Low Velocity Drop Weight Impact Research Articles

Drop-weight impact and compressive properties of repeatable self-healing carbon fiber reinforced composites

Herein, repeated self-healing of impact damage in carbon fiber reinforced composites is successfully achieved by using hollow glass fibers containing self-healing resin and two types of microcapsules (HGFs-Ms). The HGFs-Ms and microcapsules containing hardener were incorporated to fabricate repeatable self-healing carbon fiber reinforced polymer composite laminates (RSH-CFRPs). Low-velocity drop-weight impact tests and compression tests were performed to investigate the impact resistance, energy absorption, residual compressive strength and repeated self-healing performances of the RSH-CFRPs. The results revealed that the energy absorption capacity of the RSH-CFRPs could be repeatedly recovered and the barely visible impact damage (BVID) zone was almost fully healed after every healing process. Moreover, the RSH-CFRPs successfully minimized the reduction in compressive strength after repeated drop-weight impact tests due to their efficient repeated self-healing ability in impact induced damage.

Low-velocity impact-resistance of aramid fiber three-dimensional woven textile-reinforced thermoplastic-epoxy composites

The development of impact-resistant composite materials for protective applications such as helmet and body armor has attracted considerable attention. In this study, a novel aramid fiber-woven thermoplastic-epoxy composite was developed. Furthermore, three types of woven textiles, namely three-dimensional (3D) orthogonal-woven (3DOW), 3D angle-interlock woven (3DAIW), and two-dimensional plain-woven (2DPW) textiles, were used as reinforcement structures. To study the effect of the woven structure, impact energy, and damage repairment on impact-resistance performance of these composites, low-velocity drop-weight impact tests with various impact scenarios, such as single-impact, repeated-impact, as well as multiple-impact with hot-press damage repairment, were conducted. The results revealed that the woven structure exhibited an obvious effect on the composite impact-resistance performance and failure modes when subjected to specific impact scenarios. For the single-impact scenario, especially under high impact energy levels (10 and 20 J), the 3DOW structure exhibited superior impact-resistance performance as well as damage tolerance, followed by 3DAIW and 2DPW structures. Furthermore, 3DOW achieved superior impact-resistance to the other two structures for the 10-J repeated-impact scenario. The 3DAIW structure, in which debonding or delamination as well as severe resin cracks dominated, achieved superior impact-resistance to multiple impacts with damage repairment.

Repeated impact resistance of steel fibre-reinforced dry UHPC: Effects of fibre length, mixing method, fly ash content and crumb rubber

Dry concrete exhibits significantly different mechanical properties and failure patterns under dynamic loads from those under static conditions. Considering the practical applications of dry concrete, the flexural impact load renders its units/structures susceptible to unpredictable damage or even failure. In this study, the modified low-velocity drop-weight impact test was conducted on steel fibre-reinforced dry UHPC (FR-DUHPC) beam samples to simulate the frequent and multiple impact loads. The effects of steel fibre length, mixing method, fly ash content and crumb rubber addition on the impact resistance of FR-DUHPC were evaluated based on dynamic responses. Weibull distribution was then conducted to analyse the failure hit number of concrete samples in consideration of the large value variation. Test results indicated that the flexural impact performance was markedly improved with longer steel fibres, but deteriorated with increased fly ash content (especially at early ages) and considerably degraded with the inclusion of rubber aggregate. Hybrid medium/long fibre reinforcement was proposed for DUHPC that were mainly subjected to impact loads during service, while the fly ash content utilized to partially replace cement was not recommended to exceed 40%. Rubber aggregate was not proposed to be added to dry concrete mixtures since the impact load would greatly accentuate the initial matrix defects caused by the weak bonding. Additionally, the two-parameter Weibull distribution was verified to be a desirable statistical method for analysing the failure blow number of FR-DUHPC under repeated low-speed drop-weight impacts. The impact energy for the practical structural design could be preliminarily computed utilizing the derived Weibull parameters at different levels of reliability.

Improved double impact and flexural performance of hybridized glass basalt fiber reinforced composite with graphene nanofiller for lighter aerostructures

The growing demand for sustainable, lightweight yet rigid and cost-effective materials for airplane construction served as the impetus for this work. An E-glass fiber (400 GSM) is layered in a 6:2 ratio with natural basalt fiber and infused with graphene nanoparticles to produce a more appealing 40% lighter hybrid composite of 1.1 mm thickness for the aviation industry. Samples of hybrid composites with 1% and 2% graphene-to-fiber filler weight ratios are used. Then, using ASTM standard analysis tools, the damage that is caused on toughened laminates during low-velocity drop weight impact tests, tensile, 3-point bending, and Compression After Impact(CAI) is evaluated. The composites' tensile strength, flexural strength, low-velocity double impact, and compression impact strength all significantly improved at 2 wt% graphene, increasing by 37%, 55%, 56%, and 78%, respectively. Scanning Electron Microscope analysis of the damaged area demonstrated the presence of important toughening mechanisms, such as damage confinement through microcracks and improved fiber-matrix bonding. It has been established that adding an optimum blend of graphene and basalt to Glass Fiber Reinforced Polymer(GFRP) results in an unprecedented increase in effective strength with reduced weight.

Role of shear reinforcements on the punching shear resistance of two-way RC slab subjected to impact loading

• Numerical analysis of punching shear resistance of RC slab subjected to impact loading. • Impact test setup is modeled in ABAQUS/Explicit computer code. • Computational results compared with the experimental ones from literature. • Parametric study to analyze the effect of stirrups’ width, spacing, and the number of compression reinforcement bars. • Shear reinforcement was able to improve the impact resistance of slab against punching. The possibility of acting impulsive loads such as blast and impact on gravity load-carrying structural members such as slabs during their construction and service life cannot be ruled out. Studies on the response of RC slabs under impact loading are available in the literature. However, the role of the shear reinforcements in the slab under impact is not fully understood and therefore needs further investigation. The slab subjected to concentrated impact loading in the form of falling construction equipment, landslip hazards, and other similar events may cause damage through punching or perforation. Under quasi-static concentrated loading, the design parameters that contribute to the shear resistance against punching are (1) concrete strength, (2) flexural steel, and (3) shear stirrups. In this work, a three-dimensional finite element model of a square concrete slab of normal strength concrete (30.10 MPa), 1000 mm × 1000 mm × 75 mm, with tension reinforcement only (0.88 %) subjected to low-velocity drop-weight impulsive impact is developed in ABAQUS/Explicit computer code considering Concrete Damage Plasticity and Johnson-Cook models with strain rate effects and validated with the experimental results in the open literature. The nonlinear interaction between the concrete and steel reinforcements is taken into account. The drop weight is a hard steel cone frustum-headed striker/impactor with a flat impact face of a total mass of 105 kg allowed to fall from 2500 mm height, impacting the slab at its centroid. To study the effect of the shear reinforcement on the impact resistance of the slab, the shear reinforcement has been varied by varying the stirrups’ width, spacing, and the number of compression reinforcement bars while keeping the impact load and other design parameters such as concrete/steel strength, support conditions, slab thickness, span, and flexural tension steel constant. Numerical simulations are executed and the outcomes are presented in terms of displacement–time plots, damage/stress profiles, damage modes, and damage dissipation energy. The results so extracted are discussed and compared. It has been found that the increase in shear reinforcement by decreasing the spacing of the stirrups improves the impact resistance of the slab against punching.

An improved calibration of Karagozian & Case concrete/cementitious model for strain-hardening fibre-reinforced cementitious composites under explosion and penetration loadings

The ultra-high tensile capacity of strain-hardening fibre-reinforced cementitious composites makes them promising for impact dynamics applications, however, there is a lack of reference for taking the parameters of the constitutive model of materials in numerical simulations. In this study, the Karagozian & Case concrete/cementitious model parameters for strain-hardening fibre-reinforced cementitious composites were comprehensively and systematically calibrated. Multiaxial behaviour, crack-bridging constitutive relations, strain-rate effects, regularization of damage evolution parameters, and parameters scaling method for wide-range strength of materials were all considered and carefully discussed. The calibrated parameters were validated using low-velocity drop-weight impact tests, near-field explosion tests, and high-speed penetration tests. In this study, the traditional element erosion method and meshless/particle methods of Smoothed Particle Galerkin (SPG) method were used for failure analysis in penetration and explosion models. The results show that the calibrated parameters accurately predict the cratering and scabbing diameters and failure modes of explosion tests with the element erosion method. Furthermore, the residual velocity of the projectile and crack patterns of targets were also predicted with good precision with both element erosion and SPG methods. However, in the simulations of low-velocity impact tests, the predictions of maximum deflection were acceptable, and the errors in residual deflection were significant due to the inherent weakness of the material constitutive model.

Nanosized Hexagonal Boron Nitride and Polyethylene Glycol-Filled Leathers for Applications Demanding High Thermal Insulation and Impact Resistance.

Leather is a niche material used for upholsteries, gloves, and garments due to its high durability, flexibility, and softness properties. The inclusion of nanoparticles in the leather matrix provides multifunctionality for high-performance applications. Herein, we synthesized hexagonal boron nitride (h-BN) nanoparticles via a single-step hydrothermal synthesis and treated the leather after dispersing in polyethylene glycol (PEG) to yield h-BN/PEG-treated leathers. Atomic force microscopy and high-resolution transmission electron microscopy analysis ascertained the particle size of 30-50 nm for as-synthesized h-BN nanoparticles. h-BN nanoparticles along with PEG were successfully incorporated into the leather matrix, and this was confirmed by surface and morphological studies using field emission scanning electron microscopy/energy-dispersive X-ray analysis and Fourier transformed infrared spectroscopy. Leathers treated with h-BN/PEG were studied for insulation against heat and cold, and the results displayed improved thermal insulation properties compared to the control leathers. The dynamic mechanical analysis of control and treated leathers demonstrated higher storage modulus, loss modulus, and tan δ values for h-BN/PEG-treated leathers, signifying an increased energy absorption and dissipation potential, which was further ascertained by the low-velocity drop-weight impact resistance test. Thus, the results of this study open up new prospects for h-BN/PEG-treated leathers in strategic applications demanding high thermal insulation and impact resistance properties.

Studies on the effect of recycled concrete aggregates on concrete with mixed fibre and pozzolans

The steel fibre and synthetic fibres can entirely replace traditional rebars in concrete under specific circumstances like industrial floorings, which are subjected to dynamic loading due to movement of heavy machinery. The large scale availability of Recycled Concrete Aggregates (RCA) can be utilized to make these concrete floors. These are generally substantiated by laboratory test to ensure that the performance criteria are satisfied. The usefulness of combining RCA in high strength quaternary blended mixed fibre reinforced concrete (h-MFR-QB) in resisting compression, flexure, split tensile strength, and repetitive low-velocity drop-weight impact was evaluated in an experimental programme. The experiments were carried out on three different groups of specimens. Fly ash, micro silica, Nano silica, hooked end steel fibres, and PP fibres were used in each group. The advantages of both fibres were accomplished for efficient concrete using a volume fraction of 0.2% and 1% of PP and steel fibres, respectively, to offset the detrimental effect of adding RCA. When compared to non-fibrous concrete, the h-MFR-QB concrete material specimens exhibit a strong resistance to compression, flexure, split tensile strength, and repetitive low-velocity drop-weight impact drop-weight impact.

Development of three-dimensional woven weft interlock carbon-fiber-reinforced plastic composites and experimental investigation on their out-of-plane flexural performance

Developing three-dimensional (3D) woven composites using various woven structures is important in the advanced composite research field. In this study, carbon-fiber 3D woven textile-reinforced epoxy–resin composites using four different woven structures (such as 2.5D, 3D-a, 3D-b, and 3D-c) were designed and fabricated based on a dobby-weaving loom, and vacuum-assisted resin transfer molding technology. In these 3D woven structures, part of weft insertions serves as binder yarns with a special weft interlock structural design, different weft-to-binder yarn ratios are obtained. Out-of-plane quasistatic three-point bending tests and dynamic low-velocity drop-weight impact tests were conducted on these woven composites to study the effect of woven structure on their flexural performance. Nondestructive ultrasonic C-scan and X-ray microcomputed tomography were applied to characterize the failure modes of the post impacted composites. We found that woven structures affect the flexural performance and failure mode of the developed composites, these structures with lower in-plane and binder yarn waviness exhibited higher quasistatic–flexural performance; 3D-c structure with serious in-plane yarn waviness combined with through-thickness binder yarn path exhibited superior impact resistance than other structures and survived more from composite through-thickness cracks and binder yarn breakage failures. Proper structural design is a key to improving flexural performance in specific engineering applications.

Experimental and numerical damage analysis of low-velocity drop weight impact of polyethylene self-reinforced composite laminates for transportation applications

This study covers a low-velocity impact property analysis of Polyethylene self-reinforced composites (PET-HDPE/HDPE SRC)through experimental and numerical methods emphasizing the influence of interfacial properties. Self-reinforcing a polymer material has gained a lot of attention due to maximum exploration of their light density characteristics with better chemical compatibility and interfacial adhesion of matrix and reinforcement, resulting in higher fuel efficiency. Reusability of self-reinforced thermoplastic composites even without separating their constituent materials has been observed to be aiding the circular economy strategies. The study aimed to analyze the peak load characteristics, energy-absorbing characteristics, and damage response of these materials processed through the hot compaction technique and subjected to a drop mass impact test. Fractographic visual inspection, optical macrographs, Scanning electron microscopy analysis, and through transmission ultrasonic C-scan were employed to study the damage evolution and failure mechanisms under the low-velocity impact. Three levels of impact energy were included in the test matrix, and initiation of the damage, nature of the matrix, interface debonding, matrix and fibre failures could be identified through the inspection of the damage cross-section at the impact eye. A finite element model developed through commercial FEA packages (Abaqus) was utilized for the complex mechanisms of damage and failure. Weak interfacial adhesion due to the self-lubricating nature of the polyethylene fibre surface contributed to the fibre pull out during the drop weight impact. A qualitative analysis and correlation of the nature of surface damage and internal damage were also studied, which are the factors that are necessary for the development of cargo containers and marine/aerospace ultralight luggage applications.

Impact-resistant design of RC slabs in nuclear power plant buildings

The concrete structures related to nuclear safety are threatened by accidental impact loadings, mainly including the low-velocity drop-weight impact (e.g., spent fuel cask and assembly, etc. with the velocity less than 20 m/s) and high-speed projectile impact (e.g., steel pipe, valve, turbine bucket, etc. with the velocity higher than 20 m/s), while the existing studies are still limited in the impact resistant design of nuclear power plant (NPP), especially the primary RC slab. This paper aims to propose the numerical simulation and theoretical approaches to assist the impact-resistant design of RC slab in NPP. Firstly, the continuous surface cap (CSC) model parameters for concrete with the compressive strength of 20–70 MPa are fully calibrated and verified, and the refined numerical simulation approach is proposed. Secondly, the two-degree freedom (TDOF) model with considering the mutual effect of flexural and shear resistance of RC slab are developed. Furthermore, based on the low-velocity drop hammer tests and high-speed soft/hard projectile impact tests on RC slabs, the adopted numerical simulation and TDOF model approaches are fully validated by the flexural and punching shear damage, deflection, and impact force time-histories of RC slabs. Finally, as for the two low-velocity impact scenarios, the design procedure of RC slab based on TDOF model is validated and recommended. Meanwhile, as for the four actual high-speed impact scenarios, the impact-resistant design specification in Chinese code NB/T 20012-2019 is evaluated, the over conservation of which is found, and the proposed numerical approach is recommended. The present work could beneficially guide the impact-resistant design and safety assessment of NPPs against the accidental impact loadings.

Consecutive and constant low-velocity drop-weight impact loading tests of cushion rubber set RC beams

Consecutive and constant low-velocity drop-weight impact loading tests of cushion rubber set RC beams

Dynamic behaviour of Bio-inspired heterocyclic aramid Fibre-reinforced laminates subjected to Low-velocity Drop-weight impact

This paper determines the low-velocity impact response of two helicoidal laminates, where ply angles are in linear and non-linear arrangements, inspired by the laminar structures in the exoskeletons of crustaceans. For comparison, two conventional cross-ply and quasi-isotropic layups were also studied. The laminate specimens were manufactured using heterocyclic aramid fibres, and an instrumented drop-weight impact facility was used for experimental tests. The force–displacement curves were recorded for analysing the evolution of dynamic failure and energy absorption of laminates during impact. Moreover, CT-scan was employed to analyse the internal damage and delamination distribution in tested samples. The results revealed that the bio-inspired linear helicoidal laminate had the highest stiffness under out-of-plane low-velocity impact compared with other laminates. In addition, the linear helicoidal layup could resist the highest peak forces before penetrating damage occurs. However, it was found that helicoidal laminates could not absorb as much impact energy as the cross-ply counterpart.

Experimental and numerical studies on influence of impact damage and simple bolt repair on compressive failure of composite laminates

Combined experimental and numerical investigations on the influence of impact damage and effectiveness of a proposed simple bolt repair on the compressive failure of composite laminates are presented in this paper. Impact tests were conducted by low velocity drop-weight impact with three levels of impact energy, and then compressive tests of composite laminate specimen with impact damages were carried out and compared with intact specimen and damaged specimen with simple bolt repair. The experimental results indicated a significant reduction of the compressive strength for specimens with impact damage and the reduction is proportional to impact energy. It was demonstrated that the compressive strength could be partially reinstated with the proposed simple in-service bolt repair method. Preliminary numerical simulations of the compressive after impact (CAI) tests without and with the simple bolt repair were carried out to understand the failure mechanisms and effectiveness of the bolt repair. Good agreement of simulation results with the experimental results validated that the numerical analysis approach could provide useful tool for further design and optimization of the in-service repairs with less expensive experimental tests.

Strain-rate-dependent progressive damage modelling of UHMWPE composite laminate subjected to impact loading

A comprehensive strain-rate-dependent (SRD) finite element modeling procedure, based on continuum damage mechanics has been developed to predict the behavior of ultra-high molecular weight polyethylene (UHMWPE) fiber composite laminates under impact loading. A user-defined material subroutine implemented into ABAQUS/Explicit is used to define SRD constitutive damage model of UHMWPE composite. The effect of strain rate on the material properties is adapted to the experimental data by introducing a new hyperbolic function and the strain-rate effect factor (SEF) for use in the modeling. The range of [Formula: see text] to [Formula: see text] is considered for strain rate, which includes both high velocity and low velocity impact regimes. A homogenized sub-laminate approach is employed to more accurately capture the out-of-plane failure mechanisms. Cohesive Zone Model (CZM) with the constitutive model based on bilinear traction-separation is implemented to simulate the inter-laminar delamination between the sub-laminates. High velocity ballistic impact as well as low velocity drop-weight impact are simulated, and the results are validated with experimental observations from the literature. Results show that the presented SRD model, offers more accurate prediction of the projectile residual velocity compared to the SRD model using logarithmic function or without considering the strain rate effect. Moreover, detailed views of failure modes such as tension/shear fiber and matrix shear in layers, and the delamination patterns are obtained and investigated.

An experimental investigation on the low-velocity impact performance of the CFRP filled with nanoclay

In this study, the effect of the commercial nanoclay Cloisite® 20A on the impact response of the carbon fiber reinforced polymers was investigated using a low-velocity drop-weight impact machine under three impact energy levels of 10 J, 15 J, and 20 J. Contrary to other studies and for more improvement of the properties, clay nanoparticles were dispersed in the resin through solution blending methodology, and laminate samples were fabricated by vacuum infusion process. The optimal percentage of nanoclay was determined by tensile and flexural tests on the epoxy samples containing various nanoclay contents (0.2-0.8 wt.%). For a deeper understanding of the damaged nanocomposites, force-time, force-displacement, and energy-time responses were analyzed. Finally, the influence of nanoclay incorporation by solution blending method and the impact-induced damages were explored by measuring the permanent indentation, radiographic analysis, optical and field emission scanning electron microscopy. Addition of 0.2 wt.% Cloisite® 20A led to a significant increase in the maximum impact force (up to 25.7%), a reduction of the absorbed energy (up to −50.25%), and a decrease in the maximum displacement (up to −29.08%). Moreover, the permanent indentation and the delamination area were significantly decremented compared to the other studies using direct dispersion to disperse nanoclay in the resin matrix. Furthermore, it was revealed that the addition of nanoclay resulted in the transition of the failure mode of carbon fiber reinforced polymer during low-velocity impact from delamination to matrix cracking.

Simulations and Tests of Composite Marine Structures Under Low-Velocity Impact

Abstract Due to their excellent performance, composite materials are increasingly used in the marine field. It is of great importance to study the low-velocity impact performance of composite laminates to ensure the operational safety of composite ship structures. Herein, low-velocity drop-weight impact tests were carried out on 12 types of GRP laminates with different layup forms. The impact-induced mechanical response characteristics of the GRP laminates were obtained. Based on the damage model and stiffness degradation criterion of the composite laminates, a low-velocity impact simulation model was proposed by writing a VUMAT subroutine and using the 3D Hashin failure criterion and the cohesive zone model. The fibre failure, matrix failure and interlaminar failure of the composite structures could be determined by this model. The predicted mechanical behaviours of the composite laminates with different layup forms were verified through comparisons with the impact test results, which revealed that the simulation model can well characterise the low-velocity impact process of the composite laminates. According to the damage morphologies of the impact and back sides, the influence of the different layup forms on the low-velocity impact damage of the GRP laminates was summarised. The layup form had great effects on the damage of the composite laminates. Especially, the outer 2‒3 layers play a major role in the damage of the impact and the back side. For the same impact energy, the damage areas are larger for the back side than for the impact side, and there is a corresponding layup form to minimise the damage area. Through analyses of the time response relationships of impact force, impactor displacement, rebound velocity and absorbed energy, a better layup form of GRP laminates was obtained. Among the 12 plates, the maximum impact force, absorbed energy and damage area of the plate P4 are the smallest, and it has better impact resistance than the others, and can be more in line with the requirements of composite ships. It is beneficial to study the low-velocity impact performance of composite ship structures.

Crashworthiness of circular fiber reinforced plastic tubes filled with composite skeletons/aluminum foam under drop-weight impact loading

Carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP) have shown great promise in the design of light-weight thin-walled energy absorbers. Herein, circular CFRP/GFRP hybrid tubes and tubes, reinforced with internal composite skeletons (XS and OS), were fabricated to further enhance the energy absorption capacities. The crashworthiness and failure pattern of reinforced structures were compared with the hollow and aluminum foam-filled composite tubes. Moreover, low-velocity drop-weight impact tests were carried out to investigate the effect of hybridization design and filler types on the energy dissipation mechanism under axial compression. The experimental results revealed that the hollow composite tubes collapsed in progressive and the impact energy was absorbed by the generation of cracks, fiber fracture and friction. Also, the GFRP tubes exhibited better crashworthiness than CFRP tubes under low velocity impact, which was different from the quasi-static compression conditions. In contrast to hollow counterparts, the mean crushing force (MCF) of foam-filled tubes was improved by approximately 40%, whereas the specific energy absorption (SEA) was reduced by 30% due to the low weight efficiency of the aluminum foam. The filling of XS-skeleton divided the tube into four cells and improved the MCF by more than 10%. However, it reduced the SEA by around 8% due to unstable and inefficient deformation of XS-skeleton during crushing. By contrast, the OS-skeleton divided the hollow tube into more cells and collapsed progressively, resulting in superior energy absorption characteristics. Herein, the OS-filled GFRP tube was found to be the most crashworthy structure that improved the crushing force efficiency (CFE) and SEA by 50% and 7%, respectively.

Low-velocity drop weight impact behavior of Twaron® fabric investigated using experimental and numerical simulations

Low-velocity drop weight impact experiments of plain-woven Twaron® CT 612 at an impact energy of 15, 20, 30 J are carried out on a 9250HV drop weight impact tester. Specially treated specimens are designed and used to deal with boundary conditions because the fabric is too flexible and cannot be fixed precisely. Experimental results reaffirm that TwaronⓇ is an impact-rate-sensitive material and that a greater initial impact energy resulted in a larger breaking load, greater failure strain, larger energy absorption and shorter contact duration to the fabric in the impact process., The commercial code ANSYSⓇ-AUTODYN is employed for impact FE analysis on a physically based impact model which is designed basing on the fabric's geometry parameters and the experimental set-up. The dynamic mechanical parameters of TwaronⓇ is analyzed and applied to FE model to describe the rate-sensitive mechanical properties through a three-element spring-dashpot model. Standard earth gravity is applied to the impact model to reflect the impact process realistically as well. The results indicate that a remarkably close agreement is obtained between the simulation and experimental results in various impact scenarios. Thus, the energy absorption mechanisms and stress distributions during the impact process are clarified. The influence of specimen shape and size are also analyzed systemically. These results indicate that the present experimental set-up and the developed fabric geometry model are effective at investigating many additional mechanical problems in textile fabrics and/or flexible material structures.

Determination of the material model and damage parameters of a carbon fiber reinforced laminated epoxy composite for high strain rate planar compression

The progressive failure of a 0°/90° laminated carbon fiber reinforced epoxy composite was modeled in LS-DYNA using the MAT_162 material model, including the strain rate, damage progression and anisotropy effects. In addition to conventional standard and non-standard tests, double-shear and Brazilian tests were applied to determine the through-thickness shear modulus and the through-thickness tensile strength of the composite, respectively. The modulus reduction and strain softening for shear and delamination parameters were calibrated by low velocity drop-weight impact tests. The rate sensitivities of the modulus and strength of in-plane and through-thickness direction were determined by the compression tests at quasi-static and high strain rates. The fidelity of the determined model parameters was finally verified in the in-plane and through-thickness direction by the 3D numerical models of the Split Hopkinson Pressure Bar compression tests. The numerical bar stresses and damage progressions modes showed acceptable correlations with those of the experiments in both directions. The composite failed both numerically and experimentally by the fiber buckling induced fiber-matrix axial splitting in the in-plane and the matrix shear fracture in the through-thickness direction.