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
2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Hai-Ying Liu ◽  
Hang-Tian Duan ◽  
Chun-Qiu Zhang ◽  
Wei Wang

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.


2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Qingguang He ◽  
Yanxia Bai ◽  
Weike Wu ◽  
Yongfeng Du

A novel assembled self-centering variable friction (SCVF) brace is proposed which is composed of an energy dissipation system, a self-centering system, and a set of force transmission devices. The hysteretic characteristics and energy dissipation of the SCVF brace with various parameters from low-cyclic loading tests are presented. A finite element model was constructed and tested under simulated examination for comparative analysis. The results indicate that the brace shows an atypical flag-type hysteresis curve. The SCVF brace showed its stable self-centering ability and dissipation energy capacity within the permitted axial deformation under different spring and friction plates. A larger deflection of the friction plate will make the variable friction of this SCVF brace more obvious. A higher friction coefficient will make the energy dissipation capacity of the SCVF brace stronger, but the actual friction coefficient will be lower than the design value after repeated cycles. The results of the fatigue tests showed that the energy dissipation system formed by the ceramic fiber friction blocks and the friction steel plates in the SCVF brace has a certain stability. The finite element simulation results are essentially consistent with the obtained test results, which is conducive to the use of finite element software for calculation and structural analysis in actual engineering design.


2020 ◽  
Vol 57 (6) ◽  
pp. 903-920 ◽  
Author(s):  
Zongqi Bi ◽  
Quanmei Gong ◽  
Peijun Guo ◽  
Qian Cheng

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.


1971 ◽  
Vol 3 (3) ◽  
pp. 340-345 ◽  
Author(s):  
A. P. Gusenkov ◽  
N. N. Velichkin

2018 ◽  
Vol 177 ◽  
pp. 287-302 ◽  
Author(s):  
Feng Yu ◽  
Guoshi Xu ◽  
Ditao Niu ◽  
Anchun Cheng ◽  
Ping Wu ◽  
...  

2011 ◽  
Vol 374-377 ◽  
pp. 2041-2045
Author(s):  
Jing Wu ◽  
Fa Zhou Wang ◽  
Yue Li ◽  
Wen Yang ◽  
Shu Guang Hu

On the premise of maintaining certain vertical bearing capacity, the frame structure dissipates seismic energy by elastic-plastic deformation in elastic-plastic stage of earthquake action. Using lightweight concrete in structure not only can reduce the its dead weight, decrease the earthquake power; also meet the concrete strength, stiffness and elastic modulus requirements of important structure, so as to improve its energy dissipation capacity. This paper researched the effect of concrete materials, including or such as C60 high strength Lightweight concrete (HSLC), high strength concrete (HSC) and high strength Light weight aggregate concrete (HSLAC), on the seismic behavior of RC column under horizontal low cyclic loading, respectively and the match relationship between concrete and steel reinforcement cage was analyzed.


Author(s):  
David Baxter

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.


1982 ◽  
Vol 17 (6) ◽  
pp. 651-656
Author(s):  
M. Ya. Mikel'son ◽  
I. V. Grushetskii ◽  
L. V. Katinova ◽  
V. P. Tamuzh

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