scholarly journals Brazilian Test for Tensile Failure of Anisotropic Shale under Different Strain Rates at Quasi-static Loading

Energies ◽  
2017 ◽  
Vol 10 (9) ◽  
pp. 1324 ◽  
Author(s):  
Yu Wang ◽  
Changhong Li ◽  
Yanzhi Hu ◽  
Tianqiao Mao
Keyword(s):  
Static Loading ◽  
Brazilian Test ◽  
Tensile Failure ◽  
Strain Rates

Impact tensile behavior and frequency response of 3D braided composites

2011 ◽  
Vol 82 (3) ◽  
pp. 280-287 ◽  
Author(s):  
Xuehui Gan ◽  
Jianhua Yan ◽  
Bohong Gu ◽  
Baozhong Sun
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Tensile Properties ◽  
High Strain ◽  
Tensile Modulus ◽  
Tensile Failure ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Braided Composites ◽  
3D Braided Composites

The uniaxial tensile properties of 4-step 3D braided E-glass/epoxy composites under quasi-static and high-strain rate loadings have been investigated to evaluate the tensile failure mode at different strain rates. The uniaxial tensile properties at high strain rates from 800/s to 2100/s were tested using the split Hopkinson tension bar (SHTB) technique. The tensile properties at quasi-static strain rate were also tested and compared with those in high strain rates. Z-transform theory is applied to 3D braided composites to characterize the system dynamic behaviors in frequency domain. The frequency responses and the stability of 3D braided composites under quasi-static and high-strain rate compression have been analyzed and discussed in the Z-transform domain. The results indicate that the stress-strain curves are rate sensitive, and tensile modulus, maximum tensile stress and corresponding tensile strain are also sensitive to the strain rate. The tensile modulus, maximum tensile stress of the 3D braided composites are linearly increased with the strain rate. With increasing of the strain rate (from 0.001/s to 2100/s), the tensile failure of the 3D braided composite specimens has a tendency of transition from ductile failure to brittle failure. The magnitude response and phase response is very different in quasi-static loading with that in high-strain rate loading. The 3D braided composite system is more stable at high strain rate than quasi-static loading.

scholarly journals Evaluation on Rock Tensile Failure of the Brazilian Discs under Different Loading Configurations by Digital Image Correlation

2020 ◽  
Vol 10 (16) ◽  
pp. 5513
Author(s):  
Diyuan Li ◽  
Bang Li ◽  
Zhenyu Han ◽  
Quanqi Zhu
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Equivalent Stress ◽  
Peak Load ◽  
Brazilian Test ◽  
Experimental Results ◽  
Image Correlation ◽  
Tensile Failure ◽  
Rock Types ◽  
Loading Methods

The fracture behavior of the disc specimens in the Brazilian test is closely related to the reliability and accuracy of the experimental results. To comprehensively investigate the effect of various loading methods and rock material types on the failure mechanism of the Brazilian discs, five different rock types tested with three typical loading methods were employed in this work. The digital image correlation (DIC) method was applied to record and analyze the strain and displacement field of the specimens during the loading process. Experimental results indicate that the peak load and deformation characteristics of the Brazilian discs are strongly affected by the loading types. The Brazilian test with the Chinese standard is evidently not suitable for measuring the tensile strength of rocks, and the other two testing methods may lead to an invalid failure mode for rock materials with high stiffness and tensile to compressive strength ratio. Furthermore, it revealed that the maximum equivalent stress point of a disc specimen is co-controlled by the material stiffness and its tensile–compression ratio. The present work shows that it is necessary to select a suitable loading configuration for each rock type in the Brazilian test.

Tensile behaviors of co-woven-knitted fabric reinforced composites under various strain rates

2011 ◽  
Vol 45 (24) ◽  
pp. 2495-2506 ◽  
Author(s):  
Pibo Ma ◽  
Hong Hu ◽  
Lvtao Zhu ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Strain Rate ◽  
Failure Modes ◽  
Shear Failure ◽  
High Strain ◽  
Tensile Failure ◽  
Knitted Fabric ◽  
Strain Rates ◽  
High Strain Rates ◽  
Textile Composite ◽  
Interface Failure

This article reports the tensile behaviors of a novel kind of 3D textile composite, named as co-woven-knitted fabric (CWKF) reinforced composite, under quasi-static and high strain rates. The tensile tests were conducted along the warp direction (0°), bias direction (45°), and weft direction (90°) at quasi-static strain rate of 0.001/s and high strain rates ranging from 1589/s to 2586/s. The results indicate that the tensile strength, failure strain, tensile stiffness, energy absorption, and resilient energy are strain rate sensitive along all the three directions. The relationships between the mechanical parameters and the strain rate were also analyzed. The fractograph of the CWKF composite demonstrate that the tensile failure modes are matrix shear failure and fibers breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.

Hybrid composites made of unidirectional T600S carbon and E-glass fabrics under quasi-static loading

2016 ◽  
Vol 46 (7) ◽  
pp. 1511-1535 ◽  
Author(s):  
Md. Hasan Ikbal ◽  
Azzam Ahmed ◽  
Wang Qingtao ◽  
Zeng Shuai ◽  
Li Wei
Keyword(s):  
Static Loading ◽  
Composite Laminates ◽  
Failure Strain ◽  
Epoxy Composite ◽  
Hybrid Composites ◽  
Experimental Studies ◽  
Tensile Failure ◽  
Compressive Properties ◽  
Element Analysis ◽  
Hybrid Configuration

Finite element analysis and experimental studies are presented on in-plane tensile and compressive properties under quasi-static loading for two types of hybrid composites made by using unidirectional T620S carbon and E-glass fabrics in a common matrix, epoxy resin. Results are also generated for plain T620S carbon/epoxy and plain E-glass/epoxy composite laminates. Quantitative data for tensile and compressive properties are presented. It is observed that for hybrid composites, placing carbon and glass fiber parts alternately in every layer (intralayer configuration) gives higher tensile and compressive strengths. Tensile failure strain is higher for intralayer compared to interlayer hybrid configuration.

scholarly journals Fabrication and Mechanical Properties of a Micro/Nanoscale Hybrid Composite

2012 ◽  
Vol 13 (2) ◽  
Author(s):  
Genwei Wang ◽  
Han Zhao ◽  
Jinbo Bai ◽  
Ya-Pu Zhao
Keyword(s):  
Carbon Nanotubes ◽  
Hybrid Composite ◽  
Static Loading ◽  
High Strain ◽  
Strain Rates ◽  
Dynamic Tests ◽  
Multiwalled Carbon ◽  
Sic Particles ◽  
Split Hopkinson ◽  
Static And Dynamic Tests

AbstractMicroscale SiC particles with multiwalled carbon nanotubes grow on were filled in epoxy resin to construct multiscale hybrid composite. Static and dynamic compressive responses of composites were investigated. A dynamic experimental technique, split Hopkinson press bar (SHPB), was introduced to study the constitutive laws of materials at high strain rates. SEM observations show good dispersion of carbon nanotubes and SiC particles, but bad link between SiC particles and carbon nanotubes exists. Experimental results of static and dynamic tests verify that increase of strength happens with SiC/CNT as reinforcement Increment of strength under dynamic loading is bigger than under static loading.

scholarly journals Fabrication and Mechanical Properties of a Micro/Nanoscale Hybrid Composite

2012 ◽  
Vol 13 (2) ◽  
Author(s):  
Genwei Wang ◽  
Han Zhao ◽  
Jinbo Bai ◽  
Ya-Pu Zhao
Keyword(s):  
Carbon Nanotubes ◽  
Hybrid Composite ◽  
Static Loading ◽  
High Strain ◽  
Strain Rates ◽  
Dynamic Tests ◽  
Multiwalled Carbon ◽  
Sic Particles ◽  
Split Hopkinson ◽  
Static And Dynamic Tests

AbstractMicroscale SiC particles with multiwalled carbon nanotubes grow on were filled in epoxy resin to construct multiscale hybrid composite. Static and dynamic compressive responses of composites were investigated. A dynamic experimental technique, split Hopkinson press bar (SHPB), was introduced to study the constitutive laws of materials at high strain rates. SEM observations show good dispersion of carbon nanotubes and SiC particles, but bad link between SiC particles and carbon nanotubes exists. Experimental results of static and dynamic tests verify that increase of strength happens with SiC/CNT as reinforcement Increment of strength under dynamic loading is bigger than under static loading.

Experimental Study on Mechanism of Crack Coalescence between Two Pre-Existing Flaws under Dynamic Loading

2006 ◽  
Vol 324-325 ◽  
pp. 117-120 ◽  
Author(s):  
Ping Zhang ◽  
Ning Li ◽  
Ruo Lan He
Keyword(s):  
Crack Propagation ◽  
Dynamic Loading ◽  
Static Loading ◽  
Crack Coalescence ◽  
Engineering Practice ◽  
Strength Increase ◽  
Strain Rates ◽  
Inertia Effect ◽  
Coalescence Pattern ◽  
Static And Dynamic Loading

More and more engineering practice indicates rock mass is prone to lose its stability through crack coalescence under dynamic loading, such as blasting and earthquake. However, the crack coalescence pattern of rock specimens containing two or more flaws has not been studied comprehensively under dynamic loading. In this paper, the mechanism of the crack coalescence and peak strength of sandstone-like materials containing two parallel flaws are studied under uniaxial static and dynamic loading with strain rates 1.7×10-5 s-1 and 1.7×10-1 s-1. Through the comparisons of the propagation length, coalescence pattern of the cracks and strength increase of the pre-cracked specimens under static and dynamic loading, the dynamic response of the crack coalescence is found different from static loading under different geometric setting of the flaws. The inertia effect of the crack propagation is revealed under dynamic loading, that is to say, the growth of the secondary cracks tends to the original propagation direction, and the direct and immediate coalescence is taken place easily between two pre-existing flaws, which is different from the kinking coalescence under static loading. So, the inertia effect of the crack propagation is regarded as the main cause of the strength increase of the brittle material under dynamic loading for medium strain rates. In virtue of the explanation, another cause of the mode II shear fracture occurred under earthquake is opened out.

scholarly journals What is the influence of two strain rates on the relationship between human cortical bone toughness and micro-structure?

2019 ◽  
Vol 234 (3) ◽  
pp. 247-254 ◽  
Author(s):  
Rémy Gauthier ◽  
Hélène Follet ◽  
Max Langer ◽  
Françoise Peyrin ◽  
David Mitton
Keyword(s):  
Crack Propagation ◽  
Strain Rate ◽  
Cortical Bone ◽  
Static Loading ◽  
Fracture Mechanisms ◽  
Strain Rates ◽  
Micro Structure ◽  
Human Cortical Bone ◽  
Cross Links ◽  
Haversian System

Cortical bone fracture mechanisms are well studied under quasi-static loading. The influence of strain rate on crack propagation mechanisms needs to be better understood, however. We have previously shown that several aspects of the bone micro-structure are involved in crack propagation, such as the complete porosity network, including the Haversian system and the lacunar network, as well as biochemical aspects, such as the maturity of collagen cross-links. The aim of this study is to investigate the influence of strain rate on the toughness of human cortical bone with respect to its microstructure and organic non-collagenous composition. Two strain rates will be considered: quasi-static loading (10−4 s−1), a standard condition, and a higher loading rate (10−1 s−1), representative of a fall. Cortical bone samples were extracted from eight female donors (age 50–91 years). Three-point bending tests were performed until failure. Synchrotron radiation micro-computed tomography imaging was performed to assess bone microstructure including the Haversian system and the lacunar system. Collagen enzymatic cross-link maturation was measured using a high performance liquid chromatography column. Results showed that that under quasi-static loading, the elastic contribution of the fracture process is correlated to both the collagen cross-links maturation and the microstructure, while the plastic contribution is correlated only to the porosity network. Under fall-like loading, bone organization appears to be less linked to crack propagation.

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