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An experimental investigation is presented into the explosive blast response of fibre-reinforced polymer laminates used in naval ship structures. Blast tests using plastic explosive charges were performed in air on square target plates made of carbon-polyester, glass-polyester, carbon-vinyl ester or glass-vinyl ester laminates, which are composite materials used in naval ships. The laminates were dynamically loaded by shock waves of increasing pressure and impulse, and the deformation, damage and residual mechanical properties were determined. The amount of blast-induced damage and the post-blast mechanical properties depend on both the fibre reinforcement and polymer matrix. E-glass laminates have higher resistance to blast-induced delamination cracking and tow rupture than carbon fibre composites. Furthermore, glass or carbon fibre laminates with a vinyl ester matrix have superior blast damage resistance compared to composites with a polyester matrix. The higher damage resistance is attributed to the higher flexural strain energy capacity and interlaminar fracture toughness properties of laminates containing glass fibres or vinyl ester matrix. [ABSTRACT FROM AUTHOR]

This paper investigates the fragment performance of several composite panels for attaching to the inside walls of a building structure. These panels were developed using different types of fiber woven fabrics (W0, W90) combined with distinct layers orientations (angle-ply effect) of L0/0 and L0/15. Aramid, E-glass, and S-glass fiber fabrics impregnated with thermosetting epoxy resin, and a prepreg of Ultra High Molecular Weight Polyethylene (HB24) were employed. The panels are subjected to ballistic impact using different fragments under impact velocities in the range of 120 to 420 m/s. In order to measure the energy absorbed by the ballistic panels, the impact velocity and the residual velocity of the fragment were measured with laser chronographs placed before and after the laminated test specimens. The paper demonstrates quantitatively that the angle-ply laminates produced using L0/15 woven fabric orientation presented a higher impact energy absorption, promoting higher reductions on the fragment residual velocity compared to the L0/0 orientations. The laminates produced using UHMWPE fibers (HB24) presented better ballistic properties compared to the other fibers. Furthermore, it was noted that the energy dissipation rate is linearly correlated with the impact velocity and is independent of the fragment geometry. [ABSTRACT FROM AUTHOR]

This work investigates the use of blast loadings and inverse modeling for the identification of the strain rate hardening model parameters of fibre reinforced polymers. An experimental setup allowing the generation of known and predictable blast waves, leading to repeatable dynamic response in composite plates and the measurement of the displacement and strain fields, is developed. The dynamic response of the plates is measured by means of high-speed cameras and a 3D digital image correlation technique. A suitable numerical model that is able to reproduce the experimental conditions and predict the blast response of the plates is developed. Finally, the experimental measurements and the numerical calculation are combined through an inverse method in order to identify the strain rate hardening model parameters of the tensile and shear strengths of glass fibre reinforced epoxy. [ABSTRACT FROM AUTHOR]

Despite having a high strength-to-weight ratio and being chemically inert, fiber-reinforced polymer (FRP) reinforcing bars are not currently used in reinforced concrete protective design due to their brittle nature and lack of ductility. This paper presents research on the innovative use of blended mixtures of FRP and steel rebar to activate self-centering behavior to return blast-loaded elements to their original position after the inertial loads are removed. Self-centering blast-resilient members promise reductions in residual damage, repair cost, and facility downtime after a terrorist bomb attack or accidental explosion. Large-scale reinforced concrete beams with different combinations of steel and glass FRP (GFRP) rebar were designed, constructed, and tested under progressively increasing blast loads generated by the Virginia Tech Shock Tube Research Facility. The results demonstrated that beams with hybrid reinforcing experienced reduced overall residual damage in comparison with similar conventionally reinforced concrete members. Increasing the self-centering ratio (SC) of beams, defined as the ratio of the restoring moment provided by the FRP to the resisting moment provided by energy dissipating steel rebar, increased the blast self-centering tendencies of the hybrid beams. Additionally, if the GFRP rebar ruptured during the blast, the presence of steel prevented a brittle failure mechanism and provided additional energy dissipation and redundancy. To encourage the use of hybrid FRP-steel reinforcement in blast-resistant construction, a series of protective design recommendations are made. Furthermore, a new response limit based on a blast self-centering index (BSI) is proposed to explicitly account for the residual damage state in the protective design process. [ABSTRACT FROM AUTHOR]

Perforation failure of fibre metal laminate (FML) panels subjected to the localized high intensity blast loading is studied. The FMLs are based on various stacking configurations of aluminium alloy sheets and layers of woven glass fibre in a polypropylene matrix (GFPP) composite. Finite element models of the FMLs were created using the commercial software package Abaqus/Explicit, where the constitutive relationships and damage in the composite material were described through a user-defined subroutine. The composite was modelled as an orthotropically elastic material prior to damage initiation and the growth of subsequent damage was based on an instant failure rate-dependent model. The simulated deformation and failure modes in the FMLs were found to be in good agreement with published experimental data. For FMLs based on thin GFPP layers, a number of dynamic failure scenarios were captured, such as petalling, large tensile tearing and multiple debonding between the aluminium and GFPP layers. A high degree of correlation between simulated failure on the back face aluminium and the underlying GFPP damage modes was revealed. Finally, the transient behaviour of FML panels during blast loading was studied and discussed. [ABSTRACT FROM AUTHOR]

The results of blast tests on sandwich panels with honeycomb cores are reported. Two core heights (13 mm and 25 mm) and two face sheet materials (glass fiber epoxy composite and aluminum alloy) were investigated. Increasing the core thickness reduced the permanent displacements exhibited by the sandwich panels. The panels with composite face sheets also exhibited smaller residual displacements than the aluminum face sheet counterparts. Damage took the form of core crushing, core shearing, debonding of the face sheet from the core, permanent displacement, cracking of the composite face sheets, and tearing. Higher damage levels were observed at elevated impulse levels. Load localization was found to concentrate the damage to the central portion of the panel, preventing the whole panel being employed in resisting the blast. [ABSTRACT FROM AUTHOR]