International Journal of Protective Structures最新文献_第4页

Numerical modelling of blast mitigation of pre-fractal obstacles 前分形障碍物爆破缓减的数值模拟

IF 2

International Journal of Protective Structures Pub Date : 2023-08-01 DOI: 10.1177/20414196231192676

Omar Ghareeb Alshammari, Obed Samuelraj Isaac, S. Clarke, S. Rigby

{"title":"Numerical modelling of blast mitigation of pre-fractal obstacles","authors":"Omar Ghareeb Alshammari, Obed Samuelraj Isaac, S. Clarke, S. Rigby","doi":"10.1177/20414196231192676","DOIUrl":"https://doi.org/10.1177/20414196231192676","url":null,"abstract":"The mechanics of downstream blast wave attenuation caused by interaction with obstacles arranged into a pre-fractal shape based on the Sierpinski carpet was numerically investigated using a high-fidelity CFD solver. The blast mitigation was qualitatively and quantitatively assessed for four pre-fractal iterations at three different scaled distances ( Z = 1.87, 2.24, 2.99 m/kg1/3). Mitigation was seen to occur in zones associated with the location of destructive wave interference patterns in the downstream region. Crucially, these zones were found to widen spatially with increasing pre-fractal iteration, and strong shock-shock interactions that result in load amplification, commonly encountered in downstream regions of a solitary block-like obstacle, were not observed for the more fractal-like obstacles. The mechanisms of attenuation are explored in terms of wave impedance. It is found that pre-fractals reduce wave transmission in the downstream, increase reflection of the blast wave, and enhance trapping within the confines of the pre-fractal obstacle, dramatically changing the directionality and hence the strength of the transmitted wave. Reductions in peak pressure of up to 60% and peak specific impulse of up to 40% were recorded for the highest iteration pre-fractal, that is, obstacles that most closely represent a true fractal, thereby highlighting the effectiveness of such shapes for protective structure design for improved blast mitigation.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47529802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Investigating the effect of ceramic-polyurea-aluminum layers on ballistic performance of composite target 陶瓷聚脲铝层对复合靶材弹道性能影响的研究

IF 2

International Journal of Protective Structures Pub Date : 2023-07-14 DOI: 10.1177/20414196231184585

S. Jafari, A. Alavi Nia

{"title":"Investigating the effect of ceramic-polyurea-aluminum layers on ballistic performance of composite target","authors":"S. Jafari, A. Alavi Nia","doi":"10.1177/20414196231184585","DOIUrl":"https://doi.org/10.1177/20414196231184585","url":null,"abstract":"In this research, the ballistic performance of ceramic-polyurea-aluminum composite targets under the impact of flat-nose projectile was investigated for different thicknesses. The relevant experiments were designed based on the thickness of the layers and the effect of their configuration was explored. Experimental tests were carried out using two types of gas gun devices with different calibers. Residual velocity of the projectile was extracted using ls-dyna software for all targets and compared with the experimental data and after validation, the ballistic limit velocity was extracted. Taguchi method was used to design experiments and optimization and ballistic limit velocity, surface density, and strength-to-weight ratio were considered as objective functions. Moreover, the residual velocity of the projectile, damage mechanism of layers, the diameter of the hole at the back layer, central displacement of the back layer, absorbed energy, and changes in the projectile velocity were also investigated. Based on the numerical results, ceramic had the greatest effect on reducing the velocity of the projectile (approximately between 55 and 65%). Strength-to-weight ratio and armor weight were considered as two objective functions in the optimization. The effect of each of the armor materials on the target functions was investigated. According to the results, ceramic had the greatest effect on increasing the strength-to-weight ratio (about 83.88%), and polyurea had the least effect (about 14.09%) on increasing the total weight of the armor.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42998117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Quasi-static compressive performance of 3D printed polymer composite cellular cubic structures-An experimental study 3D打印聚合物复合材料细胞立方结构的准静态压缩性能实验研究

IF 2

International Journal of Protective Structures Pub Date : 2023-07-04 DOI: 10.1177/20414196231187004

A. Praveen Kumar, Ma Quanjin

{"title":"Quasi-static compressive performance of 3D printed polymer composite cellular cubic structures-An experimental study","authors":"A. Praveen Kumar, Ma Quanjin","doi":"10.1177/20414196231187004","DOIUrl":"https://doi.org/10.1177/20414196231187004","url":null,"abstract":"Light weight cellular structures have gained extensive attention in the impact energy absorption applications owing to their superior specific strength and excellent crashworthiness characteristics. The main objective of the present research work is to utilize this benefit to tailor and to improve the structural design and material type of cellular structures for crashworthiness applications. Cubic structures with four different types of design patterns such as concave, convex, hyperbola, and hexagon were proposed and fabricated through three-dimensional (3D) printing technique. Four polymeric filament materials such as Poly lactic acid (PLA), Acrylonitrile butadiene styrene (ABS), PLA mixed carbon fiber (PLA/CF), and Polyethylene terephthalate glycol (PETG), mixed carbon fiber (PETG/CF) were utilized. Accordingly, the compression tests were performed on the fabricated cellular cubic structures under quasi-static loading to examine the effect of design pattern, and material types on the compressive behavior and energy absorbing characteristics. The results revealed that the convex design pattern of 3D printed PETG/CF cubic structure showed the significant energy absorbing characteristics compared to the other three design patterns. It is emphasized that the proposed 3D printed cubic cellular structures have great prospective to substitute the traditional energy absorbing structures in automotive vehicles and high speed trains.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42991636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Influence of prestressing force on performance of concrete plates under impact loading 冲击荷载下预应力对混凝土板性能的影响

IF 2

International Journal of Protective Structures Pub Date : 2023-06-30 DOI: 10.1177/20414196231187003

Vimal Kumar, M. Iqbal, AK Mittal

{"title":"Influence of prestressing force on performance of concrete plates under impact loading","authors":"Vimal Kumar, M. Iqbal, AK Mittal","doi":"10.1177/20414196231187003","DOIUrl":"https://doi.org/10.1177/20414196231187003","url":null,"abstract":"An experimental and numerical study has been performed to explore the performance of one-way pretensioned concrete plates against impact loading. The impact resistance, experimental results and damage within the pretensioned concrete have been compared with the non-pretensioned concrete. The plate specimens of concrete grades M40 and M60 have been pretensioned to prestress level 10 and 20% of the compressive strength of the concrete. While, all the tendons employed in the non-pretensioned concrete were kept unstressed. The plates were struck at the mid-span by a steel mass (242.85 kg) dropped from 0.5 to 1.0 m heights. The numerical simulations have been executed using explicit finite element code considering the Holmquist–Johnson–Cook (HJC) and the metal plasticity model for concrete and steel, correspondingly. The performance of the plates is governed by the grade of concrete, impact energy and level of the prestress within the concrete. The induced prestress within the concrete enhanced the stiffness and, consequently, the impact resistance of the pretensioned concrete plates. The pretensioned concrete hence witnessed increased impact force and reduced deflection by 18.1% and 11.0%, correspondingly, compared to the non-pretensioned concrete. The splitting and punching crack within the plates became pronounced once the drop height increased from 0.5 m to 1.0 m. The simulations have estimated the peak impact force and reaction within 19.7% and 15.5% deviation, respectively. The displacement and energy absorption have been calculated using an analytical methodology closely correlated with the actual results within 18% and 14% deviation, respectively. Further, the simulations performed on two-way pretensioned concrete have shown improved performance of the plates witnessing no splitting crack and uniform crack distribution compared to one-way pretensioned concrete.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43426004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Development of a high-performance blast energy-absorbing system for building structures 高性能建筑结构爆炸吸能系统的研制

IF 2

International Journal of Protective Structures Pub Date : 2023-06-29 DOI: 10.1177/20414196231183006

G. Gomes, V. Lúcio, C. Cismaşiu

{"title":"Development of a high-performance blast energy-absorbing system for building structures","authors":"G. Gomes, V. Lúcio, C. Cismaşiu","doi":"10.1177/20414196231183006","DOIUrl":"https://doi.org/10.1177/20414196231183006","url":null,"abstract":"Shock absorbers have been widely used in the automotive and aeronautical industries for many years. Inspired on these devices, the paper presents an analytical and numerical assessment of a high performance protective system for building structures against blast loads, which is composed of a shielding element connected to the main structure, at the floor levels, through ductile Energy Absorbing Connectors (EACs). The EACs exploit the external tube inversion mechanism to absorb a significant part of the imparted kinetic energy from the blast wave. While the system prototype has been developed in laboratory, it was characterized and tested in a full-scale blast testing campaign. A validated finite element model was used next to analyze its performance in a more demanding design scenario. The introduction of EACs notably reduces the peak horizontal loads and the kinetic energy transferred to the protected structure, being expected a significant reduction of the stresses in the supporting vertical elements, in addition to the protection of structural and non-structural members. These results encourage further studies of the presented protective system that can be potentially employed for a large variety of blast threat scenarios, especially when increasing the stand-off is not a possible/viable option and sensitive facilities have to be protected.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43193124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Non-parametric characterization of blast loads 爆炸载荷的非参数表征

IF 2

International Journal of Protective Structures Pub Date : 2023-06-25 DOI: 10.1177/20414196231184581

Matthew R. Kirchner, Shawnasie R Kirchner, Adam A Dennis, S. Rigby

{"title":"Non-parametric characterization of blast loads","authors":"Matthew R. Kirchner, Shawnasie R Kirchner, Adam A Dennis, S. Rigby","doi":"10.1177/20414196231184581","DOIUrl":"https://doi.org/10.1177/20414196231184581","url":null,"abstract":"Mathematical analysis of blast pressures has typically involved the empirical fitting of parametric models, which assumes a specific function shape. In reality, the true shape of the blast pressure is unknown and may lack a parametric form, particularly in the negative phase following arrival of the secondary shock. In this work, we develop a non-parametric (NP) representation that makes few assumptions and relies on the observed experimental data to fit a unique and previously unknown model. This differs from traditional approaches by not arbitrarily selecting a single, restrictive class of functions and estimating a minimal set of parameters, but rather estimating the underlying function class for which the blast pressure is generated; learning the model directly from the observed data. The method was applied to experimental blast measurements and the NP estimates matched the experimental data with a high degree of accuracy, both qualitatively and quantitatively. The NP approach was shown to significantly outperform other commonly used approaches, near-perfectly track the entire pressure and specific impulse history and predicting experimental peak specific impulse to within ±0.5% in all cases (compared to ±5.0% for a trained artificial neural network (ANN) and ±7.5% for the UFC semi-empirical approach). The NP approach predicts experimental net specific impulses (positive and negative phases combined) with a maximum variation of 2.7%, compared to maximum variations of −116% and 55% for the UFC and ANN approaches, respectively. Since the framework is probabilistic in nature, it can naturally account for random noise in sensor measurements, which are typically more pronounced in blast experiments than many other machine learning applications.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49057913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Exploratory study on the use of bi-stable supports for the impact protection of point-fixed glazing systems 双稳支架用于定点玻璃系统冲击防护的探索性研究

IF 2

International Journal of Protective Structures Pub Date : 2023-06-01 DOI: 10.1177/20414196231175979

Hugo Bento Rebelo, Beatriz Assunção, Chiara Bedon, F. Amarante dos Santos

引用次数: 0

The Direction-encoded Neural Network: A machine learning approach to rapidly predict blast loading in obstructed environments 方向编码神经网络:一种机器学习方法，用于快速预测障碍物环境中的爆炸载荷

IF 2

International Journal of Protective Structures Pub Date : 2023-06-01 DOI: 10.1177/20414196231177364

Adam A Dennis, S. Rigby

{"title":"The Direction-encoded Neural Network: A machine learning approach to rapidly predict blast loading in obstructed environments","authors":"Adam A Dennis, S. Rigby","doi":"10.1177/20414196231177364","DOIUrl":"https://doi.org/10.1177/20414196231177364","url":null,"abstract":"Machine learning (ML) methods are becoming more prominent in blast engineering applications, with their adaptability to new scenarios and rapid computation times providing key benefits when compared to empirical methods and physics-based approaches, respectively. However, ML approaches commonly used for blast analyses are regularly provided with inputs relating to domain-specific parameters, restricting their use beyond the initial problem set and reducing their generality. This article presents the ‘Direction-encoded Neural Network’ (DeNN); a novel way to structure an Artificial Neural Network (ANN) to predict blast loading in obstructed environments. Each point of interest (POI) is represented by the proximity to its surroundings and the shortest travel path of the blast wave in order to prime the network to learn the underlying physics of the problem. Furthermore, a bespoke wave reflection equation creates a zone of influence around each point so that obstacles are only captured in the network’s inputs if they would alter the path of the wave. It is shown that the DeNN can predict peak overpressures with mean absolute errors ∼5 kPa for unseen, complex domains of any shape or size, when compared to the results from physics-based numerical models with ∼30 times the solution time of the DeNN. The network is used to develop maps of likely human injury following detonation of a high explosive in an internal environment, with eardrum rupture levels being correctly predicted for over 93% of unseen test points. It is therefore highly suited for use in probabilistic, risk-based analyses which are currently impractical due to excessive computational cost.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43798769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

On the estimation of near-field air blast peak overpressure from cylindrical charges 圆柱装药近场空气爆炸峰值超压的估算

IF 2

International Journal of Protective Structures Pub Date : 2023-05-19 DOI: 10.1177/20414196231177358

J. Liu, C. Gao, Z. Sun, JW Yin

引用次数: 0

Elasto-plastic analysis of foundations during emergency shutdown due to blast loading 爆炸荷载下紧急停堆地基弹塑性分析

IF 2

International Journal of Protective Structures Pub Date : 2023-05-11 DOI: 10.1177/20414196231174916

Kirtika Samanta, P. Maheshwari

{"title":"Elasto-plastic analysis of foundations during emergency shutdown due to blast loading","authors":"Kirtika Samanta, P. Maheshwari","doi":"10.1177/20414196231174916","DOIUrl":"https://doi.org/10.1177/20414196231174916","url":null,"abstract":"Behaviour of machine foundations is investigated in this study under harmonic loading with varying frequency and pulse loading. Owing to excessive vibrations from the pulse, the machine encounters an emergency shutdown where the machine’s exciting frequency reduces to zero exponentially. The analysis is performed considering an elastic plastic single degree of freedom system with hardening and softening behaviour. Two cases are analysed depending on the time of application of pulse loading to the foundation system. For both the cases, the governing equations of motion are acquired and solved numerically using the fourth order Runge-Kutta method. Using these solutions, displacement-time graphs are obtained for a variety of parameters such as time constant, hardening/softening index, mass of machine and the foundation block, stiffness, pulse load magnitude, damping ratio and decay coefficient to study their influence on the behaviour of the machine-foundation system. The study helps in predicting the dynamic response of foundations under the emergency shutdown conditions due to pulse loading. Further, these also help in taking the decision if there exists a need for vibration barriers to have the displacements well within the permissible limits.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48759884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0