Comparative Study of the Shock Resistance of Rubber Protective Coatings Subjected to Underwater Explosion

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Feng Xiao ◽  
Yong Chen ◽  
Hongxing Hua
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Protective Coatings ◽  
Dynamic Compression ◽  
Reaction Force ◽  
Compressive Load ◽  
Underwater Explosion ◽  
Finite Element Simulations ◽  
Compression Load ◽  
Shock Resistance

Finite element simulations of rubber protective coatings with different structures under two dynamic loading cases were performed. They were monolithic coating and honeycomb structures with three different cell topologies (hexachiral honeycomb, reentrant honeycomb, and circular honeycomb). The two loading cases were a dynamic compression load and water blast shock wave. The dynamic mechanical responses of those coatings under these two loading cases were compared. Finite element simulations have been undertaken using the ABAQUS/Explicit software package to provide insights into the coating's working mechanism and the relation between compression behavior and water blast shock resistance. The rubber materials were modeled as hyperelastic materials. The reaction force was selected as the major comparative criterion. It is concluded that when under dynamic compressive load, the cell topology played an important role at high speed, and when under underwater explosion, the honeycomb coatings can improve the shock resistance significantly at the initial stage. For honeycomb coatings with a given relative density, although structural absorbed energy has a significant contribution in the shock resistance, soft coating can significantly reduce the total incident impulse at the initial fluid-structure interaction stage. Further, a smaller fraction of incident impulse is imparted to the honeycomb coating with lower compressive strength.

scholarly journals Free Vibration Exploration of Rotating FGM Porosity Beams under Axial Load considering the Initial Geometrical Imperfection

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Nguyen Thi Giang
Keyword(s):  
Finite Element ◽  
Compressive Load ◽  
Shear Deformation Theory ◽  
Parameter Study ◽  
Compression Load ◽  
Large Structures ◽  
Geometrical Imperfection ◽  
Compressive Loads ◽  
Vibration Responses ◽  
Sine Functions

In practice, some components in large structures such as the connecting rods between the rotating parts in the engines, turbines, and so on, can model as beam structures rotating around the fixed axis and subject to the axial compression load; therefore, the study of mechanical behavior to these structures has a significant meaning in practice. This paper analyzes the vibration responses of rotating FGM beams subjected to axial compressive loads, in which the beam is resting on the two-parameter elastic foundation, taking into account the initial geometrical imperfection. Finite element formulations are established by using the new shear deformation theory type of hyperbolic sine functions and the finite element method. The materials are assumed to be varied smoothly in the thickness direction of the beam based on the power-law function with the porosity. Verification problems are conducted to evaluate the accuracy of the theory, proposed mechanical structures, and the calculation programs coded in the MATLAB environment. Then, a parameter study is carried to explore the effects of geometrical and material properties on the vibration behavior of FGM beams, especially the influences of the rotational speed and axial compressive load.

Shock-Resistance Research of Ship Structural Subjected to Underwater Explosion

2014 ◽  
Vol 945-949 ◽  
pp. 1180-1184
Author(s):  
Yao Guo Xie
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cross Section ◽  
Critical Radius ◽  
Underwater Explosion ◽  
Element Model ◽  
Current Standard ◽  
Envelope Analysis ◽  
Shock Resistance ◽  
Selection Of

A finite element model ships, for example design test condition of the underwater explosion, selection of explosive package quantity is 1000KG TNT, the explosive location along the direction of the ship with the bow, midship and stern, the angle of attack in three exploded cross section have 90 degrees, 60 degrees, 45 degrees, 30 degrees and 0 degrees. According to the current standard to calculate the ship damage radius, critical radius and safety radius of specific values under the effect of underwater explosion, interpolation calculation and draw the envelope. Analysis shows that the vitality of ships and shock-resistance is not only related to the explosive distance, also related to the attack position.

Three-Dimensional Finite Element Simulations of Ground Vibration Generated by High-Speed Trains and Engineering Countermeasures

2005 ◽  
Vol 11 (12) ◽  
pp. 1437-1453 ◽  
Author(s):  
Judith C. Wang ◽  
Xiangwu Zeng ◽  
Robert L. Mullen
Keyword(s):  
Finite Element ◽  
Asphalt Concrete ◽  
High Speed ◽  
Three Dimensional ◽  
Ground Vibration ◽  
Finite Element Simulations ◽  
Modified Asphalt ◽  
Vibration Attenuation ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this paper we discuss the benefits of using rubber-modified asphalt concrete in high-speed railway foundations. We present the results from a series of three-dimensional finite element simulations modeling a high-speed train foundation utilizing various trackbed materials. Four trackbed materials were tested for their relative vibration attenuation capacities: ballast, concrete, conventional asphalt concrete, and rubber-modified asphalt concrete. Additionally, studies varying the speed and the weight of the passing train were performed. Parametric studies varying the dimensions of the trackbed underlayment were also examined. From these numerical simulations, it is shown that rubber-modified asphalt concrete outperforms other traditional paving materials in ground vibration attenuation. It is also shown that the speeds and weights of the passing trains and the dimensions of the trackbed have significant effects on the relative performance of the paving materials. Implications for design are discussed.

scholarly journals Evaluation of a Kinematically-Driven Finite Element Footstrike Model

2016 ◽  
Vol 32 (3) ◽  
pp. 301-305 ◽  
Author(s):  
Iain Hannah ◽  
Andy Harland ◽  
Dan Price ◽  
Heiko Schlarb ◽  
Tim Lucas
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Element Model ◽  
Mechanical Tests ◽  
Vertical Ground Reaction Force ◽  
Dynamic Finite Element ◽  
Tetrahedral Elements ◽  
Vertical Ground

A dynamic finite element model of a shod running footstrike was developed and driven with 6 degree of freedom foot segment kinematics determined from a motion capture running trial. Quadratic tetrahedral elements were used to mesh the footwear components with material models determined from appropriate mechanical tests. Model outputs were compared with experimental high-speed video (HSV) footage, vertical ground reaction force (GRF), and center of pressure (COP) excursion to determine whether such an approach is appropriate for the development of athletic footwear. Although unquantified, good visual agreement to the HSV footage was observed but significant discrepancies were found between the model and experimental GRF and COP readings (9% and 61% of model readings outside of the mean experimental reading ± 2 standard deviations, respectively). Model output was also found to be highly sensitive to input kinematics with a 120% increase in maximum GRF observed when translating the force platform 2 mm vertically. While representing an alternative approach to existing dynamic finite element footstrike models, loading highly representative of an experimental trial was not found to be achievable when employing exclusively kinematic boundary conditions. This significantly limits the usefulness of employing such an approach in the footwear development process.

Electromagnetic Sheet Bulging: Analysis of Process Parameters by FE Simulations

2013 ◽  
Vol 554-557 ◽  
pp. 741-748 ◽  
Author(s):  
Joao Pedro M. Correia ◽  
Saïd Ahzi
Keyword(s):  
Finite Element ◽  
Process Parameters ◽  
High Speed ◽  
Finite Element Simulations ◽  
Electromagnetic Forming ◽  
Forming Process ◽  
High Speed Forming ◽  
Bulging Test ◽  
High Repeatability

Electromagnetic forming is a non-conventional forming process and is classified as a high-speed forming process. It provides certain advantages as compared to conventional forming processes: improved formability, high repeatability and productivity, reduction in tooling cost and reduction of springback and of wrinkling. However, various process parameters affect the performance of the electromagnetic forming system. Finite element simulations are very useful to optimize a process because they can reduce time and costs. With the aim of investigating the effects of the process parameters on the deformed blank geometry, finite element simulations of an electromagnetic sheet bulging test have been performed in this work. Furthermore the role of first impulse of discharged current is also investigated.

scholarly journals Crushing Behavior of Thin-Walled Hexagonal Tubes with Partition Plates

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Dai-Heng Chen ◽  
Kenichi Masuda
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Axial Compression ◽  
Compressive Load ◽  
Full Length ◽  
Compression Load ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Crushing Behavior ◽  
Element Method

The crushing behaviour of hexagonal thin-walled tube with partition plates subjected to axial compression is studied by using finite element method. It is found that, in the crushing process, the folds, which generate along the full length of the tube, come to be crushed simultaneously and the compressive load will not descend, since the compressive load produced in the central part does not descend with the folds forming on outer walls. Therefore, in order to suppress a fluctuation of the compression load in crushing of the tube and to raise its average compression load, it is an effective method to introduce corner parts, especially corner parts where three plates intersect, in the geometry of the thin-walled tube.

The Application of CEL Technique to Simulate the Behavior of an Underwater Explosion Bubble in the Vicinity of a Rigid Wall

2020 ◽  
Vol 902 ◽  
pp. 126-139
Author(s):  
Anh Tu Nguyen
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Bubble Dynamics ◽  
Underwater Explosion ◽  
Flow Simulation ◽  
Rigid Wall ◽  
Water Jet ◽  
Complex Structures ◽  
Explicit Finite Element ◽  
Jet Impact

The dynamic process of an underwater explosion (UNDEX) is a complex phenomenon that involves several facets. After detonation, the shockwave radially propagates at a high speed and strikes nearby structures. Subsequently, bubble oscillation may substantially damage the structures because of the whipping effect, water jet impact, and bubble pulse. This paper presents an application of explicit finite element analyses to simulate the process of an UNDEX bubble in the vicinity of rigid wall, in which the coupled Eulerian-Lagrangian (CEL) approach was developed to overcome the difficulties regarding the classical finite element method (FEM), large deformations, and flow simulation of fluid and gas. The results demonstrate that the method is well suited to manage the UNDEX bubble problem and can be used to model the major features of the bubble dynamics. Furthermore, the behavior of an UNDEX bubble near a rigid wall was also examined in the present study, which showed that the migration of the bubble and the development of the water jet are influenced strongly by the standoff distance between the initial bubble position and the wall. This method can be used in future studies to examine UNDEX bubbles in the vicinity of deformable and complex structures.

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