scholarly journals Influence of Freeze-Thaw Cycles on Tensile Strength and Fracture Toughness of Concrete

2021 ◽  
Author(s):  
Lingtong Meng ◽  
Shutong Yang ◽  
Song Yang
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Fracture Behavior ◽  
Boundary Effect ◽  
Fracture Load ◽  
Bending Test ◽  
Three Point Bending ◽  
Freeze Thaw ◽  
Damage Degree ◽  
Effect Model

In this paper, the fracture behavior of concrete with different initial notch lengths after freeze-thaw action was studied by using three-point bending test. Then, based on the boundary effect model, the parameters indicating the material discontinuity and inhomogeneity were introduced, and the maximum fracture load of the beam was used to determine the real tensile strength and fracture toughness of concrete under different freeze-thaw cycles. Results show that the tensile strength and fracture toughness of concrete are obviously reduced. Compared with the control specimens under indoor condition, the fracture parameters are reduced by more than 38% when the number of freeze-thaw cycles reached 75 times. In this paper, the tensile strength obtained based on the boundary effect model is significantly higher than the splitting tensile strength of concrete due to the incorporation of the discontinuity and non-uniformity of materials, and can more accurately reflect the deterioration and damage degree of concrete after freeze-thaw action.

scholarly journals Calculation for tensile strength and fracture toughness of granite with three kinds of grain sizes using three-point-bending test

PLoS ONE ◽  
2018 ◽  
Vol 13 (3) ◽  
pp. e0180880 ◽  
Author(s):  
Miao Yu ◽  
Chenhui Wei ◽  
Leilei Niu ◽  
Shaohua Li ◽  
Yongjun Yu
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Bending Test ◽  
Three Point Bending ◽  
Grain Sizes

Fracture Behavior and Microstructure of Ti 3AlC2 Ceramics Prepared by SHS/PHIP Method

2008 ◽  
Vol 385-387 ◽  
pp. 177-180
Author(s):  
Zheng Yi Ren ◽  
Chong Li ◽  
Qing Fen Li
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Bending Test ◽  
Three Point Bending ◽  
Propagation Behavior ◽  
Large Size ◽  
Ternary Carbide ◽  
Crack Propagation Behavior

Fracture behavior and the microstructure of Ti3AlC2 ceramics prepared by SHS/PHIP method were studied. Stress-strain curves at different temperature with a strain rate of 1×10-3 s-1 were obtained. Fracture toughness, flexural strength, crack propagation behavior and compressive deformation of specimens were investigated. Results show that the microstructure of the large size Ti3AlC2 ceramics prepared by SHS/PHIP method has typical layered feature of ternary carbide compound. The bridge-link phenomena induced by the flaky grains occurred in three-point bending test. It restrained the crack propagation and improved the fracture toughness of the material. Cylindrical specimens under axial compression usually smashed into chips for most of the ceramics materials, however, for the Ti3AlC2 ceramics prepared by SHS/PHIP, shear fracture along 45º incline of the specimen occurred at room temperature, and bulging deformation without any crack exhibited when temperature was high. It is concluded that the Ti3AlC2 ceramics prepared by SHS/PHIP has better fracture-resistance properties.

scholarly journals Numerical Simulation on Size Effect of Fracture Toughness of Concrete Based on Mesomechanics

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1370 ◽  
Author(s):  
Juan Wang ◽  
Qianqian Wu ◽  
Junfeng Guan ◽  
Peng Zhang ◽  
Hongyuan Fang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Numerical Model ◽  
Fracture Process ◽  
Boundary Effect ◽  
Peak Load ◽  
Specimen Size ◽  
Three Point Bending ◽  
Linear Elastic ◽  
Coarse Aggregates ◽  
Effect Model

The fracture performance of concrete is size-dependent within a certain size range. A four-phase composite material numerical model of mesofracture considering a mortar matrix, coarse aggregates, an interfacial transition zone (ITZ) at the meso level and the initial defects of concrete was established. The initial defects were assumed to be distributed randomly in the ITZ of concrete. The numerical model of concrete mesofracture was established to simulate the fracture process of wedge splitting (WS) concrete specimens with widths of 200–2000 mm and three-point bending (3-p-b) concrete specimens with heights of 200–800 mm. The fracture process of concrete was simulated, and the peak load (Pmax) of concrete was predicted using the numerical model. Based on the simulating results, the influence of specimen size of WS and 3-p-b tests on the fracture parameters was analyzed. It was demonstrated that when the specimen size was large enough, the fracture toughness (KIC) value obtained by the linear elastic fracture mechanics formula was independent of the specimen size. Meanwhile, the improved boundary effect model (BEM) was employed to study the tensile strength (ft) and fracture toughness of concrete using the mesofracture numerical model. A discrete value of β = 1.0–1.4 was a sufficient approximation to determine the ft and KIC values of concrete.

Mechanical Property and Oxidation Behavior of LPS-SiC Materials

2006 ◽  
Vol 321-323 ◽  
pp. 913-916
Author(s):  
Sang Ll Lee ◽  
Yun Seok Shin ◽  
Jin Kyung Lee ◽  
Jong Baek Lee ◽  
Jun Young Park
Keyword(s):  
Mechanical Property ◽  
Fracture Toughness ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Indentation Test ◽  
Bending Test ◽  
Secondary Phases ◽  
Three Point Bending ◽  
Different Temperatures

The microstructure and the mechanical property of liquid phase sintered (LPS) SiC materials with oxide secondary phases have been investigated. The strength variation of LPS-SiC materials exposed at the elevated temperatures has been also examined. LPS-SiC materials were sintered at the different temperatures using two types of Al2O3/Y2O3 compositional ratio. The characterization of LPS-SiC materials was investigated by means of SEM with EDS, three point bending test and indentation test. The LPS-SiC material with a density of about 3.2 Mg/m3 represented a flexural strength of about 800 MPa and a fracture toughness of about 9.0 MPa⋅√m.

scholarly journals FDEM Modelling of Rock Fracture Process during Three-Point Bending Test under Quasistatic and Dynamic Loading Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Huaming An ◽  
Yushan Song ◽  
Hongyuan Liu
Keyword(s):  
Fracture Toughness ◽  
Dynamic Loading ◽  
Fracture Process ◽  
Loading Rate ◽  
Rock Fracture ◽  
Mesh Size ◽  
Bending Test ◽  
Loading Conditions ◽  
Three Point Bending ◽  
Dynamic Loading Conditions

A hybrid finite-discrete element method (FDEM) is proposed to model rock fracture initiation and propagation during a three-point bending test under quasistatic and dynamic loading conditions. Three fracture models have been implemented in the FDEM to model the transition from continuum to discontinuum through fracture and fragmentation. The loading rate effect on rock behaviour has been taken into account by the implementation of the relationship between the static and dynamic rock strengths derived from dynamic rock fracture experiments. The Brazilian tensile strength test has been modelled to calibrate the FDEM. The FDEM can well model the stress and fracture propagation and well show the stress distribution along the vertical diameter of the disc during the Brazilian tensile strength test. Then, FDEM is implemented to study the rock fracture process during three-point bending tests under quasistatic and dynamic loading conditions. The FDEM has well modelled the stress and fracture propagation and can obtain reasonable fracture toughness. After that, the effects of the loading rate on the rock strength and rock fracture toughness are discussed, and the mesh size and mesh orientation on the fracture patterns are also discussed. It is concluded that the FDEM can well model the rock fracture process by the implementation of the three fracture models. The FDEM can capture the loading rate effect on rock strength and rock fracture toughness. The FDEM is a valuable tool for studying the rock behaviour on the dynamic loading although the proposed method is sensitive to the mesh size and mesh orientation.

scholarly journals Experimental Study on the Effect of Offset Notch on Fracture Properties of Rock under Three-Point Bending Beam

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Qifeng Guo ◽  
Xinghui Wu ◽  
Meifeng Cai ◽  
Shengjun Miao
Keyword(s):  
Fracture Toughness ◽  
Experimental Study ◽  
Tensile Strength ◽  
Peak Load ◽  
Fracture Properties ◽  
Three Point Bending ◽  
Nominal Strength ◽  
Bending Load ◽  
The Relationship ◽  
Rock Beam

To investigate the effects of offset notch on the fracture properties of rock beam under bending load, granite beam specimens with “one single offset notch” and “central and offset double notches” are made. A series of three-point bending beam tests on the specimens are carried out by controlling the displacement rate of central notch. The whole load-displacement (P-CMOD) curves are obtained. Experimental results show that the larger the distance between the offset notch and beam central is, the larger are the peak load and nominal strength of the specimen. The peak load and nominal strength for the “central and offset double notches” specimens are both larger than those for the “single central notch” specimen. A fracture model considering the effect of offset notch is developed, and the relationship between the offset notch parameter, tensile strength, and fracture toughness is established.

Size effect research of tensile strength of bamboo scrimber based on boundary effect model

2020 ◽  
Vol 239 ◽  
pp. 107319
Author(s):  
Peng Xie ◽  
Wen Liu ◽  
Yucun Hu ◽  
Xinmiao Meng ◽  
Jiankun Huang
Keyword(s):  
Tensile Strength ◽  
Size Effect ◽  
Boundary Effect ◽  
Effect Model ◽  
Bamboo Scrimber

Assessment of Fracture Toughness Using Small Punch Tests of Prenotched Specimens

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Yangyan Zheng ◽  
Xiao Chen ◽  
Zheng Yang ◽  
Xiang Ling
Keyword(s):  
Fracture Toughness ◽  
Numerical Simulations ◽  
Stress Gradient ◽  
Element Model ◽  
Bending Test ◽  
J Integral ◽  
Notched Specimen ◽  
Small Punch ◽  
Three Point Bending ◽  
The Difference

In this paper, line- and ring-notched small punch test (SPT) specimens were studied; a three-dimensional (3D) model of a ring-notched SPT specimen was established using the contour integral method, and the validity of the model was verified using ring-notched specimens. The stress and strain fields were analyzed using numerical simulations of a ring-notched SPT specimen, and the change in the stress gradient during deformation was considered. To verify the finite element model, the results of the numerical simulations were compared with those of three-point bending tests and a Gurson–Tvergaard–Needleman (GTN) model. Compared with the line-notched specimen, the ring-notched specimen was more suitable for notch propagation analysis and fracture toughness evaluation. The results of the numerical simulations were in good agreement with those of the experiments, which showed that the numerical model used in this study was correct. For a notch that initiated when the load reached its maximum value, the value of the J integral was 335 × 10−6 kJ/mm2, and at time 0.85Pmax, the value of the J integral was 201 × 10−6 kJ/mm2, and the difference from the result of the three-point bending test was 14.4%. For a notch that initiated during the stretching deformation stage, the relevant fracture toughness was 225 × 10−6 kJ/mm2, and the difference from the result of the three-point bending test was 3%.

scholarly journals Fracture Toughness, Breakthrough Morphology, Microstructural Analysis of the T2 Copper-45 Steel Welded Joints

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 488 ◽  
Author(s):  
Hao Ding ◽  
Qi Huang ◽  
Peng Liu ◽  
Yumei Bao ◽  
Guozhong Chai
Keyword(s):  
Fracture Toughness ◽  
Welded Joints ◽  
Mixed Model ◽  
Experimental Testing ◽  
Microstructural Analysis ◽  
Bending Test ◽  
Dissimilar Welding ◽  
Tensile Fracture ◽  
Three Point Bending ◽  
Welding Materials

The performance and flaws of welded joints are important features that characteristics of the welding material influence. There is significant research activity on the performance and characteristics of welding joint materials. However, the properties of dissimilar welding materials and the cracking problem have not been thoroughly investigated. This investigation focuses on the evaluation and analysis of fracture mechanics, including fracture toughness, microstructural analysis, and crack initiation of T2 copper-45 steel dissimilar welding materials. Standard tensile and three-point bending experiments were performed to calculate the ultimate strength, yield strength, and elastic modulus for fracture toughness. The macro/micro-fracture morphology for tensile fracture and three-point bending fracture were analysed. Based on these investigations, it was concluded that the fracture types were quasi-cleavage and an intergranular brittle fracture mixed model. The deflection of the crack path was discussed and it was determined that the crack was extended along the weld area and tilted towards the T2 copper. Finally, the crack propagation and deflecting direction after the three-point bending test could provide the basis for improvement in the performance of welded joints based on experimental testing parameters and ABAQUS finite element analysis.

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