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This chapter proposes a systematic simulation strategy to determine the mechanical behaviour of composite laminates under impact loading using a computational mesomechanics approach. The methodology includes modelization of the physical mechanisms of damage observed in laminates: intralaminar (ply failure) and interlaminar (delamination failure). T...
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Low-velocity impacts have a relevant importance for safety of laminated and sandwich composite structures, because they are highly susceptible to damage. In this paper, a 3D cost effective zigzag model is developed in order to efficiently simulate such impacts. It a priori fulfills the continuity of out-of-plane stresses at layer interfaces, the co...
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... A mixed macro-homogeneous and meso-heterogeneous approach has also been used to model composite plates [12,13], which allows the observation of yarn and matrix interaction in the near-impact area, while saving computational costs using macro-homogeneous modelling in areas further from the impact point, where the yarn and matrix are considered a single homogeneous entity. A similar scale of modelling defines the individual plies in which full three-dimensional stress states are considered [14]. This model allows the analysis of the interactions between the intralayer and interlayer damage mechanisms. ...
This study discusses the experimental results of the ballistic impact on thick-layered carbon fibre-reinforced polymer (CFRP), glass-based FRP (GFRP), and Kevlar-based FRP (KFRP) composite plates. Ten 10 mm plates of each type were manufactured via the hand lay-up and vacuum bagging techniques to produce plates with a thickness of 2 mm each, which were bonded together using epoxy adhesive and hot pressed at 75°C to obtain thick layered plates with a total thickness of 20 mm each. The specimen plates were tested according to the NIJ 0108.01 standard in a special firing room using a 9 mm G2 Elite handgun with a full metal jacketed round nose 9 mm × 19 mm Mu1-TJ bullets moving at a velocity of approximately 358 m/s. The results indicated that no total penetration occurred on any of the plates. The bullets were destroyed by impact, and the penetration depths of the CFRP, GFRP, and KFRP plates were 11.10, 9.95, and 22.22%, respectively. The layered structures in these plates appear to have changed the penetration behaviour compared with previous studies. In this study, delamination was the primary failure mode.
... 3 While graphite, cheaper than CF, may decrease the mechanical properties of polymers, CF-reinforced polymers can provide high strength and stiffness. 4 Therefore, considering the material cost, the combination of synthetic graphite (SG) with a low amount of CF can provide both high thermal conductivity and high mechanical strength. ...
Syndiotactic polystyrene (SPS) has attracted considerable attention recently due to its high melting temperature, low cost, and relatively low density value. The aim of the study is to reveal whether a blend of PPS and SPS (PPS-SPS) can be used instead of PPS for high thermal stability, high mechanical performance, and high thermal conductive material applications. For this aim, poly(phenylene sulfide)/syndiotactic polystyrene-based carbon-loaded composite materials were prepared using a twin screw extruder. Two carbon-based materials, carbon fiber (CF) and synthetic graphite (SG), were used to improve the mechanical properties and thermal conductivity of the PPS-SPS blends. Through-plane conductivity values of PPS-30SG-10CF and PPS-SPS-30SG-10CF were obtained to be 13.67 and 12.92 W/mK, with densities of 1.55 and 1.50 g/cm3, respectively. It was demonstrated that PPS-SPS blend-based carbon-loaded composites have great potential to be used in thermal management applications with the advantages of relatively low cost and lightweight compared to PPS-based composites.
... When the applied impact energy is beyond a certain level, the matrix cracking reaches the maximum level, exceeding energy causing the second mode of internal damage mechanism, delamination [71]. Delamination is a fracture that occurs between plies with various fibre orientations in the matrix-rich region [72]. The bending mis- laminates, which was studied by Pinto. ...
This study investigated the impact response behaviours of pineapple leaf fibre (PALF)/carbon hybrid laminate composites for different ply orientations and stacking sequences. The laminates were manufactured using a vacuum infusion approach with various stacking sequences and ply orientations classified as symmetric quasi-isotropic, angle-ply symmetric, and cross-ply symmetric. The laminates were analysed using an IMATEK IM10 drop weight impact tester with an increment of 5 J until the samples were perforated. This investigation reveals that the overall impact properties of PALF and carbon as reinforcements were improved by a beneficial hybridised effect. The laminates with an exterior carbon layer can withstand high impact energy levels up to 27.5 J. The laminate with different stacking sequences had a lower energy transfer rate and ruptured at higher impact energy. The laminates with ply orientations of [0°/90°] and [±45°]8 exhibited 10% to 30% better energy absorption than those with ply orientations of [±45°2, 0°/90°2]s and [0°/90°2, ±45°2]s due to energy being readily transferred within the same linear ply orientation. Through visual inspection, delamination was observed to occur at the interfaces of different stacking sequences and ply orientations.
... Its superior mechanical properties and light in weight permit its usage in an aircraft. In fact, carbon fibre-based composites are extensively used in Boeing 787 Dreamliner where maximum 50% of the composites are used in fuselage, tail surface and wings (Sádaba et al. 2015). Similar to the other carbon in carbon family, carbon fibre also possesses unique characteristics which could be unleashed to discover its full potential. ...
Carbon-based materials have been attaining a great interest from researchers due to its versatility. This study intended to assess the potential of carbon fibre and its composite for bone replacement. The morphological, electrical conductivity and nanomechanical properties (modulus and adhesion energy) of locally obtained carbon fibre were assessed via microscopic devices of scanning electron microscope (SEM) and an atomic force microscopy (AFM), respectively. The carbon fibre was compounded with polyamide 6 and injection moulded prior to assessment of its tensile and morphological properties. The electrical conductivity of the carbon fibre was in a range of 0–1 mA. Whereas the mean modulus and adhesion energy were 1.96 GPa and 22.97 fJ, respectively. The tensile strength and modulus of the composite increased by 14.7% and 13.7% as compared to unfilled polyamide 6. With potential cells stimulating capability owing to its electrically conductive and excellent mechanical properties, carbon fibre could be hypothetically used with selected matrix for replacement of bone in non-load bearing areas such as craniofacial part.
... simulations [2], [4], [48]. González et al. [2] used a 50 mm x 80 mm rectangular fine mesh at the impact zone, with elements aligned with the ply orientation through the thickness. ...
A finite element mesh, aligned along the fibre direction, has often been purported to yield more accurate results in the modelling of damage in composite structures constructed from unidirectional fibre reinforced polymer laminates. However, there has been a lack of a systematic assessment of this approach. This issue is addressed through modelling a selection of test cases; (i) end notched tension (ENT) coupons, (ii) simple tensile/compressive specimens, (iii) open-hole tension (OHT), (iv) low velocity impact (LVI) and (v) compression-after-impact (CAI) of laminated plates. In each case, two models were constructed, one using a uniform mesh, aligned with the global coordinate system, and independent of the fibre direction, and the other where each ply mesh was aligned along the fibre direction. In both cases the local material axes in each ply were correctly represented. Results show that a finite element mesh aligned along the fibre direction plays an important role in the prediction of damage, particularly in the presence of a crack. However, when matrix crack paths are not established a priori, or may not be the dominant damage mode, fibre mesh alignment is unnecessary. Rather, long-established approaches of refined meshes, robust damage models and well-defined material data and boundary conditions, are shown to be sufficient requirements.
... The authors of the reports [1,2] claim that aviation is currently one of the fastest growing industries in the world. New technologies and materials enable the construction of very light vessels, while maintaining their dimensions [3]. The decisive argument is obviously the economic aspect. ...
In ultralight aviation, a very important engine parameter is the power-to-weight ratio. On the one hand, there is a tendency to minimize the size and weight of engines, and on the other hand, there is a demand to achieve the highest possible power by using supercharging systems. Increasing power brings many benefits, but it also increases temperature in the exhaust system, posing a threat to delicate parts of the ultralight aircraft fuselage. Therefore, it is necessary to control temperature values in the engine exhaust system.
This article presents the temperature distribution in the exhaust system of an aircraft engine by the example of a four-cylinder Rotax 912 engine with an electronic fuel injection system. The research was conducted in two stages: measurements were made first for the engine without a turbocharger with an original exhaust system and later for its modified version with an added turbocharger system. The paper presents a comparative analysis of exhaust gas temperatures measured at three points: 30, 180 and 1000 mm from the cylinder head. The tests were conducted for the same preset engine operating conditions at constant speed and manifold air pressure.
It has been shown that the exhaust temperature in the exhaust manifold decreases with the distance from the cylinder head. The highest gradient, over three times higher than the gas temperature from 589.9 °C to 192.3 °C, occurred in the manifold with a turbocharger for 2603 RPM and 31 kPa of manifold air pressure. The introduction of turbocharging causes an increase in exhaust gas temperatures before the turbocharger by an average of 12%, with this increase being greater for operating points of higher inlet manifold pressure. Turbocharging also causes a significant decrease in exhaust gas temperatures behind the turbocharger and the silencer because the temperature drops there by an average of 25%.
... In general, it is required to estimate the failure of material quantitatively. However, the failure of composite structures is not as well understood, although numerous failure theories and models have been proposed, e.g., the maximum stress, maximum strain, von Mises, Tsai-Wu, Tsai-Hill, Modified Tsai-Hill, Hoffman, Hashin, Puck and Schurmann, and Iannucci and Robinson criteria (Reddy and Miravete 1995;Groenwold and Haftka 2006;Vasiliev and Morozov 2013;Sadaba et al. 2015;Talreja 2016). Each failure criterion has its own features. ...
... In general, it is required to estimate the failure of material quantitatively. However, the failure of composite structures is not as well understood, although numerous failure theories and models have been proposed, e.g., the maximum stress, maximum strain, von Mises, Tsai-Wu, Tsai-Hill, Modified Tsai-Hill, Hoffman, Hashin, Puck and Schurmann, and Iannucci and Robinson criteria (Reddy and Miravete 1995;Groenwold and Haftka 2006;Vasiliev and Morozov 2013;Sadaba et al. 2015;Talreja 2016). Each failure criterion has its own features. ...
... The inter-laminar strength is also important for practical strength design of laminated composite shell structures. However, in the present study, we only consider the first-ply failure (Reddy and Miravete 1995;Gürdal et al. 1999) without the inter-laminar failure using a homogenized shell model in the previous section for the sake of simplicity. We need to introduce another model and criterion such as (Brewer and Lagace 1988;Liu et al. 2016) for evaluating the interlaminar failure. ...
In this study, we propose a distributed-parameter optimization method for the material-orientation design aiming at maximizing the strength of a laminated composite shell structure with anisotropic material, which is homogenized based on a laminate theory. The modified Tsai–Hill criterion is employed as a failure criterion in this study, and its maximum value is minimized with the state equation constraint. The issue of non-differentiability inherent in this min–max problem is avoided by transforming the singular local measure to a smooth differentiable integral functional using the Kreisselmeier–Steinhauser function. The optimum design problem is formulated as a distributed-parameter optimization problem, and the sensitivity function with respect to the material-orientation variation is theoretically derived based on a variational method. The optimal material-orientation variation is determined using the H¹ gradient method with Poisson’s equation proposed by the authors, where the sensitivity function are applied as Robin condition to vary and optimize the material-orientation distribution. We transfer the sensitivity function to the internal heat generation and determine the material-orientation variation using Poisson’s equation to ensure continuous distribution of material orientation. The optimum design examples show that the proposed optimization method can effectively and efficiently obtain the optimum material orientation with the smooth curvilinear distribution and minimize the maximum strength measured by a failure criterion.
... (iii) Reducing the overall weight of the aircraft: -This includes simplifying the onboard systems, the use of light-weight seats and cabin/galley equipment, reducing the weight of the auxiliary power unit and the belly-hold freight containers, and of course the adoption of carbon fibre composites for airframe primary structure (Hamerton & Mooring, 2012;Sádaba et al., 2015). Additive manufacture, or 3D printing, is also slowly finding its way into aerospace applications (Joshi & Sheikh, 2015) where it promises to help reduce aircraft weight while increasing customization and overall construction efficiency. ...
The purpose of this paper is to see if airlines in general, and U.S. air-carriers in particular, are meeting their IATA-agreed 1.5% average annual fuel efficiency improvements between 2010 and 2020. To assess the fuel efficiency performance, a quantitative analysis was performed using data provided by ICAO, IATA and the U.S. Bureau of Transportation Statistics (BTS) Form 41 Schedules P 12(a) and T-2. The metric used to assess fuel efficiency is the one advanced by ICAO, namely Litres per Revenue Tonne Kilometre performed. Trends are examined over an extended timeframe to establish annual fuel efficiency improvements. The findings show that the overall performance of U.S. air-carriers from 2010 to 2018 has just met IATA’s 1.5% target with a 1.52% year-upon-year annual fuel efficiency improvement, with domestic operations showing a greater level of improvement than international operations. Such performance suggests that the U.S.A, and by inference, the rest of the world, are just likely to meet their IATA target by 2020. This achievement has largely been made possible through industry’s tremendous efforts to enhance aircraft engine technologies, implement operational improvements, and reduce airframe weight through the extensive application of composite materials.
First published online 27 February 2020
... Fiber reinforced polymer (FRP) composites are widely used in many important technological applications. For example, approximately 50% of the wings and fuselage of the Boeing 787 Dreamliner and the Airbus A350 XWB consist of carbon fiber reinforced epoxy matrix composites [1]. FRP composites have high strength to weight ratio and are generally more resistant to fracture and damage than traditional homogeneous materials. ...
An upper estimate for fiber/matrix modulus ratio in traditional fiber reinforced polymer (FRP) composites is 100. Matrices made from tough elastic gels can have modulus approaching kilopascals and increase this ratio to 107. We study how this extremely high modulus ratio affects the mechanical behavior of such fiber reinforced “soft” composites (FRSCs). We focus on unidirectional FRSCs with parallel fibers perfectly bonded to a soft elastic matrix. We show such composites exhibit the Mullins effect typically observed in rubbers and double network (DN) gels. We quantify size effect on mechanical properties by studying unidirectional composites consisting of finite length fibers. We determine the stress concentration factors (SCFs) for a cluster of fiber breaks in this geometry and show that there is a transition from equal load sharing (ELS) to local load sharing (LLS). We also determine the mean strength and work of extension assuming fibers obey Weibull statistics. We discuss the application of fracture mechanics to this emerging class of composites. We highlight similarities and differences between FRSCs and DN gels.
... The implementation of the numerical model follows the methodology presented in [58,25], see Fig. 12. The fixture and the clamps were discretised with rigid solid elements in contact with the panel and the clamps applied a pressure of 0.25 GPa to the specimen. ...
A constitutive model for the rate dependent mechanical behaviour of woven composites is presented. A glass fibre composite was experimentally characterised under quasi-static and dynamic regimes to determine the strain rate dependency. Afterwards, the physical findings were used to develop a constitutive model able to predict strain rate dependent phenomena. A continuum damage mechanics approach was implemented to capture the composite failure and strain rate dependency was incorporated in the ply properties together with a damping algorithm for stability purposes. As a result, the model provided strain rate dependent behaviour while ensuring the stability of the numerical simulations. Finally, the model was used to investigate the low velocity impact response of composite plates, showing the importance of considering the strain rate dependency even at medium rates to accurately predict the response laminates subjected to dynamic loads.
