Effect of Cyclic Loading Frequency on the Behavior of a Stabilized Sand Reinforced with Polypropylene and Sisal Fibers

2022 ◽  
Vol 34 (1) ◽  
Author(s):  
Paulo J. Venda Oliveira ◽  
Guilherme R. Anunciação ◽  
António A. S. Correia
Keyword(s):  
Cyclic Loading ◽  
Loading Frequency ◽  
Sisal Fibers

scholarly journals Study of the Mechanical Environment of Chondrocytes in Articular Cartilage Defects Repaired Area under Cyclic Compressive Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Hai-Ying Liu ◽  
Hang-Tian Duan ◽  
Chun-Qiu Zhang ◽  
Wei Wang
Keyword(s):  
Articular Cartilage ◽  
Cyclic Loading ◽  
Response Curve ◽  
Fluid Pressure ◽  
Cartilage Defects ◽  
Loading Frequency ◽  
Liquid Pressure ◽  
Mechanical Environment ◽  
Finite Element Software ◽  
Maximum Value

COMSOL finite element software was used to establish a solid-liquid coupling biphasic model of articular cartilage and a microscopic model of chondrocytes, using modeling to take into account the shape and number of chondrocytes in cartilage lacuna in each layer. The effects of cyclic loading at different frequencies on the micromechanical environment of chondrocytes in different regions of the cartilage were studied. The results showed that low frequency loading can cause stress concentration of superficial chondrocytes. Moreover, along with increased frequency, the maximum value of stress response curve of chondrocytes decreased, while the minimum value increased. When the frequency was greater than 0.2 Hz, the extreme value stress of response curve tended to be constant. Cyclic loading had a large influence on the distribution of liquid pressure in chondrocytes in the middle and deep layers. The concentration of fluid pressure changed alternately from intracellular to peripheral in the middle layer. Both the range of liquid pressure in the upper chondrocytes and the maximum value of liquid pressure in the lower chondrocytes in the same lacunae varied greatly in the deep layer. At the same loading frequency, the elastic modulus of artificial cartilage had little effect on the mechanical environment of chondrocytes.

Experimental study of the evolution of soil arching effect under cyclic loading based on trapdoor test and particle image velocimetry

2020 ◽  
Vol 57 (6) ◽  
pp. 903-920 ◽  
Author(s):  
Zongqi Bi ◽  
Quanmei Gong ◽  
Peijun Guo ◽  
Qian Cheng
Keyword(s):  
Particle Image Velocimetry ◽  
Cyclic Loading ◽  
Soil Structure ◽  
Particle Image ◽  
Loading Frequency ◽  
Soil Arching ◽  
Arching Effect ◽  
Filling Height ◽  
Image Velocimetry ◽  
Load Cells

Arching effect, which is a common phenomenon in any system involving soil–structure interaction, has been found to be inevitably affected by various factors, including loading conditions. This study investigated the evolution of arching effect induced by cyclic loading by conducting a series of tests using a trapdoor apparatus. The test box was instrumented to control the displacement of the moving gate and to record the variation of vertical stress distribution by using a set of dynamic load cells. Digital images were captured during tests and processed using particle image velocimetry (PIV) to determine the displacement field and hence to examine the variation of geometric features of arch and particle movements. The evolution process of arching effect, from the initial formation to the finial collapse, was identified. Depending on the analysis for the geometry appearance, displacement region, and variation of cyclic stresses, both stable and collapsed arches were observed. By increasing the amplitude of cyclic loading step by step, critical loading amplitude corresponding to the threshold of collapse of the arching effect was determined. Based on the results, the effects of trapdoor displacement, cyclic loading frequency, and filling height on arching effect are discussed.

Fatigue of steel in air at low cyclic loading frequency

2011 ◽  
Vol 64 (6) ◽  
pp. 552-555 ◽  
Author(s):  
M.H. Marvasti ◽  
W. Chen ◽  
R.L. Eadie
Keyword(s):  
Cyclic Loading ◽  
Loading Frequency ◽  
Low Cyclic Loading

A Modelling Framework for Describing the Corrosion Fatigue Behaviour of Carbon Steel Pipelines and Risers

2011 ◽  
Author(s):  
David Baxter
Keyword(s):  
Cyclic Loading ◽  
Test Data ◽  
Experimental Testing ◽  
Region Of Interest ◽  
Critical Factor ◽  
Fatigue Behaviour ◽  
Careful Consideration ◽  
Carbon Steels ◽  
Loading Frequency ◽  
Stress Range

The fatigue performance of pipeline or riser girth welds is often a critical factor during design. Under corrosive conditions the detrimental influence of an environment on anticipated fatigue lives needs to be taken into account. Fatigue design codes provide advice for the case of loading in seawater at typical wave frequencies, but in other environments, or at other cyclic loading frequencies, the required approach is less certain, and laboratory testing is often needed to provide suitable guidance. In addition to the time and expense of such an exercise, in some cases there are physical limits to the nature of data that such programmes can provide. The provision of data associated with very low cyclic loading frequencies is one such case, as in this instance the time taken for each test becomes unmanageable. This leads to the need for extrapolation of test data into the region of interest, for instance by carrying out tests at either a higher cyclic loading frequency, or a higher stress range, than that anticipated in service. Such extrapolation requires careful consideration in order to avoid potential non-conservatism. It is suggested that the availability of a model which accounted for the influence of these two key parameters (frequency and stress range) would greatly improve confidence when extrapolation is needed, and more broadly would provide a rational basis for designing experimental testing programmes and applying determined data to pipeline design. Such a model should be based on a description of the perceived underlying mechanisms of a material’s interaction with the environment. This paper provides a review of relevant test data and describes the basis for such a model. A generalised framework is developed and fitted to numerous published test data for carbon steels in seawater or sour environment.

Environment-Assisted Cracking of Zr-Based Bulk Metallic Glass

2007 ◽  
Vol 561-565 ◽  
pp. 1279-1282 ◽  
Author(s):  
Yoshikazu Nakai ◽  
Makoto Seki ◽  
Yasunori Yoshioka
Keyword(s):  
Cyclic Loading ◽  
Metallic Glass ◽  
Crack Propagation ◽  
Crack Growth ◽  
Bulk Metallic Glass ◽  
Stress Ratio ◽  
Deionized Water ◽  
Sustained Load ◽  
Loading Frequency ◽  
Nacl Solution

Crack propagation tests on a bulk metallic glass, Zr55Cu30Ni5Al10, were conducted either in aqueous sodium chloride (NaCl) solutions or deionized water. Crack growth experiments were conducted under cyclic loading at a stress ratio of 0.1 or 0.5 under a loading frequency of 20 or 1.0 Hz. The experiments were also conducted under a sustained load. Although the crack growth rate in deionized water was almost identical to that in air, the rate in NaCl solution was much higher than that in air even in a very low concentration of NaCl such as 0.01%. In 3.5% NaCl solution, the time-based crack propagation rate during cyclic loading, da/dt, was determined by the maximum stress intensity factor, Kmax, but was independent of the loading frequency and the stress ratio, and the rate was almost identical to that of environment-assisted cracking under a sustained load.

Fracture mechanics analysis of crack shapes due to cyclic loading in baria–silicate glass

2007 ◽  
Vol 22 (12) ◽  
pp. 3415-3422 ◽  
Author(s):  
K. Suputtamongkol ◽  
K.J. Anusavice ◽  
J.J. Mecholsky
Keyword(s):  
Cyclic Loading ◽  
Fracture Mechanics ◽  
Silicate Glass ◽  
Load Level ◽  
Bending Test ◽  
Repeated Loading ◽  
Aqueous Environment ◽  
Loading Frequency ◽  
Loading Test ◽  
Critical Crack

The objective of this study was to determine the geometric characteristics associated with the critical crack caused by cyclic loading. In an attempt to simulate an intraoral loading condition, the Hertzian cyclic loading of baria–silicate glass was performed using a type 302 stainless steel indenter under an aqueous environment using clinically relevant parameters, i.e., a low loading frequency (∼3 Hz) and a low load level (⩽200 N). The indenter diameter (4.76 mm) approximated the cuspal radii of molar and premolar teeth. Ten bar specimens each were subjected to loading cycles of 0, 103, 104, and 105 cycles. A four-point bending test was used to quantify the severity of the strength reduction caused by the repeated loading test. There was a decrease in fracture stress after 103 cycles that was associated with cone crack formation. No significant additional reduction was found after 105 cycles for specimens tested both in air and in deionized water. Stress-corrosion fatigue accelerated the surface crack propagation rate in baria–silicate glass specimens. Four different crack geometries were identified along with failure mechanisms. Various fracture mechanics approaches were tested against observed crack geometries. The previously unobserved triangular crack geometry was found.

scholarly journals Experimental Study on Acoustic Emission and Resistivity Response of Sandstone under Constant Amplitude Cyclic Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Kui Wang ◽  
Xue Li ◽  
Zheng Huang ◽  
Mingjie Zhao
Keyword(s):  
Acoustic Emission ◽  
Cyclic Loading ◽  
Cyclic Load ◽  
Stress Amplitude ◽  
Rate Of Change ◽  
Rapid Decline ◽  
Engineering Practice ◽  
Loading Frequency ◽  
Constant Amplitude ◽  
Ae Signal

A lot of engineering practice shows that, during the construction and operation of rock mass projects, in addition to the static load, the rock is more subjected to cyclic load. Constant amplitude cyclic load is one of the simpler cyclic loading methods. The damage of rocks gradually accumulates under the action of periodic cyclic load, and finally, fatigue damage occurs, which affects the stability of the project. Therefore, it is necessary to study the mechanical properties of the rock under the action of constant amplitude cyclic load. Acoustic emission (AE) parameters and resistivity are both sensitive to the damage process of the rock and can well describe the damage evolution law of the rock. Under the action of constant amplitude cyclic loading, different loading conditions, different state specimens, and so on, factors will make a big difference to the AE signal and resistivity, such as the difference in stress amplitude, loading rate, and saturation. Therefore, in this paper, the typical sandstone in the Chongqing area is taken as the research object, the AE characteristics and resistivity characteristics of sandstone under different test conditions such as different stress amplitude, different loading frequency, and different saturation are tested, and the evolution of AE is found. It also has a three-stage rule: in the initial stage, the deformation is faster and the AE signal is strong; in the constant velocity stage, the deformation develops slowly and the AE signal is also stable; in the acceleration stage, the deformation develops sharply and the AE signal also becomes more intense. With the increase of cyclic loading stress amplitude, or the decrease of cyclic loading frequency, or the decrease of rock sample saturation, the acoustic emission signal generated in each cycle will be stronger. The resistivity as a whole shows a rapid decline in the loading phase and a rapid rebound in the unloading phase. The changes in resistivity at different stress amplitudes show differences in the first few cycles; the overall change trend of resistivity at different frequencies is consistent, but the rate of change increases with decreasing frequency, and the variation trend of resistivity is very different under different saturation.

scholarly journals Experimental investigation of pretensioned bolts under cyclic loading: Damage assessment using acoustic emission

2019 ◽  
Vol 15 (5) ◽  
pp. 155014771984935 ◽  
Author(s):  
Tieliang An ◽  
Xigui Zheng ◽  
Dengxing Zhu ◽  
Deyu Qian ◽  
Yu Guo ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Cyclic Loading ◽  
Cyclic Load ◽  
Loading Path ◽  
Loading Frequency ◽  
Damage Factor ◽  
Acoustic Emission Energy ◽  
Pull Out ◽  
Anchorage System ◽  
The Relationship

Understanding the acoustic emission effects on bolts under cyclic loading is of great significance for the support of roadways. The presented research focuses on the acoustic emission characteristics of bolts under cyclic loading. The following main conclusions were drawn: (1) With a higher loading frequency, the acoustic emission counts rate increases, while the total energy released in a given cyclic loading path decreases. (2) A fitting formula is established according to the relationship between the tension amplitude and cumulative acoustic emission counts, which can analyze the tension magnitude level of the cyclic load. (3) A damage factor for a cyclic load is proposed based on the acoustic emission counts generated during the cyclic and monotonic loading process that can analyze the degree of damage to the anchorage system caused by the cyclic load. (4) Based on the spatial distribution of the acoustic emission orientation points and the acoustic emission energy generated during the pull-out process, the acoustic emission damage evolution process of the anchorage specimens is deduced, and the mechanism of the high stability of the pretension anchorage system after cyclic loading is analyzed. The above conclusions may provide some experimental references for the application of acoustic emission technology in bolts supporting roadways.

Membrane filter properties and application of the filter to undrained cyclic triaxial test of unsaturated materials

2017 ◽  
Vol 54 (8) ◽  
pp. 1196-1202 ◽  
Author(s):  
Hailong Wang ◽  
Junichi Koseki ◽  
Tomoyoshi Nishimura ◽  
Yukika Miyashita
Keyword(s):  
Hydraulic Conductivity ◽  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Membrane Filter ◽  
Water Pressure ◽  
Characteristic Curve ◽  
Loading Frequency ◽  
Loading Test ◽  
Pressure Plate

Properties of the membrane filter recently introduced as an alternative to the ceramic disk are revealed through diffusion and hydraulic conductivity tests. It is shown that diffusion of air through the membrane filter is significantly affected by suction magnitude and that hydraulic conductivity of the membrane filter can easily be affected by the quality of water used in the test. The application of the membrane filter to the soil-water characteristic curve tests (SWCC tests) shows that similar SWCCs can be obtained by employing pressure plate apparatuses with either the ceramic disks or the membrane filter installed, and that repeatability of the SWCC by using the membrane filter pressure plate apparatus is reasonably good. The application of the membrane filter to the undrained cyclic loading test of unsaturated sandy materials shows that the response (the duration to measure the equilibrated pore-water pressure of unsaturated materials) of the membrane filter pedestal in a modified triaxial system may be as short as ∼2 s in certain test conditions, and fairly good pore-water pressure and air pressure measurements can be obtained during undrained cyclic loading with a loading frequency of 0.1 Hz.

Prediction of High Cycle Fatigue Property of Ti-6Al-4V Alloy Using Artificial Neural Network

2016 ◽  
Vol 849 ◽  
pp. 360-367
Author(s):  
Ye Man Zhao ◽  
Hong Chao Kou ◽  
Wei Wu ◽  
Ying Deng ◽  
Bin Tang ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Cyclic Loading ◽  
Bp Neural Network ◽  
High Cycle Fatigue ◽  
Volume Fraction ◽  
Fatigue Property ◽  
Loading Frequency ◽  
Cycle Fatigue ◽  
Artificial Neural

In this paper, the relationship between microstructure, parameters of cyclic loading and high cycle fatigue property of Ti-6Al-4V alloy was established by artificial neural network (ANN) modeling. The back propagation (BP) neural network and radial basis function (RBF) neural network were established by MATLAB. The input parameters of these models were the primary α volume fraction, primary α size, cyclic loading frequency and stress ratio. The output parameter was high cycle fatigue strength. The neural networks were trained with dataset collected from the literature. The prediction results showed that both of the networks have good generalization ability. In addition, the BP neural network with Levenberg-Merquardt (LM) learning algorithm has better fault tolerance and versatility in dealing with high cycle fatigue property, which is able to predict the high cycle fatigue property with a high accuracy.

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