Pub Date : 2021-07-29DOI: 10.1177/20414196211035789
K. Senthil, R. Sharma, S. Rupali, A. Thakur, M. Iqbal, N. Gupta
The manuscript is focussed on the prediction of superior layer configuration on titanium and aluminium plates through numerical investigations using ABAQUS/Explicit finite element software. The target plate of titanium Ti-6Al-4V (Ti) and aluminium Al 2024-T3 (Al) were studied against 7.62 mm diameter soft lead core projectiles. The Johnson-Cook (JC) material model was employed to simulate the behaviour of the target as well as projectile material. The results thus predicted from the numerical simulations in terms of deformed profile, residual velocity and ballistic limit were compared with the experimental results available in literature. Overall, the results were found in good agreement with the experimental results. The simulations were performed on the target of 10, 12.7 and 15 mm thickness with three, five and ten layers in order to predict the superior layer configuration. In the case of Ti-6Al-4V, the difference in performance between three layers and monolithic was quite high, however the use of five or ten layers of equivalent thickness is not advisable as performance is reduced. For Al2024-T3, the performance of layer targets was quite similar to that of monolithic targets. It is also observed the resistance of TiTiAl target configuration found to be better as compared to AlTiTi target configuration. It is concluded that the Al plate as back layer has more efficiency for ballistic resistance of layered configuration. It is also concluded that with respect to thickness, the capacity of titanium target is approximately 1.5 times higher than aluminium target against given lead core projectile.
{"title":"Evaluation of superior layer configuration of titanium Ti-6Al-4V and aluminium 2024-T3 against soft projectiles","authors":"K. Senthil, R. Sharma, S. Rupali, A. Thakur, M. Iqbal, N. Gupta","doi":"10.1177/20414196211035789","DOIUrl":"https://doi.org/10.1177/20414196211035789","url":null,"abstract":"The manuscript is focussed on the prediction of superior layer configuration on titanium and aluminium plates through numerical investigations using ABAQUS/Explicit finite element software. The target plate of titanium Ti-6Al-4V (Ti) and aluminium Al 2024-T3 (Al) were studied against 7.62 mm diameter soft lead core projectiles. The Johnson-Cook (JC) material model was employed to simulate the behaviour of the target as well as projectile material. The results thus predicted from the numerical simulations in terms of deformed profile, residual velocity and ballistic limit were compared with the experimental results available in literature. Overall, the results were found in good agreement with the experimental results. The simulations were performed on the target of 10, 12.7 and 15 mm thickness with three, five and ten layers in order to predict the superior layer configuration. In the case of Ti-6Al-4V, the difference in performance between three layers and monolithic was quite high, however the use of five or ten layers of equivalent thickness is not advisable as performance is reduced. For Al2024-T3, the performance of layer targets was quite similar to that of monolithic targets. It is also observed the resistance of TiTiAl target configuration found to be better as compared to AlTiTi target configuration. It is concluded that the Al plate as back layer has more efficiency for ballistic resistance of layered configuration. It is also concluded that with respect to thickness, the capacity of titanium target is approximately 1.5 times higher than aluminium target against given lead core projectile.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"604 - 635"},"PeriodicalIF":2.0,"publicationDate":"2021-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/20414196211035789","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43005994","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}
Pub Date : 2021-07-24DOI: 10.1177/20414196211033310
Amir Zaghloul, A. Remennikov, B. Uy
With the increase of terrorist attacks over the past decades, many engineering societies have started issuing design guides to calculate blast loads on structures. While such guides can be successfully used to assess blast loads due to single detonations, the effects of multiple detonations are often overlooked. In this research, the enhancement in blast parameters resulting from simultaneously detonating multiple charges is investigated, emphasising the interaction of blast waves with narrow targets. A parametric CFD study using the finite volume code Viper::Blast was performed where the number of charges, their arrangement, and the scaled stand-off distances were changed. It is found that, when detonated simultaneously, multiple charges return much higher pressure and impulse values compared to an equivalent single charge. Moreover, an arced arrangement of multiple charges is more efficient than a flat arrangement in enhancing blast wave parameters. Such enhancement is beneficial in scenarios involving demolition. Approximate methods to compute blast wave parameters from multiple simultaneously detonated spherical charges are presented in this study, where pressure and impulse from multiple charges can be computed by only knowing the parameters resulting from an equivalent single charge.
{"title":"Enhancement of blast wave parameters due to shock focusing from multiple simultaneously detonated charges","authors":"Amir Zaghloul, A. Remennikov, B. Uy","doi":"10.1177/20414196211033310","DOIUrl":"https://doi.org/10.1177/20414196211033310","url":null,"abstract":"With the increase of terrorist attacks over the past decades, many engineering societies have started issuing design guides to calculate blast loads on structures. While such guides can be successfully used to assess blast loads due to single detonations, the effects of multiple detonations are often overlooked. In this research, the enhancement in blast parameters resulting from simultaneously detonating multiple charges is investigated, emphasising the interaction of blast waves with narrow targets. A parametric CFD study using the finite volume code Viper::Blast was performed where the number of charges, their arrangement, and the scaled stand-off distances were changed. It is found that, when detonated simultaneously, multiple charges return much higher pressure and impulse values compared to an equivalent single charge. Moreover, an arced arrangement of multiple charges is more efficient than a flat arrangement in enhancing blast wave parameters. Such enhancement is beneficial in scenarios involving demolition. Approximate methods to compute blast wave parameters from multiple simultaneously detonated spherical charges are presented in this study, where pressure and impulse from multiple charges can be computed by only knowing the parameters resulting from an equivalent single charge.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"541 - 576"},"PeriodicalIF":2.0,"publicationDate":"2021-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/20414196211033310","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48584966","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}
Cellular steel-tube-confined concrete (CSTCC) targets show improved anti-penetration performance over single-cell STCC targets due to the confinement effect of surrounding cells on the impacted cell. Dynamic finite cylindrical cavity-expansion (FCCE) models including radial confinement effect were developed to predict the depth of penetration (DOP) for CSTCC targets normally penetrated by rigid sharp-nosed projectiles, and stiffness of radial confinement was achieved with the elastic solution of infinite cylindrical shell in Winkler medium. Steady responses of dynamic FCCE models were obtained on the assumption of incompressibility of concrete, failure of comminuted zone with Heok–Brown criterion and two possible response modes of the confined concrete in the impacted cell. Furthermore, a DOP model for CSTCC targets normally impacted by rigid projectiles was also proposed on the basis of the dynamic FCCE approximate model. Lastly, relevant penetration tests of CSTCC targets normally penetrated by 12.7 mm armor piecing projectile (APP) were taken as examples to validate the dynamic FCCE models and the corresponding DOP model. The results show that the DOP results based on dynamic FCCE model agree well with those of the CSTCC targets normally penetrated by rigid conical or other sharp-nosed projectiles.
{"title":"Dynamic finite cylindrical cavity-expansion models for cellular steel tube confined concrete targets normally impacted by rigid sharp-nosed projectiles","authors":"Chaomei Meng, Dian-yi Song, Q. Tan, Z. Jiang, Liangcai Cai, Yong Shen","doi":"10.1177/20414196211027288","DOIUrl":"https://doi.org/10.1177/20414196211027288","url":null,"abstract":"Cellular steel-tube-confined concrete (CSTCC) targets show improved anti-penetration performance over single-cell STCC targets due to the confinement effect of surrounding cells on the impacted cell. Dynamic finite cylindrical cavity-expansion (FCCE) models including radial confinement effect were developed to predict the depth of penetration (DOP) for CSTCC targets normally penetrated by rigid sharp-nosed projectiles, and stiffness of radial confinement was achieved with the elastic solution of infinite cylindrical shell in Winkler medium. Steady responses of dynamic FCCE models were obtained on the assumption of incompressibility of concrete, failure of comminuted zone with Heok–Brown criterion and two possible response modes of the confined concrete in the impacted cell. Furthermore, a DOP model for CSTCC targets normally impacted by rigid projectiles was also proposed on the basis of the dynamic FCCE approximate model. Lastly, relevant penetration tests of CSTCC targets normally penetrated by 12.7 mm armor piecing projectile (APP) were taken as examples to validate the dynamic FCCE models and the corresponding DOP model. The results show that the DOP results based on dynamic FCCE model agree well with those of the CSTCC targets normally penetrated by rigid conical or other sharp-nosed projectiles.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"517 - 540"},"PeriodicalIF":2.0,"publicationDate":"2021-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/20414196211027288","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44367810","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}
Pub Date : 2021-06-06DOI: 10.1177/20414196211017923
H. Mehmannavaz, A. Ramezani, Mohammad Amin Nabakhteh, G. Liaghat
Shaped charges are devices used for cutting or penetrating different aerial, on land, and underwater targets, based on the concentration of the explosion energy to the liner. The purpose of this study is to present a practical review of the studies related to shaped charges in the last twenty years (2000–2020). In this regard, these studies have been reviewed in two different categories for ordinary and advanced shaped charges. In the case of ordinary shaped charges, different aspects including shaped charges against different targets, different types of shaped charges (such as linear shaped charge and explosively formed penetrators), and theoretical advancements are presented. On the other hand, the new kinds of shaped charges developed for a specific purpose are introduced in the case of advanced shaped charges. The survey of the literature indicates that different concepts such as cut-off velocity and theoretical applicability of hydrodynamics theory in shaped charge penetration still Requires effort. Also, few studies have been focused on new shaped charges, such as hyper-velocity shaped charges, annular and dual-mode ones; and the field is still open for further progress. Besides, some of these new shaped-charges, such as double-layer shaped charges, are not realistic enough to be produced for practical purposes or the market.
{"title":"A practical review study on shaped charge in the last two decades (2000–2020)","authors":"H. Mehmannavaz, A. Ramezani, Mohammad Amin Nabakhteh, G. Liaghat","doi":"10.1177/20414196211017923","DOIUrl":"https://doi.org/10.1177/20414196211017923","url":null,"abstract":"Shaped charges are devices used for cutting or penetrating different aerial, on land, and underwater targets, based on the concentration of the explosion energy to the liner. The purpose of this study is to present a practical review of the studies related to shaped charges in the last twenty years (2000–2020). In this regard, these studies have been reviewed in two different categories for ordinary and advanced shaped charges. In the case of ordinary shaped charges, different aspects including shaped charges against different targets, different types of shaped charges (such as linear shaped charge and explosively formed penetrators), and theoretical advancements are presented. On the other hand, the new kinds of shaped charges developed for a specific purpose are introduced in the case of advanced shaped charges. The survey of the literature indicates that different concepts such as cut-off velocity and theoretical applicability of hydrodynamics theory in shaped charge penetration still Requires effort. Also, few studies have been focused on new shaped charges, such as hyper-velocity shaped charges, annular and dual-mode ones; and the field is still open for further progress. Besides, some of these new shaped-charges, such as double-layer shaped charges, are not realistic enough to be produced for practical purposes or the market.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"665 - 693"},"PeriodicalIF":2.0,"publicationDate":"2021-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/20414196211017923","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49389999","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}
Pub Date : 2021-05-17DOI: 10.1177/20414196211013443
C. Langran-Wheeler, S. Rigby, S. Clarke, A. Tyas, C. Stephens, R. Walker
Research into the characterisation of blast loading on structures following the detonation of a high explosive commonly assumes that the charge is spherical. This has the advantage of simplifying experimental, analytical and computational studies. In practice, however, designers of protective structures must often consider explosive threats which have other geometric forms, which has significant influence on the loading imparted to structures very close to the explosion source. Hitherto, there has been little definitive experimental investigation of the ‘near-field’ blast load parameters from non-spherical explosive charges and studies that have been conducted are usually confined to measurement of the total impulse imparted to a target. Currently, a detailed understanding of the development of loading on a target, necessary to fully inform the design process and appraise the efficacy of predictions from computational models, is lacking. This article, the first part of a wider investigation into these geometrical effects, details work conducted to address this deficiency. Results are presented from an experimental study of loading from detonations of cylindrical charges, set with the longitudinal axis parallel to an effectively rigid target, instrumented to facilitate the capture of the spatial and temporal evolution of the loading at different radial and angular offsets from the charge. These results are compared against loads from spherical charges and the effect of charge shape is identified. Significant differences are observed in the mechanisms and magnitude of loading from cylindrical and spherical charges, which is confirmed through the use of numerical analysis. The overall study provides insights which will assist the future design of effective protection systems.
{"title":"Near-field spatial and temporal blast pressure distributions from non-spherical charges: Horizontally-aligned cylinders","authors":"C. Langran-Wheeler, S. Rigby, S. Clarke, A. Tyas, C. Stephens, R. Walker","doi":"10.1177/20414196211013443","DOIUrl":"https://doi.org/10.1177/20414196211013443","url":null,"abstract":"Research into the characterisation of blast loading on structures following the detonation of a high explosive commonly assumes that the charge is spherical. This has the advantage of simplifying experimental, analytical and computational studies. In practice, however, designers of protective structures must often consider explosive threats which have other geometric forms, which has significant influence on the loading imparted to structures very close to the explosion source. Hitherto, there has been little definitive experimental investigation of the ‘near-field’ blast load parameters from non-spherical explosive charges and studies that have been conducted are usually confined to measurement of the total impulse imparted to a target. Currently, a detailed understanding of the development of loading on a target, necessary to fully inform the design process and appraise the efficacy of predictions from computational models, is lacking. This article, the first part of a wider investigation into these geometrical effects, details work conducted to address this deficiency. Results are presented from an experimental study of loading from detonations of cylindrical charges, set with the longitudinal axis parallel to an effectively rigid target, instrumented to facilitate the capture of the spatial and temporal evolution of the loading at different radial and angular offsets from the charge. These results are compared against loads from spherical charges and the effect of charge shape is identified. Significant differences are observed in the mechanisms and magnitude of loading from cylindrical and spherical charges, which is confirmed through the use of numerical analysis. The overall study provides insights which will assist the future design of effective protection systems.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"492 - 516"},"PeriodicalIF":2.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/20414196211013443","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44381910","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}
Pub Date : 2021-04-20DOI: 10.1177/20414196211010825
Z. Rosenberg, Y. Vayig, A. Malka-Markovitz
We explore the perforation process of metallic plates impacted by rigid sharp-nosed projectiles at high velocities. In particular, we are looking at the diameters of the penetration hole in the plates through a series of 2D numerical simulations, in order to check for the occurrence of cavitation in finite-thickness plates. This phenomenon has not been observed by previous workers and we were looking for its effect on the perforation process. Our simulations show that for every projectile/plate pair there is a certain impact velocity which marks the onset of cavitation. These threshold velocities depend on the normalized thickness of the plates, as well as on their effective strength. Our simulations are supported by the results from perforation tests on plates made of a low strength lead-antimony alloy. The main conclusion from our work is that analytical models for plate perforation should take into account the cavitation phenomenon, especially for high velocity impacts.
{"title":"A note on the cavitation phenomenon in metallic plates perforated by sharp-nosed rigid projectiles","authors":"Z. Rosenberg, Y. Vayig, A. Malka-Markovitz","doi":"10.1177/20414196211010825","DOIUrl":"https://doi.org/10.1177/20414196211010825","url":null,"abstract":"We explore the perforation process of metallic plates impacted by rigid sharp-nosed projectiles at high velocities. In particular, we are looking at the diameters of the penetration hole in the plates through a series of 2D numerical simulations, in order to check for the occurrence of cavitation in finite-thickness plates. This phenomenon has not been observed by previous workers and we were looking for its effect on the perforation process. Our simulations show that for every projectile/plate pair there is a certain impact velocity which marks the onset of cavitation. These threshold velocities depend on the normalized thickness of the plates, as well as on their effective strength. Our simulations are supported by the results from perforation tests on plates made of a low strength lead-antimony alloy. The main conclusion from our work is that analytical models for plate perforation should take into account the cavitation phenomenon, especially for high velocity impacts.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"483 - 491"},"PeriodicalIF":2.0,"publicationDate":"2021-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/20414196211010825","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45091777","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}
Pub Date : 2021-04-19DOI: 10.1177/20414196211009236
Qichen Tang, N. Jiang, Yingkang Yao, Chuan-bo Zhou, Tingyao Wu
Identifying the damage effects of buried multiple-operating-pressure gas pipelines subjected to various magnitude blasting load is a prerequisite for pipeline safety assessment. In this study, the dynamic response and damage effect are assessed by a combination of both field experiments and numerical simulation. It is indicated that the error between the numerical calculation and the field measured data is small and the reliability of the model is high. The dangerous section of the whole pipeline lies directly below the explosion source. The peak particle velocity (PPV) and the peak particle effective stress (PES) on the explosion-prone side of the section are the largest. Moreover, the PPV and PES increase with the increase of the working pressure of the pipeline. Results show that the empty pipe with no working pressure is the safest state among various pipe working state. There is a certain functional relationship among the explosive charge on the ground surface, working pressure, and PES of the pipeline.
{"title":"Experimental and numerical investigation on destructive effect of gas pipeline buried in silty clay under surface explosion","authors":"Qichen Tang, N. Jiang, Yingkang Yao, Chuan-bo Zhou, Tingyao Wu","doi":"10.1177/20414196211009236","DOIUrl":"https://doi.org/10.1177/20414196211009236","url":null,"abstract":"Identifying the damage effects of buried multiple-operating-pressure gas pipelines subjected to various magnitude blasting load is a prerequisite for pipeline safety assessment. In this study, the dynamic response and damage effect are assessed by a combination of both field experiments and numerical simulation. It is indicated that the error between the numerical calculation and the field measured data is small and the reliability of the model is high. The dangerous section of the whole pipeline lies directly below the explosion source. The peak particle velocity (PPV) and the peak particle effective stress (PES) on the explosion-prone side of the section are the largest. Moreover, the PPV and PES increase with the increase of the working pressure of the pipeline. Results show that the empty pipe with no working pressure is the safest state among various pipe working state. There is a certain functional relationship among the explosive charge on the ground surface, working pressure, and PES of the pipeline.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"460 - 482"},"PeriodicalIF":2.0,"publicationDate":"2021-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/20414196211009236","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41569251","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}
Pub Date : 2021-03-05DOI: 10.1177/2041419621993492
J. J. Pannell, G. Panoutsos, S. B. Cooke, D. Pope, S. Rigby
Accurate quantification of the blast load arising from detonation of a high explosive has applications in transport security, infrastructure assessment and defence. In order to design efficient and safe protective systems in such aggressive environments, it is of critical importance to understand the magnitude and distribution of loading on a structural component located close to an explosive charge. In particular, peak specific impulse is the primary parameter that governs structural deformation under short-duration loading. Within this so-called extreme near-field region, existing semi-empirical methods are known to be inaccurate, and high-fidelity numerical schemes are generally hampered by a lack of available experimental validation data. As such, the blast protection community is not currently equipped with a satisfactory fast-running tool for load prediction in the near-field. In this article, a validated computational model is used to develop a suite of numerical near-field blast load distributions, which are shown to follow a similar normalised shape. This forms the basis of the data-driven predictive model developed herein: a Gaussian function is fit to the normalised loading distributions, and a power law is used to calculate the magnitude of the curve according to established scaling laws. The predictive method is rigorously assessed against the existing numerical dataset, and is validated against new test models and available experimental data. High levels of agreement are demonstrated throughout, with typical variations of <5% between experiment/model and prediction. The new approach presented in this article allows the analyst to rapidly compute the distribution of specific impulse across the loaded face of a wide range of target sizes and near-field scaled distances and provides a benchmark for data-driven modelling approaches to capture blast loading phenomena in more complex scenarios.
{"title":"Predicting specific impulse distributions for spherical explosives in the extreme near-field using a Gaussian function","authors":"J. J. Pannell, G. Panoutsos, S. B. Cooke, D. Pope, S. Rigby","doi":"10.1177/2041419621993492","DOIUrl":"https://doi.org/10.1177/2041419621993492","url":null,"abstract":"Accurate quantification of the blast load arising from detonation of a high explosive has applications in transport security, infrastructure assessment and defence. In order to design efficient and safe protective systems in such aggressive environments, it is of critical importance to understand the magnitude and distribution of loading on a structural component located close to an explosive charge. In particular, peak specific impulse is the primary parameter that governs structural deformation under short-duration loading. Within this so-called extreme near-field region, existing semi-empirical methods are known to be inaccurate, and high-fidelity numerical schemes are generally hampered by a lack of available experimental validation data. As such, the blast protection community is not currently equipped with a satisfactory fast-running tool for load prediction in the near-field. In this article, a validated computational model is used to develop a suite of numerical near-field blast load distributions, which are shown to follow a similar normalised shape. This forms the basis of the data-driven predictive model developed herein: a Gaussian function is fit to the normalised loading distributions, and a power law is used to calculate the magnitude of the curve according to established scaling laws. The predictive method is rigorously assessed against the existing numerical dataset, and is validated against new test models and available experimental data. High levels of agreement are demonstrated throughout, with typical variations of <5% between experiment/model and prediction. The new approach presented in this article allows the analyst to rapidly compute the distribution of specific impulse across the loaded face of a wide range of target sizes and near-field scaled distances and provides a benchmark for data-driven modelling approaches to capture blast loading phenomena in more complex scenarios.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"437 - 459"},"PeriodicalIF":2.0,"publicationDate":"2021-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/2041419621993492","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49587675","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}
Pub Date : 2021-03-01DOI: 10.1177/2041419620923129
P. Del Linz, T. Fung, C. Lee, W. Riedel
The effect of cased explosives on reinforced concrete components is important for the design of protective structures, since the interaction between the fragments and blast waves can modify or even amplify the damage caused. This work deals with the development of finite element analysis techniques to simulate the combined loading and to understand this interaction. In this work, an experiment conducted with a cased explosive and further tests from the literature were used together to develop and stepwise validate finite element analysis models of the different loading phases. The casing fragment velocities and spatial distribution were derived from explosive expansion simulations of the hull using the smooth particle hydrodynamics method together with a momentum conserving penalty contact. The blast loading applied on the concrete plate was based on established empirical formulae, acting at the same times as the fragments. Comparing the final damage with the experimental records revealed good agreement for most damage patterns. The model was used to identify the different damage evolution stages, such as shock-induced shear plug formation and subsequent structural dynamic bending with the associated damage. In addition, differential model variants with fragment and blast loading in isolation were simulated to resolve the response and damage of each loading component. The blast load caused predominantly bending deformations and damage, while the fragments caused similar cratering as seen in the combined case. However, the final combined damage was larger than that caused by each phenomenon. In the given situation, the fragments created most damage, but the established modelling approach opens the perspective to study these effects also for other ratios of explosive to casing weight and scaled distances, where the contributions might differ. Establishing a valid modelling approach is thus an important step towards more insight into the interaction of these complex loading types and damage effects.
{"title":"Response mechanisms of reinforced concrete panels to the combined effect of close-in blast and fragments: An integrated experimental and numerical analysis","authors":"P. Del Linz, T. Fung, C. Lee, W. Riedel","doi":"10.1177/2041419620923129","DOIUrl":"https://doi.org/10.1177/2041419620923129","url":null,"abstract":"The effect of cased explosives on reinforced concrete components is important for the design of protective structures, since the interaction between the fragments and blast waves can modify or even amplify the damage caused. This work deals with the development of finite element analysis techniques to simulate the combined loading and to understand this interaction. In this work, an experiment conducted with a cased explosive and further tests from the literature were used together to develop and stepwise validate finite element analysis models of the different loading phases. The casing fragment velocities and spatial distribution were derived from explosive expansion simulations of the hull using the smooth particle hydrodynamics method together with a momentum conserving penalty contact. The blast loading applied on the concrete plate was based on established empirical formulae, acting at the same times as the fragments. Comparing the final damage with the experimental records revealed good agreement for most damage patterns. The model was used to identify the different damage evolution stages, such as shock-induced shear plug formation and subsequent structural dynamic bending with the associated damage. In addition, differential model variants with fragment and blast loading in isolation were simulated to resolve the response and damage of each loading component. The blast load caused predominantly bending deformations and damage, while the fragments caused similar cratering as seen in the combined case. However, the final combined damage was larger than that caused by each phenomenon. In the given situation, the fragments created most damage, but the established modelling approach opens the perspective to study these effects also for other ratios of explosive to casing weight and scaled distances, where the contributions might differ. Establishing a valid modelling approach is thus an important step towards more insight into the interaction of these complex loading types and damage effects.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"12 1","pages":"49 - 72"},"PeriodicalIF":2.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/2041419620923129","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48010750","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}
Pub Date : 2021-01-31DOI: 10.1177/2041419621990676
A. Hill, E. Williamson
The research presented in this manuscript focuses on the development of an LS-DYNA finite element model to predict the dynamic shear strength of short riveted lap-spliced specimens. Using data collected from experimental testing at the U.S. Army Engineer Research and Development Center (ERDC), a finite element model was developed to replicate the behavior of A502 Grade short riveted connections under quasi-static loading. Subsequent analyses used published Cowper-Symonds constitutive model coefficients to replicate the behavior of these connections under dynamic loading. Computed results were then compared with available test data from ERDC. Given the challenges involved in creating physical models with riveted connections and the abundance of historical bridges constructed with rivets, the developed finite element analysis engineering solution can serve as a critical tool for researchers interested in predicting the response of short riveted connections to dynamic loading and those interested in developing strategies to mitigate against this loading.
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