Numerical Simulation and Experimental Study of Flowfield Around a Bullet With a Partial Core

2011 ◽  
Vol 78 (5) ◽  
Author(s):  
Usiel S. Silva ◽  
Juan M. Sandoval ◽  
Luis A. Flores ◽  
Narcizo Muñoz ◽  
Víctor Hernández
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Impact Force ◽  
Fluid Dynamic ◽  
Flight Path ◽  
Post Processing ◽  
Flow Conditions ◽  
Main Factors ◽  
The Impact ◽  
Full Core

The geometry, density and velocity of a typical small caliber bullet, are the main factors that stabilize its flight path, range and the impact force; thus the weight variations can indicate the presence of geometrical irregularities or damages of the bullet core, affecting its dynamic characteristics. Computational finite element method (FEM) with the computational fluid dynamic (CFD) module was used for the numerical simulation of 7.62 mm bullets with partial core, subjected to different air flow conditions. Schlieren images were obtained and with the flow visualization principle, the behavior of the projectile during its flight path was determined. The results of the simulations and the experiments showed that in certain cases, bullets with partial core maintain a stable spin during flight without a considerable variation in its range, keeping constant speed conditions with respect to the full core bullets. The importance of this analysis is found in the fact that post processing activities can be implemented in certain ammunitions with imperfections to improve their use.

Revealing Mechanical Strength of Nanopores Using Atomic Finite Element Techniques

2018 ◽  
Vol 934 ◽  
pp. 24-29
Author(s):  
Prapasiri Pongprayoon ◽  
Attaphon Chaimanatsakun
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Fluid Flow ◽  
Mechanical Strength ◽  
Impact Force ◽  
Pore Surface ◽  
Vertical Rectangle ◽  
The Impact ◽  
Graphene Nanopore

Graphene nanopore has been widely employed in nanofilter or nanopore devices due to its outstanding properties. The understanding of its mechanical properties at nanoscale is crucial for device improvement. In this work, the mechanical properties of graphene nanopore is thus investigated using atomistic finite element method (AFEM). Four graphene models with different pore shapes (circular (CR), horizontal rectangle (RH), and vertical rectangle (RV)) in sub-nm size which could be successfully fabricated experimentally have been studied here. The force normal to a pore surface is applied to mimic the impact force due to a fluid flow. Increasing pore size results in the reduction in its strength. Comparing among different pore shapes with comparable sizes, the order of pore strength is CR>RH>RV>SQ. In addition, we observe that the direction of pore alignment and geometries of pore edge also play a key role in mechanical strength of nanopores.

Kinematic Formulation of Mooring Platform During Collisions Based on Multi-Body Dynamic Theory

2018 ◽  
Author(s):  
Qiuwan Duan ◽  
Yang Yang
Keyword(s):  
Finite Element Method ◽  
Impact Force ◽  
Dynamic Theory ◽  
Kinematics Analysis ◽  
Body Dynamics ◽  
Load Analysis ◽  
Multi Body ◽  
The Impact ◽  
Analytical Expressions ◽  
Body Dynamic

When a platform is operating in a mooring, various vessels that frequently pass by result in severe accidental collisions of the platform. Thus, the kinematic response of the mooring platform should be investigated. A new analytical method, including a load analysis and kinematics analysis, is proposed in this paper. In the load analysis, the impact force is calculated using finite element method (FEM). In the kinematic analysis, closed-form analytical expressions based on multi-body dynamics are derived with the impact force as an input. Furthermore, the expressions are improved considering the fluid effect. A series of collision cases are implemented to validate the proposed method by FEM. The kinematic results solved by the proposed method agree well with FEM, which illustrates that the method is feasible and accurate. However, the proposed method taking around 30s, which is much shorter than 7200s by FEM, is proved to be more efficient.

Study on the Downburst Field Characteristics under the Influence of Two-Dimensional Continuous Mountains at Different Distance

2014 ◽  
Vol 580-583 ◽  
pp. 3111-3114
Author(s):  
Yi Sun ◽  
Yuan Ze Wu ◽  
Hai Tao Shi ◽  
Bai Feng Ji
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Wind Field ◽  
Strong Wind ◽  
Two Dimensional ◽  
Field Characteristic ◽  
Main Factors ◽  
Cfd Numerical Simulation ◽  
The Impact

Downburst is an outburst strong wind on or near the ground, and its wind field characteristics are significantly different from boundary layer winds. Continuous mountains at different distance are one of the main factors for the influence of downburst wind field characteristic. In this thesis, the changes of the wind field characteristics under the influence of continuous mountains at different distance after the downburst happened are studied by CFD numerical simulation. The impact of downburst is analysed and summarized through the charts.

Numerical Simulation Analysis of Collision between Ship and Steel Sheet Pile Quay-Wall

2015 ◽  
Vol 744-746 ◽  
pp. 1175-1179 ◽  
Author(s):  
Peng Liu ◽  
Hong Wang ◽  
Chao Zhu
Keyword(s):  
Numerical Simulation ◽  
Steel Sheet ◽  
Impact Force ◽  
Simulation Analysis ◽  
Sheet Pile ◽  
Time Curve ◽  
Finite Element Software ◽  
Quay Wall ◽  
Force Time ◽  
The Impact

The impact process of 50000t ship and steel sheet pile bulkhead is simulated by finite element software ANSYS/LS-DYNA. This article acquires the impact force-time curve, equivalent force-time curve of steel sheet pile and the pressure-time curve of breast wall. Comparing the impact force of numerical simulation with the result of ship-bridge collision specifications, and general rules and characteristics are obtained. At the same time, put forward some measures to prevent the damage of wharf structure under the ship of large velocity impact, which provide theoretical references during the design, maintenance, and transformation of similar wharf.

Adaptive FE-Meshfree-Modelling for Impacts of Liquid Filled Vessels on Thin Walled Structures

2003 ◽  
Author(s):  
Stefan Hiermaier ◽  
Martin Sauer
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
World Trade ◽  
Fluid Dynamic ◽  
World Trade Center ◽  
Meshfree Methods ◽  
Trade Center ◽  
Thin Walled ◽  
Break Up ◽  
The Impact

A principal approach to simulate the airplane impact and the collapse of World Trade Center North Tower has been shown by Quan and Birnbaum [4]. Using the general purpose hydrocode AUTODYN the impact damage, fire induced strength reduction and progressive collapse were investigated. Both for the fuel propagation after tank break up and the thermodynamic burn processes assumptions have been taken. It is the aim of this paper to focus on the numerical aspects of simulating the fluid propagation after vessel break up. The release of a fluid out of a broken vessel after impact is not easily represented in a numerical simulation as the fluid flow and its interaction with structures can not be modelled using Lagrangian type element formulations. These elements, typically applied for structural analyses, fail under massive deformation and usually need then to be taken out of the simulation. Typical fluid dynamic discretization methods, so called Eulerian grids, would have to cover the whole space potentially being reached by the fluid flow and are therefore inefficient in a large three dimensional simulation. As an alternative method a coupled discretization using Lagrange elements and Lagrange type meshfree methods is proposed here. Meshfree methods have been introduced to structural dynamics more then ten years ago specifically to simulate processes including large deformation [1]. Originally developed as pure meshfree code, the EMI SOPHIA [3] provides now a new form of adaptivity that allows for more efficiency and accuracy. This is achieved by the use of finite elements as long as deformation is capable for the elements. At definable strain or failure thresholds any element can be transformed into one or more meshfree particles. This way, mass and volume of the original elements are conserved. As the particles interact with each other as well as with the remaining elements, all physical processes can be modelled continuously. The purpose of this study was to contribute to numerical simulation of the airplane impacts into the World Trade Center. It includes impact simulations of cylindrical vessels filled with water against thin walled rectangular shaped bars. It shows that coupled discretizations and specifically an adaptive FE-meshfree discretization offer the flexibility needed to gain both accuracy and efficiency in the simulation.

scholarly journals Theoretical Analysis of Rockfall Impacts on the Soil Cushion Layer of Protective Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Xing Wang ◽  
Yongxu Xia ◽  
Tianyue Zhou
Keyword(s):  
Numerical Simulation ◽  
Energy Conservation ◽  
Penetration Depth ◽  
Impact Force ◽  
Theoretical Method ◽  
Cavity Expansion ◽  
Rockfall Hazards ◽  
Protective Structures ◽  
Cushion Layer ◽  
The Impact

During the Wenchuan Earthquake, with a magnitude of 5.12, collapses and rockfall hazards persisted for a long time after the initial investigations carried out by research fellow S. M. He and his team at the scene of the disaster in October 2008. It is possible that additional incidents of rockfalls in large quantities may continue in the same areas over the next ten to fifteen years. Furthermore, in the vast mountainous region of western China, the topographic relief is evident, and earthquakes occur frequently. Therefore, it is difficult to effectively defend against rockfall hazards. When designing protective structures, the key issue is the analysis of the mechanical response mechanism of the soil cushion layer of the upper cushion when subjected to the impact of rockfall. As such, a theoretical method was used to perform such an analysis. The cavity expansion and energy conservation model were adopted. Analytical solutions for the impact force and penetration depth were then derived. Furthermore, the impact force and penetration depth of rockfall were studied with the LS-DYNA software to obtain values for the impact forces and the penetration depth. Finally, the reliability of the theoretical method was evaluated using the cavity expansion, energy conservation, numerical simulation, Hertz, Japanese, Swiss, Australian, B. S. Guan, tunnel manual, and subgrade methods based on an engineering model. The results show that the cavity expansion and the energy conservation methods yielded consistent results. Meanwhile, the cavity expansion and the energy conservation methods also yielded consistent results with the numerical simulation, Japanese (obtained by laboratory experiment), Swiss (obtained by laboratory experiment), and Australian (obtained by field experiment) methods. The relevant methods and conclusions shall therefore be applied to the design of rockfall protection structure in future investigations.

scholarly journals Numerical Investigation on Dynamic Response of RC T-Beams Strengthened with CFRP under Impact Loading

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 890
Author(s):  
Huiling Zhao ◽  
Xiangqing Kong ◽  
Ying Fu ◽  
Yihan Gu ◽  
Xuezhi Wang
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Reaction Force ◽  
Impact Resistance ◽  
Structural Response ◽  
Element Model ◽  
Strengthening Effect ◽  
Strengthened Beam ◽  
Simulation Results ◽  
The Impact

To precisely evaluate the retrofitting effectiveness of Carbon Fiber Reinforced Plastic (CFRP) sheets on the impact response of reinforced concrete (RC) T-beams, a non-linear finite element model was developed to simulate the structural response of T-beams with CFRP under impact loads. The numerical model was firstly verified by comparing the numerical simulation results with the experimental data, i.e., impact force, reaction force, and mid-span displacement. The strengthening effect of CFRP was analyzed from the section damage evaluation. Then the impact force, mid-span displacement, and failure mode of CFRP-strengthened RC T-beams were studied in comparison with those of un-strengthened T-beams. In addition, the influence of the impact resistance of T-beams strengthened with FRP was investigated in terms of CFRP strengthening mode, CFRP strengthening sizes, CFRP layers and FRP material types. The numerical simulation results indicate that the overall stiffness of the T-beams was improved significantly due to external CFRP strips. Compared with the un-strengthened beam, the maximum mid-span displacement of the CFRP-strengthened beam was reduced by 7.9%. Additionally, the sectional damage factors of the whole span of the CFRP-strengthened beam were reduced to less than 0.3, indicating that the impact resistance of the T-beams was effectively enhanced.

Design of Experiment, Approximate Model and Optimization of a Muzzle Brake

2011 ◽  
Vol 295-297 ◽  
pp. 2563-2567
Author(s):  
Kun Jiang ◽  
Hao Wang
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Latin Hypercube Sampling ◽  
Approximate Model ◽  
Shape Parameters ◽  
Analysis Process ◽  
Surface Method ◽  
Brake Performance ◽  
Set Up ◽  
The Impact

The approximate model of the muzzle brake performance was set up and evaluated to simplify the analysis process. LHS(Latin Hypercube Sampling) and numerical simulation of inviscid muzzle flow field were applied to obtain some samples of the muzzle brake performance. The performance was weighted with the impact force on the muzzle brake. Then RSM(Response Surface Method) was adopted to get the approximate model of the muzzle brake performance to establish a mapping of muzzle brake shape parameters and the impact force. In the end GA(Genetic Algorithm) was applied to perform the optimization of the muzzle brake shape parameters with the approximate model.

Numerical Simulation of Bird Strike Damage on Jet Engine Fan Blade

2004 ◽  
Author(s):  
Kazuo Shimamura ◽  
Tadashi Shibue ◽  
Donald J. Grosch
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Bird Strike ◽  
Soft Body ◽  
Jet Engine ◽  
Fan Blade ◽  
The Impact ◽  
Interaction Problem ◽  
Numerical Simulation Technique ◽  
Good Agreement

Aircraft jet engine should be designed to keep the required performance against for the event of foreign object ingestion, such as bird-strike. For the purpose to realize highly efficient and more advanced design of fan blade of jet engine, a numerical simulation technique for bird-strike problem has developed. Good agreement was obtained between simulation results and the soft body impact tests described in this paper. It was also shown that bird-strike problem has to be recognized as a fluid-structure interaction problem, because the impacted bird behaves like fluid and the impact force is highly influenced by the deformation of fan blade.

Spectral-Domain Based Impact Force Identification for Rod Structures

2013 ◽  
Author(s):  
Pooya Ghaderi ◽  
Steven I. Rich ◽  
Andrew J. Dick
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Impact Force ◽  
Force Identification ◽  
Identification Method ◽  
Spectral Finite Element Method ◽  
Spectral Finite Element ◽  
Rod Structures ◽  
The Impact ◽  
Element Method

Indirect impact force identification has attracted researchers due to the simplicity of indirect methods for calculating the applied force during the impact incident. In this paper, an impact force identification method for rod structures is proposed. The proposed method uses the spectral finite element method. The spectral finite element method is a frequency-based finite element method that takes advantage of the benefits of spectral methods and the simplicity of the finite element method. Using the frequency domain method for impact force identification simplifies the calculations and allows for the identification of impact forces with high frequency content, including MHz and above. The impact force identification method uses the collected data of the response of a section of the structure and utilizes the spectral finite element model of the structure to calculate the impact force. The results of the numerical study display strong agreement between the simulated impact force and the identified force. The performance of the force identification method is verified by applying it to experimental data collected from an impacted rod structure.

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