scholarly journals Probabilistic size effect law for mode II fracture from critical lengths in snow slab avalanche weak layers

2019 ◽  
Vol 65 (249) ◽  
pp. 157-167
Author(s):  
D. M. McCLUNG ◽  
C. P. BORSTAD
Keyword(s):  
Shear Strength ◽  
Size Effect ◽  
Shear Fracture ◽  
Principal Component ◽  
Critical Length ◽  
Specimen Size ◽  
Mode Ii ◽  
Field Observations ◽  
Fracture Properties ◽  
Probability Of Fracture

ABSTRACTFrom field observations, dry snow slab avalanche initiation is associated with fracture within relatively thin weak layers under stronger, cohesive slabs. For risk-based avalanche prediction, it is important to understand the fracture properties of alpine snow. Alpine snow is a quasi-brittle material with a fracture mechanical size effect on nominal shear strength meaning that strength decreases with increasing specimen size. A related size effect is the critical length required for rapid propagation of a shear fracture. In that case, the probability of fracture increases with increasing crack length. In this paper, 45 sets of field-measured critical lengths are presented based on 591 individual tests. From analysis, a probabilistic size effect law based on critical lengths is derived analogous to the deterministic size effect law for nominal shear strength related to fracture mechanics. The new size effect law may be useful in applications, particularly since the critical length is easily measured in the field and it is a principal component of weak layer fracture toughness.

scholarly journals An Experimental Study on the Basic Mechanical Properties and Compression Size Effect of Rubber Concrete with Different Substitution Rates

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yanli Hu ◽  
Xuewei Sun ◽  
Aiqun Ma ◽  
Peiwei Gao
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Shear Strength ◽  
Size Effect ◽  
Substitution Rate ◽  
Failure Modes ◽  
Pure Shear ◽  
Specimen Size ◽  
Substitution Rates ◽  
Rubber Concrete

An experimental study was carried out on the uniaxial compression, uniaxial splitting, pure shear, and compression size effect of rubber concrete with 5 different substitution rates by applying hydraulic servo and direct shear apparatus. Then, by comparing the failure modes and ultimate strength eigenvalues of rubber concrete under different loading conditions, the following conclusions were drawn: with the increase of rubber substitution rate, the concrete specimens maintain a relatively good integrity under uniaxial compressive failure; on the contrary, the failure sections under uniaxial slitting and pure shear gradually become uneven with an increasing amount of fallen rubber particles. With the increase of specimen size, the integrity of rubber concrete after failure is gradually improved. Affected by an increased rubber substitution rate, the uniaxial compressive strength, splitting tensile strength, and shear strength of the concrete gradually decrease, while the plastic deformation capacity gradually increases. Specifically, the compressive strength is reduced by a maximum of 60.67%; the shear strength is reduced by a maximum of 49.85%; and the uniaxial splitting strength is reduced by a maximum of 58.38%. Then, we analyzed the strength relationship and the underlying mechanism among the three types of loading modes. It is found that, at the same rubber substitution rate, the compressive strength of rubber concrete gradually increases as the specimen size decreases, and the size effect on the compressive strength gradually decreases as the rubber substitution rate increases. Meanwhile, we performed qualitative and quantitative analysis on the equation describing the coupling effect of specimen size and rubber substitution rate on the compressive strength; the results suggest that the proposed equation is of a high level of applicability. Our research has a reference value for the application and promotion of rubber concrete in actual engineering projects.

scholarly journals A Systematic Method to Evaluate the Shear Properties of Soil-Rock Mixture considering the Rock Size Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Minghui Ren ◽  
Guangsi Zhao ◽  
Xianhao Qiu ◽  
Qinghua Xue ◽  
Meiting Chen
Keyword(s):  
Shear Strength ◽  
Size Effect ◽  
Boundary Effect ◽  
Fractal Theory ◽  
Specimen Size ◽  
Gap Effect ◽  
Strength Analysis ◽  
Systematic Method ◽  
Apparent Cohesion ◽  
Rock Size

The soil-rock mixture (S-RM) is widely applied in the geotechnical engineering due to its better mechanical properties. The shear strength, an essential aspect of S-RM which governs the stability and the deformation, is rather necessary to be revealed properly. The extraordinary issue of S-RM compared to fine-grained soils is the grain size effect on the strength analysis. This paper proposes a systematic method to obtain the realistic shear strength of S-RM by detecting the rock size effect. Firstly, based on fractal theory, the rock size was determined as 5 mm by the multifractal property of granular size distribution. Then, based on 2 selected specimen sizes combining the engineering dimension, shear gaps (T) effect and specimen size effect on the shear strength of S-RM have been investigated. It is shown that the gap of the direct shear test decides the physical mechanism of particles forming the shear resistance of S-RM based on the variation of apparent cohesion and mobilized internal friction angle. Specimen size effect is weakened by the gap effect considering the boundary effect. Realistic and stable shear strength parameters of S-RM have been researched by a reasonable gap (0.2–0.4D, where D is the largest particle size).

Measurement of the shear and tensile fracture properties of leaves of pasture grasses

1996 ◽  
Vol 47 (4) ◽  
pp. 587 ◽  
Author(s):  
DA Henry ◽  
RH Macmillan ◽  
RJ Simpson
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Festuca Arundinacea ◽  
Shear Fracture ◽  
Tensile Fracture ◽  
Shear Properties ◽  
Fracture Properties ◽  
Pasture Grasses ◽  
The Relationship ◽  
Intrinsic Strength

The shear fracture properties of leaves of pasture grasses were measured using a shearing device consisting of 2 blades at fixed angles. The mechanics of the shearing process were examined with both paper and leaves of Festuca arundinacea. The investigations indicated that the intrinsic strength of the material being cut is best represented as force exerted during the cut divided by the length of the cutting blade in contact with the material. Tensile fracture properties of leaves of 5 pasture grasses were also measured, and the relationship between tensile and shear properties was examined. Intrinsic shear strength was weakly negatively correlated with tensile strength.

scholarly journals Experimental data on strength properties of mussel shell concretes and specimen size effect

Data in Brief ◽  
2021 ◽  
Vol 35 ◽  
pp. 106954
Author(s):  
Costas A. Anagnostopoulos ◽  
Denis Cabja ◽  
Chrysi A. Papadimitriou
Keyword(s):  
Experimental Data ◽  
Size Effect ◽  
Strength Properties ◽  
Specimen Size ◽  
Mussel Shell

scholarly journals Fracture and Size Effect of PFRC Specimens Simulated by Using a Trilinear Softening Diagram: A Predictive Approach

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3795
Author(s):  
Fernando Suárez ◽  
Jaime C. Gálvez ◽  
Marcos G. Alberti ◽  
Alejandro Enfedaque
Keyword(s):  
Reinforced Concrete ◽  
Size Effect ◽  
A Priori ◽  
Plain Concrete ◽  
Specimen Size ◽  
Bending Test ◽  
Orientation Factor ◽  
Fibre Reinforced Concrete ◽  
Softening Function ◽  
Three Point Bending

The size effect on plain concrete specimens is well known and can be correctly captured when performing numerical simulations by using a well characterised softening function. Nevertheless, in the case of polyolefin-fibre-reinforced concrete (PFRC), this is not directly applicable, since using only diagram cannot capture the material behaviour on elements with different sizes due to dependence of the orientation factor of the fibres with the size of the specimen. In previous works, the use of a trilinear softening diagram proved to be very convenient for reproducing fracture of polyolefin-fibre-reinforced concrete elements, but only if it is previously adapted for each specimen size. In this work, a predictive methodology is used to reproduce fracture of polyolefin-fibre-reinforced concrete specimens of different sizes under three-point bending. Fracture is reproduced by means of a well-known embedded cohesive model, with a trilinear softening function that is defined specifically for each specimen size. The fundamental points of these softening functions are defined a priori by using empirical expressions proposed in past works, based on an extensive experimental background. Therefore, the numerical results are obtained in a predictive manner and then compared with a previous experimental campaign in which PFRC notched specimens of different sizes were tested with a three-point bending test setup, showing that this approach properly captures the size effect, although some values of the fundamental points in the trilinear diagram could be defined more accurately.

Modeling of Size Effects on the Flow Stress of Type 304 Stainless Steel and Application in Coining Process

2007 ◽  
Author(s):  
Gap-Yong Kim ◽  
Muammer Koc ◽  
Jun Ni
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Flow Stress ◽  
Size Effect ◽  
Size Effects ◽  
Specimen Size ◽  
304 Stainless Steel ◽  
Length Scales ◽  
Type 304 ◽  
Type 304 Stainless Steel

Application of microforming in various research areas has received much attention due to the increased demand for miniature metallic parts that require mass production. For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/meso-scale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the “feature/specimen size” effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with experiments obtained from previous research and showed a very good agreement. The model was also applied to forming of micro-features by coining. A flow stress model for Type 304 stainless steel taking into consideration the effect of the grain and feature size was developed and implemented into a finite element simulation tool for an accurate numerical analysis. The scaling model offered a simple way to model the size effect down to length scales of a couple of grains and extended the use of continuum plasticity theories to micro/meso-length scales.

Fracture Mechanics in Pavement Engineering: The Specimen-Size Effect

1997 ◽  
Vol 1568 (1) ◽  
pp. 10-16 ◽  
Author(s):  
Anastasios M. Ioannides
Keyword(s):  
Fracture Mechanics ◽  
Size Effect ◽  
Specimen Size ◽  
Pavement Design ◽  
Crack Model ◽  
Design Procedures ◽  
Engineering Discipline ◽  
Pavement Engineering ◽  
Slow Progress ◽  
Mechanics Concepts

Application of fracture mechanics concepts developed in various branches of engineering to the pavement problem can address current limitations, thereby advancing considerably existing pavement design procedures. The state of the art in fracture mechanics applications to pavement engineering is summarized, and an in-depth discussion of one of the major concerns in such applications, the specimen-size effect, is provided. It is concluded that the fictitious crack model proposed by Hillerborg appears most promising for computerized application to pavements. The similitude concepts developed by Bache will be very useful in such efforts. Both the desirability and the scarcity of suitable candidates to replace Miner’s cumulative linear fatigue hypothesis in conventional pavement design are confirmed. Fracture mechanics is shown to be a very promising engineering discipline from which innovations could be transplanted to pavement activities. Nonetheless, it is pointed out that rather slow progress characterizes fracture mechanics developments in general. Pavement engineers clearly need to remain abreast of and involved in fracture mechanics activities.

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