Simulation of one dimension shock initiation of condensed explosive by SPH method

2016 ◽  
Vol 33 (2) ◽  
Author(s):  
Gang Yang ◽  
Rangqi Liu ◽  
De'an Hu ◽  
Xu Han
Keyword(s):  
High Speed ◽  
Design Methodology ◽  
One Dimension ◽  
Condensed Explosive ◽  
Sph Method ◽  
Shock Initiation ◽  
Numerical Examples ◽  
Initiation Process ◽  
Alternative Method ◽  
The Impact

Purpose This paper aims to study the ability of SPH method in simulating shock initiation process. The initiation and subsequent explosion processes of condensed explosive involve high pressure propagation and material large deformation, which increase the simulation difficulty in using traditional mesh-based method. The study aims to take the SPH method as an alternative method to shock initiation simulation. Design/methodology/approach The SPH method combined with some correct aspects is applied to simulate the shock initiation process. The condensed explosive is ignited by the impact of high speed flyer. In order to avoid the non-physical penetration between particles of high velocity flyer and condensed explosive, a particle-to-particle contact algorithm is employed. After the ignition, the detonation process of condensed explosive is represented by the ignition and growth model. A modified SPH method based on Riemann-solver is applied to smooth the numerical oscillation at shock front. Two numerical examples are implemented to illustrate the capability of SPH method in shock initiation simulation. One is the interface velocity experiment of PBX-9501. Another is the plate push experiment of PBX-9502. Both of the examples include the shock initiation process of condensed explosive. Findings Numerical results show that the shock initiation process of condensed explosive can be well predicted by SPH method. The characteristics of detonation are captured in the simulation. The measured data in numerical examples are also in good agreement with the experimental data. Research limitations/implications Because of the research purpose is to study the ability of SPH for shock initiation simulation, only one-dimension numerical examples are discussed in the paper. Therefore, researchers are encouraged to extend and test the proposed method to two or three dimension shock initiation problems simulation. Originality/value This paper provides an alternative method for shock initiation simulation. The implemented method can overcome the weaknesses of traditional mesh based method in simulation of shock initiation problems.

scholarly journals Investigation of Shock Initiation in Covered Charges under Shock Wave and Fragment Impacts

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xingwang Chen ◽  
Jinxiang Wang ◽  
Kui Tang ◽  
Hongfei Wang ◽  
Yuanbo Li
Keyword(s):  
Shock Wave ◽  
Theoretical Model ◽  
Numerical Simulations ◽  
High Speed ◽  
Least Squares Method ◽  
Strong Shock ◽  
Protective Function ◽  
Shock Initiation ◽  
Metal Plates ◽  
The Impact

In the current work, a series of step-by-step research methods have been applied to address the damaging effects of near-field strong shock waves and high-speed fragments on covered charge. In the first step, the defects of covered plates due to high-speed fragments were simplified to penetrated notches, and then, these notches were used to evaluate the impact of shock wave loads on charges covered with metal plates. In the next step, we developed a theoretical model to take into account the shock initiation of charges covered with defected metal plates. Explosive initiation standards coupled with shock wave evolution characteristics were applied to specify the crucial conditions of explosive detonation. Finite element program, for instance, was applied for the simulation of shock initiation processes in pressed charges (when TNT was covered with a steel plate containing a penetrated notch), and then, numerical simulations were validated by experimental findings. Finally, the results obtained from the numerical simulations and theoretical model were applied to evaluate the impacts of shock wave intensity, the thickness of covered metal plate, and the geometrical features of penetrated notch on pressed charge shock initiation. The least squares method was applied to determine critical initiation criteria (n and K). Theoretical calculation results were found to be highly consistent with those obtained from numerical simulations, indicating that covered metal plates significantly contributed to charge protection. The results also revealed that notches could undermine the protective function of covered plates and the size and shape of notch significantly affected charge critical detonation distance. Critical detonation distances of noncontact explosions were found to be 25 and 81 mm for a 3 mm thick pressed TNT in the presence and absence of 45# steel-covered plate, respectively. According to the results, increase in the diameter of covered plates containing a cylindrical notch increased pressed TNT critical detonation distance. When dealing with a covered plate containing a normally reflected frustum notch, however, we figured out that any increase in normal reflection slope could decrease pressed TNT critical detonation distance.

Validation of SPH-FE Numerical Modeling of the Interaction between a High-Speed Water Jet and a PMMA Target by CEL Model and Experimental Study

2020 ◽  
Vol 21 (3-4) ◽  
pp. 227-238
Author(s):  
I. Ben Belgacem ◽  
L. Cheikh ◽  
E.M. Barhoumi ◽  
W. Khan ◽  
W. Ben Salem
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
High Speed ◽  
Water Jet ◽  
Fe Method ◽  
Sph Method ◽  
Impact Surface ◽  
Particle Hydrodynamics ◽  
Spherical Head ◽  
The Impact

AbstractIn this paper, we present a numerical simulation of a round impacting jet using coupled Smoothed Particle Hydrodynamics (SPH) and Finite Element (FE) methods. Numerical results are compared with the results of another simulation carried out by the CEL (Coupled Eulerian-Lagrangian) method. A water jet with a spherical head was used at an initial speed of 570 m/s to impact a flat plate made of Polymethyl-Methacrylate (PMMA). To model the entire process, the SPH method was used to model the water jet and the FE method for the PMMA structure. The distribution of the pressure on the impact surface and the resulting deformation of the structure were discussed. A Numerical model was developed using ABAQUS/Explicit version 6.14. Results of the coupled SPH-FE simulation were further validated. It is demonstrated that the CEL method presents smoother curves compared to the SPH method. These comparisons serve not only to validate the numerical simulation but also to give guidance in formulating the SPH-FEM numerical model.

Compulsory purchase and compensation update – 2014

2014 ◽  
Vol 32 (6) ◽  
pp. 653-659
Author(s):  
Gary Sams
Keyword(s):  
High Speed ◽  
Design Methodology ◽  
Critical Appraisal ◽  
Phase 1 ◽  
Content Type ◽  
The People ◽  
The Government ◽  
Compulsory Purchase ◽  
The Impact ◽  
Practical Implications

Purpose – The purpose of this paper is to summarise and analyse the new compensation provisions brought in by the government for Phase 1 of the HS2 high-speed train line. Design/methodology/approach – To summarise each of the proposals and provide a critical assessment of each of them. Findings – For the most part, and the Homeowner Payment Scheme (HPS) is a marked exception, the new HS2 compensation provisions set out a logical approach to reducing the impact of the scheme on the people most directly affected by its blighting affect. There are, however, a number of concerns as to whether there are more urgent reforms that have not been considered. Research limitations/implications – The proposals were announced in April and in respect of some of them, particularly the HPS, very little information is available as yet. Practical implications – The paper should provide factual information on a very new set of compensation provisions and a critical appraisal of their value. Originality/value – As the compensation provisions have been published only recently there will be few other similar commentaries available.

Organizational Justice and Employee Sustainability: The Mediating Role of Organizational Commitment

2020 ◽  
Vol 3 (3) ◽  
pp. 12-22
Author(s):  
Mehreen Fatima ◽  
Zeeshan Izhar ◽  
Zaheer Abbas Kazmi
Keyword(s):  
Organizational Commitment ◽  
Organizational Justice ◽  
Developing Country ◽  
Design Methodology ◽  
Direct Relationship ◽  
Banking Sector ◽  
Mediating Role ◽  
Research Gap ◽  
The Impact

Purpose- The primary purpose of the study is to determine the impact of organizational justice (OJ) on employee sustainability. Along with that, it also describes how organizational commitment mediates this direct relationship. This study includes all dimensions of OJ which are distributive, procedural and interactional (interpersonal & informational) within the context of a developing country (Pakistan). Design/Methodology- This study has considered employees working in the banking sector of Pakistan. Two hundred ten questionnaires were received back from employees. Regression analysis was used to analyze direct relationships between variables, while smart partial least squares (PLS) were used for mediation analysis. Findings- Results demonstrated that all hypothesis were accepted and it was also confirmed that organizational commitment (OC) mediates the direct relationship between OJ and employee sustainability (ES). Originality/value- Multidimensional construct of organizational justice was tested in this study, in the context of a developing country (Pakistan), to address the research gap.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

The Impact of High-Speed Rail on the Spatial Structure of Chinese Urban Agglomerations

2020 ◽  
Vol 46 (3) ◽  
pp. 379-397
Author(s):  
Chunyang Wang
Keyword(s):  
High Speed ◽  
River Delta ◽  
City Size ◽  
High Speed Rail ◽  
Local Conditions ◽  
Urban Agglomerations ◽  
Large Cities ◽  
Spatial Systems ◽  
Economic Concentration ◽  
The Impact

This paper measures the spatial evolution of urban agglomerations to understand be er the impact of high-speed rail (HSR) construction, based on panel data from fi ve major urban agglomerations in China for the period 2004–2015. It is found that there are signi ficant regional diff erences of HSR impacts. The construction of HSR has promoted population and economic diff usion in two advanced urban agglomerations, namely the Yang e River Delta and Pearl River Delta, while promoting population and economic concentration in two relatively less advanced urban agglomerations, e.g. the middle reaches of the Yang e River and Chengdu–Chongqing. In terms of city size, HSR promotes the economic proliferation of large cities and the economic concentration of small and medium-sized cities along its routes. HSR networking has provided a new impetus for restructuring urban spatial systems. Every region should optimize the industrial division with strategic functions of urban agglomeration according to local conditions and accelerate the construction of inter-city intra-regional transport network to maximize the eff ects of high-speed rail across a large regional territory.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

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