The NATO agreement STANAG 4569 defines the protection levels for the occupants of logistic and light armored vehicle.The Allied Engineering Publication,AEP-55,Volume 2 document outlines the test conditions for underbe...The NATO agreement STANAG 4569 defines the protection levels for the occupants of logistic and light armored vehicle.The Allied Engineering Publication,AEP-55,Volume 2 document outlines the test conditions for underbelly improvised explosive device(IEDs),which must be buried in water-saturated sandy gravel.The use of sandy gravel has some drawbacks,for instance reproducibility,time consumption,and cost.This paper focuses on the investigation of four alternatives to sandy gravel,which could produce similar specific and cumulative impulses:a concrete pot filled with water,a concrete pot filled with quartz sand,a steel pot without filling and a concrete pot filled with glass spheres(diameter 200μm—300μm)and different water contents.The impulses are measured with a ring technology developed at the Fraunhofer EMI.A numerical soil model based on the work of Marrs,2014 and Fi serov a,2006 and considering the soil moisture was used to simulate the experiments with glass spheres at different water contents,showing much better agreement with the experiments than the classical Laine&Sandvik model,even for high saturation levels.These results can be used to create new test conditions at original scale that are more cost-effective,more reproducible and simpler to manage in comparison to the current tests carried out with STANAG sandy gravel.展开更多
A joint international effort to improve solid propellant performance within the framework of a FP7European Project was described.Several metallized solid rocket propellants,of the broad family AP/HTPB/Metal in the rat...A joint international effort to improve solid propellant performance within the framework of a FP7European Project was described.Several metallized solid rocket propellants,of the broad family AP/HTPB/Metal in the ratio 68/14/18,were experimentally analyzed seeking to optimize the delivered specific impulse by identifying the most suitable high-energy fuel.Keeping the same nominal composition,different metallic fuels(including micrometric and nanometric Al,AlH3,and a variety of dual metal compositions)were characterized,tested,and contrasted to a conventional micrometric aluminum(30μm average grain size)certified for space flights.In order to overcome the intrinsic performance limitations of the matrix AP/HTPB,a new matrix consisting of ADN/GAP satisfying also the need for environmentally benign propellant formulation was considered as well.A comparative analysis between the two solid propellant systems in terms of ideal thermochemistry and experimental combustion properties reveals advantages and disadvantages of both.Overall,it is judged worthwhile to develop ADN/GAP propellants,with or without metallic fuels,to enhance the current status of solid rocket propulsion.Controlling morphology and mechanical properties of ADN/GAP compositions and understanding their flame structure and aggregation/agglomeration properties are the main issues still challenging industrial users.展开更多
In this paper,a modified single-degree-of-freedom(SDOF)model of reinforced concrete(RC)beams under close-in explosion is proposed by developing the specific impulse equivalent method and flexural resistance calculatio...In this paper,a modified single-degree-of-freedom(SDOF)model of reinforced concrete(RC)beams under close-in explosion is proposed by developing the specific impulse equivalent method and flexural resistance calculation method.The equivalent uniform specific impulse was obtained based on the local conservation of momentum and global conservation of kinetic energy.Additionally,the influence of load uniformity,boundary condition and complex material behaviors(e.g.strain rate effect,hardening/softening and hoop-confined effect)was considered in the resistance calculation process by establishing a novel relationship between external force,bending moment,curvature and deflection successively.The accuracy of the proposed model was verified by carrying out field explosion tests on four RC beams with the scaled distances of 0.5 m/kg~(1/3)and 0.75 m/kg~(1/3).The test data in other literatures were also used for validation.As a result,the equivalent load implies that the blast load near the mid-span of beams would contribute more to the maximum displacement,which was also observed in the tests.Moreover,both the resistance model and test results declare that when the blast load becomes more concentrated,the ultimate resistance would become lower,and the compressive concrete would be more prone to softening and crushing.Finally,based on the modified SDOF model,the calculated maximum displacements agreed well with the test data in this paper and other literatures.This work fully proves the rationality of the modified SDOF method,which will contribute to a more accurate damage assessment of RC structures under close-in explosion.展开更多
Several metallized solid rocket propellants,AP/Metal/HTPB in the ratio 68/18/14,were experimentally analyzed at the Space Propulsion Laboratory of Politecnico di Milano.Effects of the metals(micrometric and nanometric...Several metallized solid rocket propellants,AP/Metal/HTPB in the ratio 68/18/14,were experimentally analyzed at the Space Propulsion Laboratory of Politecnico di Milano.Effects of the metals(micrometric and nanometric Al,B,Mg,and a variety of dual metals) on the performance of the propellant were studied and contrasted to a conventional micrometric aluminum(30 μm average grain size) taken as reference.It is shown that the propellant microstructure plays a fundamental role in controlling the critical aggregation/agglomeration phenomena occurring below and near the burning surface.Two specific effects of microstructure in terms of steady burning rate and average agglomerate size are illustrated.展开更多
Six furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants have been investigated.It was shown that the use of some furazano-[3,4-d]-pyridazine-based derivatives as main compoun...Six furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants have been investigated.It was shown that the use of some furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants can considerably increase ballistic parameters compared with HMX if the compounds under consideration contain difluoramine groups.And the use of the compounds under consideration may be successful only in the presence of an active binder and 10%-30% of AP or ADN as additional oxidizers.展开更多
基金Bundeswehr Technical Center for Weapons and Ammunition WTD-91 GF-440 in Meppen,Germany for funding this work。
文摘The NATO agreement STANAG 4569 defines the protection levels for the occupants of logistic and light armored vehicle.The Allied Engineering Publication,AEP-55,Volume 2 document outlines the test conditions for underbelly improvised explosive device(IEDs),which must be buried in water-saturated sandy gravel.The use of sandy gravel has some drawbacks,for instance reproducibility,time consumption,and cost.This paper focuses on the investigation of four alternatives to sandy gravel,which could produce similar specific and cumulative impulses:a concrete pot filled with water,a concrete pot filled with quartz sand,a steel pot without filling and a concrete pot filled with glass spheres(diameter 200μm—300μm)and different water contents.The impulses are measured with a ring technology developed at the Fraunhofer EMI.A numerical soil model based on the work of Marrs,2014 and Fi serov a,2006 and considering the soil moisture was used to simulate the experiments with glass spheres at different water contents,showing much better agreement with the experiments than the classical Laine&Sandvik model,even for high saturation levels.These results can be used to create new test conditions at original scale that are more cost-effective,more reproducible and simpler to manage in comparison to the current tests carried out with STANAG sandy gravel.
基金supported by the HISP project(High performance solid propellants for In-Space Propulsion)of the European Community′s Seventh Framework Programme(FP7/2007-2013), under Grant Agreement No.262099,coordinated by FOI
文摘A joint international effort to improve solid propellant performance within the framework of a FP7European Project was described.Several metallized solid rocket propellants,of the broad family AP/HTPB/Metal in the ratio 68/14/18,were experimentally analyzed seeking to optimize the delivered specific impulse by identifying the most suitable high-energy fuel.Keeping the same nominal composition,different metallic fuels(including micrometric and nanometric Al,AlH3,and a variety of dual metal compositions)were characterized,tested,and contrasted to a conventional micrometric aluminum(30μm average grain size)certified for space flights.In order to overcome the intrinsic performance limitations of the matrix AP/HTPB,a new matrix consisting of ADN/GAP satisfying also the need for environmentally benign propellant formulation was considered as well.A comparative analysis between the two solid propellant systems in terms of ideal thermochemistry and experimental combustion properties reveals advantages and disadvantages of both.Overall,it is judged worthwhile to develop ADN/GAP propellants,with or without metallic fuels,to enhance the current status of solid rocket propulsion.Controlling morphology and mechanical properties of ADN/GAP compositions and understanding their flame structure and aggregation/agglomeration properties are the main issues still challenging industrial users.
基金National Natural Science Foundation of China(Grant No.12102337)to provide fund for conducting experiments。
文摘In this paper,a modified single-degree-of-freedom(SDOF)model of reinforced concrete(RC)beams under close-in explosion is proposed by developing the specific impulse equivalent method and flexural resistance calculation method.The equivalent uniform specific impulse was obtained based on the local conservation of momentum and global conservation of kinetic energy.Additionally,the influence of load uniformity,boundary condition and complex material behaviors(e.g.strain rate effect,hardening/softening and hoop-confined effect)was considered in the resistance calculation process by establishing a novel relationship between external force,bending moment,curvature and deflection successively.The accuracy of the proposed model was verified by carrying out field explosion tests on four RC beams with the scaled distances of 0.5 m/kg~(1/3)and 0.75 m/kg~(1/3).The test data in other literatures were also used for validation.As a result,the equivalent load implies that the blast load near the mid-span of beams would contribute more to the maximum displacement,which was also observed in the tests.Moreover,both the resistance model and test results declare that when the blast load becomes more concentrated,the ultimate resistance would become lower,and the compressive concrete would be more prone to softening and crushing.Finally,based on the modified SDOF model,the calculated maximum displacements agreed well with the test data in this paper and other literatures.This work fully proves the rationality of the modified SDOF method,which will contribute to a more accurate damage assessment of RC structures under close-in explosion.
基金supported by CNES(under Commande No.4700024752/DLA090 and No.4700028003/DLA094)
文摘Several metallized solid rocket propellants,AP/Metal/HTPB in the ratio 68/18/14,were experimentally analyzed at the Space Propulsion Laboratory of Politecnico di Milano.Effects of the metals(micrometric and nanometric Al,B,Mg,and a variety of dual metals) on the performance of the propellant were studied and contrasted to a conventional micrometric aluminum(30 μm average grain size) taken as reference.It is shown that the propellant microstructure plays a fundamental role in controlling the critical aggregation/agglomeration phenomena occurring below and near the burning surface.Two specific effects of microstructure in terms of steady burning rate and average agglomerate size are illustrated.
基金Ministry of Education and Science of the Russian Federation(14.613.21.0043)
文摘Six furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants have been investigated.It was shown that the use of some furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants can considerably increase ballistic parameters compared with HMX if the compounds under consideration contain difluoramine groups.And the use of the compounds under consideration may be successful only in the presence of an active binder and 10%-30% of AP or ADN as additional oxidizers.
