A FINITE ELEMENT MODEL FOR COMPRESSIVE ICE LOADS BASED ON A MOHR-COULOMB MATERIAL AND THE NODE SPLITTING TECHNIQUE

2021 ◽  
pp. 1-33
Author(s):  
Hauke Herrnring ◽  
Søren Ehlers
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Material Behavior ◽  
Double Pendulum ◽  
Strain Rates ◽  
Splitting Technique ◽  
Structure Interaction ◽  
Node Splitting ◽  
Brittle Mode

Abstract This paper presents a finite element model for the simulation of ice-structure interaction problems, which are dominated by crushing. The failure mode of ice depends significantly on the strain rate. At low strain rates the ice behaves ductile, whereas at high strain rates ice reacts in brittle mode. This paper focuses on the brittle mode, which is the dominating mode for ship-ice interactions. A multitude of numerical approaches for the simulation of ice can be found in the literature. Nevertheless, the literature approaches do not seem suitable for the simulation of continuous ice-structure interaction processes at low and high confinement ratios in brittle mode. Therefore, this paper seeks to simulate the ice-structure interaction with the finite element method (FEM). The objective of the here introduced Mohr-Coulomb Nodal Split (MCNS) model is to represent the essential material behavior of ice in an efficient formulation. To preserve mass and energy as much as possible, the node splitting technique is applied, instead of the frequently used element erosion technique. The intention of the presented model is not to reproduce individual cracks with high accuracy, because this is not possible with a reasonable element size, due to the large number of crack fronts forming during the ice-structure interaction process. To validate the findings of the model, the simulated maximum ice forces and contact pressures are compared with ice-extrusion and double pendulum tests. During validation, the MCNS model shows a very good agreement with these experimental values.

A Finite Element Model for Compressive Ice Loads Based on a Mohr-Coulomb Material and the Node Splitting Technique

2021 ◽  
Author(s):  
Hauke Herrnring ◽  
Sören Ehlers
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Material Behavior ◽  
Fe Method ◽  
Splitting Technique ◽  
Structure Interaction ◽  
Node Splitting ◽  
Element Erosion ◽  
Brittle Mode

Abstract This paper presents a finite element model for the simulation of ice-structure interaction problems, which are dominated by crushing at low and medium confinement ratios. The failure mode of ice depends significantly on the strain rate. At very low impact velocities the ice behaves ductile, whereas at high velocities the ice reacts in brittle mode. This paper focuses on the brittle mode, which is the dominating mode for ship-ice interactions. A multitude of numerical approaches for the simulation of ice can be found in the literature. Nevertheless, the literature approaches do not seem suitable for the simulation of continuous ice-structure interaction processes at low and medium confinement ratios in brittle mode. Therefore, this paper seeks to simulate the ice-structure interaction with the FE method. To preserve mass and energy as much as possible, the node splitting technique is applied, instead of the often used element erosion technique. The intention of the presented model is not to reproduce individual cracks with high accuracy, because this is not possible with a reasonable element size, due to the large number of crack fronts forming during the ice-structure interaction process. The objective of the here introduced Mohr-Coulomb Nodal Split (MCNS) model is to represent the essential material behavior of ice in a efficient formulation. To validate the findings of the model, the simulated maximum ice forces and contact pressures are compared with experiments.

Hydroelastic Modal Analysis of the Perforated Cylindrical Shell in SMART

2011 ◽  
Author(s):  
Youngin Choi ◽  
Seungho Lim ◽  
Kyoung-Su Park ◽  
No-Cheol Park ◽  
Young-Pil Park ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Element Model ◽  
Mode Shapes ◽  
Steam Generators ◽  
Structure Interaction ◽  
The Finite Element Model ◽  
Reactor Internals

The System-integrated Modular Advanced ReacTor (SMART) developed by KAERI includes components like a core, steam generators, coolant pumps, and a pressurizer inside the reactor vessel. Though the integrated structure improves the safety of the reactor, it can be excited by an earthquake and pump pulsations. It is important to identify dynamic characteristics of the reactor internals considering fluid-structure interaction caused by inner coolant for preventing damage from the excitations. Thus, the finite element model is constructed to identify dynamic characteristics and natural frequencies and mode shapes are extracted from this finite element model.

Crystallographic effects during micromachining — A finite-element model

2015 ◽  
Vol 29 (22) ◽  
pp. 1550119
Author(s):  
Shin-Hyung Song ◽  
Woo Chun Choi
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Chip Formation ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Material Behavior ◽  
Face Centered Cubic ◽  
Work Material ◽  
User Material Subroutine ◽  
Crystallographic Orientations

Mechanical micromachining is a powerful and effective way for manufacturing small sized machine parts. Even though the micromachining process is similar to the traditional machining, the material behavior during the process is much different. In particular, many researchers report that the basic mechanics of the work material is affected by microstructures and their crystallographic orientations. For example, crystallographic orientations of the work material have significant influence on force response, chip formation and surface finish. In order to thoroughly understand the effect of crystallographic orientations on the micromachining process, finite-element model (FEM) simulating orthogonal cutting process of single crystallographic material was presented. For modeling the work material, rate sensitive single crystal plasticity of face-centered cubic (FCC) crystal was implemented. For the chip formation during the simulation, element deletion technique was used. The simulation model is developed using ABAQUS/explicit with user material subroutine via user material subroutine (VUMAT). Simulations showed that variation of the specific cutting energy at different crystallographic orientations of work material shows significant anisotropy. The developed FEM model can be a useful prediction tool of micromachining of crystalline materials.

Bodner-Partom Constitutive Model and Nonlinear Finite Element Analysis

1990 ◽  
Vol 112 (3) ◽  
pp. 287-291 ◽  
Author(s):  
F. A. Kolkailah ◽  
A. J. McPhate
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Plastic Strain ◽  
Constitutive Model ◽  
Finite Element Model ◽  
Numerical Technique ◽  
Element Model ◽  
Material Behavior ◽  
Model Parameters ◽  
Elastic Plastic

In this paper, results from an elastic-plastic finite-element model incorporating the Bodner-Partom model of nonlinear time-dependent material behavior are presented. The parameters in the constitutive model are computed from a leastsquare fit to experimental data obtained from uniaxial stress-strain and creep tests at 650°C. The finite element model of a double-notched specimen is employed to determine the value of the elastic-plastic strain and is compared to experimental data. The constitutive model parameters evaluated in this paper are found to be in good agreement with those obtained by the other investigators. However, the parameters determined by the numerical technique tend to give response that agree with the data better than do graphically determined parameters previously used. The calculated elastic-plastic strain from the model agreed well with the experimental strain.

Strength Analyses of Sandwich Pipes for Ultra Deepwaters

2004 ◽  
Vol 72 (4) ◽  
pp. 599-608 ◽  
Author(s):  
Segen Farid Estefen ◽  
Theodoro Antoun Netto ◽  
Ilson Paranhos Pasqualino
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Ultimate Strength ◽  
Thermal Insulation ◽  
Research Work ◽  
Element Model ◽  
Material Behavior ◽  
Core Material ◽  
Small Scale ◽  
Mechanical Resistance

Design requirements for pipelines regarding both ultimate strength and flow assurance in ultra deepwater scenarios motivated the development of a new sandwich pipe which is able to combine high structural and thermal insulation properties. In this concept, the annulus is filled with low cost materials with adequate thermal insulation properties and good mechanical resistance. The aim of this research work is to perform small-scale laboratorial tests and to develop a finite element model to evaluate the structural performance of such sandwich pipes with two different options of core material. After calibrated in view of the experimental results, a three-dimensional finite element model incorporating nonlinear geometric and material behavior is employed to perform strength analyses of sandwich pipes under combined external pressure and longitudinal bending. Ultimate strength envelopes for sandwich pipes are compared with those generated for single-wall steel pipes with equivalent collapse pressures. The study shows that sandwich pipe systems with either cement or polypropylene cores are feasible options for ultra deepwater applications.

Long-Span Reinforced Steel Box Culverts

1998 ◽  
Vol 1624 (1) ◽  
pp. 184-195 ◽  
Author(s):  
Thomas C. McCavour ◽  
Peter M. Byrne ◽  
Timothy D. Morrison
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Plate Thickness ◽  
Metal Structure ◽  
Element Model ◽  
Structure Interaction ◽  
Long Span ◽  
Box Culverts ◽  
Reinforced Steel ◽  
Soil Metal

A comprehensive investigation of soil–metal structure interaction for long-span deep-corrugated reinforced steel box culverts was carried out in a project sponsored by the National Research Council of Canada in 1996. Two 12-m span box culverts were erected at a Dorchester, New Brunswick, test site using two backfill densities, one structural steel plate thickness, and a minimum cover of 300 mm. These structures are the largest steel box culverts erected to date. One structure was reinforced using continuous deep-corrugated crown stiffeners, and the other was intermittently reinforced using composite concrete metal-encased stiffeners. Strain and deflection of the structure were monitored in response to static axle loads positioned at six locations on the test surface. A finite element model was then used in numerical simulations of the soil–metal structure system. The measured culvert response was then compared with results from the finite element model. A nonlinear soil-structure interaction program (NLSSIP) was used to analyze the two long-span box culverts. NLSSIP was developed specifically for long-span soil–metal culverts and has been used for structures with and without stiffeners. The box culvert test provided a definitive relationship between soil stiffness and metal structure stiffness. The test was the first that evaluated intermittently reinforced composite concrete metal-encased stiffeners relative to conventional continuous reinforcement. The performance of the two types of stiffeners is evaluated and recommendations are made for future design and installation of long-span deep-corrugated steel box culverts.

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