Mixed-Mode Fracture Characteristics of Cold Recycling Mixes with Emulsified Asphalt

2012 ◽  
Vol 204-208 ◽  
pp. 1678-1683 ◽  
Author(s):  
Lei Gao ◽  
Fu Jian Ni ◽  
Mei Kun Yang
Keyword(s):  
Fracture Energy ◽  
Mixed Mode ◽  
Peak Load ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Fracture Characteristics ◽  
Loading Rates ◽  
Crack Angle ◽  
Cold Recycling ◽  
Emulsified Asphalt

In order to study the Mixed-Mode cracking behavior of cold recycling mixes with emulsified asphalt, the Arcan test configuration was chosen to perform the fracture characteristics of cold recycling mixes in five levels of Mixed-Mode (100, 75, 50, 25 and 0% Mode I) at three loading rates (1.0mm/min, 0.5mm/min, 0.1mm/min). The load and load-line displacement, peak load, crack angle and fracture energy were all used for further analysis. The process of cracking can be divided into three stages: the stage of crack arises, expand stage, and the brittle break stage; 0% Mode I has a significant difference from the others; the loading rates and levels of Mixed-Mode both have great influence on peak load; the higher level of Mode I usually gets lower crack angle; the fracture energy of 100% Mode I ranges from 168 J/m2 to 308 J/m2 and the specimen in 0.5mm/min has greater fracture energy.

Mixed mode fracture testing of adhesively bonded wood specimens using a dual actuator load frame

Holzforschung ◽  
2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Hitendra K. Singh ◽  
Abhijit Chakraborty ◽  
Charles E. Frazier ◽  
David A. Dillard
Keyword(s):  
Fracture Energy ◽  
Mixed Mode ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Mixed Mode Loading ◽  
Mode Mixity ◽  
Adhesively Bonded ◽  
Phase Angles

Abstract An experimental evaluation of mixed mode fracture tests conducted on adhesively bonded wood specimens using a dual actuator load frame is presented. This unit allows the fracture mode mixity to be easily varied during testing of a given specimen, providing improved consistency, accuracy, and ease of testing over a range of loading modes. Double cantilever beam (DCB) type specimens made of southern yellow pine (Pinus spp.) wood substrates bonded with a commercially available one part polyurethane adhesive were tested over a wide range of mode mixities from pure mode I to pure mode II. The critical strain energy release rate (SERR) values were calculated from the measured load, displacement, and crack length data, in combination with material properties and specimen geometric parameters, and compared on a versus fracture envelope plot. Mean quasi-static fracture energy values were calculated to be 390 J m-2 and 420 J m-2 for mode I and mode II fracture, respectively. For various mixed mode phase angles, the critical SERR values were partitioned into mode I and mode II components. In mixed mode loading conditions the cracks were typically driven along the interface, which resulted in lower total fracture energy values when compared with those measured under pure mode I loading conditions. A drop in measured fracture energy of approximately 45% was observed with mode mixity phase angles as small as 16°, implying that engineering designs based on results from the popular mode I DCB test could be nonconservative in some situations. Fracture surfaces obtained at different mode mixities are also discussed. An improved understanding of fracture behavior of adhesively bonded wood joints under mixed mode loading through generation of fracture envelopes could lead to improved designs of bonded wood structures.

scholarly journals Analysis of Inclined Cracks in Thin-Walled Circular Tube under Mixed-Mode I + II Fracture

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 517 ◽  
Author(s):  
Boy Raymond Mabuza
Keyword(s):  
Fracture Mechanics ◽  
Mixed Mode ◽  
Crack Tip ◽  
Theoretical Models ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Shear Stresses ◽  
Inclined Crack ◽  
Mode Fracture ◽  
Thin Walled

This paper provides a study on mixed-mode fracture mechanics in thin-walled tube which is subjected to tension, shear and torsion loading. This type of loading causes an inclined crack to develop and generate a mixture of normal and shear stresses ahead of a crack tip. The stress state ahead of a crack tip is frequently based on mixed-mode type of interactions which designate the amplitude of the crack tip stresses. The analytical expressions for the stress intensity factors for mixed-mode I + II approach are presented. The Paris law for mixed-modes I + II has been discussed. Mixed-mode fracture mechanics is used with theoretical models to predict the path of crack growth when an inclined crack is subjected to a combination of mode I and mode II deformations. The torque at which crack propagation can be expected has been determined. The numerical calculations have been carried out by using MATLAB code. The results are good and could be useful for companies working with thin-walled circular tubes.

Comparison of mixed mode fracture criteria in finite element analysis for matrix crack density estimation of laminated composites

2020 ◽  
Vol 55 (2) ◽  
pp. 277-289
Author(s):  
Mingqing Yuan ◽  
Haitao Zhao ◽  
Li Tian ◽  
Boming Zhang ◽  
Yanzhi Yang ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Density Estimation ◽  
Mixed Mode ◽  
Crack Density ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Fracture Criteria ◽  
Element Analysis ◽  
Mode Fracture

A mixed mode crack density estimation method based on the finite element analysis (FEA) for laminated composites is proposed and verified in this paper. The damaged properties of cracked ply are obtained using semi-analytical micro-mechanical method for the first time. The piecewise functions of the mode I and mode II energy release rates involving crack density are given based on Griffith’s energy principle and discrete damage mechanics (DDM). Any mixed mode fracture criteria could be simply applied to the FEA of the structure to calculate the initiation and evolution of the micro-cracks in the laminate. Mode I criterion, power law and B-K criterion are applied in the numerical examples to compare their performances in the crack density estimation. It has been concluded that the accuracy of the fracture toughness is more important than the choice of fracture criterion in crack density estimation.

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