scholarly journals Correction to: Creep and Long-Term Permeability of a Red Sandstone Subjected to Cyclic Loading After Thermal Treatments

2018 ◽  
Vol 52 (1) ◽  
pp. 297-297 ◽  
Author(s):  
Sheng-Qi Yang ◽  
Bo Hu
Keyword(s):  
Cyclic Loading ◽  
Thermal Treatments ◽  
Red Sandstone

scholarly journals Structural and mechanical defects of materials of offshore and onshore main gas pipelines after long-term operation

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Pavlo Maruschak ◽  
Sergey Panin ◽  
Iryna Danyliuk ◽  
Lyubomyr Poberezhnyi ◽  
Taras Pyrig ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Quantitative Analysis ◽  
Stress Concentration ◽  
Cyclic Loading ◽  
Fatigue Cracks ◽  
Preliminary Deformation ◽  
Term Operation ◽  
Steel Pipes

AbstractThe study has established the main regularities of a fatigue failure of offshore gas steel pipes installed using S-lay and J-lay methods.We have numerically analyzed the influence of preliminary deformation on the fatigue life of 09Mn2Si steel at different amplitudes of cyclic loading. The results have revealed the regularities of formation and development of a fatigue crack in 17Mn1Si steel after 40 years of underground operation. The quantitative analysis describes the regularities of occurrence and growth of fatigue cracks in the presence of a stress concentration.

Trabecular bone adapts to long-term cyclic loading by increasing stiffness and normalization of dynamic morphometric rates

Bone ◽  
2013 ◽  
Vol 55 (2) ◽  
pp. 325-334 ◽  
Author(s):  
Floor M. Lambers ◽  
Kathleen Koch ◽  
Gisela Kuhn ◽  
Davide Ruffoni ◽  
Claudia Weigt ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Trabecular Bone

Dynamic viscoelastic behavior of lower extremity tendons during simulated running

2000 ◽  
Vol 89 (4) ◽  
pp. 1352-1359 ◽  
Author(s):  
M. De Zee ◽  
F. Bojsen-Møller ◽  
M. Voigt
Keyword(s):  
Cyclic Loading ◽  
Achilles Tendon ◽  
Testing Machine ◽  
Viscoelastic Behavior ◽  
Muscle Spindles ◽  
Minor Effect ◽  
Velocity Feedback ◽  
Dynamic Creep

The aim of this project was to see whether the tendon would show creep during long-term dynamic loading (here referred to as dynamic creep). Pig tendons were loaded by a material-testing machine with a human Achilles tendon force profile (1.37 Hz, 3% strain, 1,600 cycles), which was obtained in an earlier in vivo experiment during running. All the pig tendons showed some dynamic creep during cyclic loading (between 0.23 ± 0.15 and 0.42 ± 0.21%, means ± SD). The pig tendon data were used as an input of a model to predict dynamic creep in the human Achilles tendon during running of a marathon and to evaluate whether there might consequently be an influence on group Ia afferent-mediated length and velocity feedback from muscle spindles. The predicted dynamic creep in the Achilles tendon was considered to be too small to have a significant influence on the length and velocity feedback from soleus during running. In spite of the characteristic nonlinear viscoelastic behavior of tendons, our results demonstrate that these properties have a minor effect on the ability of tendons to act as predictable, stable, and elastic force transmitters during long-term cyclic loading.

scholarly journals Study on the Fatigue and Durability Behavior of Structural Expanded Polystyrene Concretes

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2882 ◽  
Author(s):  
Quan You ◽  
Linchang Miao ◽  
Chao Li ◽  
Huanglei Fang ◽  
Xiaodong Liang
Keyword(s):  
Cyclic Loading ◽  
Cyclic Load ◽  
Dynamic Performance ◽  
Plain Concrete ◽  
Expanded Polystyrene ◽  
Structural Elements ◽  
Sulfate Resistance ◽  
Erosion Test ◽  
Test Process

The fatigue and durability characteristics of structural expanded polystyrene concrete (EPS) are especially important when it was applied for structural elements in long-term service. In order to study the fatigue and durability behavior of structural EPS concrete, the long-term cyclic loading experiments and wetting–drying (W-D) cyclic experiments were conducted, respectively. The structural EPS concrete was found to have a relatively large damping and a fairly low dynamic elastic modulus under long-term cyclic load, which illustrated that it had a better energy absorption effect and toughness than plain concrete of the same strength level. Even if fine cracks appeared during the cyclic loading process, the relevant dynamic performance remained stable, which indicated that the structural EPS concrete had superior fatigue stability. In W-D cyclic experiments, the structural EPS concrete exhibited superior sulfate resistance. During the erosion test process, there was a positive correlation between the mass change and the evolution of the compressive strength of the structural EPS concrete, which indicated that ΔmB could be substituted for Δf to evaluate the degree of the structural EPS concrete eroded by sulfate attack. The study focuses on the fatigue performance and sulfate resistance of structural EPS concrete and is of important engineering value for promoting practical long-term operations.

Durability of Embedded PZTs in Structural Health Monitoring Systems under Cyclic Loading

2014 ◽  
Vol 891-892 ◽  
pp. 1255-1260 ◽  
Author(s):  
Sanghyun Yoo ◽  
Akbar Afaghi Khatibi ◽  
Everson Kandare
Keyword(s):  
Cyclic Loading ◽  
Structural Health Monitoring ◽  
Lead Zirconate Titanate ◽  
Health Monitoring ◽  
Low Cycle Fatigue ◽  
Maintenance Cost ◽  
Clear Understanding ◽  
Structural Health ◽  
Service Conditions

Structural Health Monitoring (SHM) systems are developed to decrease the maintenance cost and increase the life of engineering structures by fundamentally changing the way structural inspections are performed. However, this important objective can only be achieved through the consistent and predictable performance of a SHM system under different service conditions. The capability of a Piezoelectric lead Zirconate Titanate (PZT)-based SHM system in detecting structural flaws strongly depends on the sensor signals as well as actuator performance. But service conditions can change the behaviour of transducers, raising questions about long term SHM system capability. Although having a clear understanding of the reliable sensor life is important for surface mounted systems, however, this is particularly critical for embedded sensors. This is due to the fact that opportunity for replacement of sensors exists for surface bonded transducers while for the embedded systems, sensor replacement is not straightforward. Therefore, knowledge of the long term behaviour of embedded-SHM systems is critical for their implementation. This paper reports a study on the degradation of embedded PZT transducers under cyclic loadings. Carbon/epoxy laminates with an embedded PZT were subjected to fatigue loading and their performance was monitored using Scanning Laser Vibrometery (SLV). The functionality of PZT transducers under sensing and actuating modes were studied. High and low cycle fatigue tests were performed to establish strain-voltage relationships which can be used to identify critical cyclic loading parameters (number of cycles and R value) under sensing and actuating modes.

scholarly journals Experimental Study on the Creep Behavior of Red Sandstone under Low Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Yongjun Song ◽  
Leitao Zhang ◽  
Huimin Yang ◽  
Jianxi Ren ◽  
Yongxin Che
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Deformation Characteristics ◽  
Red Sandstone ◽  
Rock Samples ◽  
Uniaxial Creep ◽  
Deformation Properties ◽  
Accelerated Creep ◽  
Different Temperatures

In cold regions, the deformation characteristics and long-term mechanical properties of rocks under low-temperature conditions are considerably different from those in other regions. To study the deformation characteristics and long-term mechanical properties of rocks in a low-temperature environment and the effect of different temperatures, we perform a multilevel loading-unloading uniaxial creep test on red sandstone samples and obtain the creep curves at different temperatures (20°C, −10°C, and −20°C). The results demonstrate that the total strain at each temperature can be divided into instantaneous and creep strains; the instantaneous strain includes instantaneous elastic and plastic strains, and the creep strain includes viscoelastic and viscoplastic strains. Temperature has a significant effect on the deformation properties of red sandstone. A decrease in temperature reduces the instantaneous and creep deformations of the rocks at all levels of stress. In addition, a decrease in temperature exponentially attenuates the total creep and viscoplastic strains of the rocks. 0°C is a critical point for the reduction of the total creep and viscoplastic strains of the rocks. When the temperature is greater than 0°C, the total creep and viscoplastic strains of the rocks decrease rapidly and linearly with decrease in temperature; however, when the temperature is less than 0°C, the decrease in the total creep and viscoplastic strains of the rocks is slow. The steady-state creep rate of the rock samples decreases with decrease in temperature, whereas the creep duration increases with decrease in temperature, especially in the case of the accelerated creep stage. The accelerated creep durations of the rock samples S4 (20°C) and S7 (–10°C) are 0.07 h and 0.23 h, respectively.

scholarly journals The changing strength of carbonate silt: parallel penetrometer and foundation tests with cyclic loading and reconsolidation periods

2020 ◽  
Vol 57 (11) ◽  
pp. 1664-1683 ◽  
Author(s):  
Z. Zhou ◽  
D.J. White ◽  
C.D. O’Loughlin
Keyword(s):  
Cyclic Loading ◽  
Soil Strength ◽  
Life Changes ◽  
Test Procedures ◽  
Coefficient Of Consolidation ◽  
Model Foundation ◽  
Order Of Magnitude ◽  
Potential Link ◽  
Surface Foundation

This paper describes a centrifuge study using novel penetrometer tests (T-bar and piezoball) and model foundation tests to explore through-life changes in the strength of a reconstituted natural carbonate silt. The test procedures include episodic cyclic loading, which involves intervals of pore pressure dissipation between cyclic packets. These loads and the associated remoulding and reconsolidation cause significant changes in the soil strength and foundation capacity. Soil strength changes from penetrometer tests differed by a factor of 15 from the fully remoulded strength to a limiting upper value after long-term cyclic loading and reconsolidation. For the model foundation tests, the foundation capacity of a surface foundation and a deep-embedded plate were studied. The soil strength interpreted from the measured foundation capacity varied by a factor of up to three due to episodes of loading and consolidation, with an associated order of magnitude increase in the coefficient of consolidation. The results show a remarkable rise in soil strength over the loading events and provide a potential link between changes in soil strength observed in penetrometer tests and the capacity of foundations, allowing the effects of cyclic loading and consolidation to be predicted.

Long-term behaviour and degradation of calcareous sand under cyclic loading

2020 ◽  
Vol 276 ◽  
pp. 105756 ◽  
Author(s):  
Shao-Heng He ◽  
Zhi Ding ◽  
Tang-Dai Xia ◽  
Wan-Huan Zhou ◽  
Xiao-Lu Gan ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Calcareous Sand
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