scholarly journals Assessing the impact of vertical heat exchangers on the response of a retaining wall

2019 ◽  
Vol 92 ◽  
pp. 16001
Author(s):  
Eleonora Sailer ◽  
David M. G. Taborda ◽  
Lidija Zdravkovic ◽  
David M. Potts
Keyword(s):  
Finite Element ◽  
Heat Exchangers ◽  
Retaining Wall ◽  
Urban Environments ◽  
Underground Structures ◽  
Finite Element Program ◽  
Soil Response ◽  
Heating And Cooling ◽  
Vertical Heat ◽  
The Impact

Shallow geothermal energy systems, e.g. borehole heat exchangers or thermo-active structures, provide sustainable space heating and cooling by exchanging heat with the ground. When installed within densely built urban environments, the thermo-hydro-mechanical (THM) interactions occurring due to changes in ground temperature, such as soil deformation and development of excess pore water pressures, may affect the mechanical behaviour of adjacent underground structures. This paper investigates the effects of vertical heat exchangers installed near a deep basement by performing fully coupled THM finite element analyses using the Imperial College Finite Element Program. Different heat exchanger configurations are considered and their influence on the response of the basement wall is assessed in two-dimensional plane strain analyses, where different methods of modelling the heat sources in this type of analysis are employed to evaluate their effect on the temperature field and the non-isothermal soil response.

scholarly journals The impact of drilling and slitting construction on damage field: evolution characteristics in low-permeability coal seam

2021 ◽  
Vol 37 ◽  
pp. 205-215
Author(s):  
Heng Chen ◽  
Hongmei Cheng ◽  
Aibin Xu ◽  
Yi Xue ◽  
Weihong Peng
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Damage Mechanics ◽  
Effective Strain ◽  
Secondary Development ◽  
Distribution Area ◽  
Finite Element Program ◽  
Element Program ◽  
Mining Face ◽  
The Impact

ABSTRACT The fracture field of coal and rock mass is the main channel for gas migration and accumulation. Exploring the evolution law of fracture field of coal and rock mass under the condition of drilling and slitting construction has important theoretical significance for guiding efficient gas drainage. The generation and evolution process of coal and rock fissures is also the development and accumulation process of its damage. Therefore, based on damage mechanics and finite element theory, the mathematical model is established. The damage variable of coal mass is defined by effective strain, the elastoplastic damage constitutive equation is established and the secondary development of finite element program is completed by FORTRAN language. Using this program, the numerical simulation of drilling and slitting construction of the 15-14120 mining face of Pingdingshan No. 8 Mine is carried out, and the effects of different single borehole diameters, different kerf widths and different kerf heights on the distribution area of surrounding coal fracture field and the degree of damage are studied quantitatively. These provide a theoretical basis for the reasonable determination of the slitting and drilling arrangement parameters at the engineering site.

The Finite Element Analysis of Dynamic Interaction of High-Speed Shinkansen, the Rail, and Bridge

1993 ◽  
Author(s):  
Makoto Tanabe ◽  
Hajime Wakui ◽  
Nobuyuki Matsumoto
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
High Speed ◽  
Response Analysis ◽  
Element Formulation ◽  
Element Analysis ◽  
Finite Element Program ◽  
The Finite Element Analysis ◽  
Element Program ◽  
The Impact

Abstract A finite element formulation to solve the dynamic behavior of high-speed Shinkansen cars, rail, and bridge is given. A mechanical model to express the interaction between wheel and rail is described, in which the impact of the rail on the flange of wheel is also considered. The bridge is modeled by using various finite elements such as shell, beam, solid, spring, and mass. The equations of motions of bridge and Shinkansen cars are solved under the constitutive and constraint equations to express the interaction between rail and wheel. Numerical method based on a modal transformation to get the dynamic response effectively is discussed. A finite element program for the dynamic response analysis of Shinkansen cars, rail, and bridge at the high-speed running has been developed. Numerical examples are also demonstrated.

Predicting the Impact of Quenching on Mechanical Properties of Complex-Shaped Aluminum Alloy Parts

1995 ◽  
Vol 117 (2) ◽  
pp. 479-488 ◽  
Author(s):  
D. D. Hall ◽  
I. Mudawar
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Boundary Conditions ◽  
Finite Element Program ◽  
Part Geometry ◽  
Heat Treated ◽  
Element Program ◽  
Nozzle Configuration ◽  
The Impact

The mechanical properties of age-hardenable aluminum alloy extrusions are critically dependent on the rate at which the part is cooled (quenched) after the forming operation. The present study continues the development of an intelligent spray quenching system, which selects the optimal nozzle configuration based on part geometry and composition such that the magnitude and uniformity of hardness (or yield strength) is maximized while residual stresses are minimized. The quenching of a complex-shaped part with multiple, overlapping sprays was successfully modeled using spray heat transfer correlations as boundary conditions within a finite element program. The hardness distribution of the heat-treated part was accurately predicted using the quench factor technique; that is, the metallurgical transformations that occur within the part were linked to the cooling history predicted by the finite element program. This study represents the first successful attempt at systematically predicting the mechanical properties of a quenched metallic part from knowledge of only the spray boundary conditions.

The Effects of Modelling Techniques and Data Uncertainty in Wellhead Fatigue Life Calculation

2012 ◽  
Author(s):  
Dara Williams ◽  
John Greene
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Environmental Data ◽  
Nonlinear Load ◽  
Soil Response ◽  
Load Response ◽  
Highly Nonlinear ◽  
Non Linear ◽  
The Impact

Offshore oil and gas exploration continues to move into deeper and more harsh environments and consequently the response of drilling riser systems and associated fatigue loading transmitted to the wellhead and conductor system are of key importance in the design of offshore wells. In addition the presence of ageing infrastructure in mature areas combined with requirements for future workover operations requires careful consideration of both past and future fatigue damage accumulation. In order to estimate remaining fatigue life for the wellhead and conductor the accumulation of damage from each stage of a drilling campaign and phase of operation of a well, including workover and completion operations, must be considered. Thus a detailed global finite element analysis of the impact of riser response, under wave and vortex induced vibration (VIV), on the conductor and wellhead structure is of critical importance. Traditional engineering evaluation methods to estimate fatigue of wellhead systems in offshore regions with limited availability of environmental data may result in an over estimation of fatigue damage accumulated in the wellhead. Any assumptions regarding fatigue current profiles can also lead to over-prediction of fatigue damage in the wellhead. This can have implications for the planning of future workover operations and may also lead to unnecessary over-design of the system. A further limitation of traditional wellhead fatigue evaluation criteria lies in the assumptions regarding riser tensioner system load response. These methods do not account for the highly nonlinear load response of the tensioner system and can thus significantly underestimate fatigue damage contribution. This paper presents a more detailed wellhead fatigue analysis methodology to incorporate new analysis techniques, as used for a number of recent applications, to assess with a greater level of refinement the impact of the riser motions on the wellhead fatigue. Specifically this methodology incorporates the generation of a detailed global finite element model of the riser and wellhead system to include detailed non-linear riser tensioner system models, accurate models of the wellhead and conductor, detailed non-linear soil response characteristics and the use of more refined current data as input to VIV calculations. The details of the riser and wellhead system model are presented and the conservatisms associated with traditional modeling methods with regard to VIV and riser tensioner load variations are discussed. A number of case studies are presented to illustrate the effects of various data assumptions and simplifications on estimated wellhead fatigue.

Finite Element Modeling of Measured Rough Surfaces for the Prediction of Thermal Contact Resistance

2007 ◽  
Author(s):  
M. K. Thompson ◽  
J. M. Thompson
Keyword(s):  
Finite Element ◽  
Contact Resistance ◽  
Surface Topography ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Element Model ◽  
Surface Metrology ◽  
Surface Geometry ◽  
Finite Element Program ◽  
The Impact

Surface topography has long been considered a key factor in the performance of many contact applications. However, essentially all analytical and numerical contact models either neglect surface topography or make simplifications and assumptions about the nature of the surface which limit the quality of the models. This work presents a method for creating surface geometry by importing surface metrology data into a commercial finite element program. The measured surface geometry is then combined with a multi-scale thermal/structural finite element model to demonstrate the impact of geometric surface assumptions on the prediction of thermal contact resistance.

Fretting Wear Damage of Heat Exchanger Tubes: A Proposed Damage Criterion Based on Tube Vibration Response

1998 ◽  
Vol 120 (3) ◽  
pp. 297-305 ◽  
Author(s):  
M. Yetisir ◽  
E. McKerrow ◽  
M. J. Pettigrew
Keyword(s):  
Finite Element ◽  
Heat Exchanger ◽  
Vibration Frequency ◽  
Vibration Amplitude ◽  
Work Rate ◽  
Nonlinear Finite Element ◽  
Fretting Wear ◽  
Finite Element Program ◽  
Wear Damage ◽  
The Impact

A simple criterion is proposed to estimate fretting wear damage in heat exchanger tubes with clearance supports. The criterion is based on parameters such as vibration frequency, midspan vibration amplitude, span length, tube mass, and an empirical wear coefficient. It is generally accepted that fretting wear damage is proportional to a parameter called work rate. Work rate is a measure of the dynamic interaction between a vibrating tube and its supports. Due to the complexity of the impact-sliding behavior at the clearance supports, work rate calculations for heat exchanger tubes require specialized nonlinear finite element codes. These codes include contact models for various clearance support geometries. Such nonlinear finite element analyses are complex, expensive and time consuming. The proposed criterion uses the results of linear vibration analysis (i.e., vibration frequency and mid-span vibration amplitude due to turbulence) and does not require a nonlinear analysis. It can be used by nonspecialists for a quick evaluation of the expected work rate, and hence, the fretting wear damage of heat exchanger tubes. The proposed criterion was obtained from an extensive parametric study that was conducted using a nonlinear finite element program. It is shown that, by using the proposed work rate criteria, work rate can be estimated within a factor of two. This result, however, requires further testing with more complicated flow patterns.

scholarly journals Evaluating geomechanical effects related to the production of a Brazilian reservoir

2021 ◽  
Vol 11 (6) ◽  
pp. 2661-2678
Author(s):  
Raquel Oliveira Lima ◽  
Leonardo José do Nascimento Guimarães ◽  
Leonardo Cabral Pereira
Keyword(s):  
Finite Element ◽  
Oil Recovery ◽  
Computational Effort ◽  
Absolute Permeability ◽  
Coupling Scheme ◽  
Reservoir Properties ◽  
Finite Element Program ◽  
Element Program ◽  
Stress Dependent ◽  
The Impact

AbstractThis paper presents a coupled finite element approach for modeling geomechanical effects induced by production/injection processes in petroleum reservoirs. The module developed employs coupled- reservoir analysis using CMG IMEX® as the flow simulator and a finite element program in MATLAB® as the stress–strain simulator, in a two-way explicit partial coupling scheme. The flow and mechanical problems are coupled by the change of effective stress due to the change in pore pressure and by varying stress-dependent reservoir properties, such as pore compressibility, absolute permeability, and porosity. The coupling procedure was applied to the Namorado Field (Campos Basin, Brazil) to quantify the impact of the rock deformation on fluid recovery. Based on the cases studied, the coupled analyses predicted higher oil recovery than the conventional reservoir simulations. The results showed that the reservoir deformation can affect its performance and must be taken into account in reservoir-engineering studies depending on production strategy and reservoir stiffness. Besides, the geomechanical calculations were performed only in the coupling timesteps, reducing the computational effort and making this coupling method feasible on a field scale.

scholarly journals Younan-Veletsos retaining wall: The exact solution

2019 ◽  
Author(s):  
Joaquin Garcia-Suarez ◽  
Domniki Asimaki
Keyword(s):  
Exact Solution ◽  
Finite Element ◽  
Fourier Transforms ◽  
Retaining Wall ◽  
Geotechnical Engineering ◽  
Finite Element Simulations ◽  
Seismic Events ◽  
Underground Structures ◽  
Wavenumber Domain ◽  
Reference Problem

The assessment of forces exerted on walls by the backfill is a recurrent problem in Geotechnical Engineering, owing to its relevance for both retaining systems and underground structures. In particular, the work by Veletsos and Younan becomes pertinent when considering pressure increments on underground structures triggered by seismic events. These scholars furnished the first satisfactory engineering solution corresponding to a simple configuration, which has become a milestone in the field. This paper presents the exact solution to this reference problem. The solution is given in horizontal wavenumber domain, hence it comes in terms of inverse Fourier transforms, which in turn are verified against finite-element simulations. Specific features of this exact solution that were not captured by prior engineering approximations are highlighted and discussed.

scholarly journals Energy Recovery from Wastewater: A Study on Heating and Cooling of a Multipurpose Building with Sewage-Reclaimed Heat Energy

2019 ◽  
Vol 12 (1) ◽  
pp. 116 ◽  
Author(s):  
Daniele Cecconet ◽  
Jakub Raček ◽  
Arianna Callegari ◽  
Petr Hlavínek
Keyword(s):  
Heat Exchangers ◽  
Urban Areas ◽  
Energy Recovery ◽  
Heat Recovery ◽  
Energy Requirement ◽  
Heat Pumps ◽  
Heat Energy ◽  
Heating And Cooling ◽  
Conventional Solution ◽  
The Impact

To achieve technically-feasible and socially-desirable sustainable management of urban areas, new paradigms have been developed to enhance the sustainability of water and its resources in modern cities. Wastewater is no longer seen as a wasted resource, but rather, as a mining ground from which to obtain valuable chemicals and energy; for example, heat energy, which is often neglected, can be recovered from wastewater for different purposes. In this work, we analyze the design and application of energy recovery from wastewater for heating and cooling a building in Brno (Czech Republic) by means of heat exchangers and pumps. The temperature and the flow rate of the wastewater flowing in a sewer located in the proximity of the building were monitored for a one-year period, and the energy requirement for the building was calculated as 957 MWh per year. Two options were evaluated: heating and cooling using a conventional system (connected to the local grid), and heat recovery from wastewater using heat exchangers and coupled heat pumps. The analysis of the scenarios suggested that the solution based on heat recovery from wastewater was more feasible, showing a 59% decrease in energy consumption compared to the conventional solution (respectively, 259,151 kWh and 620,475 kWh per year). The impact of heat recovery from wastewater on the kinetics of the wastewater resource recovery facility was evaluated, showing a negligible impact in both summer (increase of 0.045 °C) and winter conditions (decrease of 0.056 °C).

Analysis of Soil Nailing under Earthquake Loading in Malaysia Using Finite Element Method

2014 ◽  
Vol 695 ◽  
pp. 526-529 ◽  
Author(s):  
Mohd Faiz Mohammad Zaki ◽  
Wan Amiza Amneera Wan Ahmad ◽  
Afizah Ayob ◽  
Teoh Khai Ying
Keyword(s):  
Finite Element ◽  
Static Analysis ◽  
Slope Failure ◽  
Retaining Wall ◽  
Seismic Loading ◽  
Soil Nailing ◽  
Deep Excavation ◽  
Finite Element Program ◽  
Total Displacement ◽  
Element Program

Soil nailing has become a widely accepted method and offers a practical solution towards construction of permanent retaining wall, slope stabilization and protection of existing cuts from failure. In Malaysia, soil nailing is typically performed on cut slope and installed with grouting as preventatives method due to erosion problem. However, although the effectiveness of soil nailing system may be well understood by practitioners, the slope failure and collapses of deep excavation are continuously occurs, especially for the construction in the earthquake zone. Malaysia has numerous experiences of earthquake even this country has been categorized as low seismicity group. Hence, it is become important in the scope of geotechnical engineering to analyze and study the effect of earthquake to soil nailing systems in Malaysia. Aims of this paper are to focus and study this technical issue using the application of finite element program. This research study selects PGA of 0.08g based on the location of major population in Malaysia. Safety factor was calculated in this finite element program using phi-c reduction. Soil nailing relatively give satisfactory response under seismic, so pseudo-static method is applied for seismic loading study. Based on the static analysis results, the FOS for the deep excavation stabilized with soil nailing is 1.54. However, by considering the earthquake or seismic loading, the FOS reduces to 1.16 and the percentage of reduction is about 25%. Total displacement was observed slightly difference in soil nailing analysis during an earthquake and static analysis

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