scholarly journals Variable moduli of soil strain

2019 ◽  
Vol 97 ◽  
pp. 04013 ◽  
Author(s):  
Karim Sultanov ◽  
Pavel Loginov ◽  
Sabida Ismoilova ◽  
Zulfiya Salikhova
Keyword(s):  
Modulus Of Elasticity ◽  
Dynamic Compression ◽  
Soft Soil ◽  
Compressive Load ◽  
Loess Soil ◽  
Dynamic Strain ◽  
Static Compression ◽  
Nonlinear Properties ◽  
Strain Components ◽  
Soil Strain

The experimental diagrams between stress and strain components for soft soils are non-linear. Nonlinear diagrams qualitatively differ for soils of undisturbed and disturbed structures. It is believed that the manifestations of nonlinear properties of soil are associated with micro-destruction of soil structure under compression and, therefore, with changes in its mechanical characteristics under strain. It follows that the modulus of elasticity, Poisson’s ratio, viscosity and other mechanical parameters are the variables in the process of soil strain. Based on this, from the experimental results given in scientific literature, the changes in the modulus of elasticity and plasticity of soil are determined depending on the values of compression strain. In the process of static and dynamic compression of soil it is almost impossible to determine the boundaries of elastic and plastic strains in soft soil. So, the modulus under soil compression is called the strain modulus. From published results of experiments on dynamic and static compression of soil the most informative ones have been selected. Processing the selected compression diagrams of soft soil, the secant moduli of strain for loess soil and clay have been determined. It is established that the moduli of strain of clay and loess soil under static and dynamic strain vary depending on the rate of strain, the state of the structure and the level of compressive load.

STRAIN CHARACTERISTICS OF SOIL AND METHODS OF THEIR DETERMINATION

2018 ◽  
pp. 39-43
Author(s):  
K.S. Sultanov ◽  
P.V. Loginov ◽  
Z.R. Salikhova
Keyword(s):  
Dynamic Loading ◽  
Dynamic Compression ◽  
Loess Soil ◽  
Seismic Loads ◽  
Static Compression ◽  
Plastic Model ◽  
Laboratory Conditions ◽  
Coefficient Of Viscosity ◽  
Wave Problems

The method to define strain characteristics of soil under dynamic loading is proposed based on the results of experiments on dynamic compression of soils on the device for dynamic loading in laboratory conditions; the method allows solving wave problems with the statement similar to the statement of experiments. Using the proposed method, the modulus of dynamic and static compression, the modulus of unloading, the coefficient of viscosity of loess soil in the range of seismic loads are determined in accordance with elastic-visco-plastic model of soil developed by G.M.Lyakhov.

The yield behaviour of mild steel in dynamic compression

1956 ◽  
Vol 236 (1204) ◽  
pp. 24-40 ◽  
Keyword(s):  
Mild Steel ◽  
Impact Load ◽  
Dynamic Compression ◽  
Steel Specimen ◽  
Dynamic Strain ◽  
Compression Tests ◽  
Static Compression ◽  
Yield Phenomena ◽  
Stress Strain Relation ◽  
Yield Behaviour

Results of earlier investigations of dynamic yield phenomena are reviewed. Experiments are described in which a mild steel specimen is subjected a to compressive impact load causing yield in 25 to 30 μs . Stress-time curves are obtained and analyzed in terms of wave propagation, and a dynamic stress-strain relation is derived. Micrographs of specimens after dynamic yielding show that coarse slip does not occur, though there is some evidence of fine slip and grain boundary movement. Static compression tests on dynamically yielded specimens show that less hardening is caused by dynamic strain than by the same amount of static strain. The results are discussed in terms of dislocation theory.

Evaluation of Belleville Springs and Damping Through Static Cyclic Loading “Hysteresis” for pVARD Optimization: Part-I

2021 ◽  
Author(s):  
Abdelsalam Abugharara ◽  
Stephen Butt
Keyword(s):  
Data Analysis ◽  
Cyclic Loading ◽  
Dynamic Compression ◽  
Range Data ◽  
Compression Tests ◽  
Rotary Drilling ◽  
Static Compression ◽  
Drilling Performance ◽  
Wide Range ◽  
Compression Hysteresis

Abstract One unconventional application that researchers have been investigating for enhancing drilling performance, has been implemented through improving and stabilizing the most effective downhole drilling parameters including (i) increasing downhole dynamic weight on bit (DDWOB), (ii) stabilizing revolution per minutes (rpm), (iii) minimizing destructive downhole vibrations, among many others. As one portion of a three-part-research that consists of a comprehensive data analysis and evaluation of a static compression hysteresis, dynamic compression hysteresis, and corresponding drilling tests, this research investigates through static cyclic loading “Hysteresis” of individual and combined springs and damping the functionality of the passive Vibration Assisted Rotary Drilling (pVARD) tool that could be utilized towards enhancing the drilling performance. Tests are conducted on the two main pVARD tool sections that include (i) Belleville springs, which represent the elasticity portion and (ii) the damping section, which represents the viscous portion. Firstly, tests were conducted through static cyclic loading “Hysteresis” of (i) a mono elastic, (ii) a mono viscus, and (iii) dual elastic-viscus cyclic loading scenarios for the purpose of further examining pVARD functionality. For performing static compression tests, a calibrated geomechanics loading frame was utilized, and various spring stacking of different durometer damping were tested to seek a wide-range data and to provide a multi-angle analysis. Results involved analyzing loading and displacement relationships of individual and combined springs and damping are presented with detailed report of data analysis, discussion, and conclusions.

Mechanical compression alters proteoglycan deposition and matrix deformation around individual cells in cartilage explants

1998 ◽  
Vol 111 (5) ◽  
pp. 573-583
Author(s):  
T.M. Quinn ◽  
A.J. Grodzinsky ◽  
M.D. Buschmann ◽  
Y.J. Kim ◽  
E.B. Hunziker
Keyword(s):  
Morphological Changes ◽  
Dynamic Compression ◽  
Compressive Strain ◽  
Cell Length ◽  
Cartilage Explants ◽  
Proteoglycan Synthesis ◽  
Length Scale ◽  
Mechanical Compression ◽  
Static Compression ◽  
Associated Matrix

We have used new techniques of cell-length scale quantitative autoradiography to assess matrix synthesis, deposition, and deformation around individual chondrocytes in mechanically compressed cartilage explants. Our objectives were to: (1) quantify the effects of static and dynamic compression on the deposition of newly synthesized proteoglycans into cell-associated and further-removed matrices; (2) measure cell-length scale matrix strains and morphological changes of the cell and matrix associated with tissue compression; and (3) relate microscopic physical stimuli to changes in proteoglycan synthesis as functions of compression level and position within mechanically compressed explants. Results indicate a high degree of structural organization in the extracellular matrix, with the pericellular matrix associated with the most rapid rates of proteoglycan deposition, and greatest sensitivity to mechanical compression. Static compression could stimulate directional deposition of secreted proteoglycans around chondrocytes, superimposed on an inhibition of proteoglycan synthesis; these events followed trends for compressive strain in the cell-associated matrix. Conversely, proteoglycan synthesis and pericellular deposition was stimulated by dynamic compression. Results suggest that cell-matrix interactions in the cell-associated matrix may be a particularly important aspect of the chondrocyte response to mechanical compression, possibly involving macromolecular transport limitations and morphological changes associated with fluid flow and local compaction of the matrix around cells.

scholarly journals MG-63 Cell Proliferation with Static or Dynamic Compressive Stimulation on an Auxetic PLGA Scaffold

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Myeong Jin Kim ◽  
Hong Jin Choi ◽  
Jongman Cho ◽  
Jung Bok Lee ◽  
Hak-Joon Sung ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Poisson Ratio ◽  
Dynamic Compression ◽  
Control Group ◽  
Plga Scaffold ◽  
Static Compression ◽  
Static Group ◽  
Stimulation Group ◽  
Dynamic Stimulation ◽  
Stimulation Of

The effect of dynamic compressive stimulation on MG-63 cell proliferation on an auxetic PLGA scaffold was investigated. The estimated Poisson ratio of the prepared auxetic scaffold specimens was approximately (−)0.07, while the Poisson ratio estimated for conventional scaffold specimens was (+)0.12 under 10% strain compression on average. Three stimulus groups were examined: control (no stimulation), static compression, and dynamic compression. In preparation for proliferation testing, cells were seeded at 2.2 × 105 cells/80 μL on each scaffold specimen. The average proliferation rates of the static and dynamic groups were higher than those of the control group: 13.4% and 25.5% higher at culture day 1, 34.7% and 56.2% at culture day 3, and 17.5% and 43.0% at culture day 5, respectively. The static and dynamic group results at culture day 5 were significantly different (p<0.01). Moreover, proliferation rate of the dynamic stimulation group was 1.22 times higher than that of the static group (p<0.01). Conclusively, proliferation of osteoblast-like cells was enhanced through compressive stimulation, but the enhancement was maximal with dynamic compressive stimulation of auxetic scaffolds.

scholarly journals A biomechanical comparison of 3.5 locking compression plate fixation to 3.5 limited contact dynamic compression plate fixation in a canine cadaveric distal humeral metaphyseal gap model

2009 ◽  
Vol 22 (04) ◽  
pp. 1-8 ◽  
Author(s):  
O. Lanz ◽  
R. McLaughlin ◽  
S. Elder ◽  
S. Werre ◽  
D. Filipowicz
Keyword(s):  
Axial Compression ◽  
Dynamic Testing ◽  
Dynamic Compression ◽  
Plate Fixation ◽  
Locking Compression Plate ◽  
Locking Plates ◽  
Gap Model ◽  
Static Compression ◽  
Dynamic Compression Plate ◽  
Compression Plate

Summary3.5 locking compression plate (LCP) fixation was compared to 3.5 limited contact dynamic compression plate (LC-DCP) fixation in a canine cadaveric, distal humeral metaphyseal gap model. Thirty paired humeri from adult, large breed dogs were separated into equal groups based on testing: static compression, cyclic compression, and cyclic torsion. Humeral constructs stabilized with LCP were significantly stiffer than those plated with LCDCP when loaded in static axial compression (P = 0.0004). When cyclically loaded in axial compression, the LCP constructs were significantly less stiff than the LC-DCP constructs (P = 0.0029). Constructs plated with LCP were significantly less resistant to torsion over 500 cycles than those plated with LC-DCP (P<0.0001). The increased stiffness of LCP constructs in monotonic loading compared to constructs stabilised with non-locking plates may be attributed to the stability afforded by the plate-screw interface of locking plates. The LCP constructs demonstrated less stiffness in dynamic testing in this model, likely due to plate-bone offset secondary to non-anatomic contouring and occasional incomplete seating of the locking screws when using the torque-limiting screw driver. Resolution of these aspects of LCP application may help improve the stiffness of fixation in fractures modeled by the experimental set-up of this investigation.

scholarly journals A study of the influence produced by the dynamics of the working bodies of cotton-processing machines on the cotton fibre quality

2021 ◽  
Vol 1 (1 (109)) ◽  
pp. 68-76
Author(s):  
Fazil Veliev
Keyword(s):  
Porous Medium ◽  
Speed Of Sound ◽  
Raw Materials ◽  
Dynamic Compression ◽  
Dynamic Change ◽  
Static Compression ◽  
Gaseous Component ◽  
Multicomponent Media ◽  
Two Component ◽  
Working Bodies

Cotton mass is considered as a compressible porous two-component medium, consisting of a mixture of cotton fibres and air included in the porous medium, which is essential in dynamic treatment processes and requires consideration when planning technological modes. It was found that the speed of sound in multicomponent media significantly decreases with an increase in the content of the gaseous component. With a certain content of components, it can become less than in each of the components separately. This is due to the fact that with an increase in the content of the gaseous component, the density of the medium increases insignificantly, and the compressibility of air sharply decreases in the pores. As a result of the research, it was found that the value of the dynamic change in the density of cotton raw materials can significantly exceed its density during static compression. This kind of influence can have both adverse and desirable effects on the primary stage of cotton processing. The dynamic characteristics of raw cotton as an object of mechanical technology were studied. The values of the speed of sound as a function of the density of cotton raw materials were determined on the basis of the theory of a two-component porous medium. The types of the dynamic compression curve of raw cotton have been established. Experimental studies on the compressibility of raw cotton are generalized. From the analysis of the cleaning processing of fibres and seeds on cleaning machines, it follows that when assigning a technological processing mode, it is necessary to comply it with the value of the sound speed for a given density of raw materials. It is necessary to avoid such rates of penetration of the working bodies into raw materials that are commensurate with the speed of sound at a given raw material density. This local dramatic increase in cotton media characteristics is a significant cause of fibre damage

Damage Mechanism Analysis of Carbon Fiber Composites under Compressive Load

2018 ◽  
Vol 775 ◽  
pp. 36-42 ◽  
Author(s):  
Xun Lai He ◽  
Jun Hui Yin ◽  
Zhen Qian Yang ◽  
Hong Wei Liu
Keyword(s):  
Carbon Fiber ◽  
Failure Mode ◽  
Fiber Composite ◽  
Testing Machine ◽  
Compressive Load ◽  
Damage Mechanism ◽  
Fiber Composites ◽  
Carbon Fiber Composites ◽  
Carbon Fiber Composite ◽  
Static Compression

Carbon fiber composite material with light weight, high strength, corrosion resistance and other characteristics of its impact damage mechanism is different from the traditional metal materials. In this paper, the quasi-static compression of carbon fiber composites was carried out by using a material testing machine to analyze the damage mechanism. The Hopkinson bar technology was used to test the dynamic mechanical properties. The damage mechanism of the carbon fiber composites under dynamic compressive loading was studied. Stress - Strain relationship of composites under Quasi - static and dynamic compressive load. It is found that the main failure mode of out-of-plane direction of carbon fiber composite laminates is brittle shear failure, while the in-plane failure mode shows the properties of brittle materials.

scholarly journals Dynamic Compression Promotes the Matrix Synthesis of Nucleus Pulposus Cells Through Up-Regulating N-CDH Expression in a Perfusion Bioreactor Culture

2018 ◽  
Vol 46 (2) ◽  
pp. 482-491 ◽  
Author(s):  
Yichun Xu ◽  
Hui Yao ◽  
Pei Li ◽  
Wenbin Xu ◽  
Junbin Zhang ◽  
...  
Keyword(s):  
Nucleus Pulposus ◽  
Dynamic Compression ◽  
Akt Pathway ◽  
Bioreactor Culture ◽  
Nucleus Pulposus Cells ◽  
Matrix Synthesis ◽  
Static Compression ◽  
Matrix Deposition ◽  
The Matrix

Background/Aims: An adequate matrix production of nucleus pulposus (NP) cells is an important tissue engineering-based strategy to regenerate degenerative discs. Here, we mainly aimed to investigate the effects and mechanism of mechanical compression (i.e., static compression vs. dynamic compression) on the matrix synthesis of three-dimensional (3D) cultured NP cells in vitro. Methods: Rat NP cells seeded on small intestinal submucosa (SIS) cryogel scaffolds were cultured in the chambers of a self-developed, mechanically active bioreactor for 10 days. Meanwhile, the NP cells were subjected to compression (static compression or dynamic compression at a 10% scaffold deformation) for 6 hours once per day. Unloaded NP cells were used as controls. The cellular phenotype and matrix biosynthesis of NP cells were investigated by real-time PCR and Western blotting assays. Lentivirus-mediated N-cadherin (N-CDH) knockdown and an inhibitor, LY294002, were used to further investigate the role of N-CDH and the PI3K/Akt pathway in this process. Results: Dynamic compression better maintained the expression of cell-specific markers (keratin-19, FOXF1 and PAX1) and matrix macromolecules (aggrecan and collagen II), as well as N-CDH expression and the activity of the PI3K/Akt pathway, in the 3D-cultured NP cells compared with those expression levels and activity in the cells grown under static compression. Further analysis showed that the N-CDH knockdown significantly down-regulated the expression of NP cell-specific markers and matrix macromolecules and inhibited the activation of the PI3K/Akt pathway under dynamic compression. However, inhibition of the PI3K/Akt pathway had no effects on N-CDH expression but down-regulated the expression of NP cell-specific markers and matrix macromolecules under dynamic compression. Conclusion: Dynamic compression increases the matrix synthesis of 3D-cultured NP cells compared with that of the cells under static compression, and the N-CDH-PI3K/Akt pathway is involved in this regulatory process. This study provides a promising strategy to promote the matrix deposition of tissue-engineered NP tissue in vitro prior to clinical transplantation.

Comparative studies of the constitutive models for tungsten heavy alloy (95W-3.5Ni-1.5Fe) at high strain rates

2021 ◽  
pp. 095440622110451
Author(s):  
Xiuwen Lai ◽  
Zhanjiang Wang ◽  
Na Qin
Keyword(s):  
Threshold Stress ◽  
Dynamic Compression ◽  
Constitutive Models ◽  
Heavy Alloy ◽  
Tungsten Heavy Alloy ◽  
Strain Rates ◽  
Stress Model ◽  
Static Compression ◽  
Mechanical Threshold ◽  
Wide Range

The plastic behaviors’ description of a tungsten heavy alloy (95W-3.5Ni-1.5Fe) at temperatures of 298–773 K and strain rates of 0.001–11,000 s−1 is systematically studied based on four constitutive models, that is, Zerilli-Armstrong model, modified Zerilli-Armstrong model, Mechanical Threshold Stress model, and modified Mechanical Threshold Stress model. The quasi-static compression experiments using an electronic universal testing machine and the dynamic compression experiments using a split Hopkinson pressure bar apparatus are employed to obtain the true stress–strain curves at a total of three temperatures (298 K, 573 K, and 773 K) and a wide range of strain rates (0.001–11,000 s−1). The parameters of the four constitutive models are obtained by the above fundamental experimental data and Grey Wolf Optimizer. The correlation coefficient and average absolute relative error are used to evaluate the predicted performance of these models. Modified Mechanical Threshold Stress model is found to have the highest predicted performance in describing the flow stress of the 95W-3.5Ni-1.5Fe alloy. Eventually, two compression experiments whose loading conditions are not in the fundamental experiments are conducted to validate the four models.

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