Aircraft Structural Applications Research Articles

The effects of zircon particles on the mechanical and morphological properties of glass fibre reinforced epoxy composite

Recent studies have focused on improving the mechanical properties of thermosetting composites that seem to include inorganic nanoparticles dispersed throughout the matrix material. This study investigates the mechanical properties, crystallographic and morphological study of epoxy composites when ball-milled zircon filler is incorporated into epoxy at weight percentages of 0, 5, 10, and 15(wt%). Zircon nanoparticles and epoxy resin are blended using an ultrasonic liquid technique, and then compression moulding is used to make the composite materials. Using theoretical and calculated densities (g/cm3), the volume fraction of voids (%) in the prepared composites is estimated. The Mechanical tests were done in accordance with ASTM requirements. The average zircon particle size was found to be 73.26 nm using field emission scanning electron microscopy. The chemical composition, crystalline structure and the crystalline size (2.1 nm) of zircon particle was determined using X-Ray diffraction. In comparison to pure glass fibre reinforced epoxy polymer, the 10 wt% zircon particle's tensile strength, tensile modulus, flexural strength, and flexural modulus are 33.33%, 12.56%, 32.88%, and 15.74% higher, respectively. Strain energy for tensile test is 82.96%, elongation at break is 53.52% higher and strain energy for flexural test is 52.38%, elongation at break is 14.67% higher than pristine composites. As a comparison to neat sample, Shore "D" hardness at 10 wt percent ZrSiO4 is 5.88% harder, and Izod average impact strength (J/mm) is 63.20% greater. Pullout of fibre, damaged interfaces, filler dispersion and voids are identified using field emission scanning electron microscopy. Zircon filler of 10 wt% inclusion on epoxy with E-glass fibre reinforcement reportedly improves characteristics than other proportions, especially better improvement than plain sample. Because of this, the mechanical and structural properties of developed composites are enhanced by this approach. This research proposal would lead to a special combination of ZrSiO4 inclusion and E-glass fibre reinforcement in epoxy composites for aircraft structural applications.

A holistic assessment of a stiffened panel production using a novel thermoplastic material and implementing the induction welding process

PurposeThe purpose of this paper is to investigate the feasibility to produce a novel aircraft full stiffened panel using entirely a new hybrid thermoplastic composite material allowing for appreciably lower processing temperatures as compared to conventional structural thermoplastic composites.Design/methodology/approachFor stiffening the fuselage skin panel, the out of autoclave welding of four composite stringers was obtained using a modified induction welding (IW) process. The quality of the welds was investigated using micro-tomography and the mechanical strength of the lap joints was assessed by means of single-lap shear strength (SLSS) tests. Moreover, a holistic design index was implemented as a decision support tool for selecting the optimal set of IW process parameters. Based on the index used, the quality as well as the entire life cycle cost and environmental impact are accounted for.FindingsLow porosity values as well as no deconsolidation were observed at the investigated application, and the average measured SLSS, even found lower, lies within the range of the respective values encountered in other similar high-performance applications. It is exhibited that after the optimization, the IW process offers significant potential to replace the autoclave process in welding applications. Thus, it paves the way for reduced cost and increased sustainability, while still meeting the predefined quality constraints.Originality/valueAlthough several studies on the IW application have been conducted, limited results exist by using novel thermoplastic materials for aircraft structural applications.

Investigation of mechanical properties of aluminum metal matrix composites with nanomaterial reinforcement

The exceptional strength and fatigue resistance of aluminum alloy 6061 make it ideal for aircraft structural applications. Increase mechanical characteristics and corrosion behavior of AA6061 metal matrix composites by adding reinforcements are the primary goals of the current research project offered. The primary goal of this study is to construct an aluminum composite using an ultrasonic stir casting technique that incorporates two reinforcements, such as graphene and s-glass fibre, with a base alloy matrix of AA6061 as the primary reinforcement. In accordance with ASTM requirements, the cast aluminum alloy was machined and mechanical tests such as the weight percentage of reinforcements are taken in specimens such as tensile, Impact, Hardness, SEM, Wear.

Dynamic analysis of cantilever beam used carbon fiber composite for aerospace applications

The mixed carbon fibre composites and angle orientation of part is subjected to a dynamical study. Model analysis is used to identify the materials mode shapes and bending strength of composite structures. The higher outcomes of aircraft structural applications are supplied by natural frequency. The Ansys workbench module draws the cantilever beam with one end static and the other end free for analysing composite behaviours in the structural parts and linear structures. The research using finite elements showed eight different deformation shapes. The greatest values of natural frequency and comparable shapes are predicted by the mode shapes of 1 to 8. The strain rates is examined the basic frequency of 25.27 Hz determined in the cantilever beam structures. The dynamic vibration is formed 17.80 Hz of composite vibration is produced from these experiments.

An experimental study on mechanical properties of Kevlar composite for aircraft structural applications

Kevlar composite are widely used in various structural applications including aircraft wing fuselage skin, automobiles and space vehicles due to their lighter in weight and high strength material which can be replace with steel. It has low density and high modulus of para-aramid synthetic fiber. The proposed Kevlar fabric with 2D plain-woven pattern was reinforced with polyester resin is used as composite. Based on literature work, the sample laminates were designed and fabricated using compression molding process at room temperature and material cutting process was performed by using waterjet machining to achieve the accurate shape and size of the composite during the fabrication and also it reduces the manufacturing defects and provides the better binding properties. The results, in which it improves structural stability of composite with increase the mechanical properties of flexural strength and tensile strength of the Kevlar composite. In this paper, an attempt is made to investigate the mechanical properties of Kevlar composite by performing various mechanical test on UTM (flexural test and tensile test) and the evaluation of maximum tensile strength and flexural bending strength, deflection and other parameters etc. and comparative study on failure behavior of sample laminates on the post tensile test and flexural test.

On three-dimensional printing of 17-4 precipitation-hardenable stainless steel with direct metal laser sintering in aircraft structural applications

The martensitic 17-4 precipitation-hardenable stainless steel is one of the commercially established materials for structural engineering applications in aircrafts due to its superior mechanical and corrosion resistance properties. The mechanical processing of this alloy through a conventional manufacturing route is critical from the dimensional accuracy (Δ d) viewpoint for development of innovative structural components such as: slat tracks, wing flap tracks, etc. In past two decades, a number of studies have been reported on challenges being faced while conventional processing of 17-4 precipitation-hardenable stainless steel for maintaining uniform thickness of aircraft structural components. However, hitherto little has been reported on direct metal laser sintering of 17-4 precipitation-hardenable stainless steel for development of innovative functional prototypes with uniform surface hardness (HV), Δ d, and surface roughness ( Ra) in aircraft structural engineering. This paper reports the effect of direct metal laser sintering process parameters on HV, Δ d, and Ra for structural components. The results of study suggest that optimized settings of direct metal laser sintering from multifactor optimization viewpoint are laser power 100 W, scanning speed 1400 mm/s, and layer thickness 0.02 mm. The results have been supported with scanning electron microscopy analysis (for metallurgical changes such as porosity (%), HV, grain size, etc.) and international tolerance grades for ensuring assembly fitment.

Evolution of corrosion damage in an aluminum alloy: an experimental and numerical study

In this paper, the results of a recent study on the environment-induced damage behavior of aluminum (Al) alloy 2024-T3, which is often a preferred choice for use in a spectrum of aircraft structural applications, are presented and discussed. Accelerated corrosion tests by way of exposure of test specimens of the alloy to an aggressive aqueous environment were carried out at ambient temperature (27°C). A numerical approach, based on the meshless peridynamic method, was developed to study the morphology of damage caused by the aqueous environment by way of pitting. To improve the numerical accuracy while concurrently reducing the solution time, an implicit finite-difference method was developed to solve the peridynamic control equation. The numerical algorithm was implemented in a Matlab program and was applied to simulate the evolution of pits resulting as a direct consequence of sustained exposure to the aqueous environment. The numerical predictions accord reasonably well with the experimental findings and results, thereby providing adequate proof that the simulation algorithm based on the meshless peridynamic method is effective at predicting both the nucleation and growth of the damage in the form of pits arising as a direct consequence of exposure to an aggressive aqueous environment.

Predicting the delamination factor in carbon fibre reinforced plastic composites during drilling through the Gaussian process regression

The carbon fibre reinforced plastic (CFPR) has been widely used in aircraft structural applications due to the superior modulus, specific tensile strength, and fatigue strength. The inhomogeneous and anisotropic nature of these composites poses great challenges on the machining process. Particularly, the delamination is one of major defects associated with drilling, which has a significant impact on CFRP’s structure integrity and application. Machine learning approaches can help facilitate the optimization of machining processes. In this study, we develop the Gaussian process regression (GPR) model to predict delaminations in carbon fibre reinforced plastic composites during drilling from machining parameters. The model is simple and highly accurate and stable that contributes to fast delamination estimations. By combining the optimization results from the Taguchi method and GPR approach, it is expected that more quantitative data can be extracted from fewer experimental trials at the same time.

Deformation analysis of Al Alloy AA2024 through equal channel angular pressing for aircraft structures

ABSTRACT Equal Channel Angular Pressing (ECAP) is one of the most innovative Severe Plastic Deformation (SPD) methods used for grain refinement of materials up to ultra-fined or Nano structured level which leads to superior mechanical properties. Computer simulation is one of the best alternative of actual ECAP deformation to know the influence of each processing parameters on end results. In the present work, AA2024 alloys is used, which is a demanding material in aircraft structure and automotive applications. To understand the process/die design parameter, 3D FEM simulation is done on ECAP process using DEFORM-3D software. Simulation was done on different channel angles such as 90º, 105º, 120º and 135º and corner angles such as 0º, 10º, 20º and 30º. The ECAP process was simulated for a single ECAP pass. The results concern to the extrusion load, developed stresses, effectivestrain and temperature variation on the processed material were noted obtained. From the observed results, it was found that the minimum channel angle produces the maximum temperature profile on the material, develop maximum stress and strain at deformation zone. Additionally, the outcome acquired by such computational technique illustrate that the shear strain decrease with increase in channel and corner angle.

Investigation of the chip adhesion mechanisms in micro-drilling of high ceramic-content particle-filled GFRPs

Glass-fiber reinforced polymers (GFRP) are widely used for printed circuit boards (PCBs) in automotive and aircraft structural applications. The performance of micro-drilling in high ceramic-content particle-filled GFRP heavily influences the signal transmission quality and speed available from these PCBs. Chip adhesion is one of the biggest obstacles to high-performance micro-drilling especially for holes with large depth-to-diameter ratios. This paper offers the first study of the chip adhesion characteristics and formation mechanisms seen when micro-drilling ceramic particle-filled GFRP components, which is the substrate material of PCBs. A direct-contact temperature measurement method is presented to measure the temperatures seen when drilling the laminated composite material. The effects of processing parameters on drilling temperatures and chip adhesion were investigated. A method to control chip adhesion is suggested. The results show that chip adhesion can be divided into four stages. Effective measures to reduce chip adhesion include reducing the drill speed, appropriately increasing the feed rate, and, controlling the number of drilled holes before the drill is sharpened. Also, the use of cold forced air can aid heat dissipation and effective chip extraction. As a result, the chip adhesion was reduced.

Review on Fiber reinforced/modified Bismaleimide resin composites for Aircraft Structure Application

Bismaleimide (BMI) is a high performance thermoset material which possess similar characteristics as that of Polyimides which include high strength and rigidity at high temperature. It can be used for high temperature application upto 260° C. It stands between epoxy and polyimide in its thermal stability and moisture absorption properties. The resin is brittle in nature which necessitated modification with various modifiers viz epoxy, phenol Novolac, Polydimethylsiloxane (PDMS), Allyl phenol, Amines, Carbon nanotubes(CNT), ceramic materials etc. at chemical level to reduce its brittleness. The bismaleimide is used as a matrix in composite materials is reinforced with fibers viz carbon, Kevlar, Basalt, glass fibers. Various authors studied the bismaleimide composite material for its application in Aircraft and missile structures which requires thermal stability and high strength at high temperature. is the resin. In this article the fiber reinforced modified bisamleimide resin composite materials are reviewed with an intend to explore the wide application of the resin system.

Experimental analysis on wire spark erosion machining of aluminium hybrid metal matrix composites by Taguchi approach

AA 2024 an aluminium alloy, which is most commonly employed for various engineering fields, especially automobile components and aircraft structural applications. The materials added to increase the desired properties are called as reinforcement materials such as Al2O3 and BN, abrasive and leads to more wear on tool and poor quality in machining surface. Wire Electrical Discharge Machining (WEDM) is an advanced machining process mainly employed for machining of hard materials and also especially used for making complex shapes in any electrically conductive hard material. In this present study, an experimental analysis has been done on WEDM of AA 2024 based Hybrid Metal Matrix Composites (HMMC). Pulse on time ‘Pon’ (µs), Pulse off time ‘Poff’ (µs), and peak current (A) are considered as input process parameters in this present analysis. Material Removal Rate (MRR) and Surface Roughness (SR) are considered as preferred performance measures that are need to be optimized. Taguchi’s methodology has been implemented for designing and analyzing the experimental runs. An L27 Orthogonal Array (OA) has been employed for conducting the experimental runs. The effect of process parameters on desired outputs such as MRR and SR were investigated by Taguchi’s analysis. Multiple regression analysis has been adopted for correlating the relationship between the selected input and output process variables.

Development of regression models for wire electrical discharge machining of aluminium metal matrix composites

Wire Electrical Discharge Machining (WEDM) is a contemporary approach of material removal which is conceived from the concept of Electrical Discharge Machining (EDM), predominantly employed for machining of hard to machine materials and also especially used for making difficult shapes on any electrically conductive work material. AA 2024 is an aluminium alloy, generally used as important material for various engineering applications such as aircraft structural applications. The outstanding properties of AA 2024 alloys makes this material to be best suitable for various engineering applications. The parts employed for aerospace applications needs very much nearer tolerances and more accurate shape and size. In this present study an experimental investigation has been done on WEDM of Al-MMC (Aluminium 2024 alloy + Al2O3). Pulse on time ‘Pon’ (µs), Pulse off time ‘Poff’ (µs), and peak current (A) are considered as input process parameters in this present analysis. Material Removal Rate (MRR) and Surface Roughness (SR) are considered as preferred performance measure that are need to be improved. Taguchi’s approach has been adopted for designing and analyzing the experiments. An L27 Orthogonal Array (OA) was employed for conducting the experimental runs. The influence of process parameters on desired outputs such as MRR and SR were examined by Taguchi’s analysis. Multiple regression analysis has been developed for correlating the relationship amongst the selected input process variable and preferred outputs.

Parameters optimization and development of multiple regression models for wire electrical discharge machining of aluminium composites

The demand for lightweight materials are increasing nowadays due to emerging industrial applications. AA 2024 is an aluminium alloy, most commonly employed material for various engineering applications such as aircraft structural and automobile applications. The materials added to increase the desired properties are called as reinforcement materials such as Al2O3 and BN, abrasive and leads to more wear on cutting tool and meagre quality in machining surface. Wire Electrical Discharge Machining (WEDM) is an advanced method of material removal which is conceived from the concept of Spark Erosion Machining process. WEDM is mainly employed for machining of hard materials and also especially used for making complex shapes on any electrically conductive work materials. In this present study, an experimental analysis has been performed on WEDM of aluminium alloy based Metal Matrix Composites (AMMC). Peak current (A) Pulse on time (‘Pon’) (µs), Pulse off time (‘Poff’) (µs) are considered as input process parameters in this present analysis. Material Removal Rate (MRR) and Surface Roughness (SR) are considered as desired performance measures that are need to be optimized. Taguchi’s methodology has been implemented for designing and analyzing the experimental runs. An L27 Orthogonal Array (OA) was employed for conducting the experimental runs. The effect of process parameters on desired outputs such as material removal rate (MRR) and surface roughness were investigated by Taguchi’s analysis and ANOVA analysis. Multiple regression equations have been developed for correlating the relationship between the selected input process variable and output variables. Contour plot analysis also performed for disclosing the combined effect of input variables on performance measures.

A hierarchical method for the impact force reconstruction in composite structures

Impact damage is a major concern for new generation aircraft composite components due to their low impact resistance capabilities. The development of an impact location and force reconstruction algorithm would provide rapid and efficient prediction of damage occurrence, thus making structures safer and creating maintenance inspection procedures more efficient, thus saving time and costs. However, state-of-the-art impact force reconstruction algorithms use reference data from numerical simulations and require a detailed knowledge of mechanical properties, which are difficult to obtain under real operational conditions. This paper presents a hierarchical impact force reconstruction algorithm that relies on experimental structural responses measured by a sparse array of surface bonded receiving ultrasonic transducers. This algorithm uses time reversal method to retrieve the location of an impact source and interpolation techniques based on hierarchical radial basis functions to calculate the transfer function at the impact point and reconstruct the impact force history. A number of impact testing were performed on a composite plate-like structure and a wing stringer-skin panel, and compared with impact force algorithms available in literature. Experimental results revealed that the proposed impact force reconstruction method was able to extrapolate the information associated with points far from the impact location and determine the impact force history with high level of accuracy in a real aircraft structure. Since the proposed algorithm requires the calibration of transfer functions from a very sparse training set of data and it does not need numerical models of the component under investigation, it demonstrates its potential as a useful monitoring tool for impact force reconstruction in composite components for full-scale aircraft structural applications leading to timely and cost-efficient inspections.

Vibration and flexural characterization of hybrid honeycomb core sandwich panels filled with different energy absorbing materials

Vibrational analysis and flexural behavior of hybrid honeycomb core sandwich panels filled with three different energy absorbing materials is experimentally investigated in this work. Sandwich panels are developed using vacuum bag molding technique with hybrid fiber of 70% carbon fiber and 30% of ‘E’ glass fiber. For vibrational analysis, the displacement signal from the sensor is measured in a PC using DEWE software analysis system by setting the sampling rate of 6000 Hz. The natural frequency of PUF, Rohacell and wheat husk filled sandwich panel is observed under cantilever and fixed boundary conditions. Flexural test is performed at a crosshead displacement rate of 1 mm min−1 using universal testing machine. The combination of energy absorbing material filled sandwich panels had effectually enhanced the interfacial strength thereby increased the damping properties of all panels sufficiently. On comparing the natural frequency, damping factor and flexural properties of the three sandwich panels, PUF filled panel exhibits good behavior. The results obtained from both experimental and analytical values are in good agreement. The investigation leads to a light novel hybrid honeycomb sandwich panels that can be used for several applications, in particular for aircraft structural applications, such as airplane floors, doors, wings flaps, rudders and helicopter fuselages.

Tensile deformation mechanism and failure mode of different microstructures in Ti[sbnd]5Al[sbnd]5Mo[sbnd]5V[sbnd]3Cr alloy

Ti5Al5Mo5V3Cr alloy (Ti-5553) is a high strength near β titanium alloy for aircraft structural applications and has found its specific application in landing gear components. In the present paper a systematic approach was taken to generate and choose three distinct microstructures; one with full β, and the other two with two-phase lamellar α+β microstructures with distinctly different aspect ratios of α precipitates. Tensile behavior of these three microstructures was studied. Few of the distinct observations include 1) Even in the single phase β microstructure, yield strength (YS) was reasonably high, 2) For the two-phase lamellar α+β microstructure high YS and no work hardening were observed, 3) Among the lamellar microstructures, small aspect ratio of α showed much higher YS, but less ductility as compared to the larger aspect ratio of α. Detailed TEM based investigations of deformation micro-mechanisms along with study of eventual failure mechanisms were carried out to explain the above mentioned tensile responses of these microstructures. Differences between the microstructures with small vs. large aspect ratios of α were specifically addressed in terms of tensile behavior and underlying deformation micro-mechanism and failure mode.

Static and dynamic comprehensive response of additively manufactured discrete patterns of Ti6Al4V

Additively manufactured (AM) discrete patterns made of Ti6Al4V offer potential energy absorption for engineering applications, including blast and impact protection systems, aircraft structure, automotive, and medical applications. In this study, we compared three different cylindrical printed patterns fabricated by selective laser melting (SLM), patterns sharing similar cross section and mass, in order to identify the "optimal" design of such structures for energy absorption purposes. The specimens consist of one columnar and two tubular patterns. The columnar pattern (8-Column) was constructed out of uniformly distributed columns. The first tubular pattern (Tube I) was constructed with the same outer diameter and tapered inner profile. The second tubular pattern (Tube II) had adjusted internal and external diameters. Quasi-static and impact (dynamic) load tests were performed to investigate the strain rate dependency, compressive response and failure mode of each pattern, including a comparison with a printed solid reference cylinder. Numerical simulations were carried out to complement the experimental work and to develop a generic numerical tool for future structural optimization applications. The results show that the geometry has a strong influence on its overall compressive performance, including energy absorption. The most effective of the patterns investigated was Tube I for both quasi-static and dynamic regimes.

Machining parameter optimization for EDM machining of Mg–RE–Zn–Zr alloy using multi-objective Passing Vehicle Search algorithm

Mg alloys are known for their specific strength, stiffness, damping capacity, EMI shielding. Particularly, Rare earths added Mg alloys find applications in the gear box casing, transmission housing, engine mount, ribs, frames, instrument panels due to their improved corrosion resistance, pressure tightness, specific strength and creep strength. Reemergence of Mg alloys in the aircraft structural applications demands for advanced machining processes such as EDM to fabricate complex geometry parts. In this study, parametric multi-objective optimization of EDM on Mg–RE–Zn–Zr alloy is carried out using the novel meta-heuristic algorithm – Passing Vehicle Search (PVS). The input parameters considered are pulse-on (Ton), pulse-off (Toff) and peak current (A). Response surface method (RSM) is implemented through the Box–Behnken design to formulate a mathematical model for Material Removal Rate (MRR), Tool Wear Rate (TWR) and Roundness of holes. The accuracy of theoretical model has been established using the confirmation runs. Using the weighted sum method, the multi-objective PVS calculated optimal solutions for different weights to generate 2-D and surface pareto fronts. These pareto fronts were evaluated for performance determination of PVS using novel and established metrics such as spacing, spreading, hypervolume and pure diversity. The values of performance metrics indicate acceptable nature of the graphs and such analysis would facilitate better comparisons of solutions to select algorithms for optimization. Finally, decision making is illustrated with the help of level diagrams to draw up practical inferences for designing production plans and providing the best choice of machining parameters according to their preferences.

Direct-Friction Riveting of polymer composite laminates for aircraft applications

Friction Riveting is an alternative joining technology to the conventional mechanical fastening suitable for woven-reinforced polymer composites. In this paper, the feasibility of Direct-Friction Riveting is demonstrated for Ti6Al4V rivet and carbon-fiber reinforced polyether-ether-ketone laminate single lap joints. Due to high shear rates, elevated process temperatures (500–900 °C) and fast cooling rates (38 ± 2 °C/s) experienced by the rivet tip, α′-martensitic structures were identified in the rivet anchoring zone along with fiber and polymer entrapment at the rivet-composite interface. An average ultimate lap shear force of 7.4 ± 0.6 kN similar to conventional lock-bolted single lap joints was achieved. These results indicate that Direct-Friction Riveting is a competitive method with potential for improvement and further application in aircraft structures.