A numerical study of thermal ice loads on structures

1998 ◽  
Vol 25 (3) ◽  
pp. 557-568 ◽  
Author(s):  
A Azarnejad ◽  
T M Hrudey
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Variable Temperature ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Ice Cover ◽  
Analytical Prediction ◽  
Temperature Changes ◽  
Ice Loads

A numerical model is presented for the prediction of the three-dimensional stress field in an ice sheet due to temperature changes, as a function of time, under a variety of conditions. The model relies on two separate computer programs for the thermal and mechanical aspects of the problem. The thermal program uses the finite difference method to calculate the temperature distribution through the thickness of the ice cover under a variety of meteorological input conditions. The mechanical part of the analysis is conducted using the finite element method. A degenerate shell element is used, which is capable of modeling both bending and membrane behaviors of the ice cover. Relevant features of the finite element model include variable temperature and properties through the thickness, an elastic foundation representation of the underlying water, nonlinear constitutive behavior of the ice, temperature-dependent mechanical properties, flexibility of resisting structures, and boundary conditions representing a variety of shoreline types. Results are presented from simulations conducted during verification of the model. Included are simulations of uniaxial and biaxial laboratory tests on the thermal expansion of ice as well as three thermal events for which field data were available. Conclusions are presented concerning the analytical prediction of thermal ice forces.Key words: ice loads, thermal loads, ice mechanics, hydraulic structures, dams.

scholarly journals Modeling inflatable fabric with undevelopable surfaces by motion folding method

2019 ◽  
Vol 14 ◽  
pp. 155892501988640
Author(s):  
Xiao-Shun Zhao ◽  
He Jia ◽  
Zhihong Sun ◽  
Li Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Numerical Study ◽  
Technical Problem ◽  
Three Dimensional ◽  
Element Model ◽  
Model Errors ◽  
Folding Model ◽  
Study Results ◽  
The Stability

At present, most space inflatable structures are composed of flexible inflatable fabrics with complex undevelopable surfaces. It is difficult to establish a multi-dimensional folding model for this type of structure. To solve this key technical problem, the motion folding method is proposed in this study. First, a finite element model with an original three-dimensional surface was flattened with a fluid structure interaction algorithm. Second, the flattened surface was folded based on the prescribed motion of the node groups, and the final folding model was obtained. The fold modeling process of this methodology was consistent with the actual folding processes. Because the mapping relationship between the original finite element model and the final folding model was unchanged, the initial stress was used to modify the model errors during folding process of motion folding method. The folding model of an inflatable aerodynamic decelerator, which could not be established using existing folding methods, was established by using motion folding method. The folding model of the inflatable aerodynamic decelerator showed that the motion folding method could achieve multi-dimensional folding and a high spatial compression rate. The stability and regularity of the inflatable aerodynamic decelerator numerical inflation process and the consistency of the inflated and design shapes indicated the reliability, applicability, and feasibility of the motion folding method. The study results could provide a reference for modeling complex inflatable fabrics and promote the numerical study of inflatable fabrics.

Numerical Study of Welding Sequence on the Residual Stress Field in a Thick-Walled Tee Joint

2011 ◽  
Vol 219-220 ◽  
pp. 1211-1214
Author(s):  
Wei Jiang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Residual Stress Field ◽  
Factors Affecting ◽  
Welding Sequence ◽  
Welding Sequences ◽  
Three Dimensional Finite Element

Finite element simulation is an efficient method for studying factors affecting weld-induced residual stress distributions. In this paper, a validated three-dimensional finite element model consisting of sequentially coupled thermal and structural analyses was developed. Three possible symmetrical welding sequences, i.e. one-welder, two-welder and four-welder sequence, which were perceived to generate the least distortion in actual welding circumstances, were proposed and their influences on the residual stress fields in a thick-walled tee joint were investigated. Appropriate conclusions and recommendations regarding welding sequences are presented.

scholarly journals STUDY ON NONLINEAR PAVEMENT RESPONSES OF LOW VOLUME ROADWAYS SUBJECT TO MULTIPLE WHEEL LOADS / NETIESINĖS KELIO DANGOS PRIKLAUSOMYBĖS NUO MAŽO INTENSYVUMO KELIŲ, VEIKIAMŲ DAUGKARTINĖMIS RATŲ APKROVOMIS, TYRIMAS

2011 ◽  
Vol 17 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Minkwan Kim ◽  
Joo Hyoung Lee
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Asphalt Pavement ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Element Model ◽  
Element Analysis ◽  
Nonlinear Stress ◽  
Low Volume ◽  
Stress Dependent

This paper describes numerical analyses on low volume roads (LVRs) using a nonlinear three-dimensional (3D) finite element model (FEM). Various pavement scenarios are analyzed to investigate the effects of pavement layer thicknesses, traffic loads, and material properties on pavement responses, such as surface deflection and subgrade strain. Each scenario incorporates a different combination of wheel/axle configurations and pavement geomaterial properties to analyze the nonlinear behavior of thinly surfaced asphalt pavement. In this numerical study, nonlinear stress-dependent models are employed in the base and subgrade layers to properly characterize pavement geomaterial behavior. Finite element analysis results are then described in terms of the effects of the asphalt pavement thickness, wheel/axle configurations, and geomaterial properties on critical pavement responses. Conclusions are drawn by the comparison of the nonlinear pavement responses in the base and subgrade in association with the effects of multiple wheel/axle load interactions. Santrauka Straipsnyje aprašoma skaitinė mažo intensyvumo kelių analizė, taikant netiesinį—erdvinį baigtinių elementų modelį. Skirtingi dangų paviršiaus variantai analizuojami siekiant ištirti, kokiąįtaką kelio dangos elgsenai, t. y. poslinkiams ir kelio pagrindo deformacijoms, turi dangų sluoksnių storiai, eismo apkrovos ir medžiagų savybės. Kiekvienas kelio dangos variantas turi skirtingas ratų arba ašies ir geometrinių savybių formas, kad būtų galima išanalizuoti netiesinę plonos asfalto dangos paviršiaus elgseną. Šioje skaitinėje analizėje nagrinėjami netiesiniai įtempių modeliai, kurie buvo taikomi pagrindo sluoksniams, siekiant tinkamai apibūdinti geometrinę kelio dangos elgseną. Baigtinių elementų analizės rezultatai toliau nagrinėjami atsižvelgiant į asfalto dangos storį ar ašies formą ir geometrines savybes, priklausomai nuo kritinės kelio dangos būklės. Išvados buvo gautos lyginant netiesines kelių dangos priklausomybes pagrindo sluoksnyje, atsižvelgiant į jų sąveiką su daugkartine ratų apkrova.

Finite Element Analysis of Stiffness of Steel Plate with a Rectangular Cutout Bonded by Composite Patches

2013 ◽  
Vol 377 ◽  
pp. 3-7
Author(s):  
Ze Long You ◽  
Xiang Ming Zhang ◽  
Kui Du
Keyword(s):  
Finite Element ◽  
Steel Plate ◽  
Three Dimensional ◽  
Adhesive Layer ◽  
Shell Element ◽  
Element Model ◽  
Element Analysis ◽  
Spring Element ◽  
Bonded Repair ◽  
Spring Plate

An ANSYS-based "volume-spring-plate" three-dimensional finite element model is established in this paper to analyze steel plate with a rectangular hole reinforced by double-side bonding patch, in which the plate is simulated by solid45 8-node 3D element, the adhesive layer is simulated by linear elastic spring element combin14, and the patch is simulated by shell element. Relative intensity, relative stiffness and yield load rising rate of a patched steel plate with regard to parameters, such as the patch length, width, the number of patch layer and ply orientation are studied. The results indicate that composite bonded repair can effectively restore the mechanical properties of the structure and improve the service life.

scholarly journals Investigating pipeline–soil interaction under axial–lateral relative movements in sand

2011 ◽  
Vol 48 (11) ◽  
pp. 1683-1695 ◽  
Author(s):  
Nasser Daiyan ◽  
Shawn Kenny ◽  
Ryan Phillips ◽  
Radu Popescu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Lateral Interaction ◽  
Test Bed ◽  
Dense Sand ◽  
Centrifuge Tests ◽  
Soil Loading

This paper presents results from an experimental and numerical study on the axial–lateral interaction of pipes with dense sand. A series of centrifuge tests were conducted, with a rigid pipeline displaced in the horizontal plane in a cohesionless test bed. The relative pipe–soil interaction included axial, lateral, and oblique loading events. A three-dimensional continuum finite element model was developed using ABAQUS/Standard ( Hibbitt et al. 2005 ) software. The numerical model was calibrated against experimental results. A parametric study was conducted, using the calibrated finite element model to extend the investigations. The ultimate axial and lateral soil loading was found to be dependent on the angle of attack for relative movement between the pipe and soil. Two different failure mechanisms were observed for axial–lateral pipeline–soil interaction. This study confirms and improves on a two-part failure criterion that accounts for axial–lateral coupling during oblique soil loading events on buried pipelines.

A Combined Experimental and Numerical Study of the Effect of Surface Roughness on Nanoindentation

2019 ◽  
Vol 11 (07) ◽  
pp. 1950070
Author(s):  
M. Nazemian ◽  
M. Chamani ◽  
M. Baghani
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Finite Element ◽  
Rough Surface ◽  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Element Analysis ◽  
Three Dimensional Finite Element ◽  
Effect Of Surface

Gold and copper thin films are widely used in microelectromechanical system (MEMS) and nanoelectromechanical system (NEMS) devices. Nanoindentation has been developed in mechanical characterization of thin films in recent years. Several researchers have examined the effect of surface roughness on nanoindentation results. It is proved that the surface roughness has great importance in nanoindentation of thin films. In this paper, the surface topography of thin films is simulated using the extracted data from the atomic force microscopy (AFM) images. Nanoindentation on a rough surface is simulated using a three-dimensional finite-element model. The results are compared with the results of finite-element analysis on a smooth surface and the experimental results. The results revealed that the surface roughness plays a key role in nanoindentation of thin films, especially at low indentation depths. There was good compatibility between the results of finite-element simulation on the rough surface and those of experiments. It is observed that on rough films, at low indentation depths, the geometry of the location where the nanoindentation is performed is of major importance.

Analysis of Tank Car Deformations Using Multibody Systems and Finite Element Algorithms

2015 ◽  
Author(s):  
Liang Wang ◽  
Huailong Shi ◽  
Ahmed A. Shabana
Keyword(s):  
Finite Element ◽  
Plate Thickness ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Railroad Vehicles ◽  
Contact Formulation ◽  
Triangular Shell Element ◽  
Railroad Vehicle ◽  
Strong Dynamic

This investigation demonstrates the effect of the tank flexibility and plate thickness on the wheel/rail contact and the nonlinear dynamic behavior of railroad vehicles. To this end, a flexible tank is modeled using the finite element (FE) floating frame of reference formulation (FFR). The tank car finite element model is integrated with a three-dimensional railroad vehicle using computational non-linear multibody system (MBS) framework in which the wheel/rail interaction is formulated using a three-dimensional elastic contact formulation that allows for the wheel/rail separation. A triangular shell element is used to build the tank car and describe its deformation, The effect of the coupling between different modes of displacements is demonstrated by comparing the results of the simulations of the flexible and rigid tank car models. It is shown that there is a strong dynamic coupling between different modes of displacements of the tank car, the plate thickness, and the wheel/rail contact parameters. The effect of the flexibility and plate thickness of the tank car on the vehicle critical speed and dynamic characteristics are also examined.

Nonlinear Analysis of Twisted Wind Turbine Blade

2016 ◽  
Vol 34 (3) ◽  
pp. 269-278 ◽  
Author(s):  
M. Yangui ◽  
S. Bouaziz ◽  
M. Taktak ◽  
M. Haddar ◽  
A. El-Sabbagh
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Rotation Speed ◽  
Three Dimensional ◽  
Nonlinear Problems ◽  
Shell Element ◽  
Element Model ◽  
Angular Rotation ◽  
Triangular Shell Element

AbstractModal analysis is developed in this paper in order to study the dynamic characteristics of rotating segmented blades assembled with spar. Accordingly, a three dimensional finite element model was built using the three node triangular shell element DKT18, which has six degrees of freedom, to model the blade and the spar structures. This study covers the effect of rotation speed and geometrically nonlinear problems on the vibration characteristics of rotating blade with various pretwist angles. Likewise, the effect of the spar in the blade is taken into consideration. The equation of motion for the finite element model is derived by using Hamilton's principle, while the resulting nonlinear equilibrium equation is solved by applying the Newmark method combined with the Newton Raphson schema. Results show that the natural frequencies increase by taking account of the spar, they are also proportional to the angular rotation speed and influenced by geometric nonlinearity and pretwist angle.

Mixed-dimensional coupling modeling for laser forming process

2014 ◽  
Vol 228 (16) ◽  
pp. 2950-2959
Author(s):  
Hong Shen ◽  
Jun Hu ◽  
Zhenqiang Yao
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Thermomechanical Analysis ◽  
Coupling Method ◽  
Computational Time ◽  
Laser Forming ◽  
Forming Process ◽  
Shell Elements

Efficient laser forming modeling for industrial application is still in the developing stage and many researchers are in the process of modifying it. Conventional three-dimensional finite element models are still expensive on computational time. In this paper, a finite element model adopting a shell-solid coupling technique is developed for the thermomechanical analysis of laser forming process. In the shell-solid coupling method, an additional shell element plane is utilized to transfer heat flux and displacement from the solid elements to the shell elements. The effects of the additional interface shell element thickness on temperature distribution and final distortion are investigated. The presented shell-solid coupling method is evaluated by the results of three-dimensional simulations and experimental data.

Finite Element Modeling of Hybrid Friction Diffusion Welding of Tube–Tubesheet Joints

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Fadi Al-Badour
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Three Dimensional ◽  
Infrared Camera ◽  
Element Model ◽  
Optical Microscope ◽  
Steel Tube ◽  
Diffusion Welding ◽  
Temperature Dependent ◽  
Mechanical Nature

Abstract A three-dimensional thermo-mechanical finite element model (FEM) was developed and solved to study the feasibility of hybrid friction diffusion bonding (HFDB) technique for welding tube–tubesheet joints using Abaqus/explicit enviroment. Considering the process thermo-mechanical nature, temperature-dependent material properties and Johnson–Cook model were adopted. Two tube configurations were considered in the numerical study; zero projection (flush) and 3 mm projection (extended). For validation purposes, HFDB of tube–tubesheet was experimentally performed on a 19 mm (¾ in.) ASTM 179 cold-drawn carbon steel tube into ASTM A516-70 tubesheet, considering a flush tube configuration. The tool–workpiece temperature was measured using infrared camera, and produced joints were sectioned and examined under optical microscope. A good agreement was found between numericaly estimated temperatures and material deformation with experimentaly measured ones. According to the estimated results, spring back of tube was found to negatively affect the joint integrity. Also, contact stresses during processing phase were found less in the projected tube (extended) as compared to the flush one.

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