scholarly journals Multi-Parameter Yield Zone Model for Predicting Spectrum Crack Growth

2009 ◽  
pp. 85-85-18 ◽  
Author(s):  
WS Johnson
Keyword(s):  
Crack Growth ◽  
Zone Model ◽  
Yield Zone

Predictions of the Effect of Yield Strength on Fatigue Crack Growth Retardation in HP-9Ni-4Co-30C Steel

1975 ◽  
Vol 97 (3) ◽  
pp. 206-213 ◽  
Author(s):  
G. J. Petrak ◽  
J. P. Gallagher
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Test Data ◽  
Growth Rates ◽  
Zone Model ◽  
Constant Amplitude ◽  
Yield Zone

Baseline mechanical property data, constant amplitude fatigue crack growth rate data, and single-peak overload test data are presented for HP-9Ni-4Co-30C steel heat treated to three strength levels. These data are then used to evaluate a new model proposed for defining the instantaneous crack growth rate following an overload. The constant amplitude crack growth rates are affected by the strength level of the material with the higher strength exhibiting the faster cracking rates. The magnitude of retardation following an overload cycle is also shown to be influenced by the strength of the material. The lower strength steel displayed significantly more retardation for the same load levels. A general yield zone model is used to predict retarded growth rates. These predictions are shown to correlate quite well with the test data. The model successfully accounts for the different amounts of retardation associated with the different strength levels of the material.

Modeling of Crack Growth in Thin Sheet Aluminum

1999 ◽  
Author(s):  
T. Siegmund ◽  
W. Brocks ◽  
J. Heerens ◽  
G. Tempus ◽  
W. Zink
Keyword(s):  
Crack Growth ◽  
Cohesive Energy ◽  
Cohesive Zone Model ◽  
Plastic Material ◽  
Thin Sheet ◽  
High Strength ◽  
Cohesive Strength ◽  
Zone Model ◽  
Additional Material ◽  
Center Crack

Abstract The present study reports on the application of a cohesive zone model to the analyses of crack growth in thin sheet specimen of a high strength aluminum alloy. In addition to the elastic-plastic material properties, the two parameters cohesive strength and cohesive energy describe material separation. For the sheet specimen under investigation the cohesive energy is determined via a numerical-experimental approach using tests on notched tensile specimens as well as a damage indicator. The cohesive energy is found to be close to the corresponding value of plane strain fracture toughness. The cohesive strength is approximately twice the yield strength. With these two additional material parameters being determined crack growth experiments in center crack panels are analyzed. Good agreement with experimental records is found. Finally the applicability of the model to study complex crack configurations as in multi-site damaged specimens is demonstrated.

scholarly journals New CZM for Interfacial Crack Growth

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Huifen Peng ◽  
Yujie Song ◽  
Ye Xia
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Growth ◽  
Interface Crack ◽  
Interfacial Crack ◽  
Structure Design ◽  
Zone Model ◽  
Simulation Results ◽  
The Impact ◽  
Element Method

The cohesive zone model (CZM) has been widely used for numerical simulations of interface crack growth. However, geometrical and material discontinuities decrease the accuracy and efficiency of the CZM when based on the conventional finite element method (CFEM). In order to promote the development of numerical simulation of interfacial crack growth, a new CZM, based on the wavelet finite element method (WFEM), is presented. Some fundamental issues regarding CZM of interface crack growth of double cantilever beam (DCB) testing were studied. The simulation results were compared with the experimental and simulation results of CFEM. It was found that the new CZM had higher accuracy and efficiency in the simulation of interface crack growth. At last, the impact of crack initiation length and elastic constants of material on interface crack growth was studied based on the new CZM. These results provided a basis for reasonable structure design of composite material in engineering.

Nonuniformity of crack-growth resistance and breakdown zone near the propagating tip of a shear crack in brittle rock: A model for earthquake nucleation to dynamic rupture

1990 ◽  
Vol 68 (9) ◽  
pp. 1071-1083 ◽  
Author(s):  
Mitiyasu Ohnaka
Keyword(s):  
Crack Growth ◽  
Constitutive Relation ◽  
High Frequency ◽  
Crack Growth Resistance ◽  
Earthquake Source ◽  
Source Process ◽  
Zone Model ◽  
The Earth ◽  
Shear Rupture ◽  
Propagating Shear

This paper reviews our recent studies on (i) slip failure nucleation, which leads to the mechanical instability that gives rise to a dynamically propagating shear rupture, (ii) constitutive behavior during the local breakdown process near the propagating tip of the slipping zone, and (iii) the physical modeling of the earthquake-source process based on the constitutive relation inferred from laboratory experiments. Laboratory studies were done using a simulated fault in rock in the brittle regime under a mode II crack-growth condition, to gain a deeper understanding of the earthquake-source process, which is considered to be dynamically propagating shear rupture in the earth. A stable but accelerating phase of nucleation locally precedes an unstable dynamically propagating rupture even in the brittle regime. The appearance of a sizable zone of such nucleation is related to a nonuniform distribution of the crack-growth resistance on the fault. The local shear strength degrades to a residual friction stress level with ongoing slip near the propagating tip of the slipping zone. This slip-dependent constitutive relation shows that there is a breakdown zone near the propagating tip over which shear stress, slip displacement, slip velocity, and slip acceleration are highly nonuniform. This nonuniformity is responsible for generating high-frequency elastic radiation. A model of the breakdown zone, which incorporates the laboratory-based constitutive relation, does not give rise to unrealistic singularities of slip acceleration and stresses at and near the dynamically propagating tip of the slipping zone. The breakdown zone model enables one to give a common interpretation to both small-scale slip failure in the laboratory and large-scale shear failure as earthquake faulting in the earth, and it can explain the earthquake-source strong motion characterized by the high-frequency content.

Irreversible cyclic cohesive zone model for prediction of mode I fatigue crack growth in CFRP-strengthened steel plates

2020 ◽  
Vol 110 ◽  
pp. 102804
Author(s):  
M. Mohajer ◽  
M. Bocciarelli ◽  
P. Colombi ◽  
A. Hosseini ◽  
A. Nussbaumer ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Steel Plates ◽  
Mode I ◽  
Zone Model
Sign in / Sign up

Export Citation Format

Share Document