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In 1989, Nurick and Martin published two review papers on the deformation of thin steel plates subjected to impulsive air-blast loading. The state of the art has progressed significantly in the following 25 years, and this review paper restricts itself to experimental studies that investigate the response of monolithic metal plates subjected to air-blast loading generated by detonating plastic explosive. From the large number of experiments reported, it is shown that the failure progressions in circular and quadrangular plates are similar and can be adequately described by three “failure modes” – namely large plastic deformation (mode I), tensile tearing (mode II) and shearing (mode III) although the severity and location of these failures on the plates is primarily determined by spatial distribution of the blast loading across the plate surface, and that boundary conditions significantly influence the onset of shearing and tearing failures due to variation in the in-plane movement of the plate material. The non-dimensional analysis approaches used by Nurick and Martin have been expanded to include the effects of load localisation and stand-off distance, and show good correlation with the expanded sets of test data published since 1989. It is concluded that these approaches still hold merit as simple tools for evaluating the likely effect of a close proximity air blast load on a flat metal plate. [ABSTRACT FROM AUTHOR]

Composite structures due to their low strain to failure are regarded as a brittle material and are susceptible to possible impact damage during manufacture, maintenance and in use. This paper describes the influence of tension, compression and hybrid preload on E-glass/polyester composite plates under high velocity impact loading in a velocity range of 185 to 235 m/s. Six layered, E-glass plain weave woven roving [0/90] 6 composite panels were made by hand layup method. An innovative preloading apparatus, which is patented with number IRI-83450 was developed to apply the preloading in uniaxial and biaxial directions. This device was used simultaneously with a gas gun to conduct high velocity impact tests. A spherical hard body projectile was used in the impact tests. Uniaxial tension, uniaxial compression and biaxial tension and compression preload were applied to each specimen. To assess the strain rate sensitivity of the material concern under different preloading, three different impact velocities were used. Result showed, the ballistic resistance of the samples with the different preloading condition decreased compared to no preload case. Less variation was observed in exit velocities in the upper impact velocity range test (235 m/s) conducted for all boundary conditions used. A significant increase in the rate of change of residual velocity was observed for the impact velocity of 185.3 m/s compared with that of higher impact velocities tested. Delamination and fiber fracture constituted the major fracture modes followed by matrix fracture. [ABSTRACT FROM AUTHOR]

The numerical simulation of landmine detonation is an extremely difficult task. In this paper, the Smoothed Particle Hydrodynamics (SPH) method is employed to tackle explosion in soil with extremely large deformation and the effects of blast on structures. Firstly, the basic idea of the SPH method and techniques related to the Monaghan-type artificial viscosity, interface treatment with high density ratio, boundary condition implementation, artificial stress, kernel gradient correction, and physical variables update are elaborated. Then three benchmark problems are carried out to validate the explosion, soil and structure models, respectively. Afterwards, the simulations of the explosion in soil and its loading on structures have been conducted on the basis of the verification of these three models. It was observed that the numerical calculations are in good agreement with the experimental results, which shows that the SPH method can handle large deformation problems with high density ratio effectively. [ABSTRACT FROM AUTHOR]

This paper reports the results of an extensive experimental investigation on the behavior of shear-deficient reinforced circular RC columns under lateral impact loading. First, it provides a brief literature review on studies of the dynamic response induced by vehicle collisions on RC columns highlighting the lack of experimental tests on vertical elements. In this context, a novel facility for testing of vertical elements under lateral impact loading was realized. Two different types of RC columns characterized by different hoop spacing were tested, representing a one-third scaled model of a reinforced circular bridge pier, designed with obsolete design practice with particular reference to non-seismic areas. A total of 10 specimens (5 for each type) were tested under a lateral rigid-hammer impact at different impact velocities (2.25, 3 and 4.5 m/s) and boundary conditions (cantilever and fixed-simply-supported). The impact load was applied at the typical vehicular impact location, i.e. near the base. A description of the impact and reaction forces, of the lateral displacements and accelerations, of the damage development and of the post-impact damage is given. The dynamic response and the observed damage are found to be significantly affected by the column type, the impact velocity and the boundary condition. A brittle shear-type damage was observed, characterized by one main diagonal crack originating from the base of the column to the impact point, revealing the high vulnerability of these structural elements. [ABSTRACT FROM AUTHOR]

• A continuum damage mechanics approach is presented for solving impact problems. • A baseline numerical simulation using the concrete damaged plasticity model is established, which can reasonably reproduce the IRIS-2012 punching test results. • A comprehensive parametric study for 14 material, model and control parameters is performed. • Quantitative rules are formulated for proper determinations of these parameters. To investigate the effectiveness of today's analytical methods and to improve the robustness assessment methodologies for reinforced concrete (RC) structures impacted by missiles, an international research project for benchmark tests and numerical simulations of missile impacts on RC panels was launched in the OECD/NEA/CSNI framework. Significant scatter in the predicted results in terms of the target panel displacement, panel strain, support reaction, and the missile residual velocity can be observed in the punching simulations. The benchmark punching test is chosen as a topic of this paper because the concrete and rebars are damaged the most as compared to the flexural test. In this paper, the Continuum Damage Mechanics (CDM) approach with a well posed initial boundary value problem and with the adoption of the Concrete Damaged Plasticity (CDP) model is presented. To formulate a CDM approach suitable for the simulation of complex impact problems, quantitative rules for the proper determinations of the critical material, model, and simulation control parameters are presented. Based on this CDM approach, this paper aims to establish a baseline punching simulation that can reasonably reproduce the IRIS-2012 punching test results. Furthermore, a comprehensive parametric study is performed to investigate the relative susceptibility of 14 material, model, and control parameters that are used in the simulation. Based on this parametric study, it is found that the structural and missile responses are very sensitive to most of these parameters. With these quantitative rules formulated for proper determinations of these parameters, the scatter in result predictions may be significantly reduced, and the accuracy of simulation results can be improved. [ABSTRACT FROM AUTHOR]

Peridynamics is a new nonlocal theory that provides the ability to represent displacement discontinuities in a continuum body without explicitly modeling the crack surface. In this paper, an explicit dynamics implementation of the bond-based peridynamics formulation is presented to simulate the dynamic fracture process in 3D elastic solid. Based on the variational theory, the Discontinuous Galerkin (DG) approach is utilized to formulate the classic peridynamics governing equation. As a result, the spatial integration can be carried out through finite element approach to enforce the boundary conditions, constraints, contacts as well as to handle the non-uniform mesh in the engineering practices. The classic material parameters, such as the elastic modulus and fracture energy release rate are employed for the determination of material response and failure in brittle material. Several numerical benchmarks are conducted to invest the convergence and mesh sensitivity of simulations of dynamic crack propagation process with different refinements. The results demonstrate that the proposed peridynamics formulation can capture the 3D dynamic crack process in brittle material effectively and accurately including multi-crack nucleation, propagation and branching. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of the inter-fiber friction coefficient on fabric ballistic performance. Firstly, dynamic stress responses within a fabric due to first fiber failure are analyzed. Relations between inter-fiber friction and progressive fiber failure are assessed. Then, ballistic perforation processes of Kevlar KM2 fabrics are simulated using a fiber level micro-approach, the digital element approach (DEA). In this model, each yarn is discretized into many fibers and each fiber is divided into many rod elements. A Monte Carlo process is utilized to assign a unique strength to each element following a bimodal Weibull distribution function. DEA is used to simulate the ballistic perforation processes. A comparative investigation using a broad range of inter-fiber friction coefficients are conducted. Relations of ballistic limits and inter-fiber friction coefficients are presented. Simulation results show that ballistic limit improves as the inter-fiber friction coefficient increases up to a critical value. Beyond that point, ballistic strength decreases slightly as the inter-fiber friction coefficient increases. The inter-fiber friction also changes the ballistic perforation mechanisms. [ABSTRACT FROM AUTHOR]

The generation of different waveforms by axial impacts involving a non-uniform bar can be applied in percussive drilling to increase wave energy transfer. It is a good method for obtaining the force and velocity histories at the impacted ends by introducing a delta function, based on 1-D theory. However, they could not be directly predicted, considering that the two impacted ends may be separated from one another, and a clearance is therefore generated between them. In addition, the changing-status of the non-linearities given the repeated separations and contacts is discussed in this paper. The conditions of separation and contact are provided to present a procedure for predicting the parameters at the impacted ends throughout the non-linear process, and the boundary conditions are also considered. As illustrated in an example impact model, the self-recontact behavior resulting from the wave motion occurs, and the possibility for repeated contacts and separations phenomenon is revealed. [ABSTRACT FROM AUTHOR]

The present paper aims at studying the blast response of rectangular elastic thin plates that undergo large deflections. The geometrically nonlinear behavior of the rectangular plate is presented in a nonlinear SDOF model and its detailed analysis is followed. Deflections, as well as bending stresses and membrane stresses for plates with immovable edges and with fully clamped or simply supported flexural edge conditions, are calculated to a uniformly distributed blast pressure loading. Validation of the SDOF technique is carried out through numerous comparisons of large amplitude response of square and rectangular plates under real blast loading, for both clamped and simply supported boundary conditions, with several experimental data as well as with numerical solutions obtained by various authors using the nonlinear Von Karman theory of plates. The coefficients of the nonlinear SDOF model are presented for various support (simple support and clamped) and edge stress conditions (immovable constrained, movable, and stress free). The useful expressions of the Airy function as well as of the dynamic membrane stresses are obtained for the above boundary conditions. A comparison of static and dynamic nonlinear solutions is performed. The relationship between the dimensionless deflection and the maximum membrane stresses is studied as well as their relationship with the corresponding maximum bending stresses. The nonlinear SDOF model has been compared with experimental data and with numerical (FEM, FDM) predictions and good agreement is obtained. [ABSTRACT FROM AUTHOR]

• The geometrical dispersion effect is investigated by 1D Rayleigh-Love rod theory. • A kernel function in explicit form is obtained by Laplace transform method. • Dispersive propagation of four typical boundary pulses are presented. • A dispersion correction method is proposed and veri ed by FE simulation. In this paper, the longitudinal wave propagation in an elastic rod is studied based on the 1D Rayleigh-Love rod theory considering the lateral inertia effect. The Laplace transform method is applied to solve the initial boundary value problem. After conducting the inverse transform, a kernel function in form of integral is obtained, which reveals the essential dispersion characteristics of the wave propagation in a Rayleigh-Love rod. Then the general solution of stress is expressed as the convolution of the kernel function and the boundary loading. Specific examples are given for the problems of typical boundary pulses, i.e. the rectangular, trapezoidal, triangular, and two-stage pulses. Moreover, the dispersive waveforms from our analysis compare nicely with those from the finite element simulation, which indicates that our analytical solution can be used for the dispersion correction in the Hopkinson bar tests. [ABSTRACT FROM AUTHOR]