Variability of Poisson's ratio in investigating the state of stress of rubber parts

1971 ◽  
Vol 3 (4) ◽  
pp. 502-504
Author(s):  
B. M. Gorelik ◽  
G. I. Fel'dman ◽  
M. A. Maiskaya
Keyword(s):  
Poisson’S Ratio ◽  
The State ◽  
Poisson's Ratio ◽  
State Of Stress

On the mechanics of the intrusion of sills

1969 ◽  
Vol 6 (6) ◽  
pp. 1415-1419 ◽  
Author(s):  
P. E. Gretener
Keyword(s):  
Principal Stress ◽  
Upper Mantle ◽  
Poisson’S Ratio ◽  
Vertical Stress ◽  
Poisson's Ratio ◽  
Stress Axis ◽  
Principal Stresses ◽  
State Of Stress ◽  
As Stress

Diabase sills contain material originating from the base of the crust or the upper mantle. As a result they must be fed by dike- or plug-like bodies. The formation of a sill thus represents a major reorientation of the form of the intrusion. Tabular intrusive bodies tend to orient themselves perpendicular to the least compressive principal stress axis as shown by E. M. Anderson. It is suggested that diabase sills form under sedimentary strata in which the two horizontal principal stresses exceed the vertical stress (Sx > Sy > Sz). Such strata act as stress barriers and prevent further ascent of the magma, In order for this situation to occur the sediments must be in compression in the x-direction and confined in the y-direction. The parameter of importance to produce the above state of stress is the effective Poisson's ratio.

Geometric, Physical and Mechanical Properties of the Fruit-rachilla of the Macauba Palm (Acrocomia aculeata) Considering Different Sampling Sites in the State of Minas Gerais in Brazil

2019 ◽  
pp. 1-6
Author(s):  
Jéssica Pontes Rangel ◽  
Daniel Marçal de Queiroz ◽  
Francisco de Assis de Carvalho Pinto ◽  
Fábio Lúcio Santos ◽  
Domingos Sárvio Magalhães Valente
Keyword(s):  
Mechanical Properties ◽  
Poisson’S Ratio ◽  
Sampling Site ◽  
Physical And Mechanical Properties ◽  
Minas Gerais ◽  
The State ◽  
Poisson's Ratio ◽  
Maturation Stage ◽  
The Mean ◽  
Acrocomia Aculeata

This study aimed to determine the geometric, physical and mechanical properties of the fruit-rachilla system of the macauba palm (Acrocomia aculeata) from three different locations in the state of Minas Gerais. Three different sampling site wee assemble in the mature and green maturation stages. The replicates of the experiment were established, use 20 samples from four different plants for each sampling site, at different stages of maturation. For the experiment, the dimensions in three directions were determined, the mass, volume and density of the fruits and the rachilla. The modulus od elasticity and Poisson’s ratio were determined using a universal test machine. The mean values ​​of the diameter and density for the fruits were 40 mm and 1.20 g cm-3, approximately. The mean valeus of the density of the rachillae obtained ​​of 0.55 g cm-3. The dimensions and the density of the fruits and the rachillae presented significant in relation to the study of the interaction of the factors. The values of modulus of elasticity green maturation stage are higher than values for mature maturation stage in two sampling sites studied. The values of the Poisson’s ratio of the rachillae were 0.37 m m-1 and were not different with respect to none of the factors studied.

scholarly journals Theoretical and Numerical Analyses of Earth Pressure Coefficient along the Centerline of Vertical Openings with Granular Fills

2018 ◽  
Vol 8 (10) ◽  
pp. 1721 ◽  
Author(s):  
Pengyu Yang ◽  
Li Li ◽  
Michel Aubertin
Keyword(s):  
Poisson’S Ratio ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
The State ◽  
Critical Values ◽  
Poisson's Ratio ◽  
Numerical Analyses ◽  
Critical Question ◽  
K Value ◽  
Earth Pressure Coefficient

Granular filling materials are placed into confining structures for various purposes, including but not limited to silos, trenches, mine stopes, and retaining walls for backfill. Stresses in these backfilled openings are commonly estimated using theoretical arching models, with equations that often involve the earth pressure coefficient K (=σ’h/σ’v). Such stress estimation can be dramatically impacted by the magnitude of K, but its value remains debatable. Along the centerline of vertical openings with granular cohesionless fills, the value of K is sometimes obtained by Jaky’s earth pressure coefficient at rest K0, based on the assumption of fixed confining walls, whereas Rankine’s active earth pressure coefficient Ka is regarded more suitable for K as claimed by some others. Recent numerical analyses from the authors have shown that the state of stress close to the center of backfilled openings cannot be solely related to wall movement. It was also shown that the K value can vary between Ka and K0 in backfilled openings with fixed (immobile) walls, depending on the locations and respective values of fill internal friction angle ϕ’ and Poisson’s ratio ν. However, none of the existing works have addressed the mechanisms and answered this fundamental but critical question: which value of coefficient K (K0, Ka, or other) should be used with analytical solutions to assess the stresses in backfilled openings (and why)? After assessing the state of the fill placed in a confined opening, theoretical relationships and specific mechanisms are proposed, for the first time, to evaluate critical values of ν and ϕ’ for defining the at-rest and active states in fills. The approach indicates that when ν or ϕ’ are smaller than or equal to critical values, the value of K near the center line of a backfill opening should be close to Ka; otherwise, K tends to approach K0 defined from ν. The theoretical analysis is complemented and validated (in part) by numerical simulations. The results also demonstrate that Poisson’s ratio can play a major role on the stress distribution within cohesionless fills, and should thus be accurately evaluated.

The Model for Calculating Elastic Modulus and Poisson's Ratio of Coal Body

2013 ◽  
Vol 6 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Ai Chi ◽  
Li Yuwei
Keyword(s):  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Fractured Rock ◽  
Rock Block ◽  
Poisson's Ratio ◽  
Linear Elastic ◽  
Study Results ◽  
The Face ◽  
Block Face ◽  
Coal Rock

Coal body is a type of fractured rock mass in which lots of cleat fractures developed. Its mechanical properties vary with the parametric variation of coal rock block, face cleat and butt cleat. Based on the linear elastic theory and displacement equivalent principle and simplifying the face cleat and butt cleat as multi-bank penetrating and intermittent cracks, the model was established to calculate the elastic modulus and Poisson's ratio of coal body combined with cleat. By analyzing the model, it also obtained the influence of the parameter variation of coal rock block, face cleat and butt cleat on the elastic modulus and Poisson's ratio of the coal body. Study results showed that the connectivity rate of butt cleat and the distance between face cleats had a weak influence on elastic modulus of coal body. When the inclination of face cleat was 90°, the elastic modulus of coal body reached the maximal value and it equaled to the elastic modulus of coal rock block. When the inclination of face cleat was 0°, the elastic modulus of coal body was exclusively dependent on the elastic modulus of coal rock block, the normal stiffness of face cleat and the distance between them. When the distance between butt cleats or the connectivity rate of butt cleat was fixed, the Poisson's ratio of the coal body initially increased and then decreased with increasing of the face cleat inclination.

scholarly journals A Hybrid Artificial Intelligence Model to Predict the Elastic Behavior of Sandstone Rocks

2019 ◽  
Vol 11 (19) ◽  
pp. 5283 ◽  
Author(s):  
Gowida ◽  
Moussa ◽  
Elkatatny ◽  
Ali
Keyword(s):  
Poisson’S Ratio ◽  
Accurate Determination ◽  
Oil And Gas Industry ◽  
Poisson's Ratio ◽  
Elastic Behavior ◽  
Percentage Error ◽  
Ann Model ◽  
Field Development ◽  
Well Completion

Rock mechanical properties play a key role in the optimization process of engineering practices in the oil and gas industry so that better field development decisions can be made. Estimation of these properties is central in well placement, drilling programs, and well completion design. The elastic behavior of rocks can be studied by determining two main parameters: Young’s modulus and Poisson’s ratio. Accurate determination of the Poisson’s ratio helps to estimate the in-situ horizontal stresses and in turn, avoid many critical problems which interrupt drilling operations, such as pipe sticking and wellbore instability issues. Accurate Poisson’s ratio values can be experimentally determined using retrieved core samples under simulated in-situ downhole conditions. However, this technique is time-consuming and economically ineffective, requiring the development of a more effective technique. This study has developed a new generalized model to estimate static Poisson’s ratio values of sandstone rocks using a supervised artificial neural network (ANN). The developed ANN model uses well log data such as bulk density and sonic log as the input parameters to target static Poisson’s ratio values as outputs. Subsequently, the developed ANN model was transformed into a more practical and easier to use white-box mode using an ANN-based empirical equation. Core data (692 data points) and their corresponding petrophysical data were used to train and test the ANN model. The self-adaptive differential evolution (SADE) algorithm was used to fine-tune the parameters of the ANN model to obtain the most accurate results in terms of the highest correlation coefficient (R) and the lowest mean absolute percentage error (MAPE). The results obtained from the optimized ANN model show an excellent agreement with the laboratory measured static Poisson’s ratio, confirming the high accuracy of the developed model. A comparison of the developed ANN-based empirical correlation with the previously developed approaches demonstrates the superiority of the developed correlation in predicting static Poisson’s ratio values with the highest R and the lowest MAPE. The developed correlation performs in a manner far superior to other approaches when validated against unseen field data. The developed ANN-based mathematical model can be used as a robust tool to estimate static Poisson’s ratio without the need to run the ANN model.

Sign in / Sign up

Export Citation Format

Share Document