In Situ Creep Model Testing for the Tunnel Anchor Foundation of Xingkang Suspension Bridge in Luding of China

Due to the limitations of geography and geology, cast concrete tunnel anchors were used to provide counterforces for Xingkang Suspension Bridge foundation at the left bank of Daduhe River. In this study, the in situ creep tests were conducted on two model tunnel anchors at a scale of 1:10 near the real working anchor site. Thus, the long-term deformation of the real working tunnel anchors installed at the bridge foundation could be determined from the creep test of model tunnel anchors. The creep tests were conducted under three different loads and lasted for 102.2 h, 167.5 h, and 189.4 h, respectively. The model anchor, the surrounding rock, and their interface were all monitored and measured during the creep testing. In addition, the numerical calculation, in which the Burger creep constitution was used for describing the surrounding rock and the Mohr–Coulomb criterion for describing the concrete anchor, was performed to further evaluate the long-term stability of the real working tunnel anchors. The numerical calculations are in good agreement with the laboratory testing results, and the creep deformations of the anchor and the surrounding rock have the same order of magnitude. The results show that the tunnel anchor and surrounding rock of Xingkang Bridge are in a stable creep state under the three different loads.

Download Full-text

Study on creep performance of launch canister under long-term storage

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-2018-0028 ◽

2019 ◽

Vol 43 (2) ◽

pp. 199-208 ◽

Cited By ~ 2

Author(s):

Cun-Gui Yu ◽

Tong-Sheng Sun ◽

Guang-Yuan Xiao

Keyword(s):

Residual Deformation ◽

Bottom Layer ◽

Tensile Creep ◽

Creep Model ◽

Model Parameters ◽

Creep Tests ◽

Software Environment ◽

Long Term Storage ◽

Term Storage

In this paper, the creep performance of a multi-barrel rocket launch canister under long-term stacking storage is studied. Based on the Bailey–Norton model, a creep model for the frame material of a launch canister was established. Constant stress tensile creep tests under different stress levels at room temperature were carried out on the frame materials of the launch canister and the creep model parameters were obtained by test data fitting. The three-dimensional finite element model of the launch canister was established in the ABAQUS software environment and the creep deformation of the launch canister after long-term stacking storage was studied. The results indicated that the bottom layer of the launch canister frame presented an extended residual deformation when the stacking storage solution with the original support pad was used. Therefore, a position adjustment program of the support pad was put forward. The residual deformation of the launch canister frame after long-term storage could be significantly reduced, thus the performance requirements for the launch canister are guaranteed.

Download Full-text

A New Creep Constitutive Model for Eutectic Solder Alloy

Journal of Electronic Packaging ◽

10.1115/1.1462624 ◽

2002 ◽

Vol 124 (2) ◽

pp. 85-90 ◽

Cited By ~ 65

Author(s):

X. Q. Shi ◽

Z. P. Wang ◽

W. Zhou ◽

H. L. J. Pang ◽

Q. J. Yang

Keyword(s):

Constitutive Model ◽

Testing Temperature ◽

Creep Model ◽

Temperature Dependent ◽

Creep Tests ◽

Creep Flow ◽

Reliability Of Solder Joints ◽

Power Law Creep ◽

Creep Constitutive Model

In this study, a large number of creep tests were carried out to study the effect of stress level and testing temperature on the creep behavior of 63 Sn/37Pb solder in a systematic manner. Based on the dislocation controlled creep mechanism and Gibbs’ free-energy theory, a new creep constitutive model was proposed. The model was found to describe accurately the creep flow of the solder and to be capable of explaining the issues of stress and temperature dependent stress exponent and activation energy in the Arrhenius power-law creep model. Furthermore, the model was employed to predict accurately the long-term reliability of solder joints in a PBGA assembly.

Download Full-text

The Effect of Long Term Loading on Epoxy-Based Adhesive Reinforced with Nano-Particles for In Situ Timber Bonding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.545.111 ◽

2012 ◽

Vol 545 ◽

pp. 111-118 ◽

Cited By ~ 2

Author(s):

Zakiah Ahmad ◽

Martin P. Ansell ◽

Dave Smedley ◽

Paridah Md Tahir

Keyword(s):

Constant Load ◽

Nano Particles ◽

Design Stage ◽

Creep Tests ◽

Link Density ◽

Cross Link Density ◽

Term Creep ◽

Adhesive Materials

The mechanical properties of adhesive materials change over time, especially when they are subjected to long-term loading regimes. The significance of this is often overlooked at the design stage. When adhesives are subjected to a constant load, they may deform continuously, depending on temperature, humidity and cross-link density. This progressive deformation is called creep and will continue until rupture or yielding causes failure. It is imperative that reliable accelerated tests be developed to determine the long-term time-dependent performance of adhesives under different environmental conditions. The long-term creep behaviors of thixotropic and room temperature cure epoxy based adhesives reinforced with nano-particles specially formulated for in-situ bonding of pultruded rod into timber for repair and strengthening of timber structures were investigated. In this study two epoxy-based adhesives with nano-particles (silica fume and rubber) addition were subjected to bending creep tests, in accelerated environments. Experimental data showed that the adhesives reinforced with nano-rubber particles showed less creep deformation than the unreinforced adhesives.

Download Full-text

Study of the Long-Term Deformation Characteristics of Municipal Sludge Solidified Soil under the Coupling Action of Dry-Wet Cycles and Initial Static Deviatoric Stress

Advances in Civil Engineering ◽

10.1155/2020/8824414 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Aiwu Yang ◽

Shaokun Yang ◽

Guofang Xu ◽

Wei Zhang

Keyword(s):

Small Deformation ◽

Deviatoric Stress ◽

Creep Model ◽

Hyperbolic Function ◽

Deformation Characteristics ◽

Municipal Sludge ◽

Creep Tests ◽

Short Period ◽

Deviatoric Stresses

A self-developed curing agent is used to solidify the municipal sludge taken from Tianjin. Then, the long-term deformation characteristics of the sludge solidified soil are investigated by means of unconsolidated undrained creep tests with different dry-wet cycles for considering the influence of climate. The experimental results show that the attenuation rate of the shear peak strength of municipal sludge solidified soil decreases gradually with the increase of the number of dry-wet cycles, and the strength remains unchanged when the number of dry-wet cycles is greater than 10. The variation laws under different initial static deviatoric stresses are basically identical. When the applied stress is less than the yield stress of the sludge solidified soil, the duration curves of creep show only attenuated stage, i.e., with very small deformation, and the deformation reaches a constant in a short period of time. When the deviatoric stress reaches the long-term strength of the soil, the instantaneous deformation of the sludge solidified soil becomes large and damage occurs quickly. Under the same deviatoric stress, the creep deformation increases with the increase of the number of dry-wet cycles. When the load applied in each step is of the same magnitude, the higher the initial static deviatoric stress is, the larger the deformation of sludge solidified soil will be. It is found that the stress-strain relationship and the relationship between creep strain and time can be well described by an exponential function and a hyperbolic function, respectively. On this basis, a creep model is proposed for the long-term deformation considering the effect of dry-wet cycle times and initial static deviatoric stress. The model is further validated by comparing the predictions with the test results under different deviatoric stresses; the good agreement between which shows the potential application of the model to relevant practical engineering.

Download Full-text

Examining erosion in New Zealand over millennial timescales using in-situ 10Be and 14C

10.5194/egusphere-egu2020-9309 ◽

2020 ◽

Author(s):

Duna Roda-Boluda ◽

Taylor Schilgen ◽

Maarten Lupker ◽

Wittmann Hella ◽

Prancevic Jeff ◽

...

Keyword(s):

New Zealand ◽

Erosion Rate ◽

Sediment Flux ◽

Short Term ◽

Sediment Fluxes ◽

Landslide Activity ◽

Erosion Rates ◽

Order Of Magnitude

Landslides are the major erosional process in many orogens, and one of the most sensitive erosional process to tectonic and climatic perturbations. However, it remains extremely difficult to constrain long-term or past rates of landslide activity, and hence their contribution to long-term landscape evolution and catchment sediment fluxes, because the physical records of landsliding are often removed in <102 yrs. Here, we use the in-situ 10Be and in-situ 14C concentrations of recent landslide deposits and catchments from the Fiordland and the Southern Alps of New Zealand to: (a) estimate landslide frequencies over 103-104 yr timescales, which we compare against landslide inventories mapped from air photos (<102 yrs) to estimate changes in landslide activity, (b) quantify catchment-averaged erosion rates, and landslide&#8217;s contribution to those erosional fluxes, and (c) test whether paired 14C-10Be measurements can be used to trace erosional depth-provenance and identify transient erosion rate changes. We show that 10Be concentrations on landslide deposits can be used to estimate landslide recurrence intervals and frequency over 103 yr timescales, and that 14C/10Be ratios reflect the depth-provenance of sediment, and possibly transient changes in erosion rates. The comparison of our 10Be-based long-term landslide frequencies with short-term published inventories suggests that landslide frequencies have increased towards the present by up to an order of magnitude. We compare sediment fluxes inferred from these long- and short-term landslide inventories with sediment flux estimates derived from 10Be catchment-averaged erosion rates, which allows us to examine fluctuations in erosion rate estimates from 101 to 103 yrs timescales.&#160;

Download Full-text

Sea Ice Budget Studies of Baffin Bay Using A Numerical Ice Model

Annals of Glaciology ◽

10.1017/s0260305500003529 ◽

1984 ◽

Vol 5 ◽

pp. 75-80 ◽

Cited By ~ 1

Author(s):

T. E. Keliher ◽

J. S. Foley

Keyword(s):

Sea Ice ◽

Wind Fields ◽

Baffin Bay ◽

Model Average ◽

Short Period ◽

Order Of Magnitude ◽

Ice Conditions ◽

Ice Model

The dynamic-thermodynamic model of sea ice due to Hibler (1979) has been adapted for simulations of the Baffin Bay pack. The simulations were carried out for wind fields characteristic of the more common synoptic situations for July, the ice conditions of July 1969 being taken as typical of this month to initialize the model. Average long-term currents were also used. The modelled ice characteristics were consistent with expected results for the forcing fields and rheology of the ice. A comparison of advectional ice losses through Davis Strait with the melt in situ shows the melt to be an order of magnitude larger. However, the melt alone cannot clear the ice out of Baffin Bay. It seems that the mechanism for this process involves a slow consistent melt coupled with a short period of northwesterly winds.

Download Full-text

Support Effects on the Activity of Ni Catalysts for the Propane Steam Reforming Reaction

Nanomaterials ◽

10.3390/nano11081948 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1948

Author(s):

Aliki Kokka ◽

Athanasia Petala ◽

Paraskevi Panagiotopoulou

Keyword(s):

Steam Reforming ◽

Supported Catalysts ◽

Catalytic Performance ◽

Dissociative Adsorption ◽

Ni Catalysts ◽

Long Term Stability ◽

Parallel Increase ◽

Order Of Magnitude

The catalytic performance of supported Ni catalysts for the propane steam reforming reaction was investigated with respect to the nature of the support. It was found that Ni is much more active when supported on ZrO2 or YSZ compared to TiO2, whereas Al2O3- and CeO2-supported catalysts exhibit intermediate performance. The turnover frequency (TOF) of C3H8 conversion increases by more than one order of magnitude in the order Ni/TiO2 < Ni/CeO2 < Ni/Al2O3 < Ni/YSZ < Ni/ZrO2, accompanied by a parallel increase of the selectivity toward the intermediate methane produced. In situ FTIR experiments indicate that CHx species produced via the dissociative adsorption of propane are the key reaction intermediates, with their hydrogenation to CH4 and/or conversion to formates and, eventually, to CO, being favored over the most active Ni/ZrO2 catalyst. Long term stability test showed that Ni/ZrO2 exhibits excellent stability for more than 30 h on stream and thus, it can be considered as a suitable catalyst for the production of H2 via propane steam reforming.

Download Full-text

A 3D Creep Model considering Disturbance Damage and Creep Damage and Its Application in Tunnel Engineering

Mathematical Problems in Engineering ◽

10.1155/2020/7073089 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Geng-Feng Wang ◽

Fan Sun ◽

Xiao-Hui Xiong ◽

Lei He ◽

Ke-Hong Zhang

Keyword(s):

Space Dimension ◽

Creep Damage ◽

Wave Theory ◽

Creep Model ◽

Time Dimension ◽

Creep Tests ◽

Railway Tunnel ◽

Damage Theory ◽

Term Creep

Based on the Kachanov damage theory and elastic wave theory, considering the long-term creep damage from time dimension and instantaneous disturbance damage from space dimension, we presented a 3D damage creep model and converted it to difference expressions in order to write into the finite difference software FLAC3D. Then, according to the results of creep tests, we conducted parameter inversion of our damage creep model with the help of the particle swarm optimization (PSO) method. Finally, the damage creep model was applied in a railway tunnel project in Yunnan to simulate the tunnel deformation. Compared with the Burgers model and the model considering only creep damage, our model which considers both creep damage and disturbance damage yielded more reasonable results.

Download Full-text

Sea Ice Budget Studies of Baffin Bay Using A Numerical Ice Model

Annals of Glaciology ◽

10.3189/1984aog5-1-75-84 ◽

1984 ◽

Vol 5 ◽

pp. 75-80

Author(s):

T. E. Keliher ◽

J. S. Foley

Keyword(s):

Sea Ice ◽

Wind Fields ◽

Baffin Bay ◽

Model Average ◽

Short Period ◽

Order Of Magnitude ◽

Ice Conditions ◽

Ice Model

Download Full-text

An orchid (Orchidaceae)-rich area recommended for preservation in Novosibirsk Region, Russia

Acta Biologica Sibirica ◽

10.3897/abs.7.e63131 ◽

2021 ◽

Vol 7 ◽

pp. 21-38

Author(s):

Alexander Dubynin ◽

Inessa Selyutina ◽

Alexandra Egorova ◽

Mikhail Blinnikov

Keyword(s):

Population Monitoring ◽

Left Bank ◽

Red Data Book ◽

Novosibirsk Region ◽

Floral Diversity ◽

South Siberia ◽

Plant Area ◽

Data Book

The spatial distribution of 14 species of the orchid family (Orchidaceae) was studied at the left bank of the Koynikha River (Iskitimskiy District, Novosibirsk Region, Russia). Four species are listed in the Russian Federation Red Data Book, four are listed in the Novosibirsk Region Red Data Book. The number of individual plants is sufficient to ensure the long-term viability of each red-listed orchid population. What is apparently one of the largest populations of Cypripedium macranthos in the region is described (up to 5,000 individuals). Some of the orchids discovered require further study, namely interspecific hybrids of Dactylorhiza and Gymnadenia and distinctive floral developmental morphs of Platanthera. Аpplying the international criteria for allocation of an “Important Plant Area”, we nominate a new one for South Siberia. Based on the analysis of plant species composition of protected areas in Novosibirsk Region, we conclude that in situ preservation of orchids in the region is overall insufficient. It is therefore necessary to organize a new protected area “Orchid Zapovednik” in the category of “botanical Zakaznik” on 335 hectares with an explicit floral diversity conservation mandate and long-term orchid population monitoring.

Download Full-text