Finite elements simulation of improvised explosively formed projectiles

2018 ◽  
Vol 35 (8) ◽  
pp. 2844-2859 ◽  
Author(s):  
Ricardo Castedo ◽  
Anastasio Pedro Santos ◽  
José Ignacio Yenes ◽  
José Ángel Sanchidrián ◽  
Lina María López ◽  
...  
Keyword(s):  
Field Tests ◽  
Material Model ◽  
Formation Flight ◽  
Jet Formation ◽  
Lagrangian Models ◽  
Content Type ◽  
Lagrangian Simulation ◽  
Penetration Ability ◽  
2D And 3D ◽  
Finite Elements Simulation

Purpose The purpose of this paper is to investigate the applicability of the LS-DYNA software using a Lagrangian formulation in the jet formation, flight and penetration of improvised explosively formed projectiles (EFPs). Numerical results dealing with different properties of the EFPs have been validated with a significant number of field tests. Design/methodology/approach 2D and 3D Lagrangian models, using different material definition, are developed to reproduce the field-measured characteristics of copper- and steel-made EFPs: projectile size and velocity. After validation, the model has been extended to analyse the penetration features. Two different plasticity models have been used to describe the steel target, Plastic-Kinematic and Johnson–Cook. Findings Despite the difficulty in characterizing a non-industrial artefact, the results show that both Lagrangian models (2D and 3D) are able to simulate the projectile size, velocity and penetration capability with errors less than 10 per cent when using the Johnson–Cook material model for both liner and target. Practical implications These data can be used to test the penetration ability of improvised EFP’s against different targets, i.e. light armoured vehicles. Originality/value There are no references that address the application of the Lagrangian simulation of non-industrial EFPs and its validation with field tests, including penetration assessment.

Design modification of iron ore bearing transfer chute using discrete element method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Saprativ Basu ◽  
Arijit Chakrabarty ◽  
Samik Nag ◽  
Kishore Behera ◽  
Brati Bandyopadhyay ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Iron Ore ◽  
Bulk Material ◽  
Flow Behavior ◽  
Material Model ◽  
Discrete Element ◽  
Content Type ◽  
Iron Ore Fines ◽  
Cohesive Materials ◽  
Element Method

Purpose The dryer feed chute of the pellet plant plays an important role in the pelletizing process. The chute discharges sticky and moist iron ore fines (<1 mm) to the inline rotary dryer for further processing. Since the inception of the installation of the dryer feed chute, the poor flowability of the feed materials has caused severe problems such as blockages and excessive wear of chute liners. This leads to high maintenance costs and reduced lifetime of the liner materials. Constant housekeeping is needed for maintaining the chute and reliable operation. The purpose of this study is to redesign the dryer feed chute to overcome the above challenges. Design/methodology/approach The discrete element method (DEM) has been used to model the flow of cohesive materials through the transfer chute. Physical experiments have been performed to understand the most severe flow conditions. A DEM material model is also developed for replicating the worst-case material condition. After identifying the key problem areas, concept designs were proposed and simulated to assess the design improvements to increase the reliability of chute operation. Findings Flow simulations correlated well with the existing flow behavior of the iron ore fines inside the chute. The location of the problematic areas has been validated with that of the previously installed chute. Subsequently, design modifications have been proposed. This includes modification of deflector plate and change in slope and cross-section of the chute. DEM simulations and analysis were conducted after incorporating these design changes. A comparison in the average velocity of particle and force on chute wall shows a significant improvement using the proposed design. Originality/value Method to calibrate DEM material model was found to provide accurate prediction and modeling of the flow behavior of bulk material through the real transfer chute. DEM provided greater insight into the performance of the chute especially modeling cohesive materials. DEM is a valuable design tool to assist chute designers troubleshoot and verify chute designs. DEM provides a greater ability to model and assess chute wear. This technique can help in achieving a scientific understanding of the flow properties of bulk solids through transfer chute, hence eliminate challenges, ensuring reliable, uninterrupted and profitable plant operation. This paper strongly advocates the use of calibrated DEM methodology in designing bulk material handling equipment.

Iron loss simulation using a local material model

2019 ◽  
Vol 38 (4) ◽  
pp. 1224-1234
Author(s):  
Benedikt Groschup ◽  
Silas Elfgen ◽  
Kay Hameyer
Keyword(s):  
A Priori ◽  
Material Model ◽  
Edge Length ◽  
Iron Loss ◽  
Local Magnetization ◽  
Content Type ◽  
Local Loss ◽  
Cut Edge ◽  
Iron Losses ◽  
Local Material

Purpose The cutting process of the electric machine laminations causes residual mechanical stress in the soft magnetic material. A local magnetic deterioration can be observed and the resulting local and global iron losses increase. A continuous local material model for the consideration of the changing magnetization properties has been introduced in a previous work as well as an a priori assessment of iron losses. A local iron loss calculation considering both a local magnetization and local loss parameters misses yet. The purpose of this study is to introduce a local iron loss calculation model considering both a local magnetization and local loss parameters. Design/methodology/approach In this paper, an approach for local iron loss simulation is developed and a comparison to the cut-edge length-dependent loss model is given. The comparison includes local loss distribution in the lamination as well as the impact on the overall motor efficiency and vehicle range in an electric vehicle driving cycle. Findings For an analysis of the resulting local iron loss components, both the local magnetization and iron loss parameters must be considered using physically based models. Consistently, a local iron loss model is presented in the work. The developed model can be used to gain detailed information of the local loss distribution inside the machine. The comparability of this local iron loss with the cut-edge length approach for overall system characteristics, e.g. efficiency or driving range, is shown. Originality/value A local iron loss simulation approach is a physical accurate model to describe the influence of cutting techniques on electric machine characteristics. A comparison with the less complicated a priori assessment gives detailed information about the necessity of the local model under consideration of the given problem.

scholarly journals Unpacking the foundational dimensions of work integration social enterprise

2018 ◽  
Vol 14 (1) ◽  
pp. 60-70 ◽  
Author(s):  
Rosemary Lysaght ◽  
Michael J. Roy ◽  
Jack S. Rendall ◽  
Terry Krupa ◽  
Liam Ball ◽  
...  
Keyword(s):  
Organizational Development ◽  
Assessment Tool ◽  
Empirical Studies ◽  
Health Sector ◽  
Field Tests ◽  
Social Enterprises ◽  
Response Scale ◽  
Content Type ◽  
Work Integration ◽  
The Uk

Purpose The aim of this exploratory, mixed methods study was to develop and test a tool that identifies foundational dimensions of work integration social enterprises (WISEs) for use in empirical studies and enterprise self-assessment. Construction of the initial prototype was based upon a review of the literature and prior qualitative research by the authors. Design/methodology/approach A 20-item question pool with a four-point response scale was constructed to explore WISE business and employment practices and strategies for worker growth and development. Three sequential field tests were conducted with the prototype – the first with 5 Canadian WISEs, the second with 14 WISEs in the UK and the third with 6 Canadian WISEs involved in an outcome study in the mental health sector. Each field test included completion of the questionnaire by persons with managerial responsibility within the WISE and evaluative feedback captured through questions on the applicability and interpretability of the items. Findings Testing of the prototype instrument revealed the inherent diversity in the field and the difficulty in creating questions that both embrace that diversity and produce unidimensional variables definable along a spectrum. A number of challenges with question structure were identified and have been modified throughout the iterative testing process. Research limitations/implications This study identified central domains for inclusion in a multi-dimensional WISE assessment tool. Further testing will help further refine scaling and establish psychometric properties. Originality/value This measure will provide a descriptive profile of WISEs across sectors and identify WISE core dimensions for research and organizational development.

Marker-guided auto-landing on a moving platform

2017 ◽  
Vol 5 (1) ◽  
pp. 28-42 ◽  
Author(s):  
Iryna Borshchova ◽  
Siu O’Young
Keyword(s):  
Image Processing ◽  
Visual Servoing ◽  
Low Cost ◽  
Field Tests ◽  
Processing Algorithm ◽  
Prototype System ◽  
Image Processing Algorithm ◽  
Suggested Approach ◽  
Content Type ◽  
Moving Platform

Purpose The purpose of this paper is to develop a method for a vision-based automatic landing of a multi-rotor unmanned aerial vehicle (UAV) on a moving platform. The landing system must be highly accurate and meet the size, weigh, and power restrictions of a small UAV. Design/methodology/approach The vision-based landing system consists of a pattern of red markers placed on a moving target, an image processing algorithm for pattern detection, and a servo-control for tracking. The suggested approach uses a color-based object detection and image-based visual servoing. Findings The developed prototype system has demonstrated the capability of landing within 25 cm of the desired point of touchdown. This auto-landing system is small (100×100 mm), light-weight (100 g), and consumes little power (under 2 W). Originality/value The novelty and the main contribution of the suggested approach are a creative combination of work in two fields: image processing and controls as applied to the UAV landing. The developed image processing algorithm has low complexity as compared to other known methods, which allows its implementation on general-purpose low-cost hardware. The theoretical design has been verified systematically via simulations and then outdoors field tests.

RBF-based mesh morphing approach to perform icing simulations in the aviation sector

2019 ◽  
Vol 91 (4) ◽  
pp. 620-633 ◽  
Author(s):  
Corrado Groth ◽  
Emiliano Costa ◽  
Marco Evangelos Biancolini
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Ansys Fluent ◽  
Content Type ◽  
Mesh Morphing ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses ◽  
2D And 3D ◽  
First Time ◽  
Practical Implications

Purpose Numerical simulation of icing has become a standard. Once the iced shape is known, however, the analyst needs to update the computational fluid dynamics (CFD) grid. This paper aims to propose a method to update the numerical mesh with ice profiles. Design/methodology/approach The present paper concerns a novel and fast radial basis functions (RBF) mesh morphing technique to efficiently and accurately perform ice accretion simulations on industrial models in the aviation sector. This method can be linked to CFD analyses to dynamically reproduce the ice growth. Findings To verify the consistency of the proposed approach, one of the most challenging ice profile selected in the LEWICE manual was replicated and simulated through CFD. To showcase the effectiveness of this technique, predefined ice profiles were automatically applied on two-dimensional (2D) and three-dimensional (3D) cases using both commercial and open-source CFD solvers. Practical implications If ice accreted shapes are available, the meshless characteristic of the proposed approach enables its coupling with the CFD solvers currently supported by the RBF4AERO platform including OpenFOAM, SU2 and ANSYS Fluent. The advantages provided by the use of RBF are the high performance and reliability, due to the fast application of mesh smoothing and the accuracy in controlling surface mesh nodes. Originality/value As far as authors’ knowledge is concerned, this is the first time in scientific literature that RBF are proposed to handle icing simulations. Due to the meshless characteristic of the RBF mesh morphing, the proposed approach is cross solver and can be used for both 2D and 3D geometries.

Predictive model of overburden deformation: based on machine learning and distributed optical fiber sensing technology

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wenyuan Liu ◽  
Chunde Piao ◽  
Yazhou Zhou ◽  
Chaoqi Zhao
Keyword(s):  
Machine Learning ◽  
Optical Fiber ◽  
Predictive Model ◽  
Material Model ◽  
Prevention Measures ◽  
Similar Material ◽  
Content Type ◽  
Fiber Sensing ◽  
Optical Fiber Sensing ◽  
Distributed Optical Fiber

Purpose The purpose of this paper is to establish a strain prediction model of mining overburden deformation, to predict the strain in the subsequent mining stage. In this way, the mining area can be divided into zones with different degrees of risk, and the prevention measures can be taken for the areas predicted to have large deformation. Design/methodology/approach A similar-material model was built by geological and mining conditions of Zhangzhuang Coal Mine. The evolution characteristics of overburden strain were studied by using the distributed optical fiber sensing (DOFS) technology and the predictive model about overburden deformation was established by applying machine learning. The modeling method of the predictive model based on the similar-material model test was summarized. Finally, this method was applied to engineering. Findings The strain value predicted by the proposed model was compared with the actual measured value and the accuracy is as high as 97%, which proves that it is feasible to combine DOFS technology with machine learning and introduce it into overburden deformation prediction. When this method was applied to engineering, it also showed good performance. Originality/value This paper helps to promote the application of machine learning in the geosciences and mining engineering. It provides a new way to solve similar problems.

Composite beams under fire loading: numerical modeling of behavior

2016 ◽  
Vol 7 (2) ◽  
pp. 142-157 ◽  
Author(s):  
Kristi L. Selden ◽  
Amit H. Varma
Keyword(s):  
Composite Beam ◽  
Failure Modes ◽  
Concrete Slab ◽  
Material Model ◽  
Composite Beams ◽  
Bottom Flange ◽  
Stress Strain ◽  
Content Type ◽  
Beam Deflections ◽  
Fire Loading

Purpose The purpose of this study was to develop a three-dimensional (3D) finite element modeling (FEM) technique using the commercially available program ABAQUS to predict the thermal and structural behavior of composite beams under fire loading. Design/methodology/approach The model was benchmarked using experimental test data, and it accounts for temperature-dependent material properties, force-slip-temperature relationship for the shear studs and concrete cracking. Findings It was determined that composite beams can be modeled with this sequentially coupled thermal-structural 3D FEM to predict the displacement versus bottom flange temperature response and associated composite beam failure modes, including compression failure in the concrete slab, runaway deflection because of yielding of the steel beam or fracture of the shear studs. Originality/value The Eurocode stress-strain-temperature (σ-ε-T) material model for structural steel and concrete conservatively predict the composite beam deflections at temperatures above 500°C. Models that use the National Institute of Standards and Technology (NIST) stress-strain-temperature (σ-ε-T) material model more closely match the measured deflection response, as compared to the results using the Eurocode model. However, in some cases, the NIST model underestimates the composite beam deflections at temperatures above 500°C.

Towards a Better Understanding of Shaped Charge Jet Formation and Penetration

2019 ◽  
Author(s):  
David W. Price ◽  
Ernest J. Harris ◽  
Frances G. Daykin
Keyword(s):  
Phase 1 ◽  
3D Modelling ◽  
The Body ◽  
Shaped Charge ◽  
Device Design ◽  
Jet Formation ◽  
Shaped Charge Jet ◽  
2D And 3D ◽  
Data Reproducibility ◽  
Technology Demonstrator

Abstract JeMMA, a set of relatively simple shaped-charge devices, has been designed in order to generate suitable data on jet formation, break-up and penetration for code validation purposes. The JeMMA Phase 1 device incorporated a copper liner and six of these shaped charges were manufactured as a technology demonstrator and fired in a special shaped charge facility in December 2016. The radiographic results obtained from the JeMMA Phase 1 and 2 devices, along with data reproducibility between trials, was excellent. This report gives an overview of the Phase 1 and 2 trials, including device design, the results of the firings conducted in Switzerland and details of the subsequent 2D and 3D hydrocode modelling carried out at AWE. The agreement between the data and both 2D and 3D modelling of the experiments is very pleasing, but highlights where further work is required. These JeMMA experiments will enhance the body of relevant data required to provide the validation of the hydrocode materials and modelling methodologies and enable us to better model the jetting threats of our experiments and have higher confidence in the results of the modelling.

Quantification of airfield pavement condition using soft-computing technique

2020 ◽  
Vol 17 (6) ◽  
pp. 877-890
Author(s):  
Vidhi Vyas ◽  
Ajit Pratap Singh ◽  
Anshuman Srivastava
Keyword(s):  
Decision Making ◽  
Soft Computing ◽  
Field Tests ◽  
Cumulative Impact ◽  
Computing Technique ◽  
Content Type ◽  
Pavement Condition ◽  
Maintenance And Repair ◽  
Soft Computing Technique ◽  
Practical Implications

Purpose The purpose of this study is the development of an objective approach to prioritize and rank airfield pavement sections based on their condition and justify their funding requirements using a soft-computing technique. Design/methodology/approach The airfield pavement condition is evaluated by collecting data through field tests and visual surveys. The performance indicators are selected as deflection, structural index, subgrade modulus and pavement condition index, by taking the help of field experts. The condition of pavement sections is analyzed by obtaining scores for each sections using Buckley’s fuzzy analytic hierarchy process. The sections are finally ranked for performing their maintenance and repair activities. Findings The condition of pavements is represented using a single score that takes an account of cumulative impact of various parameters as well as any subjectivity associated with human perceptions. Practical implications The developed methodology is very useful for its practical implications, and it is explained using a case study of an international airport. Originality/value Decision-making for maintenance and repair practices is often based on subjective decisions and lacks a robust and judicious approach. Thus, obtaining sufficient budget for repair and maintenance becomes one of the primary challenges. This study adds a value to prevailing practices by developing an objective decision-making methodology. Additionally, the use of non-destructive testing techniques, which pose little or no necessity to destructive coring and boring, eases this task.

Effects of wave breaking on the oceanic boundary layer in hurricane conditions

2019 ◽  
Vol 29 (3) ◽  
pp. 1167-1177
Author(s):  
Zhanhong Wan ◽  
Xiuyang Lü ◽  
Chen Jiawang ◽  
Tianyu Song ◽  
Shizhu Luo
Keyword(s):  
Boundary Layer ◽  
Wave Breaking ◽  
Exchange Process ◽  
Ocean Dynamics ◽  
Upper Ocean ◽  
Langmuir Circulation ◽  
Content Type ◽  
Wind Speeds ◽  
Penetration Ability ◽  
Oceanic Boundary Layer

Purpose Wave breaking significantly affects the exchange process between ocean and atmosphere. This paper aims to simulate the upper ocean dynamics under the influence of wave breaking, which may help to figure out the transport of energy by these breakers. Design/methodology/approach The authors use a breaker-LES model to simulate the oceanic boundary layer in hurricane conditions, in which breakers become the main source of momentum and energy instead of traditional wind stress. Findings The mean horizontal velocities and energy increase rapidly with wind speed, reflecting that input from atmosphere dominates the coherent structure in the upper ocean. The penetration ability of a breaker limits its effective depth and thus the total turbulent kinetic energy (TKE) decreases sharply near the surface. Langmuir circulation is the main source of TKE in deeper water. The authors compared the dissipation rate (e) in the simulations with two estimates and found that the model tends to the scaling of ε∼z–3.4 at extreme wind speeds. Originality/value The probability distribution of breakers is also discussed based on the balance between the input from atmosphere and output by wave breaking. The authors considered the contribution of micro-scale breakers and revaluated the probability density function. The results show stability in hurricane conditions.

Sign in / Sign up

Export Citation Format

Share Document