scholarly journals Discontinuous fibrous Bouligand architecture enabling formidable fracture resistance with crack orientation insensitivity

2020 ◽  
Vol 117 (27) ◽  
pp. 15465-15472 ◽  
Author(s):  
Kaijin Wu ◽  
Zhaoqiang Song ◽  
Shuaishuai Zhang ◽  
Yong Ni ◽  
Shengqiang Cai ◽  
...  
Keyword(s):  
Fracture Energy ◽  
Pitch Angle ◽  
Fracture Resistance ◽  
Architectural Design ◽  
Initial Crack ◽  
Single Edge ◽  
Crack Orientation ◽  
Crack Bridging ◽  
Notched Specimens ◽  
3D Printed

Bioinspired architectural design for composites with much higher fracture resistance than that of individual constituent remains a major challenge for engineers and scientists. Inspired by the survival war between the mantis shrimps and abalones, we design a discontinuous fibrous Bouligand (DFB) architecture, a combination of Bouligand and nacreous staggered structures. Systematic bending experiments for 3D-printed single-edge notched specimens with such architecture indicate that total energy dissipations are insensitive to initial crack orientations and show optimized values at critical pitch angles. Fracture mechanics analyses demonstrate that the hybrid toughening mechanisms of crack twisting and crack bridging mode arising from DFB architecture enable excellent fracture resistance with crack orientation insensitivity. The compromise in competition of energy dissipations between crack twisting and crack bridging is identified as the origin of maximum fracture energy at a critical pitch angle. We further illustrate that the optimized fracture energy can be achieved by tuning fracture energy of crack bridging, pitch angles, fiber lengths, and twist angles distribution in DFB composites.

Ductile Crack Propagation Characteristics in Steel Thin Single Edge Notched Tension Specimens

2007 ◽  
Vol 539-543 ◽  
pp. 2180-2185 ◽  
Author(s):  
Yoichi Kayamori ◽  
S. Hillmansen ◽  
P.S.J. Crofton ◽  
Roderick A. Smith
Keyword(s):  
Crack Propagation ◽  
Crack Growth ◽  
Initial Crack ◽  
Manganese Steel ◽  
Dynamic Crack ◽  
Propagation Characteristics ◽  
Ductile Crack ◽  
Single Edge ◽  
Constraint Factor ◽  
Notched Specimens

Static and dynamic ductile crack propagation tests were carried out using thin single edge notched tension (SENT) specimens of carbon-manganese steel, each of which had a fatigue pre-crack or a sharp V-notch as a crack initiator. The crack tip opening angle (CTOA) was measured using digital images on the surface of the SENT specimens, and the critical values of CTOA for crack propagation decreased with increasing crack length while initial crack growth was still small. After the initial crack growth up to the distance of the specimen thickness, the critical CTOA remained almost constant. These tendencies were common in static and dynamic crack propagation specimens as well as fatigue pre-cracked and sharp V-notched specimens. There was no particular difference in the static crack propagation characteristics of both fatigue pre-cracked and sharp V-notched specimens. On average, it was observed that higher crack speeds affected the constant values of the critical CTOA by slightly reducing them. The constant CTOA tends to decrease with an increasing global constraint factor, and this suggests that the factor is insensitive to a crack starter, fatigue pre-crack or a sharp V-notch, but relatively sensitive to crack speed.

scholarly journals Evaluation of Fracture Resistance of Asphalt Mixtures Using the Single-Edge Notched Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Biao Ding ◽  
Xiaolong Zou ◽  
Zixin Peng ◽  
Xiang Liu
Keyword(s):  
Fracture Toughness ◽  
Fracture Energy ◽  
Viscoelastic Properties ◽  
Fracture Resistance ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Single Edge ◽  
Fracture Properties ◽  
Different Temperatures ◽  
Peak Value

To determine and compare the fracture properties of different asphalt mixtures, single-edge notched beam (SENB) tests using three types of asphalt mixtures were applied in this study under the conditions of different notched depths and different temperatures. The effects of notched depths and temperatures on the fracture toughness and fracture energy were analyzed. The results indicate that the notch depth has no significant effects on the fracture toughness and the fracture energy, but the gradation has relatively obvious effects on the fracture energy, which the larger contents of course aggregate leads to increase the discreteness of the fracture energy of the specimen. The temperature has significant effects on the ultimate loads, fracture energy, and fracture toughness. The ultimate loads of the SENBs reach the peak value at 0°C, which could be resulted in that viscoelastic properties of asphalt mixture depend with temperatures. The fracture toughness at −20°C of continuously graded asphalt mixtures are higher than those of gap-graded asphalt mixtures. On the contrary, the fracture toughness of gap-graded asphalt mixtures is higher at temperatures from −10°C to 20°C. The fracture energy increases with temperatures, and the fracture energy of SMA-13 is significantly larger than those of AC-13 and AC-16.

Prediction of the Initial Crack Tip Microstructure in a Single Crystal of CuAlNi

1999 ◽  
Author(s):  
Galyna M. Vasko ◽  
Perry H. Leo ◽  
Thomas W. Shield
Keyword(s):  
Stress Field ◽  
Single Crystal ◽  
Crack Opening ◽  
Crack Tip ◽  
Initial Crack ◽  
Single Edge ◽  
Opening Displacement ◽  
Elastic Crack ◽  
Maximum Work ◽  
Anisotropic Elastic

Abstract The austenite to martensite pseudoelastic transformation induced by the anisotropic elastic crack tip stress field in a single crystal of shape memory alloy is considered. It is proposed that the orientation of the initial austenite-martensite interface that forms can be predicted based on knowledge of the stress field, the crystallography of the transformation and one of two selection criteria. These criteria are based on the work of formation of the martensite in stress field and the crack opening displacement the martensite causes at the crack. Predictions of the criteria are compared to experiments on three single edge notched CuAlNi single crystal specimens. Results indicate that the maximum work criterion accurately predicts the orientation of the austenite-martensite interfaces that initially form near a crack.

Fracture energy for three-point-bend tests on single-edge-notched beams

1988 ◽  
Vol 28 (3) ◽  
pp. 266-272 ◽  
Author(s):  
L. J. Malvar ◽  
G. E. Warren
Keyword(s):  
Fracture Energy ◽  
Single Edge ◽  
Bend Tests ◽  
Point Bend

Plasticity contributions to interface adhesion in thin-film interconnect structures

2000 ◽  
Vol 15 (12) ◽  
pp. 2758-2769 ◽  
Author(s):  
Michael Lane ◽  
Reinhold H. Dauskardt ◽  
Anna Vainchtein ◽  
Huajian Gao
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Fracture Energy ◽  
Fracture Resistance ◽  
Work Of Adhesion ◽  
Interface Fracture ◽  
Cohesive Stress ◽  
Wide Range ◽  
Macroscopic Fracture ◽  
Metal Layers

The effects of plasticity in thin copper layers on the interface fracture resistance in thin-film interconnect structures were explored using experiments and multiscale simulations. Particular attention was given to the relationship between the intrinsic work of adhesion, Go, and the measured macroscopic fracture energy, Gc. Specifically, the TaN/SiO2 interface fracture energy was measured in thin-film Cu/TaN/SiO2 structures in which the Cu layer was varied over a wide range of thickness. A continuum/FEM model with cohesive surface elements was employed to calculate the macroscopic fracture energy of the layered structure. Published yield properties together with a plastic flow model for the metal layers were used to predict the plasticity contribution to interface fracture resistance where the film thickness (0.25–2.5 μm) dominated deformation behavior. For thicker metal layers, a transition region was identified in which the plastic deformation and associated plastic energy contributions to Gc were no longer dominated by the film thickness. The effects of other salient interface parameters including peak cohesive stress and Go are explored.

Fracture resistance curve for single edge notched tension specimens under low cycle actions

2019 ◽  
Vol 211 ◽  
pp. 47-60 ◽  
Author(s):  
Tianyao Liu ◽  
Xudong Qian ◽  
Wei Wang ◽  
Yiyi Chen
Keyword(s):  
Fracture Resistance ◽  
Resistance Curve ◽  
Single Edge

scholarly journals Investigation of mixed mode fatigue crack propagation in SEN-specimen under in-phase and out-of-phase conditions due to tension-compression and torsional loading

2019 ◽  
Vol 300 ◽  
pp. 11006
Author(s):  
Paul Koester ◽  
Christopher Benz ◽  
Manuela Sander
Keyword(s):  
Crack Propagation ◽  
Mixed Mode ◽  
Testing Machine ◽  
Theoretical Background ◽  
Residual Lifetime ◽  
Single Edge ◽  
Notched Specimens ◽  
Precise Knowledge ◽  
Twisting Angle ◽  
Phase Angles

Numerous cases of damage by fatigue in structures are related to mechanical stresses due to mixed mode loading conditions. To prevent such cases of failure a precise knowledge of the corresponding theoretical background is indispensable. Unfortunately, it is not yet possible to describe the crack propagation considering a superposition of all three crack modes satisfactory. For this purpose, experiments on single-edge notched specimens made of 34CrNiMo6 using a tension-torsion testing machine under different mixed mode ratios and phase angles were performed. The focus of the investigations is especially on the kinking and the twisting angle of the crack as well as on the influence on the residual lifetime. Further, existing concepts concerning the prediction of the crack growth under mixed mode are evaluated.

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