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This article presents the results of an investigation into the response of partially confined hollow stainless steel cylinders to internal air-blast loading. Numerical, theoretical and experimental analyses were performed to gain insight into the factors governing the deformation processes. Numerically, LS-DYNA was used to simulate the response of the steel single-walled cylinders and compare it to the response of various equivalent mass sandwich-walled cylinders with different mass distributions through the wall thickness. It was established that sandwich-walled cylinders with low density foam core outperform the single-walled cylinder while the higher density foam core sandwich-walled cylinders respond by larger maximum deflections compared to the single-walled equivalent. A theoretical model was developed for the deformation of a sandwich-walled ring configuration and used to analyse and interpret the process of the dynamic foam compaction and stress transmission to the outer wall of a sandwich-walled cylinder. The results from the numerical parametric study and theoretical analysis are used further to design a sandwich-walled cylinder which would outperform the equivalent mass single-walled steel tube. Experimentally, the blast loading was generated by detonating spheres of plastic explosive at the mid-point of the centre line of the cylinders. Partial confinement was created by closing one end of the cylinder and leaving the other end free to vent to air. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports results from impact and blast loading experiments on aluminium foam. The impact tests covered the velocity range required to induce non-uniform strain, and the propagation of a densification front through the specimen (often referred to as ‘shock’). In the direct impact tests, the velocity and test direction influenced the material response, with the stress tending to increase with velocity in the reverse direction. No significant increase in the stress was exhibited during the forward direction tests. This is in accordance with shock theory. Taylor test results confirmed the presence of shock in the foam specimens at impacts in excess of 60m/s. For the blast tests, the impulse range produced by detonating plastic explosive did not result in shock loading of foam core cladding specimens. As strength enhancement due to shock may be undesirable in cladding structures due to the increased stress transfer to the protected structure, the cladding was considered acceptable. [Copyright &y& Elsevier]

Abstract: This two-part article examines the behaviour of aluminium alloy–glass fibre-reinforced polypropylene-based fibre–metal laminates (FMLs) subjected to localised explosive blast loading. Part I presents observations from the experiments on samples of varying thickness and material distribution, and investigates the influence of stacking configuration. This extensive study examines panels which have between two and five layers of aluminium, and up to eight plies of composite between each pair of aluminium layers. Diamond and cross-shaped back face damage is observed and varies according to panel thickness. Pitting, global displacement and ring buckling of the front face are also discerned. Some observations are related to wave propagation effects. Part II reports a quantitative analysis of the experimental data. Expressed in terms of non-dimensional parameters, front and back face displacements fall within one plate thickness of a linear trend line. The threshold impulse for the onset of tearing is found to increase linearly with panel thickness. [Copyright &y& Elsevier]

Abstract: This three-part article presents the results of experimental, analytical and numerical studies on the response of scale stainless steel blast wall panels and connection systems. The panel design was based on a deep trough trapezoidal profile with welded angle connections top and bottom and free sides. The loading applied to the panel was a triangular pulse pressure representative of a gas explosion overpressure. The aim of this work was to investigate the influence of the connection detail on the overall performance of the panel/connection system under pulse pressure loading and to develop appropriate analytical and numerical models for correlation with the test results. Part I reported on the experimental investigations, whilst the analytical modelling considerations were examined in Part II. Finite element analysis, with ABAQUS, was used to simulate the blast wall panel behaviour and is discussed in Part III. Large permanent plastic deformations were produced in the panels without rupture, and localised buckling developed at the centre of the corrugations. The work highlights the importance of correctly modelling the support details and the variation in strength with blast direction (the blast wall panels being stronger in the design direction). The modelling approaches predict a design capacity that is 39% higher than the current design guidance predicts, as a result of modelling the supports and including membrane action. [Copyright &y& Elsevier]

An experimental and analytical study is presented of the inelastic deformation and failure (rupture) of clamped aluminium plates measuring 0.5 m×0.5 m at the clamped edge by 1 mm thick under pulse pressure loading. The pulse loading was applied by generating a dynamic pressure gradient across the plates using a fast differential pressure device. Both static and dynamic test results are reported together with the results of an investigation of the failure surface using scanning electron microscopy. An assumed-modes, elastic–plastic analysis of the plates using a finite strip model was used to predict the maximum displacement of the plates. A simple uniaxial strain-based failure criterion was used in the analysis to predict the failure pressure of the ruptured plates. The rigid-plastic method was used to estimate the permanent deformation of some of the plates. Reasonable agreement is obtained between the predictions of the simplified elastic–plastic analysis and the experimental results. The rigid-plastic results were less accurate at predicting the permanent deformation of the plates due to the long duration of the loading relative to the fundamental natural period of the plates. [Copyright &y& Elsevier]

Abstract: This paper reports the findings of a research study investigating the energy-absorbing characteristics of polymer foams reinforced with small carbon fibre reinforced epoxy tubes. Initial attention focuses on establishing the influence of tube diameter on the specific energy absorption (SEA) characteristics of the chamfered CFRP tubes. Here, it is shown that the SEA of the tubes increases rapidly with decreasing diameter/thickness ratio, with the highest values being close to 93kJ/kg. Similar tests were conducted at dynamic rates of strain, where it was observed that the measured values of SEA were lower than the corresponding quasi-static data, possibly due to rate-sensitive effects in the delamination resistance of the composite material. In the next stage of the investigation, the composite tubes were embedded in a range of polymer foams in order to establish the influence of both tube arrangement and foam density on the crush behaviour of these lightweight structures. In addition, a limited number of blast tests have been undertaken on structures based on these core materials. Here, extensive crushing of the composite tubes was again observed, suggesting that these structures should be capable of absorbing significant energy when subjected to this severe loading condition. Finally, the results of these tests are compared with previously-published data from studies on a range of different cores materials. Here, it has been shown that the energy-absorbing characteristics of these systems exceed values associated with other core materials, such as aluminium honeycombs, polymer honeycombs and metal foams. [Copyright &y& Elsevier]

Abstract: This paper reports on experimental and numerical investigations into the response of flexible sandwich-type panels when subjected to blast loading. The response of sandwich-type panels with steel plates and polystyrene cores are compared to panels with steel face plates and aluminium honeycomb cores. Panels are loaded by detonating plastic explosive discs in close proximity to the front face of the panel. The numerical model is used to explain the stress attenuation and enhancement of the panels with different cores when subjected to blast induced dynamic loading. The permanent deflection of the back plate is determined by the velocity attenuation properties (and hence the transmitted stress pulse) of the core. Core efficiency in terms of energy absorption is an important factor for thicker cores. For panels of comparable mass, those with aluminium honeycomb cores perform “better” than those with polystyrene cores. [Copyright &y& Elsevier]

Abstract: This two part paper examines the behaviour of fibre-metal laminates (FMLs) subjected to localised explosive blast loading. Part I presents the experimental observations of diamond and cross-shaped back face deformation, as well as pitting, global displacement and ring-buckling of the front face are also discerned. Part II presents quantitative analysis of the experimental data. When expressed in terms of non-dimensional parameters front and back face displacements fall within one plate thickness of a linear trend line. The threshold impulse for the onset of tearing is found to increase linearly with panel thickness. [Copyright &y& Elsevier]

Abstract: A range of metallic lattice structures have been manufactured using the selective laser melting (SLM) rapid manufacturing technique. The lattice structures were based on [±45°] and [0°, ±45°], unit-cell topologies. Initially, the structures were loaded in compression to investigate their progressive collapse behaviour and associated failure mechanisms. Tests were then undertaken at crosshead displacement rates up to 3m/s in order to characterise the rate-dependent properties of these architectures. A series of blast tests were then undertaken on a ballistic pendulum in order to investigate the behaviour of lattice structures under these extreme loading conditions. During the compression tests, a buckling mode of failure was observed in the [0°, ±45°] lattice structures, whereas a stable progressive mode of collapse was evident in the [±45°] structures. The yield stress of the lattice structures exhibited moderate rate sensitivity, increasing by up to 20% over the range of conditions considered. The blast resistance of the lattice structures increased with increasing yield stress and has been shown to be related to the structures specific energy-absorbing characteristics. An examination of the lattice samples indicated that the collapse mechanisms were similar following both the compression and blast tests. [Copyright &y& Elsevier]