Papers by Keyword: Creep Test

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Authors: Yong Hong
Abstract: This paper presents the monitoring records of the deformation on the North Slope of Lishan Mountain in Lintong County, Shanxi, China. On the basis of the monitoring results on the site and the creep tests on the soil samples, the mechanism of the potential dangerous landslide was analyzed. The existence of lock segment in the slope and its time effect are regarded as the important controlling factors in the development process of Lishan potential landslide which has the possibility of becoming a rapid disastrous landslide.
Authors: Yan Hai Yang, Hua Cai, Min Jiang Zhang, Yan Xu
Abstract: The recycle of asphalt pavement material is not only accordance with the policy of national energy conservation and emission reduction, but also can significantly reduce the project cost. Viscoelastic mechanical model of recycled asphalt mixture is studied based on pavement maintenance engineering of Shenyang-Shanhaiguan expressway, and with analysis of material performance we could collect testing data from bending creep test on small beam, obtain testing parameters through fitting method. The results indicate that general Maxwell model could nicely reflect the viscoelastic mechanical behavior of recycled asphalt mixture.
Authors: Amir Kavussi, Rashid Tanzadeh
Abstract: Recycling of bituminous mixes is extending worldwide with the aim of conserving natural resources and the environment. Rejuvenating agents are generally used in recycling processesin order to soften the aged binders in mixes. Cutback bitumens have been used in Iran mainly in preparing conventional cold mixes. However, the long term good performance of these cold mixes in various parts of the country has shown less hardening of these mixes, compared with conventional HMA mixes. In this research the application of a cutbackbitumen has been investigatedas a rejuvenating agent in mixes containing laboratory aged binders. A 60-70 penetration grade bitumen from Refinery of Tehran was aged under Thin Film Oven Testing (TFOT) conditions. Asphalt Concrete samples were prepared using TFOT aged and virgin binders. Additional samples were prepared using the aged binders together with various amounts of a slow curing SC-250 cutback bitumen from the above refinery. The compacted four inchdiameter samples were tested under static creep testing. The results showed promising effects of the cutback binder in rejuvenating the aged mixes. Based on the results of this study, a mix design criteria wasset for recycled mixes containing cutback bitumen as the rejuvenating agent.
Authors: Piet Stroeven, Huan He, Pham Huu Hanh
Abstract: Paper presents and discusses data obtained in a testing program on the replacement of limestone powder in asphalt concretes by fly ashes. This would combine economic, environmental and technical benefits. The finest fly ash of Vietnamese origin scored best. This is proposed due to the gap-graded design of the particulate mixture of coarse crushed rock fractions, fine fluvial sand and the mineral admixture. The test program encompassed Marshall tests, creep tests and splitting tensile tests.
Authors: Gui Bo Nie, Xu Dong Zhi, Feng Fan, Tusomu Kokawa, Shuang Niu, Zhi Wei Yu
Abstract: The city of Harbin is famous with its ice art and which attract the attention from the whole world. Ice shell is a kind of new architectural form in China which can be a suitable method for structure by using ice and snow-ice as structural material especially in cold regions. In this paper, an ice shell with span 9m and height 3.5 was completed to investigate the performance of this special structure under human loads and temperature. The results show that the ice shell maintains a bearing capacity under human loads due to the well-known mechanical behavior pf shell. However, the bearing capacity of the shell was largely depend on the variation of temperature. Furthermore, some rational suggests were given during the design and construct the ice shell. Finally, the works of this paper provides some material for the revision of ice code.
Authors: Makoto Sugamata, Masayuki Genei, Masahiro Kubota, Junichi Kaneko
Abstract: Creep and creep rupture tests were carried out for friction-stir-welded (FSW) joints of 5052 aluminum alloy plates at temperatures between 573 and 723 K. The results were compared with those of the base metal. 5052-O plates of 20 mm in thickness were joined by FSW and round bar creep specimens were machined out of the welded plates. Tensile tests were also conducted at RT, 623 and 723K for both FSW joints and base metal. The tensile strength of the joints was almost the same as that of the base metal at room and elevated temperatures. However, the FSW joints showed appreciably higher minimum creep rate and shorter rupture time than the base metal at all the tested temperatures and initial creep stresses. Creep rupture of the joints always occurred within the plastically stirred zone with lower contraction of cross-sectional area. Thus, FSW joints of 5052 alloy plates showed lower creep strength than the base metal.
Authors: Sheng Zhong, Chuan Xiao Liu, Zhi Hao Liu, Long Wang
Abstract: Based on general instantaneous strength test and uniaxial creep tests under devastating or integrated states, strain characteristics of mudstone in different stages have been determined. Analyzing strain features of mudstone developing in every stage of different tests, evolving creep law of mudstone under uniaxial devastating state may be validated, which axial limited creep strain under the decided loading standard is equal to that value at uniaxial complete strain-stress curve rearwards ultimate strength. Relationship between designed loading stress and its corresponding creep strain can be linear in uniaxial creep test of mudstone under integrated state, while must not be a determinate secant of uniaxial complete strain-stress curve. Studying results present that terminal creep strain of rock with certain loading levels and under devastating state can be only corresponded with an exclusive point of traditional uniaxial complete strain-stress curve rearwards the ultimate strength, and the extended limited creep courses of mudstone will answer for Boltzmann function.
Authors: Agata Kierzek, Janusz Adamiec
Abstract: Magnesium alloys of Mg-Y-RE-Zr series are characterized by creep resistance up to a temperature of 250 ° C, and can work up to a temperature of 300oC. These properties allow for the application of alloys of Mg-Y-RE-Zr series for the elements of racing car engines operating in the conditions of high loads and temperatures. The requirement of high reliability components of aircraft propulsion system, with high strength and corrosion resistance, also led to the use of these alloys in the aerospace industry. Welding technologies in cast magnesium alloys are applied in order to repair defects in castings, occurring in the casting process, as well as to regenerate worn out castings. Joints made of magnesium alloys should have at least the same properties as a finished casting. The literature lacks information on the properties of joints welded of cast magnesium alloys.This work includes examination of influence of heat treatment on creep resistance of alloy WE43. Material for the study comprised joints made by the TIG method, welded in the cast state. Creep tests were carried out on joints without heat treatment and joints after heat treatment. The tests were performed at the temperatures of 200 ° C and 250 ° C during 100h. It was found that there is an increase in creep resistance of the joints after heat treatment.
Authors: Chun Qiu Wang, Shi Bin Gu, Zhong Ju Wei, Bo Li, Shao Jie Chen
Abstract: The creep test of the No. 3 coal seam of Daizhuang Coal Mine is carried. Based on the experiment results, the creep support effect of deep pillar is analyzed with LS-DYNA. The results show that the circumferential initial creep stress of the tested coal is 3.061MPa and the circumferential initial creep stress is far below the axial initial creep stress which is 7.020MPa. In addition, the creep strength is 9.3266MPa and the creep coefficient is 0.6472. According to the test results, the creep support effect of deep strip pillar can be simulated excellently with LS-DYNA. Stress and deformation in simulated strip pillar show evident rheology. Many changes will take place in the stable situation of pillar after the working face mining. Under the effect of the overlying strata, this pillar turns into steady creep state after 15~16 months, then the pillar is able to maintain long-term stable state.
Authors: Michael Modigell, M. Hufschmidt
Abstract: Oscillation experiments, creep tests and shear stress ramps have been performed to analyze the yield stress and its time dependency. It has to be distinguished between iso-structural, dynamic and static yield stress. The iso-structural yield stress occurs immediately after shearing. Since the slurry structure remains unchanged, it is equivalent to the structure during shearing. At rest an internal structure builds up, this leads to an increase of the yield stress, which is referred to as the dynamic yield stress. It increases until its maximum value, the static yield stress, is reached.
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