
Vol 16 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Dhaval P. Makhecha ◽  
Rakesh K. Kapania ◽  
Eric R. Johnson ◽  
David A. Dillard ◽  
George C. Jacob ◽  
...  
Keyword(s):  
Crack Growth ◽  
Cohesive Zone ◽  
Epoxy Adhesive ◽  
Cohesive Zone Modeling ◽  
Unstable Crack ◽  
Unstable Crack Growth ◽  
Rate Dependent ◽  
Zone Modeling

The Characterization of Mixed-Mode Energy Release Rates in Orthotropic Materials

1996 ◽  
Vol 210 (1) ◽  
pp. 33-42 ◽  
Author(s):  
C A Walker ◽  
Jamasri
Keyword(s):  
Finite Element ◽  
Energy Release Rate ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Mode I ◽  
Mode Ii ◽  
Finite Element Models ◽  
Release Rates ◽  
Energy Release Rates

The aim of this work was to predict, from the material constants, mixed-mode energy release rates in orthotropic materials, in particular the general cases in which the crack is aligned at a random angle to the principal material direction, normal to the plane of orthotropy. Two-dimensional finite element models with various fibre orientations were generated. The finite element models were validated by comparing two sets of contour plots of deformation, one resulting from the finite element analysis and the other from moiré interferograms of the experimental work. On comparison there was shown to be a strict similarity between experimentally determined and computational deformation fields. Variations of the energy release rates were investigated for both rapid and stable crack growth. This was accomplished by generating two-dimensional stable crack growth finite element models. In general, energy release rates were found to be strongly affected by the fibre orientation. An increase of the angle of the crack growth direction caused a decrease of the mode I energy release rate and, by contrast, an increase of the mode II energy release rate, but the mode II energy release rate was always a small fraction of the mode I value. Crack extension caused a gradual increase of the mode I energy release rate both for coplanar and non-coplanar crack growth. However, there was no significant effect found on the mode II energy release rate.

scholarly journals An alternative numerical method for calculating C* parameter under mode I loading utilizing rate-dependent energy release rate

2020 ◽  
Vol 109 ◽  
pp. 102737
Author(s):  
Xianhe Du ◽  
Yanwei Dai ◽  
Qiang Han ◽  
Yinghua Liu ◽  
Peng Cao ◽  
...  
Keyword(s):  
Energy Release Rate ◽  
Numerical Method ◽  
Energy Release ◽  
Release Rate ◽  
Mode I ◽  
Rate Dependent ◽  
Mode I Loading

Interlaminar Mode I crack growth energy release rate of carbon/carbon composites

2013 ◽  
Vol 100 ◽  
pp. 38-51 ◽  
Author(s):  
T. Krause ◽  
K. Tushtev ◽  
D. Koch ◽  
G. Grathwohl
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Mode I ◽  
Carbon Composites ◽  
Mode I Crack ◽  
Growth Energy

Poroelastic Effects on the Time- and Rate-Dependent Fracture of Polymer Gels

2019 ◽  
Vol 87 (3) ◽  
Author(s):  
Yalin Yu ◽  
Nikolaos Bouklas ◽  
Chad M. Landis ◽  
Rui Huang
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Cohesive Zone ◽  
Polymer Gels ◽  
Time Dependent ◽  
Crack Speed ◽  
Delayed Fracture ◽  
Solvent Diffusion ◽  
Rate Dependent

Abstract Fracture of polymer gels is often time- and rate-dependent. Subject to a constant load, a gel specimen may fracture immediately or after a delay (time-dependent, delayed fracture). When a crack grows in a gel, the fracture energy may depend on the crack speed (rate-dependent). The underlying mechanisms for the time- and rate-dependent fracture of gels could include local molecular processes, polymer viscoelasticity, and solvent diffusion coupled with deformation (poroelasticity). This paper focuses on the effects of poroelasticity. A path-independent, modified J-integral approach is adopted to define the crack-tip energy release rate as the energetic driving force for crack growth in gels, taking into account the energy dissipation by solvent diffusion. For a stationary crack, the energy release rate is time-dependent, with which delayed fracture can be predicted based on a Griffith-like fracture criterion. For steady-state crack growth in a long-strip specimen, the energy release rate is a function of the crack speed, with rate-dependent poroelastic toughening. With a poroelastic cohesive zone model, solvent diffusion within the cohesive zone leads to significantly enhanced poroelastic toughening as the crack speed increases, rendering a rate-dependent traction-separation relation. While most of the results are based on a linear poroelastic formulation, future studies may extend to nonlinear theories with large deformation. In addition to the poroelastic effects, other mechanisms such as viscoelasticity and local fracture processes should be studied to further understand the time and rate-dependent fracture of polymer gels.

Mode I Steady Crack-Growth in Superelastic Shape Memory Alloys

2012 ◽  
Author(s):  
Theocharis Baxevanis ◽  
Dimitris Lagoudas ◽  
Chad Landis
Keyword(s):  
Shape Memory Alloys ◽  
Energy Release Rate ◽  
Shape Memory ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Crack Tip ◽  
Scale Transformation ◽  
Small Scale ◽  
Mode I

A numerical analysis of quasi-static, steady state crack growth in superelastic Shape Memory Alloys (SMAs) under small-scale transformation conditions is carried out for plane strain, mode I loading. Crack growth is assumed to proceed at a critical level of the crack-tip energy release rate. Finite-element results concerning the mechanical fields near the advancing crack tip are presented and the ratio of the far-field applied energy release rate to the crack-tip energy release rate is obtained for a range of thermomechanical parameters. A substantial fracture toughening is observed associated with closure stresses placed on the crack tip by the transformed material left behind in the wake of the advancing crack tip.

The Spherical Indentation Approach for Fracture Toughness Evaluation: A Study Based on the Energy Release Rate

2018 ◽  
Author(s):  
Tairui Zhang ◽  
Weiqiang Wang ◽  
Aiju Li
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Damage Mechanism ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Spherical Indentation ◽  
Material Damage ◽  
Fracture Tests

In this study, we investigated the drawbacks of previous studies regarding the evaluation of fracture toughness from spherical indentation tests (SITs). This was achieved by an examination of the material damage mechanism during indentation tests, uniaxial tensile tests, and Mode I/II fracture tests. A new approach based on the energy release rate was proposed in this study to evaluate the fracture toughness of ductile metals. Scanning electron microscope (SEM) observations revealed that the mechanism for material damage during an indentation test was different with the material damage in uniaxial tensile tests and Mode I fracture tests, but similar to that in Mode II fracture tests. Thus, the energy release rate during SITs should be correlated with JIIC. Compared with previous studies, this new proposed method was more consistent with the actual damage mechanism and did not rely on the specific critical damage values. Experiments on SA508, SA533, 15CrMoR, and S30408 revealed that the maximum error from this energy release rate-based approach was no more than 13% when compared with their conventional counterparts (compact tension tests), and thus can meet the precision requirement of engineering applications.

scholarly journals R-curve Evaluation of Copper and Nickel Single Crystals Using Atomistic Simulations

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 441 ◽  
Author(s):  
Xiao Zhuo ◽  
Jang Kim ◽  
Hyeon Beom
Keyword(s):  
Energy Release Rate ◽  
Single Crystals ◽  
Crack Growth ◽  
Release Rate ◽  
Edge Crack ◽  
Strain Energy ◽  
Critical Strain ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Crack Growth Resistance

The technique of molecular statics (MS) simulation was employed to determine the crack growth resistance curve of Cu and Ni single crystals. Copper and Ni single crystal nanoplates with an edge crack subjected to a tensile displacement were simulated. Stress-displacement curves and snapshots of the atomic configuration corresponding to different displacement levels were presented to elucidate the deformation mechanism. It was observed that the edge crack propagated step by step in a brittle manner, and the amount of crack growth at each step was half the lattice parameter. Through an energy consideration, the critical strain energy release rate at the onset of crack propagation and the crack growth resistance were calculated. The crack growth resistance is larger than the critical strain energy release rate because of the crack growth effect.

Accurate evaluation of strain-energy release rate in unidirectional FRP compact-tension specimen

1997 ◽  
Vol 58 (3) ◽  
pp. 163-172 ◽  
Author(s):  
R. Ramesh Kumar ◽  
M.K. Jana ◽  
G. Venkateswara Rao ◽  
K.S. Anoop Kumar
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Tension Specimen ◽  
Accurate Evaluation
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