Discrete fracture in quasi-brittle materials under compressive and tensile stress states

2004 ◽  
Vol 193 (27-29) ◽  
pp. 3035-3056 ◽  
Author(s):  
P.A. Klerck ◽  
E.J. Sellers ◽  
D.R.J. Owen
Keyword(s):  
Tensile Stress ◽  
Brittle Materials ◽  
Discrete Fracture ◽  
Stress States

scholarly journals Mesoscale Modelling of Concretes Subjected to Triaxial Loadings: Mechanical Properties and Fracture Behaviour

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1099
Author(s):  
Qingqing Chen ◽  
Yuhang Zhang ◽  
Tingting Zhao ◽  
Zhiyong Wang ◽  
Zhihua Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Stress ◽  
Failure Criterion ◽  
Mesoscale Model ◽  
Fracture Behaviour ◽  
Descent Method ◽  
Triaxial Stress ◽  
Gradient Descent Method ◽  
Stress States ◽  
Shear Failures

The mechanical properties and fracture behaviour of concretes under different triaxial stress states were investigated based on a 3D mesoscale model. The quasistatic triaxial loadings, namely, compression–compression–compression (C–C–C), compression–tension–tension (C–T–T) and compression–compression–tension (C–C–T), were simulated using an implicit solver. The mesoscopic modelling with good robustness gave reliable and detailed damage evolution processes under different triaxial stress states. The lateral tensile stress significantly influenced the multiaxial mechanical behaviour of the concretes, accelerating the concrete failure. With low lateral pressures or tensile stress, axial cleavage was the main failure mode of the specimens. Furthermore, the concretes presented shear failures under medium lateral pressures. The concretes experienced a transition from brittle fracture to plastic failure under high lateral pressures. The Ottosen parameters were modified by the gradient descent method and then the failure criterion of the concretes in the principal stress space was given. The failure criterion could describe the strength characteristics of concrete materials well by being fitted with experimental data under different triaxial stress states.

Methods for Determining the Strength of Brittle Materials in Compressive Stress States

1976 ◽  
Vol 4 (6) ◽  
pp. 383 ◽  
Author(s):  
RL Meltzer ◽  
YR Fiorini ◽  
RT Horstman ◽  
IC Moore ◽  
AL Batik ◽  
...  
Keyword(s):  
Compressive Stress ◽  
Brittle Materials ◽  
Stress States

The Characteristics of the Magnetic Memory Signals under Different States for Q235 Defect Samples

2010 ◽  
Vol 97-101 ◽  
pp. 500-503 ◽  
Author(s):  
Jian Wei Li ◽  
Min Qiang Xu ◽  
Jian Cheng Leng ◽  
Ming Xiu Xu
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Magnetic Behavior ◽  
Ferromagnetic Materials ◽  
Magnetic Memory ◽  
Testing Environment ◽  
Memory Signals ◽  
Stress States ◽  
Testing Environments ◽  
Different Characteristics

Magnetic behavior of ferromagnetic materials has been using to detect defects of materials. To evaluate the stress states of the components by the magnetic memory signal, Q235 defect asymmetrical samples were made. The characteristics of magnetic memory of Q235 have been studied in the three different testing environments which are online-loading, online-unloading and offline-unloading under cycle tensile stress. The results show that magnetic memory signals have different characteristics in different testing environment. It is feasible to evaluate preliminarily the stress state by the magnetic memory signals.

Stress Concentrations for Filled and Unfilled Closely Spaced Cylindrical Defects

1985 ◽  
Vol 107 (4) ◽  
pp. 271-276 ◽  
Author(s):  
T. Ihara ◽  
M. C. Shaw
Keyword(s):  
Brittle Fracture ◽  
Tensile Stress ◽  
Young’S Modulus ◽  
Fracture Stress ◽  
Brittle Materials ◽  
Critical Value ◽  
Stress Concentrations ◽  
High Quality ◽  
Close Spacing ◽  
The Matrix

All real materials contain defects which significantly reduce the fracture stress of brittle materials. It has been proposed by Griffith [3] that brittle fracture occurs when the maximum intensified tensile stress on the surface of a defect reaches a critical value. It has recently been found [1] that for many brittle materials of high quality, the nature and density of the defects are such that they may be modelled by isolated cylindrical voids. This study considers the stress intensification consequences of the close spacing of cylindrical defects that are filled with a material having a Young’s modulus different than that of the matrix.

An Improved Fracture Criterion for Three-Dimensional Stress States

1976 ◽  
Vol 98 (2) ◽  
pp. 159-163 ◽  
Author(s):  
B. Paul ◽  
L. Mirandy
Keyword(s):  
Applied Stress ◽  
Stress Fracture ◽  
Fracture Criterion ◽  
Three Dimensional ◽  
Brittle Materials ◽  
Two Dimensional ◽  
Stress Concentrations ◽  
State Of Stress ◽  
Stress States ◽  
Free Material

A theory is developed to predict the onset of fracture in isotropic, brittle materials when subjected to three dimensional states of applied stress. It is assumed that fracture is precipitated by stress concentrations emanating from material flaws. The flaw model which has been adopted consists of randomly oriented, microscopic, flat triaxial ellipsoidal voids imbedded in an otherwise defect-free material. It is shown that the ensuing fracture criterion may be expressed as a parabolic Mohr’s envelope. These results are qualitatively similar to Paul’s earlier three-dimensional generalization of Griffith’s two-dimensional stress fracture criterion. To handle three-dimensional states of applied stress, Paul used an approximation based on two-dimensional elasticity to obtain the state of stress around a flat spheroid. Newly developed results for flat ellipsoidal cavaties are utilized herein to analyze the three-dimensional cavity. Pertinent effects due to Poisson’s ratio and ellipsoid geometry are reported.

Optimal Matching of Processing Parameters of Horizontal V-Shaped Anvils for Heavy Axial Forgings Manufacturing

2011 ◽  
Vol 52-54 ◽  
pp. 2170-2175
Author(s):  
B. Li ◽  
J. Yu ◽  
Suo Qing Yu ◽  
A.B. Wang ◽  
Y.H. Jiang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Theoretical Foundation ◽  
Axial Stress ◽  
Processing Parameters ◽  
Middle Part ◽  
Reduction Ratio ◽  
Width Ratio ◽  
Stress States

The forging method with horizontal V-shaped anvils (HVA) is effective in the control of inner stress states, metal tissue, etc. FEM numerical simulation is conducted for the HVA forging method, under various processing parameters. The results show that during HVA forging, the transversal and axial stress states in the middle part of forgings are influenced by not only the ratio of the anvil width to billet height (anvil-width ratio )but also the ratio of the blank width to billet height (blank-width ratio) and the reduction ratio, while the end parts are influenced little. Among those processing parameters, the reduction ratio plays an important role. When the reduction ratio is 5% or 10%, it is possible to obtain axial and transversal tensile stress. When the reduction ratio is larger than 15%, it is easy to obtain two-way compressive stress. Therefore, in order to control the two-way tensile stress, big reduction ratio should be adopted. Small blank-width ratios result in the forgings cracks because of transversal tensile stress in common flat-anvil stretching method. On the contrary, even if the blank-width ratio is small, transversal compressive stress can be generated in forgings for the HVA forging method, only if the matching of the anvil-width ratio and the reduction ratio is suitable. The feature of the HVA forging method benefits the preventing forgings from inner cracks. The results provide the theoretical foundation for the application of the HVA forging method.

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