Effect of initial stress field on propagation velocity and shape of strain pulse

2004 ◽  
Author(s):  
V.F. Chekurin ◽  
O.Z. Kravchyshyn
Keyword(s):  
Stress Field ◽  
Initial Stress ◽  
Propagation Velocity ◽  
Initial Stress Field ◽  
Strain Pulse

3D Back Analysis of Initial Stress Field Based on Neural Network RBF Model

2011 ◽  
Vol 243-249 ◽  
pp. 3223-3228
Author(s):  
Zhong Fu Wang ◽  
Han Dong Liu ◽  
Tong Jiang ◽  
Si Wei Wan
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Initial Stress ◽  
Linear Regression Analysis ◽  
Back Analysis ◽  
Element Model ◽  
Training Sample ◽  
Geological Condition ◽  
Initial Stress Field ◽  
Factory Building

Based on geological condition of underground factory building in Hohhot pumped storage power station, research and analysis are taken for the fundamental element which affect initial stress field, 3D finite element model of underground factory building is build for the analysis. Beigin with regrssion analysis, adopt linear elasticity caculation of finite element method to take linear regression analysis, and obtain range of optimized parameters. Adopt homogeneous design to definite various assemblies of optimized parameters at different levels. Obtain training sample by elasto plastic caculation of finite element, train for RBF model in oder to get inverse model of ground stress field. The calculation result shown that: RBF model overcome the disadvantages such as slow calculating speed and overfitting of BP model, and it could obtain distrubution rule of initial stress filed by inverse analysis in a reasonable way.

Initial Strain Field and Fatigue Crack Initiation Mechanics

1983 ◽  
Vol 50 (2) ◽  
pp. 367-372 ◽  
Author(s):  
S. R. Lin ◽  
T. H. Lin
Keyword(s):  
Shear Stress ◽  
Stress Field ◽  
Initial Stress ◽  
Strain Field ◽  
Fatigue Crack Initiation ◽  
Inelastic Strain ◽  
Slip Lines ◽  
Thin Slice ◽  
Initial Stress Field ◽  
Reversed Loading

On single aluminum crystals under cyclic loadings, fresh slip lines appeared during the reversed loading, lying very close to, but not coincident with the slip lines formed in the forward loading. These slip lines indicate the start of extrusion or intrusion as commonly observed in fatigue specimens. An initial stress field is present in all metals. The initial stress field favorable to the aforementioned sequence of slip is one having a positive shear stress in one thin slice P and a negative one in a closely located thin slice Q. A forward loading causes a positive shear stress, which is of the same sign as the initial shear stress in P, but of opposite sign to that in Q. Hence the shear stress in P will reach the critical value first to cause slip. Due to the continuity of the stress field, slip in P relieves not only the positive shear stress in P but also in Q. This has the same effect as increasing negative shear stress in Q. During the reversed loading, Q has the highest negative shear stress and hence slides. Similarly, this slip causes P to be more ready to slide in the next forward loading. This process is repeated to cause a monotonic alternate sliding in P and Q. In this way, an extrusion or intrusion is nucleated. A crack can be started from an intrusion. The thin slices P and Q are considered to be in a most favorably oriented crystal located at a free surface. An initial stress field giving positive shear stress in P and negative in Q is calculated from an assumed initial inelastic strain field which, in turn, can be caused by distribution of dislocations. The buildup of plastic shear strain in P and Q causing the start of extrusion or intrusion is shown.

scholarly journals Impact of initial stress field heterogeneity in dynamic soil–structure interaction

2021 ◽  
pp. 875529302110416
Author(s):  
Marc-Denis Rioux ◽  
Marie-José Nollet ◽  
Bertrand Galy
Keyword(s):  
Stress Field ◽  
Initial Stress ◽  
Soil Structure ◽  
Soil Structure Interaction ◽  
Foundation Soil ◽  
Structure Interaction ◽  
Initial Stress Field ◽  
Geophysical Surveys ◽  
Field Heterogeneity ◽  
The Impact

This article covers the impact of soil initial stress field heterogeneity (ISFH) in wave-passage analysis and in prescribed structural acceleration in the context of dynamic soil–structure interaction (DSSI) analysis. ISFH is directly related to the natural behavior of soil where a significant increase in net effective confinement, as is the case in the foundation soil under a building, tends to increase the soil’s modulus and strain. This creates a heterogeneous stress field in the vicinity of the foundation elements, which results in a modification of the dynamic behavior of the soil–structure system. A simple method for considering the impact of ISFH on the value of the soil’s modulus and strain was developed using the direct DSSI approach. The method was used to analyze numerical artifacts and its impact on the surface acceleration values of a nonlinear two-dimensional (2D) numerical soil deposit under transient loading. This analysis was followed by a sample application for a three-story, three-bay concrete moment-resisting frame structure erected on a deep soil deposit. Floor acceleration and relative displacement were used for comparison. The soil deposit was modeled using the typical geotechnical properties of fine-grained, post-glacial soil samples obtained in Eastern Canada from in situ geotechnical borehole drilling, geophysical surveys, and laboratory testing. Ground motion was based on eastern calibrated seismic signals. The results of the soil deposit analysis show that ISFH had a significant impact on surface acceleration values. The effect was found to be period-dependent and to have a direct impact on prescribed acceleration values at the base of structure. Thus, failure to take the effects of ISFH into consideration can lead to errors in calculating prescribed structural accelerations (i.e. over- or underestimation).

INITIAL STRESS FIELD ESTIMATION IN UNDERGROUND MINE PLANNING

2017 ◽  
Vol 12 ◽  
pp. 37-49
Author(s):  
A.N. Shashenko ◽  
◽  
A.V. Smirnov ◽  
N.V. Khozyaykina ◽  
◽  
...  
Keyword(s):  
Stress Field ◽  
Initial Stress ◽  
Underground Mine ◽  
Mine Planning ◽  
Initial Stress Field ◽  
Field Estimation

On the Methodology of Numerical Etching

1999 ◽  
Vol 563 ◽  
Author(s):  
X. H. Wang ◽  
K. Shyu ◽  
C.-T. Chang ◽  
D. W. Zheng ◽  
Weijia Wen
Keyword(s):  
Thin Film ◽  
Residual Stress ◽  
Stress State ◽  
Numerical Analysis ◽  
Stress Distribution ◽  
Stress Field ◽  
Initial Stress ◽  
Silicon Wafer ◽  
Initial Stress Field ◽  
Actual Stress

AbstractA methodology to study the stress distribution of a patterned thin film residing on a silicon wafer was developed. Si underlying the pattern was thinned down through etching so that the deformation caused by residual stress in the microstructure could be detected by a Twyman- Green interferometer. A procedure called "numerical etching" was implemented to simulate the etching process, which linked the stress state of the microstructure on a regular wafer to that on a Si diaphragm. An initial stress field on the pattern was assumed, and its effect on the deformation of the Si diaphragm beneath was calculated and compared with experimental results. The discrepancy between them was used to modify the initially assumed stress field and repeated until a satisfactory match was achieved. The stress field from numerical analysis accurately predicts the actual stress distribution in and around the patterned structure under investigation. The stress distribution in a Ti pad on a Si3N4/ SiO2/Si composite diaphragm is used as an example.

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