Fiber Failure Modes Research Articles

Dynamic splitting tensile properties of high-strength ultrahigh-toughness cementitious composites (HS-UHTCCs)

In this study, the splitting tests were conducted to examine the effect of strain rate on the splitting tensile performance of high-strength ultrahigh-toughness cementitious composites (HS-UHTCCs). Hydraulic machine and split Hopkinson pressure bar (SHPB) were used to investigate the tensile properties of HS-UHTCCs. The strain rates ranged from 10-6 to 10-3 s−1 for hydraulic machine experiments and from 5 to 15 s−1 for SHPB tests, respectively. The splitting tensile strength, tensile stress-strain curves, dynamic increase factor (DIF) and energy absorption ability of HS-UHTCCs were analyzed. The new DIF models proposed for HS-UHTCCs fit well with the experimental data. In addition, the failure modes of specimens and fibers were investigated. The splitting tensile strain was obtained from digital image correlation (DIC) tests. The results indicate that the strain rate has a significant effect on the splitting tensile strength and energy absorption ability of HS-UHTCCs. On the contrary, the average splitting tensile strain showed a decreasing trend with the increase of strain rate. Besides, the DIF model of HS-UHTCCs was proposed with experimental data. The failure modes of specimens changed at high strain rates, transitioning from remaining intact to completely splitting into half. Two failure patterns of polyethylene (PE) fibers included pull-out failure and rupture were observed, while steel fibers experienced pull-out failure.

Bridging Behavior of Palm Fiber in Cementitious Composite

This study addresses the growing need for sustainable construction materials by investigating the mechanical properties and behavior of palm fiber-reinforced cementitious composite (FRCC), a potential eco-friendly alternative to synthetic fiber reinforcements. Despite the promise of natural fibers in enhancing the mechanical performance of composites, challenges remain in optimizing fiber distribution, fiber–composite bonding mechanism, and its balance to matrix strength. To address these challenges, this study conducted extensive experimental programs using palm fiber as reinforcement, focusing on understanding the fiber–matrix interaction, determining the pullout load–slip relationship, and modeling fiber bridging behavior. The experimental program included density calculations and scanning electron microscope (SEM) analysis to examine the surface morphology and diameter of the fibers. Single fiber pullout tests were performed under varying conditions to assess the pullout load, slip behavior, and failure modes of the palm fiber, and a relationship between the pullout load and slip with the embedded length of the palm fiber was constructed. A trilinear model was developed to describe the pullout load–slip behavior of single fibers, and a corresponding palm-FRCC bridging model was constructed using the results from these tests. Section analysis was conducted to assess the adaptability of the modeled bridging law calculations, and the analysis result of the bending moment–curvature relationship shows a good agreement with the experimental results obtained from the four-point bending test of palm-FRCC. These findings demonstrate the potential of palm fibers in improving the mechanical performance of FRCC and contribute to the broader understanding of natural fiber reinforcement in cementitious composites.

Dynamic response mechanisms of thin UHMWPE under high-speed impact

This study systematically explores the dynamic response mechanisms and energy dissipation mechanisms of ultra-high-molecular-weight polyethylene (UHMWPE) fiber laminated plates with thicknesses of 1.1 mm, 2.8 mm, and 5.4 mm under high-speed steel ball impacts through experimental, theoretical analysis, and dimensional analysis. By analyzing the damage mechanisms from experimental results, the main modes of energy absorption were identified, and a relatively accurate predictive model for ballistic limit speed was established. The results show that under high-speed steel ball impacts, the primary failure modes of UHMWPE fiber laminated plates are localized permanent bulging plastic deformation and perforation failure caused by compressive shear. The ballistic limit speeds for UHMWPE with thicknesses of 1.1 mm, 2.8 mm, and 5.4 mm are respectively 233.5 m/s, 415.7 m/s, and 602.9 m/s. The theoretical calculations of the energy model align well with the experimental results, indicating that as the speed increases, the proportion of tensile energy absorption gradually decreases, consistent with the observed phenomena. Near the ballistic limit, there are significant turning points in the level of energy absorption and the height of the rear bulge. The ballistic limit increases linearly with target thickness, and the unit area density energy absorption also increases continuously. Finally, this study established a dimensionless ballistic limit model considering the mechanical properties of fibers and the matrix, which through regression analysis, can accurately describe the ballistic limits of various strengths and types of fiber laminated plates, suitable for predicting the ballistic performance of various composite materials.

An efficient multi-scale method for failure mechanism analysis of SiCf/Ti composites with experimental validation

This study focuses on developing and validating a high-precision concurrent multi-scale finite element model considering the progressive damage model (PDM) and the cohesive zone model (CZM) for predicting the damage evolution of SiCf/Ti composites. At the macro-scale, a constitutive model describing the anisotropic damage criterion of SiCf/Ti composites was implemented by means of a user-defined subroutine (VUMAT). Meanwhile, based on the submodelling, a representative volume element (RVE) model was developed to systematically analyze the failure modes of the SiC fibers, the matrix, and the interface, respectively. Specifically, the crack initiation and propagation in the stress concentration zones were further discussed. Simultaneously, experimental methods were employed to verify the feasibility of the current model. During the uniaxial compression, the brittle fracture of the SiC fibers and ductile fracture of the matrix are the predominant failure modes of SiCf/Ti composites, with fiber fracture being the dominant factor. The crack initiates at the fibers, propagates rapidly to the fiber-matrix interface, and then extends into the matrix. Moreover, the fracture locations are suscepticle to stress concentrations, leading to the crack initiation and propagation. The predicted results show that the local damage has a significant effect on the failure mechanism of SiCf/Ti composites and this multi-scale model provides a scientific reference for the design and optimization of composites.

Influence of Rock Block Content on Mechanical Properties of Coarse-Grained Fillers Stabilized with Fiber and Geopolymer

This study employed fiber and geopolymer to enhance the engineering performance of coarse-grained fillers. By conducting a series of comparative mechanical tests, the ideal mass mixing ratio design of geopolymer and fiber was investigated first. Then, the influence of rock block content on the mechanical properties of coarse-grained fillers stabilized with fiber and geopolymer was explored. The deformation damage characteristics of fiber- and geopolymer-stabilized coarse-grained fillers with different rock block contents were also discussed in the final test. The results show that the ideal mass mixing ratio of geopolymer for coarse-grained filler stabilization was 15% of dry fine-grained soil in weight and the ideal dosage and length of fiber was 0.4% of dry fine-grained soil in weight and 1.2 × 10−2 m. The compressive strength of fiber- and geopolymer-stabilized coarse-grained fillers shows a tendency to increase first, then decrease, and then re-increase with the increase in rock block contents. The best compressive strength and resistance to deformation were achieved when the rock block content was 30%. The failure mode of fiber- and geopolymer-stabilized coarse-grained fillers translated from shearing slip to vertical splitting as the rock block content increased. This study can provide a reference and support for the engineering application of coarse-grained fillers stabilized with fiber and geopolymer.

Study of synergistic and competitive mechanisms on toughening CFRP composites with intrinsic and extrinsic multiscale interleaves

Delamination damage is a common failure mode of carbon fiber reinforced polymer (CFRP) laminates, which severely limits their application. This paper proposes a novel interlaminar toughening structure based on intrinsic and extrinsic multiscale toughening mechanisms using nanoscale multi-walled carbon nanotubes (MWCNTs) and microscale core-shell rubber (CSR). The resin sample M-0.5/C-8, containing 0.5 wt% MWCNTs and 8 wt% CSR, exhibited significant improvements in fracture toughness, with increases of 183.3 % in the mode-I critical stress intensity factor (KIC, Resin) and 412.0 % in the critical energy release rate of resin (GIC, Resin). However, its flexural strength and modulus decreased by 3.1 % and 3.3 %, respectively. Introducing MWCNTs and CSR into the interlayers of the CFRP, the interleaved toughened CFRP laminate exhibited a 123.3 % improvement in the mode-I critical energy release rate (GIC, Comp) and a 79.6 % increase in the mode-II critical energy release rate (GIIC, Comp) during the crack propagation stage, without sacrificing flexural performance. This remarkable enhancement in interlaminar fracture toughness results from the simultaneous triggering of nanoscale extrinsic toughening and microscale intrinsic toughening during crack growth. The flexural properties and fracture toughness of Epoxy/MWCNTs/CSR composites were also investigated to understand the properties transformation from resin matrix to CFRP. Morphological characterization and numerical analysis were used to analyze the synergies and constraints between two energy dissipation behaviors.

Performance and failure modes of continuous fibre-reinforced energy absorption tubes by cylindrical layered 3D printing

ABSTRACT Precisely controlling the distribution of continuous fibres on a cylindrical surface is crucial for manufacturing high-performance continuous fibre-reinforced composite (CFRC) tubular structures. Existing manufacturing processes are complex, hindering the regulation of fibre orientation and content. Therefore, this study achieved unrestricted control of 3D-printed continuous fibres in terms of content and arbitrary orientation on a cylindrical surface using a cylindrical layered path planning strategy. The study investigated the impact of different fibre orientations and printing parameters on the compressive performance and energy absorption of 3D-printed CFRC tubes under quasi-static axial compression by analysing fibre distribution and failure modes. Compared to the flat layered printing strategy, the cylindrical layered printing strategy showed significant increases in compressive strength and energy absorption, by 44.3% and 85.2%, respectively. A cusp height analysis model demonstrated that the cylindrical layered printing strategy significantly enhances forming accuracy compared to the conventional flat layered method. The CFRC lightweight energy absorption tubes fabricated with this strategy demonstrated the viability of the manufacturing process. This new manufacturing technology has significant potential for producing high-performance and high-precision CFRC energy absorption tubes, applicable in aeronautics and astronautics.

Effect of carbon fibers and graphite particles on mechanical properties and electrical conductivity of cement composite

The utilization of self-sensing concrete for structural monitoring is currently a significant research focus. This study involves fabricating self-sensing cement-based composites(SCC) with different carbon fiber contents; the graphite powder content remains fixed at 20 % by mass. The investigation focuses on assessing the influence of carbon fiber on the mechanical strength, electrical conductivity, and piezoresistive properties of cement-based composites incorporating graphite. Furthermore, the study examined the modification mechanisms of carbon fiber in SCC through Nuclear Magnetic Resonance (NMR) and Scanning Electron Microscopy (SEM). The compressive strength initially increases and then decreases with the addition of carbon fibers, reaching a peak of 43.01 MPa at a carbon fiber concentration of 0.6 vol%. SEM analysis revealed that the primary failure mode of carbon fibers is pull-out behavior, which enhances the damage pathway of SCC, thereby improving their mechanical properties. According to NMR results, the porosity of the SCC decreases to varying degrees with the inclusion of carbon fibers, showing an 11.36 % reduction at a carbon fiber concentration of 0.6 vol%. Under cyclic compressive loading within the elastic range, the change in resistivity can reach up to −76.8 %, with a strain sensitivity factor of 1300. Based on the results, it was determined that the addition of 0.6 vol% carbon fibers can significantly improve the mechanical, electrical conductivity, and piezoresistive properties of SCC with a graphite-modified cement matrix.

Effect of grain size on ductility and failure mechanism of fiber-reinforced coral sand cement-based composites

Fiber offers the potential for enhancing the resistance to deformation in engineering cement-based composites (ECC). However, replacing quartz sand in ECC with coral sand containing a large number of internal pores will make the interaction between aggregate, interface transition zone, and cementitious materials more complex. To investigate the influence of coral sand particle size and Polyvinyl alcohol (PVA) fiber content on the compression behaviour and internal microstructure of fiber-reinforced coral sand cement-based composites (FRCSCC), we conducted uniaxial compressive strength tests and real-time measurements of P-wave and S-wave velocities. We tested various mechanical parameters, such as density, elastic modulus, compressive strength, wave velocities, and toughness index. The findings revealed a notable trend in relation to the coral sand particle size. Specifically, as the particle size increased, the compressive strength of FRCSCC decreased by 26 % and the elastic modulus reduced by 11 %. During uniaxial compression, the calculated cumulative voltage energy (CVE) from P-wave and S-wave can be divided into three stages: elastic deformation, microcrack and macrocrack propagation, and main crack formation. Moreover, the increase of coral sand particle size from 0.075 mm to 1.00 mm resulted in the rise of residual stress from 8.7 % to 18.2 %, followed by the increase of toughness index from 2.5 to 3.2. Scanning electron microscope (SEM) images reveal that the main failure modes of PVA fiber in FRCSCC specimens during uniaxial compression are debonding pull-out and tearing. Larger particle sizes of coral sand are associated with uneven fiber dispersion, increased fiber fractures, and diminished ductility of the specimens. The results establish a theoretical foundation for offshore engineering construction.

Microscale and mesoscale modeling for compressive failure in unidirectional carbon fiber reinforced polymer composites with random distribution of fiber misalignments

AbstractCompressive strength and failure mode of carbon fiber reinforced polymer (CFRP) composites are affected by the severity of fiber misalignment. In this paper, numerical models based on computational micromechanics are proposed to investigate the correlation between fiber misalignment and compression failure. A single‐fiber micromodel including fiber, matrix, and interface phases is first developed to capture the influence of misalignment severity on the material failure mode. The failure longitudinal stress distribution in the fiber predicted by the micromodel indicates that the failure mode depending on the initial misalignment can be identified as uniform compression failure, compression‐bending combination collapse, and fiber buckle. A mesoscale 2D model with multiple fibers is then constructed to investigate the kink band formation. This model takes into account the distribution of fiber misalignments to capture the key geometric features of fiber misalignment that influent the compression failure in realistic composite materials at the structural scale. The results show that fiber misalignment angle amplitude, misalignment dispersion (characterized by the standard deviation), and misalignment wavelength are the key parameters of fiber misalignment, which have significant effects on compression strength and kink band geometry.Highlights Single‐fiber model to capture the effect of misalignment severity on failure mode. Multi‐fiber model with randomly distributed fiber misalignments. Failure mode depending on the severity of initial misalignment was identified. Key parameters of misalignment on compression strength and kink band geometry.

Cut resistance of climbing ropes – A comparative analysis of existing measurement methods and a simulated accident

The cut resistance of climbing ropes remains unsolved despite numerous attempts to address it over the past 20 years. Recently, new laboratory test methods have been developed to evaluate rope performance better. This paper compares the fiber failure modes induced by these tests to those observed after a simulated climbing accident. Characteristic fiber failure modes were identified for each test, depending on the position within the rope’s cross-section. The results show that current laboratory methods do not comprehensively replicate the breaking mechanisms in the sheath and core that can occur during actual climbing accidents. The UIAA 101 test, however, shows the most potential for accurately reproducing failure modes with certain modifications.

Progressive failure analysis of perforated composite laminates considering nonlinear shear effect

Composites are widely used in high performance structures such as aerospace structures due to their excellent properties. The analysis of failure evolution of composite perforated structures by finite element simulation is of great significance for practical work as engineering composite structures often contain notches and voids. In this paper, the numerical simulation of failure evolution and failure modes of carbon fiber reinforced resin composite laminates with large openings was carried out. A UMAT subroutine was written based on the 3D Hashin-Ye failure criterion and progressive damage model theory. The characteristic length and viscosity coefficient were introduced into the model to reduce mesh dependency and improve computational convergence. The nonlinear shear constitutive relationship defined by the Ramberg–Osgood equation was introduced into the continuous damage degradation model. The effect of nonlinear shear on the failure evolution of laminates with different stacking sequence was studied.

Effect of Basalt Fiber Diameter on the Properties of Asphalt Mastic and Asphalt Mixture.

In this study, basalt fiber having two types of diameters (16 μm and 25 μm) was selected and added to asphalt mastic and asphalt mixtures using different fiber proportions. The influences of fiber diameters and proportions on the properties of asphalt mastic and mixtures were studied. The adhesion behavior of the fiber-asphalt mastic (FAM) interface was evaluated by a monofilament pullout test, and the rheological properties of FAM were evaluated by temperature sweep, linear amplitude sweep, and bending beam rheological tests. In addition, the high-temperature stability, intermediate and low-temperature cracking resistance, and water stability of fiber-modified mixtures were studied by wheel tracking, ideal cracking, a low-temperature bending beam, and a water-immersed Marshall test. The results showed that the interface adhesion behavior between 16 μm fiber and asphalt mastic was more likely in the fiber failure mode at both -12 °C and 25 °C. Adding basalt fiber can significantly improve the high-temperature and fatigue properties of asphalt mastics. Moreover, 16 μm fiber had a better modifying effect on asphalt mastic than 25 μm fiber. The same enhancement trend can be observed in asphalt mixtures. Basalt fibers with 16 μm diameters can improve the high-temperature performance of asphalt mixtures more significantly. In addition, 16 μm fiber could sharply enhance the cracking performance of the mixtures at intermediate and low temperatures, while the enhancing effect of 25 μm fiber on the mixture is insignificant, though both diameters of the fibers have a minor effect on the water stability.

Improved interlaminar property of carbon fiber/epoxy composites with polyurethane/RGO core-shell structure fibrous mat

Interlaminar delamination is the most common failure mode of carbon fiber reinforced epoxy (CF/EP) composites, which severely limits their practical application. In this work, reduced graphene oxide (RGO) was decorated on electrospun polyurethane (PU) fibrous veil to produce a hybrid core-shell structure fibrous mat, which was integrated into CF/EP to thoroughly evaluate their influence on the interlaminar fracture toughness and interlaminar shear strength of laminates. The results show that, compared to those of plain composite, the mode I and II interlaminar fracture toughness of the PU/RGO interleaved composites increases by 170 % and 21 %, respectively, while their interlaminar shear strength synchronously increases by 14 %. The improved fracture toughness could be attributed to the plastic deformation of PU and epoxy mixture, crack deflection caused by RGO and pull out and separation behavior of RGO, etc. Henceforth, our hybrid interleaf can be considered as a promising candidate for designing high delamination resistance composites for structural applications.

Effects of calcium sulfate as activator on mechanical properties of PVA fiber reinforced cementitious composites with high-volume fly ash

In order to study the role of calcium sulfate as activator in cementitious composites, mixtures with different calcium sulfate content ratios were designed. On the basis of satisfying the engineering castability, the effects of calcium sulfate on the mechanical properties of PVA-ECC with high-volume fly ash were investigated by uniaxial compression and tensile tests. The microstructure was analyzed by SEM and XRD. The results show that the addition of calcium sulfate has a certain activation effect and can promote the formation of ettringite. The early strength of PVA-ECC with high-volume fly ash was improved, and the tensile strain decreased by less than 0.92%. The fiber failure mode was analyzed according to the material failure mechanism. The “slip-hardening type” makes ECCs work better with PVA fibers, showing obvious strain hardening and multiple cracking characteristics. Based on the theoretical analysis, the evaluation method of obtaining high tensile strain was established, and the optimal mix ratio and calcium sulfate content of PVA-ECC with high-volume fly ash were proposed.

In situ damage characterization of CFRP under compression using high-speed optical, infrared and synchrotron X-ray phase-contrast imaging

The strain rate dependency and failure modes of carbon fiber reinforced plastic (CFRP) laminate were investigated under out-of-plane compressive loading. Simultaneous high-speed optical and infrared imaging were used to measure full-field deformation and temperature in the dynamically loaded specimens. The damage initiation and propagation inside the CFRP laminates at high strain rates were characterized using in-situ ultra-fast synchrotron X-ray phase contrast imaging (XPCI). The visually observed damage onset occurs at the strain value of 4.2 ± 0.6% as a transverse shear fracture at the free edge of specimens. The local temperature increases significantly to 185 °C due to damage initiation at high strain rates, while at low strain rates the temperature rise occurs after the final shear band forms. The XPCI and post-failure analysis provide an integrated perspective on the formation of a diagonal shear crack and disintegration of the specimen into two pieces with the fracture of plies in the in-plane transverse direction. Scanning electron microscopic (SEM) study was integrated with XPCI results to append the time scale for the post-mortem failure pattern as well as the length scale for microcracks and filament-level failure.

Experimental characterization of tensile and compressive translaminar fracture toughness coupling multi-physics measurements

The study of the failure modes of carbon fiber reinforced polymers is essential due to their extensive use in industry. Translaminar failure (at the scale of the laminate) has been studied extensively the main goal being to compute the critical strain energy release rate in mode I of the ply GIC_ply but large variations can be observed between papers. This study investigates this failure mode of a carbon/epoxy laminate, using Compact Tension (CT) and Compact Compression (CC) specimens. The stacking sequence used is [45/-45/(0/90)4]s where 45° plies on the outside efficiently prevented the buckling of the specimen to be observed, as well as plasticity of the matrix. Moreover, this layup is rather similar to real-life industrial stacking sequences. Strains fields and axes displacement were obtained using digital image correlation. Infrared images were used to follow the crack propagation during the loading of the specimen and compared to DIC and X-ray tomography crack length measurements. IR measurements studied from a qualitative point of view were thus shown to be an efficient and reliable method. GIC of the laminate GIC_lam was computed with both the ASTM-E399 and compliance methods, and finally GIC_ply was computed using a rule of mixtures. Secondary damage was detected and its effects on the energy dissipated were quantified using strain fields, X-ray and infrared images. This enabled a more accurate rule of mixtures to be redefined. The failure scenarios of all specimens were eventually exhibited. GIC_ply values in tension were found to be higher than in the literature whereas in compression it was found to be lower than in the literature, due to crack propagation being detected earlier by means of IR measurements.

Effect of Al2O3 fibers mixing methods and in-situ formed SiC nanowires on the properties of silica-sol ceramic shells for investment casting

In this study, a silicone resin solution was used as a supplementary binding agent, and two different techniques were employed to add varying amounts and layers of Al2O3 fibers within the shell to improve the performance of investment casting shells. The Al2O3 fiber-toughened shells were characterized using a combination of three-point bending and high-temperature self-loading deformation experiments. Additionally, the fracture morphology of samples and the fiber failure mode were demonstrated through SEM (Scanning Electron Microscope). Results showed that the added Al2O3 fibers greatly improved the bending strength and the high-temperature self-loading deformation of the ceramic shells. After spraying the silicone resin solution, the green and sintered strengths of the shells reached 8.02 MPa and 9.60 MPa, respectively, when Al2O3 fibers were added to the 3–6 layers of the shell. The high-temperature self-loading deformation reached a minimum of 0.44% when Al2O3 fibers were added at 0.4 wt%. SEM analysis indicated that the incorporation of Al2O3 fibers in the backing sand resulted in a disordered and non-directional distribution pattern, which could lead to the splitting of the ceramic matrix. In contrast, Al2O3 fibers within each shell layer could uniformly disperse the external load and increase the fracture resistance of the substrate. Furthermore, the pyrolysis of the silicone resin led to the deposition of free carbon in the matrix pores, resulting in the spontaneous formation of SiC nanowires. These nanowires were observed to attach to the Al2O3 fibers, which ultimately impeded the propagation of matrix cracks.

Influence of carbon fiber failure mode caused by TiO2 coating on the high temperature tensile strength of carbon fiber reinforced 7075 Al alloy composites

To enhance the mechanical properties of carbon fiber (CF) reinforced 7075 Al alloy material at high temperature conditions, TiO2 coating was prepared on the surface of CF by chemical vapor deposition. The composites were prepared by hot pressing sintering and hot extrusion methods. The evolution of the compositional components of the composite interface was investigated. The density, hardness, and tensile strength of the samples were measured, and the strength/density ratio of the samples was calculated at 150 °C. The results indicate that the tensile strength of coated CF reinforced composite (535 MPa) was increased by 21.3% and 5.7% compared to the tensile strength of 7075 Al alloy (441 MPa) and uncoated CF reinforced composite (506 MPa), respectively. Furthermore, the strength/density ratio of the composite also increased with the addition of TiO2 coating. The enhancement of coating on CF on tensile strength is attributed to the transformation of CF failure mode.

Hybridization effects on ballistic impact behavior of carbon/ aramid fiber reinforced hybrid composite

Fiber reinforced polymer and its hybrid composites are widely used in bulletproof production. The ballistic limit, failure mode and energy absorption of a hybrid fiber reinforced polymer target (HFRPT) composed of carbon fiber reinforced polymer (CFRP) and aramid fiber composite (AF) were studied in this paper. A finite element model was formulated to investigate the hybridization effect of layer thickness and stacking sequence on the ballistic behavior. A theoretical method was proposed to predict the ballistic limits of HFRPT, demonstrating an error percentage of less than 10% in most of the hybridization. Four typical failure modes including compression failure, tensile failure, shear plugging failure and tension shear coupling failure were observed in HFRPT, and the influence of hybridization on the alternations of failure modes was observed. Additionally, the effect of stacking sequences and layer thickness on energy absorption of HFRPT was examined. For the HFRPTs with a total thickness of 10 mm, the AF/CFRP hybridization proves to offer better ballistic impact resistance performance than the CFRP/AF hybridization. The HFRPT with a stacking sequence of 9 mm AF and 1 mm CFRP achieves a maximum ballistic limit of 420 m/s and the highest impact energy areal density ratio of 323 J/(g/cm2).