Large-strain dynamic cavity expansion in a granular material

2005 ◽  
Vol 52 (1-3) ◽  
pp. 185-198 ◽  
Author(s):  
V. A. Osinov
Keyword(s):  
Granular Material ◽  
Large Strain ◽  
Cavity Expansion

scholarly journals Undrained Elastoplastic Solution for Cylindrical Cavity Expansion in Structured Cam Clay Soil Considering the Destructuration Effects

2022 ◽  
Vol 12 (1) ◽  
pp. 440
Author(s):  
Zhanghui Zhai ◽  
Yaguo Zhang ◽  
Shuxiong Xiao ◽  
Tonglu Li
Keyword(s):  
Cylindrical Cavity ◽  
Soil Structure ◽  
Large Strain ◽  
Cavity Expansion ◽  
Initial Structure ◽  
Cylindrical Cavity Expansion ◽  
Structure Degradation ◽  
Present Solution ◽  
Structured Soils ◽  
Cam Clay

Soil structure has significant influences on the mechanical behaviors of natural soils, although it is rarely considered in previous cavity expansion analyses. This paper presents an undrained elastoplastic solution for cylindrical cavity expansion in structured soils, considering the destructuration effects. Firstly, a structural ratio was defined to denote the degree of the initial structure, and the Structured Cam Clay (SCC) model was employed to describe the subsequent stress-induced destructuration, including the structure degradation and crushing. Secondly, combined with the large strain theory, the considered problem was formulated as a system of first-order differential equations, which can be solved in a simplified procedure with the introduced auxiliary variable. Finally, the significance and efficiency of the present solution was demonstrated by comparing with the previous solutions, and parametric studies were also conducted to investigate the effects of soil structure and destructuration on the cavity expansion process. The results show that the soil structure has pronounced effects on the mechanical behavior of structured soils around the cavity. For structured soils, a cavity pressure that is larger than the corresponding reconstituted soils when the cavity expands to the same radius is required, and the effective stresses first increase to a peak value before decreasing rapidly with soil structure degradation and crushing. The same final critical state is reached for soils with different degrees of the initial structure, which indicates that the soil structure is completely destroyed during the cavity expansion. With the increase of the destructuring index, the soil structure was destroyed more rapidly, and the stress release during the plastic deformation became more significant. Moreover, the present solution was applied in the jacking of a casing during the sand compact pile installation and in situ self-boring pressuremeter (SBPM) tests, which indicates that the present solution provides an effective theoretical tool for predicting the behavior of natural structured soils around the cavity.

Hypervelocity Cavity Expansion in Porous Elastoplastic Solids

2012 ◽  
Vol 80 (1) ◽  
Author(s):  
Tal Cohen ◽  
David Durban
Keyword(s):  
Large Strain ◽  
Constitutive Relations ◽  
Critical Value ◽  
Cavity Expansion ◽  
Expansion Velocity ◽  
Jump Conditions ◽  
Gurson Model ◽  
Numerical Examples ◽  
The Mathematical Model ◽  
Material Porosity

Dynamic steady-state spherical cavitation fields are examined with emphasis on material porosity at large strain. Cavity expansion is driven by constant internal pressure in presence of remote tension or compression. The plastic branch of constitutive relations is described by the Gurson model, with arbitrary strain hardening. The mathematical model is reduced to a system of four ordinary nonlinear coupled differential equations. Numerical examples show that a plastic shock wave builds up as expansion velocity approaches a critical value and jump conditions across the shock are accounted for. At critical levels of remote tension, quasi-static cavitation of all internal voids is induced before dynamic cavity expansion occurs.

scholarly journals Impinging Fluid in Immersed Granular Material to Obtain Local Fluidization for Breaking Sedimentation

2020 ◽  
Vol 55 (4) ◽  
Author(s):  
Eko Yudiyanto ◽  
I. Nyoman Gede Wardana ◽  
Nurkholis Hamidi ◽  
Denny Widhiyanuriyawan
Keyword(s):  
Granular Material ◽  
High Speed ◽  
Reynold Number ◽  
Granule Size ◽  
Cavity Expansion ◽  
Cavity Formation ◽  
Long Time ◽  
Granular Behavior ◽  
Short Time ◽  
Fluidization Process

Granular material is the most abundant material type in industry. Efforts to improve the efficiency of handling of granular material are continually ongoing. Sedimentation is one of the problems in transporting this material; when sedimentation occurs, the flow of material is obstructed and requires significant energy to clean the pipelines. The problem of sedimentation in pipes is thus an issue that merits serious attention. To solve the sedimentation problem, it is proposed to use the impinging method, which is a shock flow that is inserted into the granular sediment. This experiment to impinge immersed granular material is proposed to solve this depositional problem. Shooting high-speed fluid in a short time is expected to be one of the methods of preventing sedimentation that occurs in handling granular material. The material used in this experiment varies in granule size: very fine, fine, and medium-sized granules. These experiments provide an overview of post-impinging granular behavior with fluidization movement. For very fine granular size, post-impinging fluid cavity expansion occurs, followed by slow fluidization. This fluidization movement occurs for a long time. For fine granules, fluid cavity formation happens much faster, and fluidization occurs immediately. For medium-sized granules, post-impinging fluidization occurs immediately. To measure the impinging process to produce fluidization, the Reynold Number of Impinging (Re*) is used. The fluidization process occurs at Re* < 4000. The internal fluidization movements occur mainly at Re* values 2000-4000 (i.e. transition regions).

Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers

1977 ◽  
Vol 35 ◽  
pp. 576-577
Author(s):  
Joachim R. Sommer ◽  
Nancy R. Wallace
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Granular Material ◽  
Nuclear Envelope ◽  
Intracellular Calcium ◽  
Ruthenium Red ◽  
Threshold Concentration ◽  
Rapid Freezing ◽  
Frog Skeletal Muscle ◽  
Electrical Isolation

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.

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