GLAss Fiber REinforced Aluminum Research Articles

Deterministic and probabilistic buckling response of fiber–metal laminate panels under uniaxial compression

PurposeThe purpose of this paper is to study the deterministic elastic buckling behavior of cylindrical fiber–metal laminate panels subjected to uniaxial compressive loading and the investigation of GLAss fiber-REinforced aluminum laminate (GLARE) panels using probabilistic finite element method (FEM) analysis.Design/methodology/approachThe FEM in combination with the eigenvalue buckling analysis is used for the construction of buckling coefficient–curvature parameter diagrams of seven fiber–metal laminate grades, three glass-fiber composites and monolithic 2024-T3 aluminum. The influences of uncertainties concerning material properties and laminate dimensions on the buckling load are studied with sensitivity analyses.FindingsIt is found that aluminum has a stronger impact on the buckling behavior of the fiber–metal laminate panels than their constituent uni-directional or woven composites. For the classical simply supported boundary conditions, it is found that there is an approximately linear relation between the buckling coefficient and the curvature parameter when the diagrams are plotted in double logarithmic scale. The probabilistic calculations demonstrate that there is a considerable probability to overestimate the buckling load of GLARE panels with deterministic calculations.Originality/valueIn this study, the deterministic and probabilistic buckling response of fiber metal laminate panels is investigated. It is shown that realistic structural uncertainties could substantially affect the buckling strength of aerospace components.

Experimental and analytical assessment of the hypervelocity impact damage of GLAss fiber REinforced aluminum

This article addresses the response of GLAss fiber REinforced aluminum to hypervelocity impacts of micrometeoroid analogs at impact velocities of 7 km/s and beyond. In relation, the damage modes of different GLAss fiber REinforced aluminum configurations have been exemplified. The GLAss fiber REinforced aluminum configurations comprised six to twelve variably thick aluminum layers and up to four plies of glass fiber reinforced epoxy per composite laminate. Hypervelocity impact experiments have been conducted with the help of a two-stage light-gas gun, wherein aluminum- and stainless steel projectiles were launched at velocities up to 7.15 km/s. Visual inspection of the damage area suggested the dissipation of impact energy in elastic-plastic deformation, petalling, delamination, debonding, tensile failure of fibers, and pyrolysis of epoxy. A prevailing damage mode was not apparent albeit. The quasi-isotropic ply orientation of S2-glass/FM94-epoxy laminates promoted the interference of shock- and rarefaction waves and suppressed the damage area of GLAss fiber REinforced aluminum. To discriminate between the impact performance of different GLAss fiber REinforced aluminum configurations, the energy dissipated in different damage modes of GLAss fiber REinforced aluminum has been assessed quantitatively. In terms of normalized energy, the cross-ply GLAss fiber REinforced aluminum dissipated higher energy in petal formation than in other primary damage modes. The normalized petalling energy was found to decline with the increase of impact energy. The outcomes of this study will help to optimize the GLAss fiber REinforced aluminum laminate, which will be employed as a bumper shield to prevent the fatal damage and the unzipping of a spacecraft pressure bulkhead.

Experimental and numerical analysis of anti-icing a GLARE laminate

Abstract This study aimed at developing a numerical model to estimate the power consumption of a GLAss fiber REinforced aluminum-based electro-thermal ice protection system for anti-icing. The GLAss fiber REinforced aluminum laminate was embedded with recurred S-shaped copper meshes thermally energized by a surface power density. The model determined the influence of a forced convective heat loss and copper-mesh dimension on anti-icing. As a test case, the numerical model addressed the anti-icing performance of a GLAss fiber REinforced aluminum 5A-3/2 laminate at a sub-freezing ambient temperature of 267.95 K. The model demanded a surface power density of 13.03 kW/m2 in order to keep the temperature of the outer aluminum-skin at 285.44 K, which was clearly beyond the water freezing point. The numerically predicted power consumption for anti-icing was in excellent agreement with that from the experiment. The experiment was conducted in a miniature icing wind tunnel by incorporating the comparable icing condition of the numerical analysis. In the experiment, an infrared thermography camera determined the spatio-temporal temperature history of the outer aluminum skin in contact with the free-stream. The infrared thermography camera measurements of surface temperature collapsed in close proximity to that from the numerical analysis. The outcomes of this study will consolidate the confidence of aircraft manufacturers on the proposed anti-icing system.

Deicing of a GLAss fiber REinforced aluminum laminate – Part 2: Influence of substrate curvature

This two part study investigated the deicing performance of a GLAss fiber REinforced aluminum laminate and the influence of its surface curvature on the ice-to-water phase change. Part-1 of this study described the numerical model and the experiments conducted to validate the numerical model. In companion, Part-2 focused on interrogating the influence of substrate curvature on the phase transition based on a numerical model, in which an ice-to-water phase change method in a Lagrangian numerical framework predicted the deicing of a rectangular flat- and a curved GLAss fiber REinforced aluminum 5A-3/2 laminate embedded with a recurring S-shaped copper-mesh. As seen, deicing of the rectangular flat GLAss fiber REinforced aluminum 5A-3/2 model demanded a surface power density of 14.62 kW/m2 at an ambient temperature of 267.15 K. The numerically predicted deicing time, surface power density and deicing temperature of the rectangular flat GLAss fiber REinforced aluminum model were in excellent agreement with that of the rectangular flat GLAss fiber REinforced aluminum specimen of the experiment. Using the identical surface power density and power pulse duration, the curved GLAss fiber REinforced aluminum model required a deicing time 9 s shorter than that needed by the rectangular flat GLAss fiber REinforced aluminum model. After the melting of the entire ice-aluminum interface, temperature of the curved GLAss fiber REinforced aluminum model exhibited a steep increase and surpassed the temperature of the rectangular flat counterpart. A higher temperature of GLAss fiber REinforced aluminum is appreciated for efficient deicing, if the cyclic change of temperature does not induce thermal fatigue.

Deicing of a GLAss fiber REinforced aluminum laminate – Part 1: Experiments and numerical simulation

Deicing is a mandatory procedureto ensure the required aerodynamic lift of aircraft. Countless experimental and numerical investigations have been conducted to determine the deicing efficiency of various ice protection systems. The literature review, however, yielded no single study that has been dedicated to investigate the deicing performance of a GLAss fiber REinforced aluminum (GLARE)-based electro-thermal ice protection system. Of notes, the upper fuselage of the front- and the rear section of Airbus A380 comprises circa 469 m2 of GLARE. This study, therefore, proposed a phase change model based on thermo-dynamics to determine the power consumption and the de-icing performance of a GLARE laminate embedded with recurring S-shaped copper heater elements. The model addressed the influence of copper mesh length and orthotropic properties of GLARE on deicing.As a test case, the power budget for deicing a GLARE 5A-3/2 laminate was predicted numerically. The numerical analysis demonstrated that a surface power density of 14.62 kW/m2 sufficed to deice a GLARE 5A-3/2 laminate covered with a 0.8 mm thick ice layer at an ambient temperature of 267.15 K. To corroborate the numerical predictions, deicing experiments had been conducted in a miniature icing wind tunnel by incorporating icing conditions comparable to that of the numerical analysis. It was found that the predicted surface power density was in excellent agreement with that determined in the deicing experiment. In the experiment, an infrared camera measured the temperature gradient of the GLARE specimen, which was also in close proximity to that of the GLARE model in the numerical analysis.

Experiment and numerical investigation of the aero-thermal demise of pristine and pre-damaged GLARE™ fiber-metal laminates

Since many decades researchers have been interrogating the re-entry physics of lunar objects in the Earth’s atmosphere. A request like ‘demise + re-entry’ in a web search engine gives hundreds if not thousands of studies concerned with the breakup and the disappearance of space flotsam in the Earth’s atmosphere. However, it is hard to comprehend a rational reason why the engineering physics involved in the thermal degradation of spacecraft structures still can be explained with inherent uncertainties. Many derelict satellites and spacecraft are orbiting the Earth. They will gradually enter the Earth’s atmosphere attributed to the gravitational force and may will not survive the aero-thermal load induced by the dense Earth’s atmosphere. This study, therefore, investigated the propensity to aero-thermal demise of a pristine and a pre-damaged spacecraft shielding structure during atmospheric re-entry. The shield was made of a GLAss fiber REinforced aluminum panel, which accommodated five quasi-isotropic S2-glass fiber reinforced FM94-epoxy laminates alternately stacked between six aluminum 2024-T3 alloy sheets. The pre-damage of the shielding system was akin to a damage can be generated by an impact of a micrometeoroid. To impart the pre-damage, a GLAss fiber REinforced aluminum plate was first impacted with a 2 mm diameter stainless steel spherical projectile at 5.49 km/s. The projectile perforated through the plate. Next, the perforated GLAss fiber REinforced aluminum plate was exposed to an air plasma-jet (oxygen dissociated) of a specific enthalpy of 5.4 × 103 kJ/kg at standard air pressure conditions. The high enthalpy plasma thermally degraded the pre-damaged plate, while debris was discharged uprange and downrange out of the plate. The dynamic pressure of the plasma flow exacerbated the debris discharge. The endothermic destruction of a pristine GLAss fiber REinforced aluminum specimen followed several steps: first, layer-after-layer oxidation and melting of the aluminum sheets; next, decomposition and sublimation of epoxy accompanied by thermal and viscous diffusion of molten aluminum and molten glass fibers; finally, the onset of a hole in the pristine specimen. By contrast, the plasma-jet that streamed through the punched hole of the pre-damaged GLAss fiber REinforced aluminum specimen, had thermally decomposed the frontal material layers of the specimen to a large extent in the initial few seconds. The punched hole, however, did not succumb to enlarge after the surface temperature of the GLAss fiber REinforced aluminum specimen reached an asymptote. To reproduce the experimental findings, a new Moving Mesh Front procedure had been developed and implemented in a Lagrangian finite element framework. The numerical analysis considered the temperature-dependent thermal properties of orthotropic S2-glass/FM94-epoxy composites and isotropic aluminum alloys. For a comparable heating condition, the agreement between the predicted and the measured temperatures of the specimen front surface was within 4.4%, while the corresponding agreement was within 6.7% for the rear surface temperature of the test specimen.

Interface Failure of Heated GLARETM Fiber–Metal Laminates under Bird Strike

Many high-strength composite materials have been developed for aircraft structures. GLAss fiber REinforced aluminum (GLARE) is one of the high-performance composites. The review of articles, however, yielded no study on the impact damage of heated GLARE laminates. This study, therefore, aimed at developing a numerical model that can delineate the continuum damage of GLARE 5A-3/2-0.3 laminates at elevated temperatures. In the first stage, the inter-laminar interface failure of heated GLARE laminate had been investigated at room temperature and 80 °C. The numerical analysis employed a three-dimensional GLARE 5A-3/2-0.3 model that accommodated volumetric cohesive interfaces between mating material layers. Lagrangian smoothed particles populated the projectile. The model considered the degradation of tensile and shear modulus of glass fiber reinforced epoxy (GF/EP) at 80 °C, while incorporated temperature-dependent critical strain energy release rate of cohesive interfaces. When coupled with the material particulars, an 82 m/s bird impact at room temperature exhibited delamination first in the GF/EP 90°/0° interface farthest from the impacted side. Keeping the impact velocity, interface failure propagated at a slower rate at 80 °C than that at room temperature, which was in agreement with the impact damage determined in the experiments. The outcomes of this study will help optimize a GLARE laminate based on the anti-icing temperature of aircraft.

Penetration Mechanics of GLARE™ Fiber-Metal Laminates upon Collision with Micrometeoroids

The spacecraft designed for long-duration service are susceptible to hypervelocity impacts of micrometeoroids and orbiting space debris. Such impacts on spacecraft structures can cause spacecraft failure and loss of life. In order to adequately protect the spacecraft bulkhead and flight critical systems, many high-strength composite materials have been developed for debris bumper. GLAss fiber REinforced aluminum is one of the high-performance composites. The review of articles, however, yielded no single study, which has been dedicated to interrogate the damage mechanics of GLAss fiber REinforced aluminum upon collision with micrometeoroids. This study, therefore, aimed at the numerical investigation of penetration phenomena of thick GLAss fiber REinforced aluminum 5-6/5-0.4 laminates upon hypervelocity impact of a projectile. The numerical study employed a predictive model that merged the smoothed particle hydrodynamics and the finite element methods. The model could predict the colossal damage modes of GLAss fiber REinforced aluminum. As seen, the normal impact of a 2 mm diameter spherical 2024-T3 aluminum projectile on GLAss fiber REinforced aluminum, at a relative velocity of 7.11 km/s, resulted into membrane stretching and fiber failure of the glass fiber reinforced epoxy composite laminates. By contrast, the aluminum layers experienced an enormous strain-rate and consequently, suffered thinning, fracture and large mass erosion. The perpetual release waves fragmented the projectile and dispersed the projectile mass prior to the further penetration of GLAss fiber REinforced aluminum. To verify the accuracy of the numerical model, experiments had been conducted by using a two-stage light-gas gun. The experiments generated damage modes of GLAss fiber REinforced aluminum in good correspondence to that of the predictive model. Yet, disparity between the estimations of experiments and simulations had been apparent, which is anticipated due to the phase change of material had not been accounted for in the analysis.

Micrometeoroid impact-induced damage of GLAss fiber REinforced aluminum fiber-metal laminates

Through several decades of development, engineers have made the GLAss fiber REinforced aluminum material fit for aviation structures, e.g., the fuselage of Airbus A380. A request like ‘GLARE + impact’ in a web search engine gives hundreds if not thousands of scientific articles address the high impact resistance of GLAss fiber REinforced aluminum. GLAss fiber REinforced aluminum can be a suitable material for shielding systems to protect manned and unmanned spacecraft against micrometeoroids and orbital debris. However, it is hard to comprehend a rational reason why a thorough search in the relevant literatures yielded only a couple of articles focused on the ballistic impact response of GLAss fiber REinforced aluminum. Handful of studies have interrogated the damage of GLAss fiber REinforced aluminum using analytical, numerical and experimental methods. No physical model, yet has been proposed and validated to capture the damage of GLAss fiber REinforced aluminum upon collision with micrometeoroids. This study, therefore, introduced a new numerical model based on the smoothed particle hydrodynamics and the finite element method. The model was able to predict the exorbitant strain-rate of GLAss fiber REinforced aluminum. Besides, the model could approximate the cataclysmic amount of energy dissipated in the shockwave-induced collapse of GLAss fiber REinforced aluminum. The model assumed that the behavior of the S2-glass/FM94-epoxy composite material was orthotropic elastic prior to the onset of damage. After the damage initiation, the energy-based orthotropic softening governed the damage accumulation in the composite material. Looking at the outputs of the model, an impact of a 2 mm 2024-T3 aluminum sphere on a GLAss fiber REinforced aluminum 5–6/5–0.4 plate led to petals in the front aluminum layer, spallation of the rear aluminum layer and buckling of the inner aluminum layers. By contrast, the S2-glass/FM94-epoxy composite laminates conserved the imparted energy through membrane stretching before had been pierced. A test campaign, with the aid of a two-stage light-gas gun facility, was pursued to assess the model accuracy. It was found that the model predicted many of the experimental observations with a high degree of fidelity.

Lightweight scheme selection for automotive safety structures using a quantifiable multi-objective approach

Abstract The main objective of this paper is to propose a quantifiable multi-objective evaluation approach method to rationalize the subjective evaluation in the selection of lightweight scheme for automotive safety components, which can be applied in the selection of materials and structures in lightweight design of automobiles and other products. The proposed method combines intuitionistic fuzzy number theory, entropy method and Technique for Order Preference by Similarity to Ideal Solutions (TOPSIS) to deal with uncertainty in the decision-making process. Intuitionistic fuzzy number theory was used to quantifies the subjective evaluation of decision makers. Entropy method and fuzzy logic theory were utilized to objectively weight the criteria and decision makers, and The TOPSIS method is used to assess the pros and cons of alternatives. To assess and validate the effectiveness of the proposed method, three automotive bumper systems using different materials and structures, namely, high strength steel (HSS), polymer composite-metal hybrid (PMH), and glass fiber-reinforced aluminum laminates (GLARE) were taken as example, some qualitative criteria including recyclability and easy manufacturability as well as several quantitative criteria such as the weight, cost, crash safety (energy absorption, peak impact force and maximum deflection), were considered and balanced. According to the findings, the evaluation results of the proposed method are consistent with the evaluation results of the existing VIKOR method and TOPSIS method, which verifies the correctness of the proposed method. In addition, from the perspective of sensitivity analysis results and method principles, it is proved that the proposed method is superior to the other two methods in robustness and efficiency.

Drawing potential of fiber metal laminates in hydromechanical forming: A numerical and experimental study

It is known that fiber metal laminates as one of hybrid materials with thin metal sheets and fiber/resin layers have limited formability in conventional forming methods. This paper presents an experimental and numerical study for drawability of glass fiber-reinforced aluminum laminates under hydromechanical drawing technique. Fiber metal laminates comprised of a layer of woven glass fiber-reinforced prepreg, sandwiched between two layers of aluminum alloy. In order to produce fiber metal laminates, the laminates were subjected to a sufficient squeezing pressure under a controlled heating time and temperature by using a hydraulic hot press. A hydromechanical tooling equipped with blank-holder force and fluid pressure control system was used to form the initial circular fiber metal laminate blank. Finally, the effect of parameters such as pre-bulging pressure, final chamber pressure, and drawing ratio on process variables was evaluated. Also, the characteristic curve of hydromechanical drawing of fiber metal laminate i.e. chamber pressure in terms of drawing ratio was achieved by means of experimental tests and numerical simulations. The results showed that the maximum drawing ratio of defect-free fiber metal laminates, namely without any tearing, wrinkling, and delamination was obtained at pre-bulging and chamber pressure of 35 and 80 bar, respectively.

Experimental investigation on normal and oblique ballistic impact behavior of fiber metal laminates

In this work, the normal (0°) and oblique (30° and 45°) ballistic impact behavior of glass fiber-reinforced aluminum laminates (fiber metal laminate, FMLs) impacted by a rigid cylindrical projectile (with a flat nose) has been investigated from an experimental point of view. The ballistic impact tests were conducted on the FMLs using a one-stage gas gun at different impact angels, i.e. 0°, 30° and 45°. A high-speed camera was used to capture and record the experimental images and data during the impacting process. Different failure patterns were observed in the FMLs under oblique and normal impact, with the differences concentrated on the initial crack (in the back surface) and plugging damage (in both the front and back surface). The angular change in direction of the projectile during perforation was only observed during oblique impact tests while the maximum value of the angular change was observed when the impact velocity was close to its ballistic limit velocity. In addition, the angular change decreases with increasing impact velocity and is almost constant when the value of [Formula: see text] reaches a critical value. It can also be observed from the impact test results (both normal and oblique impacts) that FMLs exhibited the lowest ballistic limit velocity when the impact angle was close to 30°. In particular, normal impact shows a higher ballistic limit velocity than that of oblique impact while the ballistic limit velocity at impact angle 45° is slightly higher than that at 30°.

Shot peen forming of fiber metal laminates on the example of GLARE®

GLARE (GLAss-fiber REinforced aluminum) is a sandwich material that combines thin aluminum sheets with intermediate layers of glass fiber that are bonded using epoxy. Due to the resulting low specific weight and high strength as well as superior deterioration resistance the material has found its application in aircraft structures. GLARE parts are typically manufactured using the so-called self-forming technique, which is a very expensive and labor-intensive manufacturing process. If it was feasible to form GLARE from flat stock material using conventional forming processes, substantial savings could be achieved. Several attempts to form GLARE from flat stock reported in the literature are restricted by the limited formability of the glass fibers and/or delamination of the layers. This work analyses the possibilities to form GLARE using shot peen forming (SPF), which is an established forming process, e.g. for the production of fuselage parts. It is shown that GLARE shows a similar deformation behavior as monolithic sheets under quasi-static indentation with single steel balls. The process limits are analyzed using SPF tests and lock-in thermography, which is a non-destructive testing procedure for the detection of delamination. A process window for shot peen forming of GLARE is established, and it is shown that curvature radii of less than 2500 mm can be accomplished with no evidence of failure, which is a typical curvature radius of fuselage components for the Airbus A380.

Numerical Simulation and Experimental Charcterisation of Direct Hypervelocity Impact on a Spacecraft Hybrid Carbon Fibre/Kevlar Composite Structure

This article addresses the response of GLAss fiber REinforced aluminum to hypervelocity impacts of micrometeoroid analogs at impact velocities of 7 km/s and beyond. In relation, the damage modes of different GLAss fiber REinforced aluminum configurations have been exemplified. The GLAss fiber REinforced aluminum configurations comprised six to twelve variably thick aluminum layers and up to four plies of glass fiber reinforced epoxy per composite laminate. Hypervelocity impact experiments have been conducted with the help of a two-stage light-gas gun, wherein aluminum- and stainless steel projectiles were launched at velocities up to 7.15 km/s. Visual inspection of the damage area suggested the dissipation of impact energy in elastic-plastic deformation, petalling, delamination, debonding, tensile failure of fibers, and pyrolysis of epoxy. A prevailing damage mode was not apparent albeit. The quasi-isotropic ply orientation of S2-glass/FM94-epoxy laminates promoted the interference of shock- and rarefaction waves and suppressed the damage area of GLAss fiber REinforced aluminum. To discriminate between the impact performance of different GLAss fiber REinforced aluminum configurations, the energy dissipated in different damage modes of GLAss fiber REinforced aluminum has been assessed quantitatively. In terms of normalized energy, the cross-ply GLAss fiber REinforced aluminum dissipated higher energy in petal formation than in other primary damage modes. The normalized petalling energy was found to decline with the increase of impact energy. The outcomes of this study will help to optimize the GLAss fiber REinforced aluminum laminate, which will be employed as a bumper shield to prevent the fatal damage and the unzipping of a spacecraft pressure bulkhead.