The Eulerian Abaqus method
The Eulerian method is a numerical technique used to analyze fluid mechanics problems. In this approach, the fluid is treated as a fixed grid, where the nodes remain stationary while the fluid flows through them. This method is particularly useful when dealing with problems that involve large deformations or high strain rates, as it can simulate fluid dynamics without causing mesh distortion. Eulerian Abaqus modeling is fully discussed here.
The Eulerian Abaqus method can be used to analyze fluid-structure interactions, such as the fluid impact on structures or the behavior of fluids in containers. To use the Eulerian method in Abaqus, the desired geometry must first be meshed using Eulerian elements. The material behavior of the fluid is then defined using appropriate equations of state. Finally, the boundary conditions and loading are applied, and the system is solved using the appropriate numerical method, such as the finite element method.
The Eulerian method is important because it provides an efficient way to simulate complex fluid dynamics problems without causing mesh distortion or element distortion, which can lead to inaccurate results. Additionally, it can be used to analyze a wide range of fluid-structure interactions, including those involving high-velocity impacts or explosive phenomena. By accurately predicting the behavior of fluids, the Eulerian Abaqus method can help improve the design and safety of structures that interact with fluids, such as pipelines, dams, and offshore platforms.
Workshop 1: Damage analysis of an underground box tunnel subjected to surface explosion
In recent times, the safety of tunnel structures has been significantly impacted by external terrorist activities due to the lack of adequate measures to detect such incidents in a timely manner and prevent them. To investigate the behavior of an underground box frame tunnel subjected to a surface explosion, a simulation was conducted using ABAQUS software. In this simulation, TNT waves were propagated through the air and soil using Explicit analysis, resulting in the creation of stress in the concrete tunnel.
Workshop 2: Damage mechanism and the response of reinforced concrete containment structure under internal explosion
It is imperative to construct and operate a reinforced concrete containment for nuclear power plants to safeguard both the population and environment against uncontrolled radioactive release during severe internal or external accidents like earthquakes, large fires, or jet aircraft impact, which may occur during the plant’s operational lifetime. Precisely determining the response of the reinforced concrete containment to blast loading parameters for a specific distance scale is essential. Most parameters for modeling the interactions of blast shock waves are available and have been extensively documented. This tutorial investigates the dynamic response and damage mechanism of the reinforced concrete containment under internal blast loading at varying distance scales. The extent of concrete cracking, the stress in steel bars and concrete after yielding, and deflections are presented as measures of the effects of an explosion inside the containment. This tutorial specifically examines a Abaqus CEL explosion within the RC Concrete vessel, and the volume fraction method has been implemented to model the Eulerian Abaqus explosion.
Workshop 3: Liquid storage tank dynamic analysis subjected to blast loading using coupled Euler–Lagrange method
The human civilization faces an increasing threat from terrorist attacks all around the world. Over the past 20 years, bomb explosions in crowded areas like business districts, underground railway stations, and busy roads have caused significant loss of life and property damage in various parts of the world. However, the blast response of many critical civil infrastructures still remains poorly understood due to the complex material behavior, loading, and nonlinearity involved. One such example of crucial civil infrastructure is liquid storage tanks, which are integral components of any society for storing water, milk, liquid petroleum, and chemicals in industries. A blast loading on these structures can lead to a crisis in water and milk supply, health hazards due to chemical spread, and fire hazards due to the spread of liquid fuel. Therefore, it is crucial to understand the dynamic behavior of liquid storage structures under blast loading through numerical simulations. This study presents 3D finite element simulations of a steel water storage tank for different tank aspect ratios using Abaqus software. The tutorial outlines the modeling procedure for a blast simulation over a water-filled tank, where the CONWEP procedure is implanted to model the blast effect. The water is modeled as an Eulerian Abaqus part to visualize its sloshing during the explosion, and the tank is modeled using shell elements.
Workshop 4: Tunnel dynamic analysis subjected to internal blast loading using the Abaqus CEL method
This tutorial uses the CEL method in Abaqus to explore the dynamic analysis of a soil tunnel subjected to internal blast loading. The concrete tunnel is modeled as a solid part, while the domain is represented by an Eulerian Abaqus part. Additionally, the TNT and soil are modeled as solid parts, while the wire part represents the beam.
Underground tunnels, including roadways, railways, utility lines, and water pipelines, are essential components of civil infrastructure. However, in recent decades, the threat of explosion incidents caused by terrorist activities within these tunnels has increased, posing a significant risk to human safety. Internal explosions in tunnels can be particularly dangerous due to the multiple reflections of the shock wave on the tunnel walls, causing channeling of the shock wave. To protect tunnels from such incidents, it is necessary to design them to withstand blast loading, which requires a thorough understanding of their response to such loading, both experimentally and numerically. The current study focuses on advanced numerical analysis of tunnels subjected to blast loading, with the aim of improving their safety and resilience against potential terrorist threats.
In this study, the materials used for the beams, soil, TNT, and concrete tunnel were selected based on their specific properties. The beams were made of steel with elastic-plastic behavior and a ductile damage criterion, while the soil was modeled with elastic and Mohr-Coulomb plasticity. The TNT was described using the JWL equation of state, and the concrete tunnel was modeled using the Johnson-Holmquist model due to the high pressure and potential for failure. A dynamic explicit procedure was considered appropriate for this type of analysis. General contact was used for all contacts in the domain, and an embedded region was used for the beams inside the concrete host. The volume fraction method was used to determine the location and amount of TNT in the Eulerian Abaqus model. Proper boundary conditions were assigned to the Eulerian domain and concrete tunnel. The mesh size had a significant effect on the results, and a smaller mesh size was deemed necessary.
Once the simulation is complete, all results, including variables such as concrete damage, stress, damage to beams, and strain, can be obtained.
Workshop 5: Water column collapsing simulation using the Eulerian Abaqus simulation
In this workshop, a dynamic fluid flow event involving large deformation is modeled using the pure Eulerian Abaqus analysis technique. The event involves the collapse of a water column under gravity load. To model the water and the domain, only one Eulerian part has been created. The dynamic explicit method is suitable for Eulerian Abaqus analysis, and due to the height of the column, geostatic stress has been applied to it.
workshop 6: 3D orthogonal simulation using CEL method
Most of the current finite element models for cutting are limited to the 2D plane strain orthogonal cutting configuration. While this is useful for studying the fundamental aspects of the process, it does not fully represent practical cutting operations. On the other hand, 3D models typically involve a 2D tool path with a non-straight cutting edge, and the step just after 2D orthogonal cutting, which is the 3D orthogonal cutting, is rarely addressed. Due to its high complexity and involvement of various phenomena, the process is primarily studied in orthogonal cutting to reduce the geometrical difficulties and number of degrees of freedom of the models. However, the physical coupled phenomena, such as large strains, strain rates, high temperatures and temperature gradients, and friction, must still be considered and addressed. This has led to numerous publications. To address this issue, this video introduces a 3D finite element Coupled Eulerian-Lagrangian (CEL) model for the simulation of orthogonal cutting.
The Johnson-Cook constitutive model, which is well-known in metal cutting modeling, is used to describe the behavior of the Ti6Al4V titanium alloy workpiece material. The Johnson-Cook material model is suitable for analyzing high strains with rapid loading speeds. In this study, the Johnson-Cook equation with temperature is considered. Dynamic Temp Explicit is a suitable method for this type of analysis, and the Volume Fraction method is used to define the initial volume of the workpiece.
workshop 7: FSW of two pieces of copper
This file includes a CAE file and a video that provides a step-by-step explanation of the Friction Stir Welding process. The Eulerian Abaqus element is used for two copper pieces, while the Lagrangian element is used for the tool. During the analysis, the temperature distribution in the two pieces can be observed.
Friction Stir Welding (FSW) is a joining process that involves the frictional heating and plastic deformation of two parts that are in contact with a non-consumable welding tool. Experiments for FSW can be time-consuming and expensive. To address these issues, numerical analysis has been increasingly used in recent years. Various simplified numerical models have been developed to better understand the complex thermo-mechanical phenomena associated with FSW.
Pakkaphon –
Hello, I have a question regarding Workshop 4 for dynamic analysis of a tunnel subjected to blast loading using the CEL method in Abaqus software. Do geometric parameters such as tunnel dimensions and wall thickness have an influence on the behavior and response of the structure to an explosion?
Experts Of CAE Assistant Group –
It is clear it does because it is a structural parameter and has effect on stiffness and the structural response