D-53 Changes in Elastic Strain Profiles Around a Crack Tip During Tensile Loading and Unloading Cycles

2004 ◽  
Vol 19 (2) ◽  
pp. 199-199
Author(s):  
Y. Sun ◽  
P. K. Liaw ◽  
Y. L. Lu ◽  
B. Yang ◽  
H. Choo ◽  
...  
Keyword(s):  
Elastic Strain ◽  
Crack Tip ◽  
Tensile Loading ◽  
Loading And Unloading

Neutron diffraction studies on lattice strain evolution around a crack-tip during tensile loading and unloading cycles

2005 ◽  
Vol 53 (8) ◽  
pp. 971-975 ◽  
Author(s):  
Yinan Sun ◽  
Hahn Choo ◽  
Peter K. Liaw ◽  
Yulin Lu ◽  
Bing Yang ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Lattice Strain ◽  
Crack Tip ◽  
Tensile Loading ◽  
Strain Evolution ◽  
Loading And Unloading

scholarly journals A Study of Internal Damage of Metal Matrix Composites by Neutron Diffraction

1994 ◽  
Vol 376 ◽  
Author(s):  
N. Shi ◽  
M. A. M. Bourke ◽  
J. A. Goldstone
Keyword(s):  
Neutron Diffraction ◽  
Elastic Strain ◽  
Tensile Loading ◽  
Uniaxial Tensile ◽  
Strain Response ◽  
Matrix Composites ◽  
Internal Damage ◽  
Sic Composites ◽  
Phase Stresses ◽  
Phase Strains

ABSTRACTUsing neutron diffraction, we have measured the elastic phase strains of Al/TiC and Al/SiC composites under uniaxial tensile loading. The phase strains were used to reconstruct the global elastic strain. It has been found that, above macroscopic yield, the global elastic strain response is not linear. A theoretical model shows that the nonlinearity is dictated by changes in the ratio of longitudinal phase stresses. Furthermore, the changes in this ratio resulting from matrix plasticity and reinforcement fracture are different which leads to distinct slope changes in the global elastic strain response that can be used to distinguish the onset of these two processes on the global elastic strain loading curve.

The Elastic Behaviour of Metal Powder Compacts

2007 ◽  
Vol 534-536 ◽  
pp. 325-328
Author(s):  
Jose Manuel Prado
Keyword(s):  
Mathematical Model ◽  
Simple Model ◽  
Elastic Strain ◽  
Elastic Behaviour ◽  
Compression Tests ◽  
Linear Elastic ◽  
Loading And Unloading ◽  
Powder Compacts ◽  
The Mathematical Model ◽  
Different Levels

In this work the elastic behaviour of metallic powder compacts is studied. Cylindrical specimens with different levels of density have been submitted to uniaxial compression tests with loading and unloading cycles. The analysis of the elastic loadings shows a non linear elasticity which can be mathematically represented by means of a potential law. Results are explained by assuming that the total elastic strain is the contribution of two terms one deriving from the hertzian deformation of the contacts among particles and another that takes into account the linear elastic deformation of the powder skeleton. A simple model based in a one pore unit cell is presented to support the mathematical model.

The behavior of screw dislocations dynamically emitted from the tip of a surface crack during loading and unloading

1995 ◽  
Vol 10 (1) ◽  
pp. 183-189 ◽  
Author(s):  
C.C. Huang ◽  
C.C. Yu ◽  
Sanboh Lee
Keyword(s):  
Surface Crack ◽  
Crack Tip ◽  
Friction Stress ◽  
Critical Stress Intensity Factor ◽  
Dislocation Model ◽  
Dislocation Emission ◽  
Screw Dislocations ◽  
Free Zone ◽  
Discrete Dislocation ◽  
Loading And Unloading

The behavior of screw dislocations dynamically emitted from the tip of a surface crack during loading and unloading has been investigated using a discrete dislocation model. The critical stress intensity factor at the crack tip for dislocation emission is a function of friction stress, core radius of dislocation, and dislocations near the crack tip. During motion, the velocity of dislocation is assumed to be proportional to the effective shear stress to the third power. The effect of crack length and friction stress on dislocation distributions, plastic zone, and dislocation-free zone during loading and unloading was examined.

Modeling Viscoelastic and Viscoplastic Behavior of High Density Polyethylene (HDPE)

2006 ◽  
Vol 128 (4) ◽  
pp. 572-578 ◽  
Author(s):  
Ozgen U. Colak ◽  
Necmi Dusunceli
Keyword(s):  
Strain Rate ◽  
Rate Equation ◽  
High Density Polyethylene ◽  
Elastic Strain ◽  
High Density ◽  
Cyclic Behavior ◽  
Compression Tests ◽  
Rate Dependency ◽  
Loading And Unloading ◽  
Simulation Results

The viscoelastic and viscoplastic behaviors of high density polyethylene (HDPE) under uniaxial monotonic and cyclic loading are modeled using the modified viscoplasticity theory based on overstress (VBO). The viscoelastic modeling capabilities of the modified VBO are investigated by simulating the behavior of semicrystalline HDPE under uniaxial compression tests at different strain rates. In addition, the effects of the modification (introducing the variable “C” into an elastic strain rate equation) on VBO that has been made to construct the change in the elastic stiffness while loading and unloading are investigated. During first loading and unloading, the modification in the elastic strain rate equation improves the unloading behavior. To investigate how the variable “C” that is introduced in the elastic strain rate equation evolves during reloading, the cyclic behavior of HDPE is modeled. For a complete viscoelastic and viscoplastic behavior, the relaxation and creep behaviors of HDPE are simulated as well in addition to stress and strain rate dependency. The influences of the strain (stress) levels where the relaxation (creep) experiments are performed are investigated. The simulation results are compared with the experimental data obtained by Zhang and Moore (1997, Polym. Eng. Sci., 37, pp. 404–413). A good match between experimental and simulation results are observed.

Study on Anisotropic Mechanical Behavior at near Pre-Crack for AZ31B Sheet under Biaxial Stress

2013 ◽  
Vol 750 ◽  
pp. 196-199
Author(s):  
Jian Gang Wang ◽  
Dong Ying Ju ◽  
F.X. Yin ◽  
Lei Mao
Keyword(s):  
Stress State ◽  
Deformation Behavior ◽  
Basal Slip ◽  
Crack Tip ◽  
Tensile Loading ◽  
Biaxial Stress ◽  
Deformation Twins ◽  
Biaxial Tensile ◽  
Biaxial Stress State ◽  
Loading Ratio

In this study, a biaxial tensile test of cruciform specimens containing centre notch was conducted in order to clarify the deformation behavior near the crack tip at the early stages of crack initiation when objected to a biaxial stress state. Results show that the hardness and stress value within the deformed zone increased with increase in the loading ratio. Observation of the microstructure reveals that the deformation is dominated by basal slip under equal biaxial tensile loading. The asymmetrical biaxial tensile loading generates deformation twins near the crack tip. These results indicate that existing deformation twins contribute to higher hardness, and there is obvious anisotropism in the vicinity of crack tip under asymmetrical biaxial tensile loading.

Elastic–Plastic Response of Clamped Square Plates Subjected to Repeated Quasi-Static Uniform Pressure

2018 ◽  
Vol 10 (06) ◽  
pp. 1850067 ◽  
Author(s):  
Shiyun Shi ◽  
Ling Zhu ◽  
Tongxi Yu
Keyword(s):  
Elastic Strain ◽  
Plastic Material ◽  
Elastic Strain Energy ◽  
Uniform Pressure ◽  
Elastic Plastic ◽  
Whole Process ◽  
Perfectly Plastic ◽  
Plastic Regime ◽  
Loading And Unloading ◽  
Elastic Perfectly Plastic

In this paper, an elastic–plastic analytical method is proposed to predict the cyclic deformation of the fully clamped square plates made of elastic–perfectly plastic material under repeated quasi-static uniform pressure. The whole process can be divided into the loading and unloading phases. The loading phase is formulated as three separate regimes: the elastic regime, the mixed elastic–plastic regime and the fully plastic regime. Unloading from a status in each phase is modeled as an elastic process. The total and elastic strain energies are characterized by the loading and unloading paths together with the displacement profiles, respectively. It is theoretically revealed that the elastic strain energy and the structural stiffness of the plate increase with the increasing transverse deflection. In addition, the effect of material elasticity is highlighted in the scenario of repeated loadings. The theoretical results are validated against the numerical simulations conducted by the commercial software ABAQUS. It is shown that the proposed elastic–plastic theoretical model has reasonable accuracy and can be employed to predict pressure–deflection relationship for this class of problems.

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