scholarly journals Deformation Behavior of Saturated Marine Silt under Principal Stress Rotation as Induced by Wave Loading

2021 ◽  
Vol 11 (20) ◽  
pp. 9458
Author(s):  
Lan Cui ◽  
Qian Sheng ◽  
Zhenzhen Niu ◽  
Liuming Chang
Keyword(s):  
Cyclic Loading ◽  
Shear Strain ◽  
Deformation Behavior ◽  
Amplitude Ratio ◽  
Development Trend ◽  
Cyclic Stress ◽  
Complex Stress ◽  
Wave Loading ◽  
Cyclic Stress Ratio ◽  
Stress Rotation

An experimental study aimed at providing insights into the cyclic deformation behavior of saturated marine silt under principal rotation, as induced by wave loading, is presented. Using the GDS hollow cylinder apparatus, a series of undrained tests are performed and the specimens at identical initial states are subjected to combined axial–torsional cyclic loading that imposes different levels of stress rotation. The cumulative generalized shear strain γg is used to describe the deformation of the silt under complex stress paths. The test results show that the cumulative generalized shear strain is significantly dependent on the cyclic stress ratio (CSR) and cyclic loading amplitude ratio δ. The cumulative generalized shear strain increases with the increase in CSR and decreases with the increase in δ. The development trend of γg can be well predicted through the correct Monismith model in the non-liquefaction silt, with a low error that is generally less than 10%.

scholarly journals Experimental and Estimation Studies of Resilient Modulus of Marine Coral Sand under Cyclic Loading

2020 ◽  
Vol 8 (4) ◽  
pp. 287 ◽  
Author(s):  
Shao-Heng He ◽  
Qiong-Fang Zhang ◽  
Zhi Ding ◽  
Tang-Dai Xia ◽  
Xiao-Lu Gan
Keyword(s):  
Cyclic Loading ◽  
South China Sea ◽  
Effective Stress ◽  
South China ◽  
Stress Ratio ◽  
Resilient Modulus ◽  
Cyclic Stress ◽  
Marine Transportation ◽  
Cyclic Stress Ratio ◽  
Coral Sand

Coral sand is an important filler resource that can solve the shortage of terrestrial fillers in coastal areas. Recently, the foundations of many infrastructures in the South China Sea have been built with coral sand as fillers, which have been subjected to wave and traffic cyclic loads. Resilient modulus (Mr) is an important design parameter in marine engineering, but there are few studies on the resilient modulus response of coral sand under cyclic loading. A series of drained cyclic triaxial tests were carried out to investigate the effects of the initial mean effective stress (p0) and cyclic stress ratio (ζ) on the resilient modulus response of the coral sand from the South China Sea. The change of fractal dimension (αc) can reflect the rule of particle breakage evolution. The αc of coral sand shows a tendency of almost maintaining stable and then increasing rapidly with the increase of mean effective stress p0 under each cyclic stress ratio ζ. There is a threshold of p0, when the p0 exceeds this threshold, αc will increase significantly with the increase of p0. The increase of p0 has a beneficial effect on the improvement of the Mr, while the increase of ζ has both beneficial and detrimental effects on the improvement of the Mr. A new prediction model of the Mr considering particle breakage was established, which can better predict the Mr of coral sand in the whole stress interval. The research results can provide guidance for the design of marine transportation infrastructures, which can promote the development of marine transportation industry and energy utilization.

Strain degradation of saturated clay under cyclic loading

2001 ◽  
Vol 38 (1) ◽  
pp. 208-212 ◽  
Author(s):  
Jian Zhou ◽  
Xiaonan Gong
Keyword(s):  
Mathematical Model ◽  
Cyclic Loading ◽  
Stress Ratio ◽  
Axial Strain ◽  
Influence Factors ◽  
Cyclic Stress ◽  
Point Of View ◽  
Triaxial Tests ◽  
Cyclic Stress Ratio ◽  
Saturated Clay

Soil degradation is studied from the point of view of cyclic axial strain through stress-controlled triaxial tests on Hangzhou normally consolidated clay. Different influence factors on strain, such as cyclic stress ratio, overconsolidation ratio, and frequency, are studied. Degradation index is redefined according to the tests. A mathematical model for strain degradation is presented and verified.Key words: cyclic loading, saturated clay, strain degradation, mathematical model.

scholarly journals Shear modulus and damping ratio of a nonplastic silt at large shear strains

2019 ◽  
Vol 92 ◽  
pp. 08007
Author(s):  
Alper Sezer ◽  
Eyyub Karakan ◽  
Nazar Tanrinian
Keyword(s):  
Shear Modulus ◽  
Relative Density ◽  
Shear Strain ◽  
Stress Ratio ◽  
Damping Ratio ◽  
Cyclic Stress ◽  
Triaxial Tests ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Cyclic Stress Ratio

Site response analyses and solution of dynamic soil-structure interaction problems need determination of variation of shear modulus and damping ratio with shear strain. Since many studies in literature concern evaluation of behavior of sands and silty sands, a series of cyclic triaxial tests were performed to determine the variation of shear modulus and damping ratio of a nonplastic silt with shear strain. Stress controlled cyclic triaxial tests on silt specimens of initial relative densities ranging among 30%, 50% and 70% were performed. Tests were carried out on identical samples under different CSR levels, and the confining pressure was selected as 100 kPa. Variation of shear modulus and damping ratio of silts with cyclic stress ratio amplitude, relative density and number of cycles were investigated. It was understood that soil relative density and cyclic stress ratio amplitude has a significant influence on shear modulus and damping ratio of silts. It was also observed that, as the cyclic stress ratio amplitude is increased, greater shear modulus and lower damping ratio values were obtained.

Effects of frequency and cyclic stress ratio on creep behavior of clay under cyclic loading

2016 ◽  
Vol 35 (2) ◽  
pp. 281-291 ◽  
Author(s):  
Huayang Lei ◽  
Jingjin Liu ◽  
Min Liu ◽  
Zhipeng Zhang ◽  
Mingjing Jiang
Keyword(s):  
Cyclic Loading ◽  
Creep Behavior ◽  
Stress Ratio ◽  
Cyclic Stress ◽  
Cyclic Stress Ratio

The Study of the Influence of Different Drained Conditions for Seabed Stability Under Wave Loading

2009 ◽  
Author(s):  
Lien-Kwei Chien ◽  
Chi-Ling Yang ◽  
Wen-Chien Tseng
Keyword(s):  
Stress Ratio ◽  
Wave Theory ◽  
Cyclic Stress ◽  
Wave Action ◽  
Engineering Practice ◽  
Wave Loading ◽  
Cyclic Stress Ratio ◽  
Cyclic Shear ◽  
Sea Bed ◽  
Seabed Soil

A series of partial drained dynamic triaxial test were performed to understand the seabed stability under wave induced wave loading. In order to evaluate the real behavior of the strength of sea bed soil under wave action, the field sands in Kinhu were adopted in the study. The specimens were prepared by multi-pluviation through water method to simulate the particle aggregation in-situ. The marine soils stress states were simulated by Ko consolidation in laboratory. Moreover, the stability of marine sands is discussed under different drained conditions by using flow valve to control the soil drained states. In this study, the typhoon waves induced loading were simulated in small amplitude wave and Stoke’s 2nd order wave theory to evaluate the cyclic stress ratio in sea bed. From the test results found that the marine soil was liquefaction immediately by using the Stoke’s 2nd order theory. The drained efficiency is defined in this study. The relationship between strain, cyclic numbers, and cyclic stress ratio (CSR) were discussed under different drained efficiency conditions. Under the drained efficiency is 86% and the number cycle is one, the double amplitude strain (DA) of seabed soil will induce 10% by Stoke’s 2nd order wave theory induced the cyclic shear stress ratio. But under the drained efficiency is 100%, the DA of seabed soil will only induce 7%. Combined with the time concept of wave action, when the seabed soil reach to DA = 10% under wave loading, the time of wave action request 1296 sec. From the results indicated that the drained efficiency have significantly influence on deformation resistance of sea bed soil. Therefore, the study analysis could be provided the reference for near shore structure design and engineering practice, and reduce storm induced damages.

Application of the R-Curve Concept to Fatigue Crack Growth

1978 ◽  
Vol 100 (4) ◽  
pp. 416-420 ◽  
Author(s):  
D. P. Wilhem ◽  
M. M. Ratwani
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Extension ◽  
Stress Ratio ◽  
Cyclic Stress ◽  
Crack Growth Resistance ◽  
Resistance Curve ◽  
Cyclic Stress Ratio ◽  
Wide Range

Crack growth resistance for both static (rising load) and for cyclic fatigue crack growth has been shown to be a continuous function over a range of 0.1 μm to 10 cm in crack extension for 2024-T3 aluminum. Crack growth resistance to each fatigue cycle of crack extension is shown to approach the materials ordinary undirectional static crack resistance value when the cyclic stress ratio is zero. The fatigue crack extension is averaged over many cycles and is correlated with the maximum value of the crack tip stress intensity, Kmax. A linear plot of crack growth resistance for fatigue and static loading data shows similar effects of thickness, stress ratio, and other parameters. The effect of cyclic stress ratio on crack growth resistance for 2219 aluminum indicates the magnitude of differences in resistance when plotted to a linear scale. Prediction of many of these trends is possible using one of several available crack growth data correlating techniques. It appears that a unique resistance curve, dependent on material, crack orientation, thickness, and stress/physical environment, can be developed for crack extensions as small as 0.076 μm (3 μ inches). This wide range, crack growth resistance curve is seen of immense potential for use in both fatigue and fracture studies.

Experimental Study on the Combined Effect of Cyclic and Static Loads on the Mechanical Properties of the Saturated Soft Clay Material

2016 ◽  
Vol 723 ◽  
pp. 843-848
Author(s):  
Yi Wei ◽  
Ying Zhu ◽  
Jing Ni
Keyword(s):  
Mechanical Properties ◽  
Cyclic Load ◽  
Stress Ratio ◽  
Axial Strain ◽  
Soft Clay ◽  
Cyclic Stress ◽  
Excess Pore Pressure ◽  
Static Loads ◽  
Cyclic Stress Ratio ◽  
Excess Pore

The combined effect of cyclic and static loads on the mechanical properties of the soft clay was experimentally investigated by conducting undrained cyclic triaxial tests on Shanghai clay. The results show that an increment in either static or cyclic load increases excess pore pressures and axial strains. For a given value of combined cyclic and static loads, the mechanical properties of the soft clay are more sensitive to the cyclic load. Furthermore, the accumulated excess pore pressure and axial strain for a larger cyclic stress ratio and a lower combined stress ratio might overcome that for a lower cyclic stress ratio and a higher combined stress ratio. The mechanical properties of the soft clay after the cyclic load was unloaded were also discussed. It was observed that the excess pore pressure and axial strain under the static load alone decrease gradually with time. The trend of them largely depends on the ratio of cyclic load to static load.

scholarly journals Influence of the microstructure on the cyclic stress-strain behaviour and fatigue life in hypo-eutectic Al-Si-Mg cast alloys

2018 ◽  
Vol 165 ◽  
pp. 15004 ◽  
Author(s):  
Jochen Tenkamp ◽  
Alexander Koch ◽  
Stephan Knorre ◽  
Ulrich Krupp ◽  
Wilhelm Michels ◽  
...  
Keyword(s):  
Solid Solution ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Weight Ratio ◽  
Cyclic Stress ◽  
Stress Strain ◽  
Strain Behaviour ◽  
Eutectic Morphology ◽  
Cast Alloys ◽  
Incremental Step

Aluminium alloys are promising candidates for energy-and cost-efficient components in automotive and aerospace industries, due to their excellent strength-to-weight ratio and relatively low cost compared to titanium alloys. As modern cast processing and post-processing, e.g. hot isostatic pressing, result in decreased frequency and size of defects, the weakest link depends on microstructural characteristics, e.g. secondary dendrite arm spacing (SDAS), Si eutectic morphology and α-Al solid solution hardness. Hereby, fatigue investigations of the effect of the microstructure characteristics on the cyclic stress-strain behaviour as well as fatigue mechanisms in the low cycle and high cycle fatigue regime are performed. For this purpose, samples of the aluminium cast alloy EN AC-AlSi7Mg0.3 with different Si eutectic morphology and α-Al solid solution hardness were investigated. To compare the monotonic and cyclic stress-strain curves, quasistatic tensile tests and incremental step tests were performed on two microstructure conditions. The results show that the cyclic loading leads to a hardening of the material compared to monotonic loading. Based on damage parameter Woehler curves, it is possible to predict the damage progression and fatigue life for monotonic and cyclic loading in hypo-eutectic Al-Si-Mg cast alloys by one power law.

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