scholarly journals Settlements around pumping wells: analysis of influential factors and a simple calculation

2021 ◽  
Author(s):  
Estanislao Pujades
Keyword(s):  
Porous Medium ◽  
Mechanical Response ◽  
Simple Calculation ◽  
Influential Factors ◽  
Mechanical Parameters ◽  
Specific Storage ◽  
Storage Coefficient ◽  
Soil P ◽  
Boundary Constraints ◽  
Pumping Wells

Estimated and measured settlements caused by pumping rarely agree. Several reasons could explain this mismatch, including the influence of layering, the mechanical parameters used in the predictions, or the relationship between settlements and drawdown. We analyze the influence of the above issues by investigating the mechanical response of pumped elastic porous media under different conditions. A radially symmetric conceptual model is considered and several hydro-mechanical simulations are performed varying the boundary conditions, the size of the modeled domain and the presence or not of an overlying layer. The simplicity of the considered problem allows us to compare our results with existing analytical solutions, to identify the role of each variable on pumping settlements and to generalize the results. The most relevant results are as follows: (1) settlements are proportional to drawdown only outside a circle of radius equal to 0.7 times the thickness of the pumped porous medium; inside, they are virtually constant, which leads to two simple procedures for computing pumping settlements. (2) Poorly conductive layers located above (or below) a pumped porous medium (with higher hydraulic conductivity) reduce and smooth settlements. (3) Boundary constraints affect the local specific storage coefficient and the displacements occurred. (4) The specific storage coefficient evaluated by interpreting pumping tests with the Cooper and Jacob method (1946) leads to overestimation of the actual Young’s Modulus of the soil. The main conclusion is that settlements are less differential than expected near pumping wells. Still, they must always be evaluated acknowledging the nature of layering, the boundary constraints and carefully selecting the mechanical parameters of the soil.

scholarly journals Settlements around pumping wells: Analysis of influential factors and a simple calculation procedure

2017 ◽  
Vol 548 ◽  
pp. 225-236 ◽  
Author(s):  
Estanislao Pujades ◽  
Silvia De Simone ◽  
Jesus Carrera ◽  
Enric Vázquez-Suñé ◽  
Anna Jurado
Keyword(s):  
Simple Calculation ◽  
Influential Factors ◽  
Calculation Procedure ◽  
Pumping Wells

scholarly journals Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Marco Ferroni ◽  
Beatrice Belgio ◽  
Giuseppe M. Peretti ◽  
Alessia Di Giancamillo ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Developmental Stage ◽  
Mechanical Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Mechanical Stimulus ◽  
Specific Response ◽  
Mechanical Parameters ◽  
Biochemical Analyses

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress–relaxation tests comprised of increasing strains followed by stress–relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.

Testing and Modeling of Mechanical Parameters in Resistance Welding Machines

2013 ◽  
Vol 712-715 ◽  
pp. 1235-1240
Author(s):  
Pei Wu ◽  
Yong An Zhang ◽  
Chuan Zhong Xuan ◽  
Yan Hua Ma
Keyword(s):  
Mechanical Response ◽  
Resistance Welding ◽  
Work Piece ◽  
Mechanical Parameters ◽  
Test Set ◽  
Dynamic Mechanical ◽  
Projection Welding ◽  
Welding Machine ◽  
Equivalent Mass ◽  
Set Up

The dynamic mechanical responses of resistance welding machine,which is mainly governed by the mechanical parameters of the machine, is very important to the weld quality especially in projection welding when collapse or deformation of work piece occurs. In this paper, a mathematical model for characterizing the dynamic mechanical response of resistance welding machine and a special test set-up called breaking test set-up have been developed. Based on the model and the test results, the mechanical parameters of the machine were identified, including the equivalent mass, the damping coefficient, and the stiffness for both electrode systems.

scholarly journals Plain and Fiber-Reinforced Concrete Subjected to Cyclic Compressive Loading: Study of the Mechanical Response and Correlations with Microstructure Using CT Scanning

2019 ◽  
Vol 9 (15) ◽  
pp. 3030 ◽  
Author(s):  
Jesús Mínguez ◽  
Laura Gutiérrez ◽  
Dorys C. González ◽  
Miguel A. Vicente
Keyword(s):  
Mechanical Response ◽  
High Performance Concrete ◽  
Compressive Strain ◽  
Compressive Loading ◽  
Fiber Reinforced Concrete ◽  
Mechanical Parameters ◽  
Fiber Reinforced ◽  
High Resolution Computed Tomography ◽  
Internal Damage ◽  
Number Of Cycles

The response ranges of three principal mechanical parameters were measured following cyclic compressive loading of three types of concrete specimen to a pre-defined number of cycles. Thus, compressive strength, compressive modulus of elasticity, and maximum compressive strain were studied in (i) plain, (ii) steel-fiber-reinforced, and (iii) polypropylene-fiber-reinforced high-performance concrete specimens. A specific procedure is presented for evaluating the residual values of the three mechanical parameters. The results revealed no significant variation in the mechanical properties of the concrete mixtures within the test range, and slight improvements in the mechanical responses were, in some cases, detected. In contrast, the scatter of the mechanical parameters significantly increased with the number of cycles. In addition, all the specimens were scanned by means of high resolution computed tomography, in order to visualize the microstructure and the internal damage (i.e., internal micro cracks). Consistent with the test results, the images revealed no observable internal damage caused by the cyclic loading.

Mechanical Bending Simulation of Thin Stainless Steel by Using Isotropic and Orthotropic Properties

2011 ◽  
Vol 421 ◽  
pp. 312-315
Author(s):  
Somsak Siwadamrongpong ◽  
Usanee Kitkamthorn ◽  
Chaiyapak Sajjawattana
Keyword(s):  
Stainless Steel ◽  
Material Properties ◽  
Mechanical Response ◽  
Thin Sheet ◽  
Disk Drive ◽  
Simple Calculation ◽  
Orthotropic Materials ◽  
Mechanical Bending ◽  
Orthotropic Properties ◽  
Good Agreement

The most important factors in hard disk drive suspension manufacturing is the suspension preload, so call “gram load”. The suspensions were generally made from cold rolled stainless steel (SUS304). The suspensions were formed by mechanical forming and gram load was adjusted by mechanical bending until reached a specification. The material properties in mechanical bending simulation of thin stainless steel were usually as isotropic for simple calculation. But the properties of thin stainless steel should be defined as orthotropic materials. Therefore, this work aimed to study gram load results of using isotropic and orthotropic properties. The thin stainless sheet was cut and test for mechanical properties in rolling and transverse directions. The properties of the thin sheet were applied to simulation model. It was found that orthotropic material properties shows a good agreement with the experimental results more than using isotropic material properties. Therefore, the results of this work could be used to explain and predict the mechanical response on the suspension manufacturing.

scholarly journals EVALUATION OF THE LEVEL OF PHYSICAL ACTIVITY THROUGH MUSCULO-ARTICULAR STIFFNESS IN YOUNG ADULTS

2017 ◽  
Vol 2 (1) ◽  
pp. 447
Author(s):  
Federico París-García ◽  
Miguel Ángel Oviedo-Caro ◽  
Javier Bueno Antequera
Keyword(s):  
Physical Activity ◽  
Young Adults ◽  
Mechanical Response ◽  
Pearson Correlation ◽  
Maximum Voluntary Contraction ◽  
Repeated Measurements ◽  
Clear Correlation ◽  
Physical Parameters ◽  
Mechanical Parameters ◽  
Drop Jump

Abstract.The purpose of the study is to evaluate the level of physical activity of young adults by means of the Musculo-articular stiffness and to analyse its correlation with the physical performance measured in jump capacity. The proposed protocol includes a Muscle-articular test of both legs, a test of maximum voluntary contraction in isometric conditions (MVCi), a countermovement jump test (CMJ), and a drop jump (DJ) protocol from different heights (20, 40 and 60 cm). 21 healthy young adult subjects (12 males and 9 females). The mechanical variables are: force (f), Muscle-articular stiffness (k) and Muscle-articular Unitary stiffness (ku). Physical variables: Jump flight height (h) and force generated (f). An Anova of repeated measurements was performed to analyse the influence of gender and laterality and a Pearson correlation to analyse the relationship between mechanical and physical parameters. The results obtained show a clear symmetry in physical and mechanical parameters. There were significant differences between men and women (f and k) (p<0.05) being in absolute terms higher in men than in women but not in relative terms (ku). A clear correlation was obtained between mechanical parameters and MVCi in absolute terms (p<0.05). Ku allows comparisons between different subjects but its interpretation is not as intuitive as in absolute terms due to the application of the Hill’s model on the mechanical response of muscle-tendon complexes that establishes a nonlinear relationship between f and k.Keywords: Stiffness, Viscoelastic properties, laterality, drop jump.Resumen.El propósito del estudio consiste en evaluar el nivel de actividad física de adultos jóvenes mediante la obtención de la rigidez Musculo-articular y analizar su correlación con el rendimiento físico medido en capacidad de salto. El protocolo propuesto engloba un test Músculo-articular de ambas piernas, un test de Máxima contracción isométrica (MCIV) voluntaria en las mismas condiciones, un test de salto de contramovimiento, y un protocolo de salto de drop jump desde diferentes alturas (20, 40 y 60 cm). 21 sujetos adultos jóvenes sanos (12 hombre y 9 mujeres) conforman la muestra. Las variables mecánicas son: fuerza (f), Rigidez Músculo-articular (k) y rigidez Músculoarticular Unitaria (ku). Variables físicas: Altura de vuelo de salto (h) y fuerza generada (f). Se llevó a cabo un Anova de mediciones repetidas para analizar la influencia del género y lateralidad y una correlación de Pearson para analizar la relación entre parámetros mecánicos y parámetros físicos. Los resultados obtenidos muestran una simetría clara tanto en parámetros físicos como en parámetros mecánicos. Se obtuvieron diferencias significativas entre hombres y mujeres (f y k) (p<0.05) siendo en términos absolutos mayores en hombres que en mujeres pero no en términos relativos (ku). Se obtuvo una clara correlación entre parámetros mecánicos y MCIV términos absolutos (p<0.05). Ku permite comparar entre diferentes sujetos pero su interpretación no es tan intuitiva como en términos absolutos debido a la aplicación del modelo de Hill sobre la respuesta mecánica de los complejos músculo-tendón que establece una relación no lineal entre f y k.Palabras clave: Rigidez, Propiedades viscoeláticas, lateralidad, drop jump.

scholarly journals Chemo-Rheological Study of Hardening of Epoxy Modified Bituminous Binders with the Finite Element Method

2018 ◽  
Vol 2672 (28) ◽  
pp. 190-199 ◽  
Author(s):  
P. Apostolidis ◽  
X. Liu ◽  
C. Kasbergen ◽  
M.F.C. van de Ven ◽  
G. Pipintakos ◽  
...  
Keyword(s):  
Activation Energy ◽  
Mechanical Response ◽  
Chemical Interaction ◽  
Influential Factors ◽  
Polymerization Rate ◽  
Gel Point ◽  
Physical Factors ◽  
Modified Bitumen ◽  
Reaction Extent ◽  
Bituminous Binders

The chemical irreversible hardening of epoxy modified bitumen is affected by various physical factors and the successful application of this technology is directly linked with full understanding of chemo-rheological material characteristics. This study proposes a model to describe the material viscosity evolution during hardening of epoxy modified bitumen. The findings from numerical analyses performed to assess the mechanical response of epoxy modified bituminous binders are presented. Information of the chemical interaction of epoxy within a bituminous matrix was collected and all the influential factors have been determined. The proposed chemo-rheological model accounting for the polymerization of the epoxy in the bitumen was formulated and the sensitivity of material parameters, such as activation energy, reaction order and extent of hardening reaction until the gel point of epoxy modified binders, was demonstrated. Results of the analyses suggest that lower levels of activation energy increase the degree of hardening and the rate of viscosity development. By decreasing the hardening reaction until the gel point the achieved viscosity of epoxy modified bitumen was increased showing the importance of gel reaction extent on material viscosity evolution. The numerical studies have shown also that the polymerization rate in the epoxy modified bitumen is highly dependent on the temperature under various (non-) isothermal conditions. Also, the polymerization rate should be considered through all the material curing processes to avoid unwanted variations in the mechanical properties.

Numerical Simulation of Humidity-Stress in Unsaturated Argillite Tunnel

2006 ◽  
Vol 306-308 ◽  
pp. 1409-1414
Author(s):  
Wei Zhong Chen ◽  
Fei Li ◽  
Guo Jun Wu ◽  
Shu Cai Li ◽  
Jian Fu Shao
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Porous Medium ◽  
Relative Permeability ◽  
Mechanical Response ◽  
Water Saturation ◽  
Field Investigation ◽  
Saturation Degree

An extension of Hoek-Brown criteria to include unsaturated behavior of argillite in porous medium is presented. The model is applied to simulate evolution of saturation degree in argillite and concrete in an experimental tunnel where field investigation of thermo-hydro-mechanical response of argillite and concrete will be done. Based on the laboratory experimental data, two different flow rules of water relative permeability and water saturation degree were suggested. The general evolution rules of saturation degree in argillite and concrete with time considering the effects ventilation are obtained.

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