Physicomechanical approaches to an analysis of macroscopic failure criteria. Report 3. Brittle failure

1989 ◽  
Vol 21 (7) ◽  
pp. 841-852 ◽  
Author(s):  
G. P. Karzov ◽  
B. Z. Margolin ◽  
V. A. Shvetsova
Keyword(s):  
Brittle Failure ◽  
Failure Criteria ◽  
Macroscopic Failure

Brittle failure criteria for components containing U-notches under Mode I loading

2018 ◽  
Vol 200 ◽  
pp. 86-103 ◽  
Author(s):  
Dai-Heng Chen ◽  
Kuniharu Ushijima ◽  
Wesley J. Cantwell
Keyword(s):  
Brittle Failure ◽  
Failure Criteria ◽  
Mode I ◽  
Mode I Loading

scholarly journals Mode-Independent and Mode-Interactive Failure Criteria for Unidirectional Composites Based on Strain Energy Density

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2813
Author(s):  
Nian Li ◽  
Cheng Ju
Keyword(s):  
Failure Mode ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Axial Loading ◽  
Failure Criteria ◽  
Physical Reality ◽  
Failure Envelopes ◽  
Wide Range ◽  
Axial Compressive Stress ◽  
Macroscopic Failure

The strain energy released plays a crucial role in generating macroscopic failure in unidirectional (UD) composites. This paper proposes two new strain energy-based failure criteria, regarding fiber-dominated and matrix-dominated failure mode as independent and interactive, respectively. The failure expression is formulated based on rigorous mathematical deducing, accompanied by physical interpretation. Based on the lack of experimentally feasible multi-axial strengths, a predefined assumption of infinite strength under bi-axial and tri-axial compressive stress provides the possibility for determining all coefficients only by using conventional uniaxial strengths. The failure envelopes predicted by the proposed criteria have been validated against experimental results under biaxial, off-axis and tri-axial loading cases. A better agreement with physical reality was achieved by the failure mode-interactive criterion, suggesting a wide range of applicability.

scholarly journals An evaluation of the failure modes transition and the Christensen ductile/brittle failure theory using molecular dynamics

2018 ◽  
Vol 474 (2219) ◽  
pp. 20180361 ◽  
Author(s):  
Richard Christensen ◽  
Zhi Li ◽  
Huajian Gao
Keyword(s):  
Molecular Dynamics ◽  
Brittle Failure ◽  
Failure Modes ◽  
Shear Bands ◽  
Failure Criteria ◽  
Test Material ◽  
Full Density ◽  
Modes Of Failure ◽  
Failure Theory ◽  
Voids Growth

The Christensen ductile/brittle failure theory can be interpreted in terms of the associated failure modes, those of shear bands and voids nucleation. Their conjunction is then termed as the failure modes transition and it is studied here using molecular dynamics. The test material is taken as a particular metallic glass, CuZr. First the theoretical failure criteria are evaluated and then the theoretical failure modes transition is evaluated. Both are found to perform extremely well. The overall failure theory contains three modes of failure, the two already mentioned plus a fracture criterion. A general conclusion from the work is that the voids nucleation criterion is of unusually broad relevance. Voids nucleation leads to voids growth and then further deteriorating mechanisms and ultimately failure. But the voids nucleation is the precipitating event of all that subsequently occurs in this process. Access to these capabilities is gained through the failure theory for all homogeneous, full density, isotropic materials. Only two standard testing measurements are needed to calibrate the entire failure theory, including the transitions.

Hoek-Brown parameters for predicting the depth of brittle failure around tunnels

1999 ◽  
Vol 36 (1) ◽  
pp. 136-151 ◽  
Author(s):  
C D Martin ◽  
P K Kaiser ◽  
D R McCreath
Keyword(s):  
Rock Mass ◽  
Brittle Failure ◽  
Failure Process ◽  
Damage Index ◽  
Failure Criteria ◽  
Field Observations ◽  
Underground Openings ◽  
Rock Mass Failure ◽  
Brittle Rock Mass ◽  
Flat Roof

A review of underground openings, excavated in varying rock masstypes and conditions, indicates that the initiation of brittlefailure occurs when the damage index, Di, expressed as theratio of the maximum tangential boundary stress to the laboratoryunconfined compressive strength exceeds approx0.4. When thedamage index exceeds this value, the depth of brittle failure around a tunnel can be estimated by using a strengthenvelope based solely on cohesion, which in terms of theHoek-Brown parameters implies that m = 0. It is proposed that inthe brittle failure process peak cohesion and friction are notmobilized together, and that around underground openings thebrittle failure process is dominated by a loss of the intrinsiccohesion of the rock mass such that the frictional strengthcomponent can be ignored for estimating the depth of brittlefailure, an essential component in designing support for theopening. Case histories were analyzed using the Hoek-Brownfailure criterion, with traditional frictional parameters, and withthe proposed brittle rock mass parameters: m = 0 and s = 0.11. Theanalyses show that use of a rock mass failure criteria withfrictional parameters (m > 0) significantly underpredicts thedepth of brittle failure while use of the brittle parametersprovides good agreement with field observations. Analyses usingthe brittle parameters also show that in intermediate stressenvironments, where stress-induced brittle failure is localized, atunnel with a flat roof is more stable than a tunnel with anarched roof. This is consistent with field observations. Hence,the Hoek-Brown brittle parameters can be used to estimate thedepth of brittle failure around tunnels, the support demand-loadscaused by stress-induced failure, and the optimum geometry of theopening.Key words: spalling, depth of failure, rock mass strength, brittle failure criterion, cohesion loss, Hoek-Brown brittle parameters

Modeling and Simulation of the Failure and Stiffness Degradation of a Graphite Epoxy in a Three Point Bending Test

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
E. H. Irhirane ◽  
M. Abousaleh ◽  
J. Echaabi ◽  
M. Hattabi ◽  
A. Saouab ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Experimental Approach ◽  
Failure Modes ◽  
Failure Criteria ◽  
Bending Test ◽  
Geometrical Parameters ◽  
Three Point Bending ◽  
Stiffness Reduction ◽  
Biaxial Tests ◽  
Macroscopic Failure

The use of composite materials with continuous fibers in the aeronautic and aerospace industries requires reliable and precise methods for the prediction of failure. Predicting failure stresses and failure modes in composite laminates is very difficult. The choice between failure criteria is complex, and there is a lack of experimental study to validate the result obtained partly because the biaxial tests are still difficult to perform. This work employs a mixed methodology based on a theoretical and an experimental approach to develop a procedure for the choice and the validation of the failure criterion. The comparison is concerned not only with the macroscopic failure but also with the succession of the failure, the failure mode, and the effect of the geometrical parameters of the test specimen. The most general failure criteria are tested by using two approaches of the stiffness reduction. A finite element code has been elaborated within our laboratory for postfailure treatment. The numerical simulation results are compared with the experimental ones and permit us to make a conclusion on the validity of the failure criteria used.

scholarly journals Brittle failure criteria of CNRB specimen for fracture toughness test

2020 ◽  
Vol 7 (4) ◽  
pp. 19-00621-19-00621
Author(s):  
Manato KANESAKI ◽  
Kiyotaka OBUNAI ◽  
Tadao FUKUTA ◽  
Yoshihito KUROSHIMA ◽  
Koichi OZAKI
Keyword(s):  
Fracture Toughness ◽  
Brittle Failure ◽  
Failure Criteria ◽  
Fracture Toughness Test ◽  
Toughness Test
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