Papers by Keyword: Composite Structure

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Authors: Ya Jie Sun, Yong Hong Zhang, Cheng Shan Qian, Zi Jia Zhang, Qi Wang
Abstract: The Lamb wave phased array theory is utilized to analysis the damage scattered signals to identify the structure defect. The damage scattered signals are gotten by comparing the health signals with the damage signals. Phased array theory based structural health monitoring can scan the structure in a certain range of 0°~180° by controlling the time delay of the excitation signals and the response signals. The processed signals in monitoring direction is shown on 3-D imaging to express the damage location in the structure. The method is verified by the experiment on the composite structure and the result shows that the Lamb wave phased array method can detect the damage in the composite structure and the 3-D image clearly displays the structure damage location.
Authors: Jiang Hui Dong, Xing Ma, Julie E. Mills, Zhu Ge Yan
Abstract: This paper provides a comprehensive review of various methods used for skin buckling analysis in composite components. The skin buckling phenomenon is one of the governing criteria in composite design. It is a kind of contact buckling in which partial sections of skin buckle away from the filler material. In general, the problem can be modelled as a thin plate (skin) in unilateral contact with elastic medium (filler material). The theoretical analysis of contact buckling is complicated due to the nonlinearity arising from changing contact regions. To simplify the calculations, the filler material was usually modelled as a tensionless elastic foundation. The skin buckling coefficient varies in terms of the relative foundation stiffness factors. Because the Eigen-value method is not applicable to nonlinear systems, the finite element (FE) method was usually employed for post-buckling analysis, while initial buckling performance was investigated through analytical or semi-analytical methods such as rigid foundation model, infinite plate model and finite plate model. The compressive buckling and shear buckling problems for thin plates resting on tensionless foundations have been solved successfully. However, there are still urgent needs for future research on the topic. For example, the load carrying capacity of the buckling plates needs to be formulated for practical application. Complicated problems with complex loadings and/or corrugated skins need further investigation as well.
Authors: Guo Ning Liu, Hua Dong Zhao, Qian Qian Guo, Sheng Gang Ma
Abstract: A commercially available PET thin film material with pure aluminum material deposited on its two surfaces is studied in this work to investigate the relationship between the mechanical behaviors and the structure of this “composite” material with the application of the concepts for the composite mechanics. This kind of structure has excellent anti-corrosion properties and can act as the good functional barrier material. Experimental researches are further carried out here to study the mechanical performance under various loading conditions as well as the influence of loading rates over the structure’s failure behavior, and over its mechanical properties like the yielding strength and the elastic modulus.
Authors: Sung Cheol Yoon, Joon Hyung Ryu, Jeong Guk Kim
Abstract: This study introduces the structural analysis and the testing results of the composite structure which is applied to tilting train in Korea. The composite structure is made of aluminum honeycomb structure materials like a sandwich. The static load test was performed to evaluate the structural characteristic and stability of the composite structure. Considering the vertical, compressive, torsional load and 3-point supporting type as a testing terms, the structural stability of a carbody was evaluated. Load test are based on "Performance Test Standard for Electrical Multiple Unit" with the reference code JIS E 7105. The test results have been very safety and stable for design load conditions.
Authors: Lei Qiu, Shen Fang Yuan, Tian Xiang Huang
Abstract: Composite structures adopted in aerospace structures have attracted much interest to structural health monitoring (SHM) for localization of impact and damage positions due to their poor impact resistance properties. Propagation mechanism and frequency dispersion characteristics of Lamb wave signals on composite structures are more complicated than that on simple aluminum plates. Recently, much attention has been paid to the research of time reversal focusing method because this method shows a promising advantage to give a focusing image of the structural damage, improve the signal-to-noise ratio and compensate the dispersion of Lamb wave signals. In this paper, aiming at developing a practical method for on-line localization of impact and damage on aircraft composite structures which can take advantage of time reversal focusing and does not rely on the transfer function, a new phase synthesis based time reversal focusing method is proposed. Impact and damage images are given out directly through time reversal focusing based on phase synthesis process of the signals. A SHM demonstration system is built on a composite panel of an aircraft wing box with many bolt holes and stiffeners using the phase synthesis based time reversal focusing method. The demonstration results show that this method can estimate the positions of impact and damage efficiently with a low sensitivity of velocity errors.
Authors: Mark J. Eaton, Rhys Pullin, C.A. Featherston, Karen M. Holford
Abstract: Damage detection and location in aerospace composites is currently of great interest in the research community and is being driven by the need to reduce weight of commercial aircrafts and hence make substantial environmental improvements. The increased use of composites as safety critical components has led to the need for development of structural health monitoring (SHM) systems. Acoustic Emission (AE) offers an excellent potential for delivering the necessary information of damage detection to maintenance engineers in terms of location however there are currently no methodologies that can use AE signals to characterise damage sources. This paper explores a methodology for damage characterisation based on measuring the amplitude ratio (MAR) of the two primary plate wave modes, to allow identification of in-plane (matrix cracking) and out-of-plane sources (delamination). Results from a large-scale buckling test show good correlation between signal characterization and observed damage mechanisms.
Authors: Yan Wang, Yao Feng Zhu, Ya Qin Fu
Abstract: In this paper, four models of PVC composites reinforced with glass fabric were designed based on the arrangement of the V-structure, using V-structure discontinuous glass fabric as the sandwich structure and PVC resin as matrix. The acoustic insulation properties of the composites with V-structure discontinuous glass fabric as the sandwich structure were analyzed with a two-channel acoustic analyzer. The results show that the orientation of the V-structure has a strong effect on the acoustic insulation property. In the case where the raw material, thickness and density of the V-PVC composites are almost the same, the composite with the opening of the V-structure toward the source of sound shows better acoustic insulation than that with the opening of the V-structure away from the sound source. This difference is even more pronounced with increasing layers of glass fabric.
Authors: Nur Azam Abdullah, Erwin Sulaeman
Abstract: This paper presents aeroelastic tailoring optimization of a swept back supersonic wing with external stores using composite structure material for the wing skin. The analysis has been conducted to calculate the flutter speeds at several altitudes ranging from a negative altitude of-7,943 ft until 30000 ft. MSC Nastran software is used to determine the flutter speed. The objective is to get the lowest possible wing weight by varying the wing skin composite fly angle and thickness as the optimization variables and by considering flutter speed as the optimization constraint. The constraint is imposed such that the flutter speed should be similar or higher than flutter speed of a previously investigated supersonic wing having similar planform but using aluminum as wing skin. The use of composite suggested that each composite layer thickness and fiber angle can be manipulated to achieve the target. The present results indicate that the weight of the composite wing skin can be reduced by 70 % compared to the aluminum wing skin while retaining similar or better flutter speed boundary envelope.
Authors: Marion Lorgouilloux, Robert Gaertner, Thierry Chopin
Abstract: A new low density mineral material has been synthesized via a simple, flexible, cheap and easy to control process. This material is a synthetic carbonate produced by carbonation of a solid phase composed of a calcic part and a magnesian part. Typically, its production process includes the calcination of a raw dolomite (general formula CaCO3.MgCO3) into the oxide form, followed by an at least partial hydration of this oxide and a subsequent carbonation step. This process is thus close to the well-known process used for the production of Precipitated Calcium Carbonate (PCC), a common filler and pigment in plastic, paper and rubber, except that the raw material is a dolomite instead of a limestone. It has to be pointed out that flue gases from different industries can be used as a source of CO2 for the carbonation. Many parameters have been studied, such as the hydration conditions or the carbonation conditions, allowing the production of a whole range of products. The products obtained via this process are composed of a calcic part, mainly as calcite and aragonite (CaCO3), and a magnesium containing part, mainly as hydromagnesite (4MgCO3.Mg (OH)2.4H2O). Compared to standard PCC, this material has a particularly low density (100-250 kg/m3 instead of 300-600 kg/m3 for standard PCC), a rather high BET specific surface area (15-35 m2/g instead of 4-15 m2/g for standard PCC) and a specific particle morphology and structure. The particles are indeed commonly spherical particles composed of a core of calcite/aragonite covered by a layer of hydromagnesite. This structure can be described as a core-shell structure. Due to these special features, this product could be used in multiple applications, such as raw material for the manufacture of insulation material, flame retardant, filler in plastics, paints, paper, rubber, and many more.
Authors: Carlos A. Ramos, José Luís Esteves, Rui A. Silva, António Torres Marques
Abstract: Structural health monitoring of composite structures may be accomplished by measuring strains with embedded optical fibre sensors. In this paper, we present the performance of Bragg grating sensors, which are embedded into a carbon composite laminate and them bonded to the structure in analyse. The paper will briefly discuss the results and compare them with a free fibre Bragg grating bonded in the surface of the carbon composite laminate, with existing electrical strain gauge installation and with a numerical analysis by the finite element method.
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