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• A steel–concrete-steel sandwich panel with energy absorbing supports (SSP-EAS) was developed for impact resisting. • The impact resistant performances of the SSP-EAS were experimentally and numerically investigated. • Impact response modes and failure modes of the SSP-EAS were studied. • The effects of crushing force of EAS and initial impact momentum on impact behaviors of the SSP-EAS were analyzed. A new steel–concrete-steel sandwich panel with energy absorbing supports (SSP-EAS) was firstly proposed, and its dynamic responses under impact loading were investigated through conducting impact tests and numerical simulations. Three types of impact response modes of SSP-EASs were categorized according to the different crushing magnitudes of energy absorbing supports (EASs). In addition, the steel–concrete-steel sandwich panel (SSP) exhibited the combination of the global flexural deformation, local indentation and local bulging during the impact. The EAS could effectively absorb impact energy through the plastic bending of steel plates and the crushing of aluminum foam blocks, except for the response mode I with insignificant crushing of EASs. Moreover, the effects of crushing force of EASs and initial impact momentum on the dynamic responses of SSP-EAS were numerically analyzed. The impact resistance of the SSP-EAS could be improved through properly designing the EAS and assuring its maximum displacement slightly smaller than the compaction displacement during impact. In addition, the crushing force of EAS should not exceed the ultimate resistance of the SSP to assure the EAS being triggered to crush. Moreover, the SSP-EAS exhibited enhanced impact performances under higher initial impact momentum. [ABSTRACT FROM AUTHOR]

In this paper, the drop-weight impact loading tests were conducted to study the dynamic crushing behaviors of the proposed energy absorption connectors with curved plate and aluminum foam as energy absorber. The dynamic collapse modes of the connectors were obtained from the tests and three deformation processes were identified. The effects of loading rate, filled aluminum foam, curved plate thickness and radius on the energy absorption performances of the connectors were quantitatively evaluated, which showed that filling the connector with aluminum foam as well as increasing loading rate, curved plate thickness and radius generally led to increase of energy absorption capacity of the connector. Besides the experimental works, the numerical and analytical models were also developed to predict the force–displacement responses of the connectors and the accuracies of the two models were validated against the test results. The developed analytical model could be utilized as a convenient tool to quickly evaluate the energy absorption performances of such connectors under impact loading. [ABSTRACT FROM AUTHOR]

In this paper, the energy absorption performances of the aluminum foam filled connectors under drop-weight impact loading were first evaluated via using experimental method. The dynamic crushing behaviors of the connectors were examined and three deformation processes were identified from the experiments. The effects of loading rate, filled aluminum foam, pleated plate thickness and angle θ o (the angle between flat plate and pleated plate) on the energy absorption performances of the connectors were experimentally investigated, which showed that the energy absorption capacity was improved by filling the connector with aluminum foam as well as increasing loading rate, pleated plate thickness and angle θ o . Moreover, the numerical and analytical models were also developed to predict the force–displacement responses of the connectors, which showed good agreement with the test results. The developed analytical model could be used as a convenient tool to quickly evaluate the energy absorption performances of such connectors under impact loading. [ABSTRACT FROM AUTHOR]

• A SCS panel with energy absorption connectors (SCS-EC) was proposed for impact resisting. • Drop-weight impact tests and Finite Element simulations were conducted on the SCS-EC. • Failure modes and impact responses of the SCS-EC were obtained. • The effect of variant parameters on impact response of the SCS-EC was analyzed. This paper developed a new steel-concrete-steel sandwich panel with energy absorption connectors (SCS-EC) for resisting impact load, and the impact responses of the SCS-EC were studied by conducting impact tests and Finite Element (FE) simulations. The failure modes of the SCS-EC under impact loading could be categorized into two types based on the crushing magnitude of the energy absorption connector (EC). The EC was found to effectively dissipate impact energy via the plastic deformation of pleated steel plates and the compression of aluminum foam fillers. The steel-concrete-steel (SCS) panel showed the combination of global and local deformation under impact loading. Moreover, the influences of pleated plate thickness (t p) and angle (θ p), aluminum foam filler and initial momentum on the impact performances of the SCS-EC were studied quantitatively. The results showed that the SCS-EC exhibited enhanced impact resistance via increasing initial momentum of the impactor as well as filling aluminum foam in the EC and assuring the maximum crushing displacement of the EC being equal to its densification displacement. [ABSTRACT FROM AUTHOR]

Two type novel aluminum foam filled energy absorption connectors were proposed to be inserted between the blast resistant façade and building to absorb blast energy and reduce blast load transferred to the building. In this paper, the nonlinear finite element (FE) method was adopted to study the energy absorption performances of the two type connectors. The FE models of the connectors under quasi-static compression loading were first established and the accuracies of the FE models were verified by comparing the force–displacement curves obtained from tests and FE analyses. Then, the FE models were used to investigate the effects of filled aluminum foam, plate thickness and geometry as well as aluminum foam width on the energy absorption performances of the two type connectors. It was found that the two type connectors showed comparable energy absorption performances and the specific energy absorption could be significantly improved by filling the connector with aluminum foam. [ABSTRACT FROM AUTHOR]

A novel energy absorption connector with pleated plate and aluminum foam as energy absorber was proposed to be inserted between the blast resistant façade and building to absorb blast energy and reduce blast load transferred to the building. The energy absorption performance of the connector under quasi-static compression loading was first studied by using experimental method. The deformation mechanisms were observed from the experiment and three different deformation processes were also identified. The effects of aluminum foam, pleated plate thickness and angle θ o (the angle between flat plate and pleated plate) as well as pleat number on the energy absorption performance of the connector were experimentally investigated, which showed that the energy absorption capacity could be improved by filling the connector with aluminum foam and increasing the pleated plate thickness, angle θ o and pleat number. Moreover, an analytical model for determining the load–displacement curve of the energy absorption connector was also developed and the predictions by the analytical model were proven to be reasonable by comparing with the experimental data. [ABSTRACT FROM AUTHOR]

A novel multilayer façade system, which consisted of a water steel tank integrated with a layer of energy absorbing aluminum foam panel and a stiffened steel panel, was developed to resist blast loading. The blast resistance and response behavior of the proposed façade system were investigated using nonlinear finite element method. The accuracy of the numerical model was verified by comparing the predicted results with the test results. The analyses showed that the energy absorbing aluminum foam layer was capable of reducing the blast load acting on the façade panel and building. The blast resistance of the multilayer façade system could be further enhanced by increasing the aluminum foam layer thickness. An analytical model considering Dynamic Increase Factor (DIF) and coupled deflection mode shapes was developed to predict the displacement response of the façade system subjected to blast loading. The accuracy of the analytical model was validated by comparing the predicted results with the numerical results. It was found that the analytical model with varying DIF could provide better prediction of the displacement response of the multilayer water façade system as compared to the method using a constant DIF. [ABSTRACT FROM AUTHOR]

The blast performance of water tank with an innovative energy absorbing support was studied to reduce the support reaction force and mitigate the damage on the water tank. The aluminum foam was adopted as the energy absorbing material, since it has high energy absorbing potential during crush plateau and safety backup zone after the compaction strain. Finite element model considering fluid and structural interaction in which the water is modeled using the Eulerian formulation and the steel tank by Lagrangian formulation is proposed. The proposed numerical model of water tank was verified by comparing the predicted results with the test results obtained from dynamic pressure tests on steel tanks filled with water. The numerical results showed that the support reaction force depends on the density and yield strength of the aluminum foams and the reaction force could be reduced significantly if softer aluminum foam was chosen. The total displacement of the water tank was increased by up to 38% due to the increase in deformation of the energy absorbing foam. The aluminum foam was proposed to absorb the blast energy and reduce the damage on the water tank. However, more damage on the water tank was observed when a very low density aluminum foam support was used. This was attributed to the increased external work done by blast loading which was higher than the energy absorbed by the aluminum foam support. [ABSTRACT FROM AUTHOR]

In this paper, a novel cladding sandwich panel with aluminum foam-filled tubular cores (AFTC panel) was proposed to enhance the impact resistant performance of the traditional sandwich panel with empty tubular cores (ETC panel). The impact force and displacement responses, failure modes and energy absorption of the ETC and AFTC panels under impact loading were studied via drop-weight impact tests and numerical simulations. It was found that the impact process of the sandwich panel could be divided into three stages. In addition, the tubular cores and aluminum foam filler were found to dissipate the majority of the impact energy. The effects of impactor shape, impact position, aluminum foam filler and thickness ratio of flat steel plate to tube ( t f / t t ) on the impact behaviors of the sandwich panels were quantitatively studied. The results indicated that the impact force and energy absorption could be improved via filling aluminum foam, increasing the aluminum foam density and increasing the contact area between the impactor and sandwich panel. Filling aluminum foam could also avoid the sharp increase of the impact force after the compaction of the sandwich panel. The impact position exhibited little effect on the energy absorption of the sandwich panel when it was away from the edge of the sandwich panel. Moreover, the sandwich panel generally exhibited better energy absorption performances via specifying the flat steel plate and tubular cores to be of similar thickness. • A novel cladding sandwich panel was proposed for dissipating impact energy. • Drop-weight impact tests and FE simulations were conducted on the sandwich panel. • Failure modes and energy absorption behaviors of the sandwich panel were obtained. • The effect of variant parameters on responses of the sandwich panel was analyzed. [ABSTRACT FROM AUTHOR]

Nowadays, the aluminum alloy building structure is at risk of the accidental impact loadings, which seriously threatens the personal security and the safety of the property. However, the existing research on the local lateral impact performance of the aluminum foam-filled tube applied to building structures is limited. In this study, impact tests on 9 aluminum foam-filled tubes with fixed boundaries were conducted by using a drop hammer impact test device to investigate the dynamic performance of the foam-filled tube under local lateral low-velocity impact loadings. The failure modes, impact force histories, displacement histories, and permanent deformation of the foam-filled tubes were obtained and compared with those of the empty tubes under the same impact loading. The finite element (FE) model was also established via the software ANSYS/LS-dyna and the accuracy of the FE method was verified against impact test results. Based on the experimental and numerical results, the aluminum foam-filled aluminum tube shows better lateral impact resistant performance than the empty tube due to the support effect of the aluminum foam on the tube wall by good energy absorption and deformation characteristics. Especially, filling the aluminum foam prevents the generation of cracks for the composite tube near the impact position when the impact energy is high. The influence law of the aluminum foam filler and its density, shape of hammer head on the lateral impact resistant performance of the aluminum foam-filled composite tube was then investigated based on the experimental and numerical results by consideration of the damage level, energy absorption, impact force–lateral displacement relationship, and permanent deformation. By filling the aluminum foam into the empty tube, the energy absorption is improved by up to 67.2% and 44.9%, respectively, when the hammer displacement reaches 20 mm and 40 mm within the impact load condition conducted in this study. • Local lateral impact behavior on fully clamped AL foam-filled tube is studied. • AL foam filler improves the impact resistance and energy absorption capacity. • The interaction between AL foam and tube wall decreases deformation degree of tube. • Both depth and length of the local deformation region are reduced after filling. [ABSTRACT FROM AUTHOR]

A novel cladding–connector system with excellent energy absorption capacity was proposed to protect vulnerable walls in frame structures subjected to blast load in the present study. The cladding–connector system was constructed by combining a sacrificial cladding consisting of an aluminum foam core sandwiched by two steel plates and four connectors made of corrugated steel tubes. On one hand, the cladding absorbed a considerable amount of blast energy. On the other hand, the connectors controlled the load transfer to the protected structure to certain specific pre-defined value. With this approach, both relatively high energy absorption and relatively low load transfer can be achieved simultaneously. Specifically, based on the quasi-static compression test on the connectors and the field blast test on the sacrificial cladding, the numerical model of the proposed system was established with ANSYS/LS-DYNA and validated with the test results. Then the deformation mode, energy dissipation, and load transfer of the cladding–connector systems with flexible or rigid connectors under various charge weights were numerically studied and compared. Results showed that the proposed cladding–connector​ systems could dissipate a considerable amount of energy under blast, in which the major part was dissipated by the cladding and the rest by the connectors. Particularly, compared to the cladding–connector system with rigid connectors, the cladding–connector system with flexible connectors exhibited superior performance in terms of energy absorption and load transfer, especially under intense blast. With the merits of excellent energy absorption, significant blast intensity reduction, and load shift from the vulnerable walls to the load-bearing components, the proposed cladding–connector system with flexible connectors was more promising to effectively protect the existing frame structures against blast. • A cladding–connector system is proposed to protect walls of frame structures subjected to blast. • The proposed system shifts the blast load applied on the wall to the load-bearing frame. • The system simultaneously realizes favorable energy absorption and load transfer control. • The system absorbs a considerable amount of energy in a designable manner. • The system reduces the transferred load intensity in a designable manner. [ABSTRACT FROM AUTHOR]

• Small face plate mass led to a significant increase in energy input to system. • Foam core absorbed the majority of energy input to the system through crushing. • Protection effectiveness was governed by energy input increase and energy absorption. • Increasing face plate mass and foam core strength contributed to positive protection. The protection effectiveness of the sacrificial cladding, consisting of a steel face plate and an aluminum foam core, subjected to near-field blast was experimentally and numerically investigated in the present study. It was proposed to evaluate the protection effect of the sacrificial cladding from two perspectives, namely, the increased energy input to the cladding-structure system as well as the increased energy absorption of the system. First, a blast test was conducted on the monolithic steel plates without and with sacrificial cladding under the TNT equivalent charge weights of 400 g and 1400 g, in which both the positive protection effect with 400 g charge weight as well as the negative protection effect with 1400 g charge weight were observed. Subsequently, numerical simulation with the model validated by the test data was employed to further investigate the blast mitigation effectiveness. The numerical results suggested that applying sacrificial cladding would lead to a significant increase in the energy input to the cladding-structure system, thus the negative protection effect of the cladding occurred when the increased energy input to the system was more than the energy absorption of the cladding. Furthermore, from the viewpoint of the energy input to the system and the energy absorption of the cladding, the influence of some important factors including the face plate thickness (mass), core strength, and stand-off distance on the protection effectiveness of the sacrificial cladding was further investigated with numerical simulation. The results showed that with cladding, a near-field blast with a small stand-off distance with the same charge weight was likely to lead to a negative protection effect due to the significantly increased energy input to the system. To realize the positive protection effect of the cladding, the measures of increasing the face plate thickness (mass) and the core strength were feasible since they could significantly reduce the energy input to the system and increase the energy absorption of the cladding simultaneously. The results in the present study provided a reference for the preliminary design and application of sacrificial cladding in structural protection. [ABSTRACT FROM AUTHOR]