High Velocity Impact Response Research Articles

Effect of reinforcement type on high velocity impact response of GRP plates using a sharp tip projectile

High velocity impact performance of glass reinforced polyester (GRP) resin composite plates with different type of reinforcement was investigated. The projectile used was a sharp tipped (30°) conical head with total length of 30 mm and shank length of 15 mm with weight of 9.74 g. Five different types of E-glass fiber reinforcement were used, including chopped strand mat (CSM), plain weave, satin weave, unidirectional and cross-ply unidirectional fiber reinforcements. A smooth barrel gas gun was used to conduct high velocity impact tests in the velocity range of 80–160 m/s. Composite plates with size of 15 cm × 15 cm were prepared in 3 and 6 mm thickness. Results showed higher ballistic limit velocity (velocity at which samples fully penetrated the target plates with zero residual velocity) for 3 mm GRP plates with cross-ply unidirectional reinforcement followed by unidirectional reinforcement and plain weave, the plates with satin weave and CSM reinforcements were almost in same level. The thicker specimens (6 mm), plates with plain weave reinforcement showed better ballistic performance towards sharp tipped conical projectile impact, followed by cross-ply unidirectional, satin weave, unidirectional and CSM reinforced plates. Experimentally determined ballistic limit velocity for all specimens correlate well with estimated ballistic limit values obtained in full perforation tests. Damage assessment conducted on all specimens indicated fiber tension and shear failure for thin-walled and sever delamination for the thick-walled specimens as the dominant failure modes.

Experimental and Numerical Investigation on the High Velocity Impact Response of GLARE with Different Thickness Ratio

GLARE is a fiber metal laminate that is a novel hybrid composite, consisting of thin aluminum and glass/epoxy layers. The main advantage of GLARE is its high fatigue and impact loading resistance. Also its areal density is lower than metals or composites when they are used alone. In fact, it has benefits of metals and composites simultaneously. In this paper some 2/1 GLARE laminates are manufactured and impacted by 8.7mm diameter blunt cylinder projectiles at energies up to that required to achieve complete perforation of the target using a helium gas gun. Aluminum and composite layers in these laminates have different thicknesses so the effect of changing thickness of aluminum or composite layers on the ballistic performance of GLARE, ie. Ballistic limit velocity and specific perforation energy, can be investigated. The efficient thickness ratio to maximize the specific perforation energy is obtained, too. The same tests are analyzed numerically by LS-DYNA and the results show good agreement with experimental data. The results are discussed and commented upon.

A Numerical Study of the High-Velocity Impact Response of a Composite Laminate Using LS-DYNA

The failure of a Kevlar29/Phenolic composite plate under high-velocity impact from an fragment simulation projectile was investigated using the nonlinear explicit finite element code, LS-DYNA. The composite laminate and the impactor were idealized by solid elements, and the interface between the laminas was modeled as a tiebreak type in LS-DYNA. The interaction between the impactor and laminate was simulated using a surface-to-surface eroding contact algorithm. When the stress level meets the given failure criteria, the layer in the element is eroded. Numerical results were verified through existing test results and showed good agreement.

A wave propagation model for the high velocity impact response of a composite sandwich panel

A solution methodology to predict the residual velocity of a hemispherical-nose cylindrical projectile impacting a composite sandwich panel at high velocity is presented. The term high velocity impact is used to describe impact scenarios where the projectile perforates the panel and exits with a residual velocity. The solution is derived from a wave propagation model involving deformation and failure of facesheets, through-thickness propagation of shock waves in the core, and through-thickness core shear failure. Equations of motion for the projectile and effective masses of the facesheets and core as the shock waves travel through sandwich panel are derived using Lagrangian mechanics. The analytical approach is mechanistic involving no detail account of progressive damage due to delamination and debonding but changes in the load-bearing resistance of the sandwich panel due to failure and complete loss of resistance from the facesheets and core during projectile penetration. The predicted transient deflection and velocity of the projectile and sandwich panel compared fairly well with results from finite element analysis. Analytical predictions of the projectile residual velocities were also found to be in good agreement with experimental data.

The impact resistance of fiber–metal laminates based on glass fiber reinforced polypropylene

The high velocity impact response of a range of fiber–metal laminates (FMLs) based on a woven glass fiber reinforced polypropylene and an aluminum alloy has been investigated. Tests on FMLs, based on 2024-O and 2024-T3 aluminum alloys, were undertaken using a nitrogen gas gun at velocities up to 150 m/s. The failure processes in the FMLs were investigated by examining the samples after impact and by sectioning a number of specimens through the point of impact. The impact response of these multilayered samples was also characterized by measuring the residual out-of-plane displacement of the targets after testing. Energy absorption in the FMLs occurred through gross plastic deformation, membrane stretching and tearing in the aluminum plies, as well as delamination, fiber fracture, and matrix cracking in the composite layers. In the multilayered FMLs, the permanent displacement at the perforation threshold remained roughly constant over a range of target configurations, suggesting that the aluminum layers deform almost independently through a membrane stretching mechanism during the perforation process. The impact resistances of the laminates investigated were compared by determining their specific perforation energies (s.p.e.), where it was shown that s.p.e. of several of laminates was almost three times that of the corresponding aluminum alloy. The perforation resistances of the FMLs as well as those of the plain composite were predicted using the Reid–Wen perforation model. Here good agreement was noted between the model and the experimental data for the range of laminates investigated here. POLYM. COMPOS. 27:700–708, 2006. © 2006 Society of Plastics Engineers

The impact resistance of polypropylene-based fibre–metal laminates

The high velocity impact response of a range of polypropylene-based fibre–metal laminate (FML) structures has been investigated. Initial tests were conducted on simple FML sandwich structures based on 2024-O and 2024-T3 aluminium alloy skins and a polypropylene fibre reinforced polypropylene (PP/PP) composite core. Here, it was shown that laminates based on the stronger 2024-T3 alloy offered a superior perforation resistance to those based on the 2024-O system. Tests were also conducted on multi-layered materials in which the composite plies were dispersed between more than two aluminium sheets. For a given target thickness, the multi-layered laminates offered a superior perforation resistance to the sandwich laminates. The perforation resistances of the various laminates investigated here were compared by determining the specific perforation energy (s.p.e.) of each system. Here, the sandwich FMLs based on the low density PP/PP core out-performed the multi-layer systems, offering s.p.e.’s roughly double that exhibited by a similar Kevlar-based laminate. A closer examination of the panels highlighted a number of failure mechanisms such as ductile tearing, delamination and fibre failure in the composite plies as well as permanent plastic deformation, thinning and shear fracture in the metal layers. Finally, the perforation threshold of all of the FML structures was predicted using the Reid–Wen perforation model. Here, it was found that the predictions offered by this simple model were in good agreement with the experimental data.

The high velocity impact response of composite and FML-reinforced sandwich structures

The high velocity impact response of a range of novel aluminium foam sandwich structures has been investigated using a nitrogen gas gun. Tests were undertaken on sandwich structures based on plain composite and fibre-metal laminate (FML) skins. Impact testing was conducted using a 10 mm diameter projectile at energies up to that required to achieve complete perforation of the target. High velocity impact tests on the sandwich structures resulted in a number of different failure modes. Delamination and longitudinal splitting of the composite skins were observed in the unidirectional glass fibre/polypropylene-based systems. In contrast, the woven glass fibre/polypropylene-based sandwich structures exhibited smaller amounts of delamination after high velocity impact testing. In addition, the aluminium foam in both systems exhibited a localised indentation failure followed by progressive collapse at higher impact energies. The ballistic limit of all of the sandwich structures was predicted using a simple analytical model. It has been shown that the predictions of the model are in good agreement with the experimental data. Finally, it has been shown that these novel systems offer excellent energy absorbing characteristics under high velocity impact loading conditions.

The effect of low temperatures on the intermediate and high velocity impact response of CFRPs

Abstract The influence of low temperature on the damage produced on CFRPs by intermediate and high velocity impacts is analyzed. Spherical projectiles were launched against different carbon fiber/epoxy laminates (tape and woven). Experimental tests were done at temperatures ranging from 25 to −150 °C. The extension of the damage was measured by C-Scan. Results show a clear dependence of damage on temperature, impact velocity and the type of the laminate.

Simulation methodology for high velocity impact in composite aircraft structures

Abstract The paper summarises the IMT Project HICAS on ‘High Velocity Impact of Composite Aircraft Structures’ which was concerned with developing a design methodology and FE simulation tools for predicting the high velocity impact response of composite aircraft structures. Achievements include measurement of high rate mechanical properties of three aircraft composite systems, development of new failure models for composites under high rate loads, implementation of models into commercial FE codes and code validation by simulation of impact in test structures.

Comparison of the Low and High Velocity Impact Response of Kevlar Fiber-Reinforced Epoxy Composites

Failure mechanisms of basket weave and 3-D braided Kevlar-fabric reinforced epoxy composites under low and high velocity impacts have been studied. The purpose of this study is to examine the initiation and development of damage under these two widely differing loading conditions on 2-D and 3-D structure fabric composites. The critical evaluation of post-damage composite panels was conducted using a combination of high magnification photography, optical microscopy, and scanning electron microscopy (SEM). The first objective, quantification, has been realized in principle with regards to laminated composites, and it has been demonstrated that dispersive failure occurs in these composites. The second objective in this work established the relationship between kinetic energy absorbed and the damage tolerance of inter-leaved composites as assessed by the impact tests. High velocity impact loading by a small projectile is generally more detrimental to the integrity of a composite structure than low velocity dropweight impact loading.

Comparison of the low and high velocity impact response of cfrp

A series of low and high velocity impact tests has been conducted on a wide range of cfrp laminates to examine the initiation and development of damage under these two widely differing loading conditions. For conditions of low velocity impact loading the size and shape of the target determines its energy-absorbing capability and therefore its impact response. High velocity impact loading by a fast moving projectile induces a localized form of target response and the level of damage incurred does not, therefore, appear to be governed by the areal size of the component. The effect of such loading on the residual tensile strength has also been assessed. High velocity impact loading by a small projectile is generally more detrimental to the integrity of a composite structure than low velocity drop-weight impact loading.

The influence of fibre stacking sequence on the high velocity impact response of CFRP

The influence of fibre stacking sequence on the high velocity impact response of CFRP

The influence of target geometry on the high velocity impact response of CFRP

The influence of geometrical parameters on the high velocity impact response of CFRP has been studied. Impact velocities between 10 m/s and 500 m/s were obtained using a high pressure nitrogen gas gun. The resulting impact damage was assessed visually, by optical microscopy and by thermally deplying specimens in an oven at 420°C. It has been shown that increasing the flexural stiffness of a target by varying the fibre stacking sequence or increasing its thickness changes the mode of initial fracture from a lower surface flexural failure to a top surface contact failure. For a given incident energy, increasing the target thickness results in a lower level of damage as detected by ultrasonic inspection. Further, changing the specimen geometry in this way leads to significant increases in the perforation threshold energy. Increasing the surface area of the target by varying its length or width does not alter the amount of damage incurred under high velocity impact loading. Indeed, it appears that smallscale test coupons are fully capable of reproducing damage levels incurred by operational structures when subjected to high velocity impact by a light projectile.