Ice Projectiles Research Articles

Investigations of ice impact damage and residual performance of 3D angle-interlock woven composites based on in-situ sampling

This paper investigates the ice impact damage and residual performance of three-dimensional (3D) angle-interlock woven composites. Clear ice projectiles (free of microbubbles and ice cracks) are produced using the unidirectional freezing method, and subsequently launched against composite panels at velocities ranging from 85 m/s to 145 m/s. The impact process and full-field deflection are recorded through a 3D high-speed digital image correlation (DIC) system, and post-impact analysis is conducted via C-scan and microscope observations. Unlike hard body impacts, almost all external damage caused by ice impacts initially appears on the front face rather than the back face. Moreover, to better characterize the impact resistance, an improved compression after impact (CAI) method based on in-situ sampling is proposed, and contour maps of 65%, 80%, and 95% are constructed to illustrate the quantitative relationship between impact energy and residual performance. In particular, the area enclosed by the 80% contour map closely aligns with the damaged area detected by C-scan imaging, reflecting the limitation of C-scan in detecting tiny cracks. Finally, a multi-scale model has also been established for mutual verification with ice impact tests, where the meso-scale model predicts necessary input parameters for the macro-scale model. The current work can provide valuable guidance for developing experimental standards and damage assessment systems for 3D woven composites under hail threats.

Mechanical responses and damage characteristics of the high-velocity impact of ice projectiles on foam sandwich structure

The integration of composite sandwich structures in aircraft design necessitates consideration of hail impacts within aerospace applications. This investigates the dynamic response and damage characteristics of a carbon fibre/PMI foam sandwich structure under hail impact through both experimental and numerical simulation methods. These methods analyse the impact velocity, fibre panel thickness, and angle of incidence of the ice projectiles. The study establishes relationships among various parameters such as ice projectile impact force, foam absorption energy, and target plate deformation in relation to the impact velocity and angle of incidence. The damage sustained by the carbon fibre/PMI foam sandwich (CPS) structure due to ice projectile impact was systematically categorized and examined. Additionally, the effects of normal and tangential impact velocities on the target plate's dynamic response during oblique impacts were investigated. This research serves as a valuable reference for understanding the dynamic response and damage characteristics of composite foam sandwich structures subjected to ice projectile impacts, With a focus on the carbon fibre/PMI foam sandwich structure.

Numerical modelling of ice: Mechanical behaviour of ice under high strain rates

Ice impact is quite common and may become critical especially if it involves the transportation sector. Simulation tools may help in the structural design phase to increase the ability to withstand this kind of impact and/or to analyse the effect under extreme weather conditions. Such tools require an accurate description of the mechanical behaviour and therefore a detailed investigation about the dynamic mechanical properties of ice is of great interest. In the present work, material characterizations of ice, including tensile and compressive tests, were carried out under different strain rates. Two different material models (i.e., the modified Johnson-Cook model and Johnson-Holmquist II model) were calibrated. Then, impact tests using ice as a projectile with aluminium panels as a target were conducted to validate the material models of ice under impact loading. Furthermore, the replication effect of ice projectiles was investigated under different impact energies based on the mechanical responses and damage phenomena of ice for both models. Results showed that while both models are able to provide reliable predictions of the impact behaviour of ice projectiles, the Johnson-Holmquist II model presents a better performance as impact energy increases.

Damage mechanism of composite laminates under multiple ice impacts at high velocity

Unlike most research on ice impact threats with single impact and multiple repeated impact, different impact schemes such as single-point repeated impact and multi-point sequential impact were carried out in this article, considering the actual circumstance of hail impacts on aerospace structures. To study the response of CFRP laminates to multiple ice impacts, ice projectiles with a diameter of 25 mm were projected onto laminates. Three different routes, including visual analysis, C-Scan analysis and X-ray tomography, were then used to observe the intralaminar and interlaminar damage patterns. An innovative damage category induced by different impact schemes was summarized from the whole experimental results through the visual analysis. The extent of delamination damage was characterized by C-Scan and CT. Both the damage mode and the area of delamination are not only related to the magnitude of single impact energy, but also to the density of impact points. For numerical approach, a strain-rate dependent continuum damage model with interlayer cohesive element was used to predict the damage evolution in CFRP laminates. It was first verified and then combined with the test data to reveal different damage mechanisms of single-point repeated impact and multi-point sequential impact.

Damage characteristics of ice projectile impacting on CF/BMI composite target at high speed

In order to simulate the dynamic mechanical response and damage characteristics of aircraft airframe materials under the impact load of hail, the Carbon Fiber/Bismaleimide (CF/BMI) composite materials used widely in aircraft airframes were taken as the research object in this paper. The finite element analysis software ABAQUS/Explicit was used to simulate the ice projectiles impacting on CF/BMI composite target. The influences of impact velocity, impact angle and ice projectiles size on the damage characteristics of CF/BMI composite target were studied by combining experiment with numerical simulation. The results show that the velocity threshold of macro-scale failure of the CF/BMI composite target is between 251m/s and 278m/s when the ice projectiles vertically impact on the CF/BMI composite target; The delamination failure of the CF/BMI composite target first occurs at the interface between braided layer and laminated structure, and the delamination failure area expands with the increase of ice projectile velocity. When the ice projectile velocity exceeds 278m/s, the damage area of the CF/BMI composite target increases linearly with the increase of ice projectile velocity. However, when the ice projectile obliquely impacts on the CF/BMI composite target, the stress and strain peaks of the CF/BMI composite target increase with the increase of the ice projectile velocity. For the same size ice projectile impacts on the CF/BMI composite target at the same speed, the damage caused by the impact angle of 60° is greater than that by the impact angle of 45°.

An experimental study of the dynamic responses of carbon fiber reinforced polymer composite laminates subjected to ice impact

The aircraft structures are threatened by soft material impact such as birds and hail ices. The main objective of this study is to develop a comprehensive experimental method to evaluate the resistance performance of carbon fiber reinforced polymer laminate subjected to ice impact loadings. First, a hollow tube sensor was adopted to measure the impact force of ice projectiles. Based on the deformation process captured by a high-speed camera and the analysis on transmitted energies obtained by the tube sensor, the repeatability of the ice impact loadings was confirmed and its impact behavior was analyzed. Second, six T700/epoxy carbon reinforced polymer laminates were impacted with different loading velocities, where the transient deformation data during impact were obtained by 3D digital image correlation method The post-test detection was realized using both optical microscopes and scanning acoustic microscopes. The impact of ice projectiles resulted in distributed loadings on the laminate targets with invisible inner matrix cracks and delaminations. Irregular distributions of delaminated areas subjected were observed and their sized increased with the impact velocity. The experimental method showed its practicability on impact issues with projectiles of unknown properties.

Parameter determination for ice material model based on a bidirectional long short-term memory neural network

Parameter determination is a common problem in engineering activities. For impact problems subjected to ice projectiles, however, very few researches have addressed the inverse method to determine the material parameters of ice for finite element simulations. The present study introduced a novel method based on a sequence-to-sequence bidirectional long short-term memory (LSTM) neural network to learn the relationship between the input impact force histories and output material parameters of the finite element model, which was built to reproduce the ice impact test using a hollow tube sensor. After the trained network was evaluated by testing data set, the experimental data was used to predict the parameters for the numerical model to precisely match the test results.

Soft projectile impact forces measurement using Hopkinson bars: application to ice, artificial bird and rubber

This work presents an experimental campaign of impacts of soft projectiles to measure the induced force during the impact. Three different materials acting as soft impactors that could strike against a aeronautical structural component: ice, artificial bird and rubber have been impacted at several velocities against an aluminium Hopkinson bar. This device has been instrumented with semiconductor strain gauges that allow to obtain the induced compression strain. Additionally, all the impacts were recorded using high-speed video cameras, allowing the kinematic analysis of the projectile during the impact. After the results study, it has been concluded that there is a linear dependency between the kinetic energy and the peak force for all three materials. Added to that, it has been proved that the higher peak force corresponds to ice, despite the kinetic energy, followed by rubber and finally the artificial bird. In addition, while ice and artificial bird projectiles get radially dispersed after the impact, rubber spheres rebound due to its different behaviour. The obtained data is of great interest to design structures which could be subjected to impacts of soft materials such as aeronautic structures

Feasibility of Enceladus plume biosignature analysis: Successful capture of organic ice particles in hypervelocity impacts

AbstractEnceladus is a compelling destination for astrobiological analyses due to the presence of simple and complex organic constituents in cryovolcanic plumes that jet from its subsurface ocean. Enceladus plume capture during a flyby or orbiter mission is an appealing method for obtaining pristine ocean samples for scientific studies of this organic content because of the high science return, reduced planetary protection challenges, and lower risk and expense compared to a landed mission. However, this mission profile requires sufficient amounts of plume material for sensitive analysis. To explore the feasibility and optimization of the required capture systems, light gas gun experiments were carried out to study organic ice particle impacts on indium surfaces. An organic fluorescent tracer dye, Pacific Blue™, was dissolved in borate buffer and frozen into saline ice projectiles. During acceleration, the ice projectile breaks up in flight into micron‐sized particles that impact the target. Quantitative fluorescence microscopic analysis of the targets demonstrated that under certain impact conditions, 10–50% of the entrained organic molecules were captured in over 25% of the particle impacts. Optimal organic capture was observed for small particles (d ~ 5–15 µm) with velocities ranging from 1 to 2 km s−1. Our results reveal how organic capture efficiency depends on impact velocity and particle size; capture increases as particles get smaller and as velocity is reduced. These results demonstrate the feasibility of collecting unmodified organic molecules from the Enceladus ice plume for sensitive analysis with modern in situ instrumentation such as microfluidic capillary electrophoresis (CE) analysis with ppb organic sensitivity.

Micro CT Analysis of Dynamic Damage in Laminates: Impact vs. blast loading

Dynamic loading is often an unavoidable condition in various applications of carbon-fibre-reinforced polymers and can cause various modes of damage. Realisation of dynamic damage in composites can differ significantly from that under quasi-static loading conditions. A comprehensive study of damage in composites caused by a wide variety of impact and blast loading is currently lacking. The work presents a detailed analysis of damage in specimens of a 2×2 twill weave T300 carbon-fibre/epoxy composite subjected to ballistic loading with both steel and ice projectiles (with energies from 95 J to 865 J at 70-90 m/s and 300-500 m/s, respectively) and air blast (with incident pressures of 0.4 MPa, 0.6 MPa and 0.8 MPa and wave speeds between 650 m/s and 950 m/s). The resultant damage was analysed in-depth based on detailed volumetric data obtained with high-resolution X-ray micro computed tomography.

Experimental analysis of ice sphere impacts on unidirectional carbon/epoxy laminates

This work analyses the behaviour of carbon/epoxy unidirectional laminates subjected to high velocity impacts of ice spheres. To this end, ice projectiles were launched against composite laminates in a wide range of velocities (50 − 250 m/s). Two different ice diameters (40 and 50 mm) and two laminate thicknesses (4 and 6 mm) were considered. The internal damage was measured using both destructive and non-destructive techniques, which allow an accurate quantification of the delaminated area. Finally the influence of the different parameters considered on the damage of the laminate is analysed by means of a dimensionless variable.

Dynamic Fracture in Carbon-fibre Composites: Effect of Steel and Ice Projectiles

In this study the resultant ballistic dynamic response observed in a 2x2 twill weave T300 carbon fibre/epoxy composite flat-plate specimen is examined, using a combination of non-invasive analysis techniques. The study investigates deformation, damage and fracture following the impacts with both solid (steel) and fragmenting (ice) projectiles travelling with velocities of 70-90 m/s and 300-500 m/s, respectively. Digital image correlation was employed to obtain displacement data for the rear surfaces of the specimens in each experiment, and used to assess the effect of impact velocity and projectile material on the specimen’s response. 3D X-ray computed tomography was used to image and visualize the resultant internal cloud of damage and fracture, initiated by dynamic loading in each specimen. It was shown that solid projectiles led to greater localized deformation and, in some cases, penetration, whereas fragmenting projectiles destroyed on impact resulted in more distributed loading leading to major front-surface damage depending on the depth on indentation before fragmentation.

Silicate impact-vapor condensate on the Moon: Theoretical estimates versus geochemical data

We numerically simulated the impacts of asteroids and comets on the Moon in order to calculate the amount of condensate that can be formed after the impacts and compare the results with data for lunar samples. Using available equations of state for quartz and dunite, we have determined pressure and density behind shock waves in these materials for particle velocities from 4 to 20km/s and obtained release adiabats from various points on the Hugoniot curves to very low pressures. For shock waves with particle velocities behind the front below 8km/s the release adiabats intersect the liquid branch of the two-phase curve and, during the following expansion, the liquid material vaporizes and does not condense, forming a two-phase mixture of melt and vapor. The condensate can appear during expansion of material compressed by a shock with higher (>8km/s) velocities. Using our hydrocode SOVA, we have conducted numerical simulations of the impacts of spherical quartz, dunite, and water–ice projectiles into targets of the same materials. Impact velocities were 15–25km/s for stony projectiles and 20–70km/s for icy impactors, and impact angles were 45°and 90° to the target surface. Along with the masses of condensates we calculated the masses of vaporized and melted material. Upon the impact of a projectile consisting of dunite into a target of quartz at a speed of 20km/s at an angle of 45°, vaporized and melted masses of the target are equal to 1.6 and 11 in units of projectile mass, respectively, and the mass of condensate is 0.19. Vaporized and condensed masses of the projectile are 0.16 and 0.02, more than 80% of the projectile mass is melted. The calculated ratio of vaporized to melted mass proved to be on the order of 0.1. However, we calculated that, at impact velocities below 20km/s, the condensate mass is only a small fraction of the vaporized and melted masses and, consequently, the major part of vapor disperses in vacuum in the form of separate molecules or molecular clusters. At an impact velocity of 15km/s, the abundance of silicate condensates relative to melt is 0.001–0.0001, in agreement with data from lunar samples. Should the observed condensate abundances be representative, the velocities of major asteroid impacts on the Moon could not substantially exceed 20km/s. Comet impacts at the same velocities produce much smaller amounts of vapor condensate because the low densities of cometary material induce lower shock pressures in the target.

High-velocity Impact Location on Aircraft Panels Using Macro-fiber Composite Piezoelectric Rosettes

In this article, an approach based on an array of macro-fiber composite (MFC) transducers arranged as rosettes is proposed for high-velocity impact location on isotropic and composite aircraft panels. Each rosette, using the directivity behavior of three MFC sensors, provides the direction of an incoming wave generated by the impact source as a principal strain angle. A minimum of two rosettes is sufficient to determine the impact location by intersecting the wave directions. The piezoelectric rosette approach is easier to implement than the well-known time-of-flight-based triangulation of acoustic emissions because it does not require knowledge of the wave speed in the material. Hence, the technique does not have the drawbacks of time-of-flight triangulation associated to anisotropic materials or tapered sections. The experiments reported herein show the applicability of the technique to high-velocity impacts created with a gas-gun firing spherical ice projectiles.

On the collisional disruption of porous icy targets simulating Kuiper belt objects

We present results from 27 impact experiments using porous (porosity ranging from 0.39 to 0.54) ice targets and solid ice projectiles at impact speeds ranging from 90 to 155 m/s. These targets were designed to simulate Kuiper Belt Objects (KBOs) in structure. We measured a specific energy for shattering, Q S * , of 2.1 × 10 5 erg / g for those snowball targets hit by intact ice projectiles; this is of the same order as that measured for solid ice targets. The fragment mass distribution follows a power law, although the exponent is not simply related to the largest fragment size as assumed by fragmentation models. We provide the first measurement of the three-dimensional mass-velocity distribution for disrupted ice targets and find that fragment speeds range from ∼2 to ∼20 m/s. The fraction of collisional kinetic energy that is partitioned into ejecta speeds is between 1 and 15% (although it should be noted that the lower limit is more reliable than the upper).

A Laboratory Impact Study of Simulated Edgeworth–Kuiper Belt Objects

This paper reports on a series of laboratory impact experiments designed to provide basic data on how simulated Edgeworth–Kuiper belt objects (EKOs) fragment in an impact event. In September–October 1997 we carried out 20 low-velocity airgun shots at the Ames Vertical Gun Range into porous and homogeneous ice spheres using aluminum, fractured ice, and solid ice projectiles. We found that the porous ice targets behaved as strongly as solid ice in collision. Energy is apparently well dissipated by the void spaces within the target, such that these fragile ice structures respond as if they were strong in impacts. Therefore, it would appear that if EKOs are porous, they are not collisionally weak. Also, our data show that collisional outcomes for low-velocity impacts into ice targets depend on the type of projectile used as well as the properties of the target. We observed that the degree of fragmentation for a given type of target increases as the strength of the projectile increases. Aluminum projectiles are far more damaging to the target at the same collisional energy than are solid ice projectiles, which, in turn, are more damaging than fractured ice projectiles. One possible explanation for this behavior is the variable depth of penetration of the projectile for the different cases—stronger projectiles penetrate more deeply and couple more energy into the target than do weak projectiles. Based on this, if we assume that there has not been significant heating or differentiation in the Edgeworth–Kuiper (E–K) belt, the most applicable impact strength for the low-velocity E–K belt collisions is likely to be that derived from similar target/projectile materials impacting each other. The laboratory data from this analysis indicate that a value for impact strength>5×10 5 erg/cm 3 is appropriate for porous ice targets impacted with solid/porous ice projectiles.

Ejection Velocity of Ice Impact Fragments

Laboratory experiments on the impact disruption of ice were carried out to investigate the collisional phenomena of an icy planet. Ice projectiles were impacted on ice targets at impact velocities of 30 to 530 m/sec, and mass ratios of the projectile to the target of 0.1 to 0.0035. An ejection velocity at an antipodal point (Va) and a largest-fragment mass normalized by the target mass (ml/Mt) were used to examine two scaling parameters, an energy density (Q) and a nondimensional impact stress (Pl). The largest-fragment mass and the antipodal velocity have good correlations to Q but show apparent differences from a basalt target obtained by previous studies. The ice target begins to break up at 83 J/kg, which is two to five times smaller than for basalt. The ejection velocity is about two times higher than for basalt at the same Q. A modified nondimensional impact stress, P*l , that involves a variable decay constant depending on the impact pressure is suggested. This eliminates the size dependence in the relation between Pl and the largest fragment. If we assume a simple relation to the antipodal velocity, Va /V* = 2P*l, where V* is a characteristic velocity, the decay constant decreases with increasing impact velocity. The revised P*l improved the relation between ml /Mt and the nondimensional impact stress. Ejection velocity in a center-of-mass frame was used to estimate a collisional condition for the icy planet to reaccumulate the disrupted fragments by planetary gravity.