Mechanical Modal and Numerical Simulation of Fracture Process of Block Wall

2011 ◽  
Vol 217-218 ◽  
pp. 1438-1443
Author(s):  
Yan Li ◽  
Xin Sheng Yin ◽  
Bo Wang
Keyword(s):  
Numerical Simulation ◽  
Fracture Toughness ◽  
Fracture Process ◽  
Concrete Block ◽  
Critical Value ◽  
Specimen Size ◽  
Linear Elastic ◽  
Block Wall ◽  
Elastic Fracture ◽  
Aerated Concrete

Aerated concrete is a typical non-uniform quasi-brittle materials, the fracture process is very complicated. To slove the problem of cracks in this block walls, a practical analytical method was proposed based on the vertical mortar joint model to solve the equivalent fracture toughness (the critical value which the crack occurred to spread unstable) With the use of the basic principle of composite material mechanics and linear elastic fracture mechanics. Against the results of the related experiments, the standard deviation and the coefficient of variation of Analytical Solution are smaller, , and the equivalent fracture toughness is the effective fracture parameters of independent of specimen size. So the suggested method is more feasible and applicable, which can forecast autoclaved aerated concrete block wall’s cracking and destroying.

scholarly journals Peridynamic analysis of dynamic fracture: influence of peridynamic horizon, dimensionality and specimen size

2021 ◽  
Author(s):  
Sahir N. Butt ◽  
Günther Meschke
Keyword(s):  
Dynamic Fracture ◽  
Fracture Process ◽  
Three Dimensional ◽  
Specimen Size ◽  
Surface Topology ◽  
Linear Elastic ◽  
Brittle Solids ◽  
Non Local ◽  
Elastic Fracture ◽  
Three Dimensional Simulations

AbstractIn peridynamic models for fracture, the dissipated fracture energy is regularized over a non-local region denoted as the peridynamic horizon. This paper investigates the influence of this parameter on the dynamic fracture process in brittle solids, using two as well as three dimensional simulations of dynamic fracture propagation in a notched plate for two loading cases. The predicted crack speed for the various scenarios of the initially stored energy, also known as the velocity toughening behavior as well as characteristics of the crack surface topology obtained in different crack propagation regimes in 3D computational simulations are compared with the experimentally observed crack velocity and fracture surfaces for Polymethyl Methacrylate (PMMA) specimens. In addition, we investigate the influence of the specimen size on the dynamic fracture process using two dimensional peridynamic simulations. The fracture strengths and the velocity toughening relationship obtained from different specimen sizes are compared with the Linear Elastic Fracture Mechanics (LEFM) size effect relationship and with results from experiments, respectively.

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.

scholarly journals Evaluation of linear-elastic fracture toughness of the teeth restored with different post and core systems

2015 ◽  
Vol 7 (8) ◽  
pp. 125-129
Author(s):  
Lamartine De Moraes Melo Neto Clovis ◽  
Afonso Franciscone Paulo ◽  
Mondelli Jose ◽  
Sbeghen Sabio Silvia ◽  
Lorenzi Poluha Rodrigo ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Post And Core

Fracture Toughness and Cracking Behaviour of SCC Compared to VC

2013 ◽  
Vol 577-578 ◽  
pp. 205-208
Author(s):  
Sara Korte ◽  
Veerle Boel ◽  
Wouter de Corte ◽  
Geert de Schutter
Keyword(s):  
Fracture Toughness ◽  
Fracture Process ◽  
Critical Value ◽  
Fracture Parameter ◽  
Self Compacting Concrete ◽  
Bending Tests ◽  
Three Point Bending ◽  
Notched Specimens ◽  
Subsequent Determination

Vibrated concrete (VC) and self-compacting concrete (SCC) have a substantially different composition, resulting in dissimilar mechanical properties regarding cracking behaviour. The critical value of the mode I stress-intensity factor KICis an appropriate fracture parameter for evaluating fracture toughness and can be obtained from three-point bending tests (3PBT) on small, notched specimens. Subsequent determination of the energy release rate thus allows to examine the crack propagation and fracture process of both concrete types. This paper describes the results of such 3PBTs on samples, made from VC and SCC. Evaluation of the cracking behaviour, derived from these results, reveals remarkable differences.

Validation of Linear Elastic Fracture Mechanics in Predicting the Fracture Toughness of Polyethylene Pipe Materials

2015 ◽  
Author(s):  
Tarek M. A. A. El-Bagory ◽  
Hossam E. M. Sallam ◽  
Maher Y. A. Younan
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Linear Elastic Fracture Mechanics ◽  
Operating Conditions ◽  
Specimen Thickness ◽  
Crosshead Speed ◽  
Linear Elastic ◽  
Piping Systems ◽  
Elastic Fracture ◽  
Point Bend

The main purpose of the present paper is to compare between the fracture toughness based on linear elastic fracture mechanics (GIC), and that based on nonlinear fracture mechanics (JIC). The material of the investigated pipe is a high-density polyethylene (HDPE), which is commonly used in natural gas piping systems. The welds at the pipe junction are produced by butt-fusion (BF), welding. Curved three-point bend (CTPB), fracture specimens are used. The crosshead speed ranged from 5 to 500 mm/min and specimen thickness ranged from 9 to 45mm for both welded and unwelded specimens at room temperature Ta, equal 23°C. The study reveals that the crosshead speed has a significant effect on the fracture toughness of both welded and unwelded specimens. The results of GIC for different specimen thickness and crosshead speed found previously by the authors [1] have been compared with JIC under the same operating conditions [2]. The comparison between welded and unwelded specimens revealed that in the welded specimens there is a marginal difference between fracture toughness measured using linear elastic fracture mechanics LEFM and elastic plastic fracture mechanics EPFM, for both crosshead speeds.

A Theory of Fracture Based Upon an Extension of Continuum Mechanics to the Nanoscale

2005 ◽  
Vol 73 (5) ◽  
pp. 792-798 ◽  
Author(s):  
Eun-Suok Oh ◽  
Jay R. Walton ◽  
John C. Slattery
Keyword(s):  
Numerical Simulation ◽  
Long Range ◽  
Continuum Mechanics ◽  
Bulk Material ◽  
Stress Singularity ◽  
Intermolecular Forces ◽  
Square Root ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Root Stress

A theory of fracture is presented that is based upon an extension of continuum mechanics to the nanoscale through the incorporation of long-range intermolecular forces which correct bulk material descriptions near interfaces. The surface energy on crack surfaces, which is given in terms of the long-range intermolecular forces, plays an important role in an expression for the stress distribution near the crack tip. It is observed through numerical simulation that the incorporation of these long-range intermolecular forces removes the square-root stress singularity predicted by classical linear elastic fracture mechanics.

Fracture Toughness Study on Zr-based Bulk Metallic Glasses

2007 ◽  
Vol 1048 ◽  
Author(s):  
Jin-yoo Suh ◽  
Mary Laura Lind ◽  
C. Paul Kim ◽  
R. Dale Conner ◽  
William L Johnson
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Fracture Surfaces ◽  
Linear Elastic ◽  
Elastic Fracture

AbstractThe fracture toughness of Zr-based bulk metallic glasses of various compositions was studied in the as-cast and annealed condition. Properties were characterized using x-ray and differential scanning calorimetry (DSC) and fracture surfaces were examined using electron microscopy (SEM). Quaternary Zr-Ti-Cu-Be alloys consistently had linear elastic fracture toughness values greater than 80 MPa·m1/2, while Vitreloy 1, a Zr-Ti-Cu-Ni-Be alloy, had an average fracture toughness of 48.5 MPa·m1/2 with a large amount of scatter. The addition of iron to Vitreloy 1 reduced the fracture toughness to 25 MPa·m1/2. Fracture surfaces were carefully analyzed using electron microscopy. Some samples had highly jagged patterns at the beginning stage of crack propagation, and the roughness of this jagged pattern correlated well with the measured fracture toughness values. These jagged patterns, the main source of energy dissipation in the sample, were attributed to the formation of shear bands inside the sample. The Zr-Ti-Cu-Be alloy, having KQ=85 MPa·m1/2 as cast, was annealed at various time/temperature combinations. When the alloy was annealed 50°C below Tg, the fracture toughness dropped to 6 MPa·m1/2, while DSC and X-ray showed the alloy to still be amorphous. The roughness of the fracture surfaces on relaxed samples also compared well with the relative fracture toughness.

scholarly journals Void Content and its Influence on the Fracture Behaviour of Long Fibre Reinforced Injection Molded Polypropylene

2004 ◽  
Vol 13 (6) ◽  
pp. 096369350401300
Author(s):  
Victor Iliev Rizov
Keyword(s):  
Fracture Toughness ◽  
Testing Machine ◽  
Compact Tension ◽  
Void Content ◽  
Linear Elastic ◽  
Static Testing ◽  
Glass Fibre Reinforced ◽  
Injection Molded ◽  
Elastic Fracture ◽  
Static Testing Machine

The influence of void content on the fracture performance of discontinuous long glass fibre reinforced injection molded polypropylene was studied. Compact tension specimens were machined from simple plate-tools and were loaded in a static testing machine in a laboratory environment. From the resulting load-displacement curves the fracture toughness was determined on the basis of the linear elastic fracture mechanics. It was found that higher void content causes a decrease in the fracture toughness.

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