Experimental research on fracture toughness II of undisturbed frozen soil

2011 ◽  
Author(s):  
Xiao-zhou Liu ◽  
Qiao Sun
Keyword(s):  
Fracture Toughness ◽  
Experimental Research ◽  
Frozen Soil

scholarly journals Experimental research on evolving rules of segregation ice in artificial frozen soil

2009 ◽  
Vol 1 (1) ◽  
pp. 544-549 ◽  
Author(s):  
Zhou Jin-sheng ◽  
Zhou Guo-qing ◽  
Zhang Qi ◽  
Liu Zhi-qiang ◽  
Zhao Guang-si
Keyword(s):  
Experimental Research ◽  
Frozen Soil

Experimental investigation of fracture toughness KIIC of frozen soil

2000 ◽  
Vol 37 (1) ◽  
pp. 253-258 ◽  
Author(s):  
Hongsheng Li ◽  
Haitian Yang ◽  
Zengli Liu
Keyword(s):  
Fracture Toughness ◽  
Experimental Study ◽  
Experimental Investigation ◽  
Loading Rate ◽  
Fracture Behaviour ◽  
Frozen Soil ◽  
Slight Effect ◽  
Factors Affecting ◽  
Four Point Bending ◽  
Main Factors

This paper describes an experimental study on the fracture toughness KIIC of pure frozen soil and the behaviour of the interface between frozen soil and concrete. A four-point bending device is used in the test. Experimental results indicate that water content and temperature are the main factors affecting fracture toughness. Within the range of the experiment, loading rate has a very slight effect on fracture toughness. Some formulae are suggested to evaluate the fracture behaviour of frozen soil.Key words: frozen soil, fracture mechanics, fracture toughness, interface.

Experimental Research on Size Effect of Mode II Fracture Toughness of Concrete

2013 ◽  
Vol 438-439 ◽  
pp. 229-234
Author(s):  
Shao Wei Hu ◽  
Liang Hu
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Size Effect ◽  
Fracture Energy ◽  
Experimental Research ◽  
Shear Fracture ◽  
Concrete Strength ◽  
Displacement Curve ◽  
Fracture Parameters ◽  
Mode Ii Fracture Toughness

Based on specimen size, which is the main reason of the shear fracture toughness of concrete, experimental research was carried out by 5 groups including 40 symmetrically loading specimens with different length and height. Through load and crack tip sliding displacement curve P-CTSD, load and strain curve P-ε and load and time curve P-t, the effects of length and height of specimens to shear fracture toughness were studied. Specimen stability is strengthened with increasing of length and weakened with increasing of height. Size effect of fracture toughness is weakened with increasing of length, is strengthened with the increasing of height. Fracture toughness increases with the increasing of length, decreases with the increasing of height. Research Background The size effect exists in parameters of concrete, such as concrete strength, modulus of elasticity, fracture toughness, fracture energy and so on [1-. In 1961, the theory of fracture mechanics was applied to concrete structure for the first time by Kaplan [. A vast majority of research work about concrete fracture mechanics was carried out by international scholars [6-. As the development of fracture theory of concrete, the size effect of fracture parameters became the focal point in theory study. Karihaloo [ pointed out that the size effect of concrete strength strengthens with the increasing of components size, however, the size effect weakens when crack length decreased relative to the size of specimens. Hu [3, 10, 11] accounted for the size effect by applying the theory of boundary effect and carried out the concept of local fracture energy which changes with width of fracture process zone. Based on the fictitious crack model, an analytical method [12, 13] for predicting the effective fracture toughness of concrete of three-point bending notched beams is proposed and the effects of initial seam height ratio and height on fracture parameters were carried out by Wu and Xu. At present, research on shear fracture toughness of concrete is immature and there are almost no papers about the size effect of shear fracture toughness of concrete. Aiming at the issue, this paper conducts a study on the size effect of shear fracture toughness of concrete by using symmetrically single-edge notched specimen.

Fracture toughness of frozen base and subbase soils in pavement

2001 ◽  
Vol 38 (5) ◽  
pp. 967-981 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Julie Cummings
Keyword(s):  
Fracture Toughness ◽  
Frozen Soil ◽  
Test Method ◽  
Moisture Distribution ◽  
Crushed Stone ◽  
Base Layer ◽  
Frozen Sand ◽  
Average Grain Size ◽  
Pavement Structure ◽  
Ice Content

Temperature distribution in the pavement structure, moisture distribution in granular soils, modulus of the asphalt concrete, and fracture toughness of material in the pavement structure strongly influence the propagation and spacing of thermal contraction cracks. Fracture toughness was determined for frozen sand (subbase layer) and frozen crushed stone (base layer) by adapting established fracture mechanics test procedures recommended in American Society for Testing and Materials standard test method E399-83 for metals. It was established that fracture toughness increases with decreasing temperature and increasing volumetric ice content. For a temperature of –5°C, the fracture toughness of frozen crushed stone increased almost linearly from 0.05 to 0.40 MPa·m0.5 when the volumetric ice content increased from 6 to 14%. For frozen sand, the fracture toughness KIC in a wedge-opening mode increased from 0.04 to 0.70 MPa·m0.5 when the volumetric ice content increased from 8 to 28%. It was also established that the fracture toughness of frozen soil decreases with decreasing soil average grain size according to a logarithmic law.Key words: fracture, toughness, experimental, frozen, granular soil, pavement.

Precipitation in Al-Li-Zr alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 186-187
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Fracture Toughness ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Transmission Electron ◽  
Water Quench ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

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