scholarly journals 3D Finite Element Model Simulating the Behaviour of Filling Soils Used to Set Up a New Placement Method for Separate Sewer Systems

2019 ◽  
Vol 8 (3) ◽  
pp. 87-98
Author(s):  
Alaa Abbas ◽  
Felicite Ruddock ◽  
Rafid Alkhaddar ◽  
Glynn Rothwell ◽  
Iacopo Carnacina ◽  
...  
Keyword(s):  
Finite Element ◽  
Soil Properties ◽  
Model Simulation ◽  
New Method ◽  
Traffic Load ◽  
Scale Model ◽  
Fe Model ◽  
Fe Method ◽  
Buried Pipes ◽  
The Impact

The use of a finite element (FE) method and selection of the appropriate model to simulate soil elastoplastic behaviour has confirmed the importance and sensitivity of the soil properties on the accuracy when compared with experimental data. The properties of the filling soil play a significant role in determining levels of deformation and displacement of both the soil and subterranean structures when using the FE model simulation. This paper investigates the impact of the traffic load on the filling soil deformation when using the traditional method, one pipe in a trench, and a new method, two pipes in a single trench one over the other, for setting up a separate sewer system. The interaction between the buried pipes and the filling soils has been simulated using an elastoplastic FE model. A modified Drucker–Prager cap constitutive model was used to simulate the stress-strain behaviours of the soil. A series of laboratory tests were conducted to identify the elastoplastic properties of the composite soil used to bury the pipes. The FE models were calibrated using a physical lab model for testing the buried pipes under applied load. This allows the FE model to be confidently upgraded to a full-scale model. The pipe-soil interactions were found to be significantly influenced by the soil properties, the method of placing the pipes in the trench and the diameters of the buried pipes. The deformation of the surface soil was decreased by approximately 10% when using the new method of setting up the separate sewer.

FE Modeling of the Three-Layer Human Carotid Artery Under Impact Loadings

2007 ◽  
Author(s):  
Aihong Zhao ◽  
Ken Digges ◽  
Mark Field ◽  
David Richens
Keyword(s):  
Finite Element ◽  
Carotid Artery ◽  
Model Simulation ◽  
Material Model ◽  
Element Model ◽  
Traumatic Rupture ◽  
Aortic Tissue ◽  
Fe Model ◽  
Arbitrary Lagrangian Eulerian ◽  
The Impact

Blunt traumatic rupture of the carotid artery is a rare but life threatening injury. The histology of the artery is key to understanding the aetiology of this injury. The carotid artery is composed of three layers known as the tunica intima, media, and adventitia, with distinct biomechanical properties. In order to examine the behaviour of the carotid artery under external load we have developed a three layer finite element model of this vessel. A rubber-like material model from LS-DYNA was selected for the FE model. The Arbitrary-Lagrangian Eulerian (ALE) approach was adopted to simulate the interaction between the fluid (blood) and the structure (carotid). To verify the FE model, the impact bending tests are simulated using this FE model. Simulation results agree with tests results well. Furthermore, the mechanical behaviour of carotid artery tissues under impact loading were revealed by the simulations. The results provide a basis for a more in-depth investigation of the carotid artery in vehicle crashes. In addition, it provides a basis for further work on aortic tissue finite element modeling.

Numerical and Experimental Investigation on the Energy Absorption Capability of a Full-Scale Composite Fuselage Section

2019 ◽  
Vol 827 ◽  
pp. 19-24 ◽  
Author(s):  
Donato Perfetto ◽  
Giuseppe Lamanna ◽  
M. Manzo ◽  
A. Chiariello ◽  
F. di Caprio ◽  
...  
Keyword(s):  
Finite Element ◽  
Energy Absorption ◽  
Load Condition ◽  
Element Model ◽  
Full Scale ◽  
Research Centre ◽  
Fe Method ◽  
Explicit Finite Element ◽  
Crashworthiness Design ◽  
The Impact

In the case of catastrophic events, such as an emergency landing, the fuselage structure is demanded to absorb most of the impact energy preserving, at the same time, a survivable space for the passengers. Moreover, the increasing trend of using composites in the aerospace field is pushing the investigation on the passive safety capabilities of such structures in order to get compliance with regulations and crashworthiness requirements. This paper deals with the development of a numerical model, based on the explicit finite element (FE) method, aimed to investigate the energy absorption capability of a full-scale 95% composite made fuselage section of a civil aircraft. A vertical drop test, performed at the Italian Aerospace Research Centre (CIRA), carried out from a height of 14 feet so to achieve a ground contact velocity of 30 feet/s in according to the FAR/CS 25, has been used to assess the prediction capabilities of the developed FE method, allowing verifying the response under dynamic load condition and the energy absorption capabilities of the designed structure. An established finite element model could be used to define the reliable crashworthiness design strategy to improve the survival chance of the passengers in events such as the investigated one.

scholarly journals Study on the Impact Resistance of Metal Flexible Net to Rock fall

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Gaosheng Wang ◽  
Yunhou Sun ◽  
Ao Zhang ◽  
Lei Zheng ◽  
Yuzheng Lv ◽  
...  
Keyword(s):  
Finite Element ◽  
Impact Force ◽  
Impact Resistance ◽  
Time History ◽  
Rock Fall ◽  
Fe Model ◽  
Element Analysis ◽  
Inclination Angles ◽  
Fall Protection ◽  
The Impact

Based on experiments and finite element analysis, the impact resistance of metal flexible net was studied, which can provide reference for the application of metal flexible net in rock fall protection. The oblique (30 degrees) impact experiment of metal flexible net was carried out, the corresponding finite element (FE) to the experiment was established, and the FE model was verified by simulation results to the experimental tests from three aspects: the deformation characteristics of metal flexible net, the time history curves of impact force on supporting ropes, and the maximum instantaneous impact force on supporting ropes. The FE models of metal flexible nets with inclination angles of 0, 15, 30, 45, 60, and 75 degrees were established, and the impact resistance of metal flexible nets with different inclination angles was analyzed. The research shows that the metal flexible net with proper inclination can bounce the impact rock fall out of the safe area and prevent rock fall falling on the metal flexible net, thus realizing the self-cleaning function. When the inclination angle of the metal flexible net is 15, 30, and 45 degrees, respectively, the bounce effect after impact is better, the remaining height is improved, the protection width is improved obviously, and the impact force is reduced. Herein, the impact force of rock fall decreases most obviously at 45 degrees inclination, and the protective performance is relatively good.

Effect of a Degenerated C5-C6 Disc on the Biomechanics of Adjacent Levels: A Poroelastic Finite Element Investigation

2007 ◽  
Author(s):  
Mozammil Hussain ◽  
Raghu N. Natarajan ◽  
Gunnar B. J. Andersson ◽  
Howard S. An
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Morphological Changes ◽  
Axial Strain ◽  
Fe Model ◽  
Fe Method ◽  
Regional Effect ◽  
In Vitro Techniques

Degenerative changes in the cervical spine due to aging are very common causes of neck pain in general population. Although many investigators have quantified the gross morphological changes in the disc with progressive degeneration, the biomechanical changes due to degenerative pathologies of the disc and its effect on the adjacent levels are not well understood. Despite many in vivo and in vitro techniques used to study such complex phenomena, the finite element (FE) method is still a powerful tool to investigate the internal mechanics and complex clinical situations under various physiological loadings particularly when large numbers of parameters are involved. The objective of the present study was to develop and validate a poroelastic FE model of a healthy C3-T1 segment of the cervical spine under physiologic moment loads. The model included the regional effect of change in the fixed charged density of proteoglycan concentration and change in the permeability and porosity due to change in the axial strain of disc tissues. The model was further modified to include various degrees of disc degeneration at the C5-C6 level. Outcomes of this study provided a better understanding on the progression of degeneration along the cervical spine by investigating the biomechanical response of the adjacent segments with an intermediate degenerated C5-C6 level.

A New Method to Quantify the Impact of Soil Carbon Management on Biophysical Soil Properties: The Example of Two Apple Orchard Systems in New Zealand

2008 ◽  
Vol 37 (3) ◽  
pp. 915-924 ◽  
Author(s):  
Markus Deurer ◽  
Siva Sivakumaran ◽  
Stefanie Ralle ◽  
Iris Vogeler ◽  
Ian McIvor ◽  
...  
Keyword(s):  
New Zealand ◽  
Soil Properties ◽  
Soil Carbon ◽  
Apple Orchard ◽  
New Method ◽  
Carbon Management ◽  
The Impact

Comprehensive FEA of Thermal Mitigation Buoyancy Module (TMBM)–Soil Interaction Using the Coupled Eulerian–Lagrangian (CEL) Method

2010 ◽  
Author(s):  
Kenton Pike ◽  
Gang Duan ◽  
Jason Sun ◽  
Paul Jukes
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Lateral Displacement ◽  
Gas Production ◽  
Fe Model ◽  
Fe Method ◽  
Lateral Buckling ◽  
Global Buckling ◽  
Thermal Mitigation ◽  
Large Soil

Thermal expansion and global buckling is a critical design aspect for subsea flowline systems subjected to high pressure and high temperature (HPHT). In the Gulf of Mexico, HPHT oil/gas production is becoming exceedingly common as drilling and production depths extend deeper. Advanced finite element analysis becomes essential for flowline expansion and buckling design which is highly dependent on pipe-soil interaction behavior. For decades, pipe-soil interaction has been the focus of many research studies and joint industry projects. For HPHT flowline systems, thermal mitigation is decisive for safe design. Thermal mitigation acts to control global buckling at designate locations and avoid buckling in unknown locations. Thermal mitigation results in significant cost savings by lowering the welding class besides the buckling locations and increases safety in terms of local buckling, fracture, and fatigue. One widely used thermal mitigation method involves attaching a buoyancy module around a segment of the flowline. In this paper the Coupled Eulerian Langrangian (CEL) finite element (FE) formulation is utilized to simulate the interaction between soil and the thermal mitigation buoyancy module (TMBM). The paper demonstrates the capability of the CEL FE method to simulate large soil deformation without the numerical difficulties that are commonly associated with other numerical formulations e.g. ALE (Arbitrary Lagrangian Eulerian) or more conventional Lagrangian. Initially, a three dimensional (3D), continuum, FE model is used to establish the variation of initial embedment along the length of the buoyancy and adjoining pipe. The study then establishes the lateral displacement/resistance relationships under different levels of contact pressure and soil embedment for a series of buoyancy-soil interaction segments, also using the CEL FE method. Current practice for global pipeline thermal expansion FEA is to utilize the same friction model for both buoyancy-soil interaction and pipe-soil interaction. The obtained buoyancy-soil interaction model from the current study is to be used as input to the global FE model to more precisely simulate flowline lateral buckling behavior. This paper presents a practical application of the current state of the art in modeling large soil deformations in providing an improved approach for modeling buoyancy-soil interactions in the global FEA of pipeline thermal expansion and lateral buckling.

Modeling IPMC Material With Dynamic Surface Characteristics

2009 ◽  
Author(s):  
Deivid Pugal ◽  
Alvo Aabloo ◽  
Kwang J. Kim ◽  
Youngsoo Jung
Keyword(s):  
Finite Element ◽  
Time Moment ◽  
Surface Characteristics ◽  
Dynamic Resistance ◽  
Charge Movement ◽  
Fe Model ◽  
Metal Composite ◽  
Fe Method ◽  
Element Analysis ◽  
Dynamic Surface

This paper presents the Finite Element Analysis (FEA) of an ionic polymer-metal composite (IPMC) material. The IPMC materials are known to bend when electric field is applied on the electrodes. The material also produces potential difference on the electrodes when is bent. Several authors have used the FEA to describe that fenomenon and rather precise basic Finite Element (FE) models already exist. Therefore the current study is mainly focused on the modeling of the electrodes of IPMC. The first goal of this research is to model the electric currents in the electrodes. The basis of the electric current calculations is the Ramo-Shockley theorem, which has been used in the other areas of physics to describe the currents in a circuit due to a charge movement in a media. We have used the theorem to calculate the current density in the continuous electrodes of IPMC due to the ion migration in the backbone polymer. Along the current densities we are able to calculate voltage on the electrode at a given time moment. The model is demonstrated to give some physically reasonable results. However, the model is rather complex and as the solution times are quite large, some possible optimizations have been considered as well. The second goal of this study is to include the dynamic resistance and capacitance of the electrodes in our model. Lot of research has been done to develop a physically reasonable capacitor-resistor model of an IPMC and the results have been promising. Furthermore, some authors have managed to develop partial differential equations (PDE) to describe the model. We try to include some simplified versions of those equations into our physical model. As the FE model for IPMC is nonlinear and gets complicated very fast when additional equations are added, the final sections of this paper briefly considers some novel optimization ideas in regard to modeling IPMC with FE method.

Output-Only Modal Analysis of an Internal Unreachable Module Embedded in a Space Electronic Equipment

2012 ◽  
Author(s):  
Lassaad Ben Fekih ◽  
Georges Kouroussis ◽  
David Wattiaux ◽  
Olivier Verlinden ◽  
Christophe De Fruytier
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Transverse Direction ◽  
Mode Shapes ◽  
Fe Model ◽  
Fe Method ◽  
Numeric Model ◽  
Stiffness Matrices ◽  
Output Only

An approach is proposed to identify the modal properties of a subsystem made up of an arbitrary chosen inner module of embedded space equipment. An experimental modal analysis was carried out along the equipment transverse direction with references taken onto its outer housing. In parallel, a numerical model using the finite element (FE) method was developed to correlate with the measured results. A static Guyan reduction has led to a set of master degrees of freedom in which the experimental mode shapes were expanded. An updating technique consisting in minimizing the dynamic residual induced by the FE model and the measurements has been investigated. A last verification has consisted in solving the numeric model composed of the new mass and stiffness matrices obtained by means of a minimization of the error in the constitutive equation method.

scholarly journals Numerical analysis of circular and square section concrete filled aluminum tubes under axial compression

2020 ◽  
Vol 14 (54) ◽  
pp. 169-181
Author(s):  
Pan Jinlong ◽  
Li Guanhua ◽  
Jingming Cai
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Axial Compression ◽  
Parametric Analysis ◽  
Concrete Strength ◽  
Fe Model ◽  
Fe Method ◽  
The Core ◽  
Aluminum Tubes ◽  
Core Concrete

In this paper, the finite element (FE) method was used to investigate the axial compressive behaviors of circular and square concrete filled aluminum tubes (CFAT). Firstly, the simulational results were compared with the experimental results and the accuracy of the proposed FE model was verified. On this basis, the FE model was further applied to compare the mechanical properties of both circular and square CFATs under axial compression. It was found that the circular CFATs have a better effect on restraining the core concrete than square CFATs. The parametric analysis was also conducted based on the proposed FE model. It was noticed that the mechanical differences of the two kinds of CFATs gradually decreased with the increase of the aluminum ratio, aluminum strength and concrete strength.

Stress Prediction of Buried Pipes Subjected to Operational Loadings in Unsaturated Soils

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Chamal Randeniya ◽  
Dilan Robert ◽  
Chun-Qing Li
Keyword(s):  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Three Dimensional ◽  
Soil Condition ◽  
Temporal Variations ◽  
Soil Conditions ◽  
Fe Model ◽  
Fe Method ◽  
Buried Pipes ◽  
Stress Prediction

Abstract Pipelines are used to provide variety of services in modern community and have grown rapidly in past few decades due to growing socio-economic requirements. Most of the water mains are buried in shallow depths where the soil is partially saturated with significant spatial and temporal variations. Even though the behavior of buried pipes in such unsaturated soil condition is substantially different when compared to dry or fully saturated soil, the effect of soil saturations is overlooked in the current pipe stress prediction methods, leading to unrealistic predictions of the pipe stresses. In this study, three-dimensional (3D) finite element (FE) method was employed with advanced constitutive soil models to analyze the behavior of pipes buried in unsaturated soil condition. Having validated the FE model using reported field test data, an analytical model was proposed to predict the maximum stress in buried pipes considering soil saturation effect using a series of 3D FE analyses. Results from the FE analyses reveal that the maximum pipe stress can be significantly different when soil is in unsaturated condition when compared to dry condition. The proposed formula shows a good agreement with the field data and FE results, so that the expression can be used in the prediction of maximum pipe stress when they are buried under realistic (i.e., nondry) soil conditions.

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