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This work focuses on an advanced coupling of computational fluid dynamics (CFD) and structural finite element analysis (FEA) on the aeroelastic behavior of a single element inverted composite wing with the novelty of including the ground effect. The front wing of the formula one (F1) car can become flexible under the fluid loading due to elastic characteristics of composite materials, resulting in changing the flow field and eventually altering overall aerodynamics. The purpose of this study is to setup an accurate fluid-structure interaction (FSI) modeling framework and to assess the influence of elastic behavior of the wing in ground effect on the aerodynamic and structural performance. Different turbulence models are studied to capture better the changes of the flow field and variation of ride heights are considered to investigate the influence of ground effect on aerodynamic phenomena. A steady-state two-way coupling method is exploited to run the FSI numerical simulations using ansys, which enables simultaneous calculation by coupling CFD with FEA. The effect of various composite structures on the wing performance is extensively studied concerning structure configuration, ply orientation, and core materials. The numerical results generally represent good agreement with the experimental data, however, discrepancy, especially in the aerodynamic force, is presented. This may be a consequence of a less effective angle of attack due to the wing deflection and deterioration of vortex-induced effect. For the structural analysis, the woven structure gives rise to more stable structural deflection than the unidirectional structure despite the associated weight penalty. [ABSTRACT FROM AUTHOR]

A sandwich structure consists of a two thin and strong facesheets, bonded to a thick lightweight core material. The mechanical response of a sandwich structure depends on the properties of its constituents. A numerical model and experimental validation of the three-point bending test of sandwich composites are presented in this study. The core material is aluminum honeycomb. The facesheets are made of IM7/Cycom5320-1, which is a carbon fiber/epoxy prepreg system. A comprehensive model of the failure under flexural loading was developed. Facesheet failure was modeled using Hashin's failure criteria. A detailed meso-scale model of the honeycomb core was included in the model. The experiments indicated that failure initiation was due to local buckling in the honeycomb core. Failure propagation was in the form of core failure, facesheet compressive failure, and interlaminar failure. The developed meso-scale model was able to accurately simulate failure initiation and propagation in the composite sandwich structure. The effect of elevated temperature on the three-point bending behavior was studied numerically as well as experimentally. An increase in test temperature to 100°C resulted in a drop of 9.2% in flexural strength, which was also predicted by the numerical model. [ABSTRACT FROM AUTHOR]

Composite sandwich structure possesses unique characteristics in which the facings' material provides a high in-plane stiffness/strength, while the core material keeps the facings a part to enhance the flexural stiffness/strength. However, sandwich structure is susceptible to shear failure due to the weak bond between the facings and the core materials. This article addresses this issue and provides an efficient semi-circular shear keys concept to be inserted in the interfacial surface between the sandwich structural elements to improve the facings–core interaction with marginal sacrifice in the strength-to-weight ratio. Composite sandwich panels composed of glass fibre–reinforced polymer skins and polyurethane foam core material have been investigated in this study. Mechanical tension, compression and shear tests were performed on the facings, while compression tests were conducted on the core materials to define the elasto-plastic response of the constituent's materials. Four-point bending tests were performed on the conventional composite sandwich panel and panels incorporated with shear keys concept. Considerable improvement in the flexural stiffness and strength along with detouring the crack path was noticed for the samples incorporated with shear keys. A non-linear finite element analysis was established to verify the experimental results. Comparisons between the experimental and finite element results were presented and showed good agreement between both results which justified the parameters used in the finite element models and their capabilities to capture the mechanical behaviour and the damage mode of the investigated models. [ABSTRACT FROM AUTHOR]

Sandwich composite structures are high-performance materials with greater specific strength and specific stiffness properties, than widely used conventional metals. In this study, sandwich composite structures under dynamic loads were optimized using the equivalent static load method (ESLM). First, a finite element analysis was performed on the sandwich composite structure, using the high-order sandwich panel theory (HSAPT), considering the core material to be compressible. Further, it was optimized by applying the ESLM to three different sandwich composite structures under different types of dynamic loads. The results of the proposed method and conventional dynamic response optimization method were compared. The ESLM was observed to attain a convergence at a rate 1/24 times faster than the conventional method. [ABSTRACT FROM AUTHOR]

Sandwich composite consists of panel material with higher strength and core material with lower strength, and the tensile elastic modulus and compressive modulus of these materials are often not equal. At present, the theoretical calculation and numerical calculation methods of bi-module materials are mainly applicable to single material and simple geometric structure, meanwhile, there will be situations such as slow convergence speed or even non-convergence of iterative algorithm. Therefore, when calculating sandwich composites, it is usually considered that the tensile modulus and compressive modulus are equal, which will bring great errors to the calculation. In order to better predict the cross-section characteristics and stiffness characteristics of bi-modulus sandwich composites, this paper developed the theoretical and numerical methods calculation methods suitable for bi-modulus sandwich composite structures. Example results show that the proposed finite element method based on field variables is consistent with the theoretical formula for bi-module materials, which can be used for structural design and safety check of marine sandwich composites. •A simple method was proposed to calculate the cross-sectional characteristics and load-bearing characteristics of typical sandwich composite structures. •A improved method for analyzing the load-bearing capacity of sandwich composite materials considering the bi-modulus based on field variables was proposed. •The typical examples of sandwich composite structure verify the effectiveness of numerical method. [ABSTRACT FROM AUTHOR]

• Investigate space of tie bars on the ultimate capacity of steel-UHPC-steel slabs experimentally. • Establish a suitable finite element model and analyze failure modes of steel-UHPC-steel slabs. • Develop a design method for the ultimate capacity of SCS composite slabs. • Put forward design suggestions for the space of shear connectors of SCS composite slabs. In steel–concrete-steel (SCS) structures, the external steel plates and the internal concrete core are composite through the shear connectors, such as tie bars and headed studs. Compared to traditional reinforced concrete (RC) structures, excellent mechanical performances and modular construction are significant advantages for SCS composite structures. To satisfy the extreme service environment for nuclear power containments and offshore platforms, ultra-high performance concrete (UHPC) is applied as the core material which forms steel-UHPC-steel composite structure. In this paper, static tests of three steel-UHPC-steel composite slabs with simple supports on four sides were conducted under concentrated loads. The failure characteristics and failure mechanism were summarized, in which a punching shear cone developed in the UHPC core and steel fibers resisted the propagation of cracks. Besides, refined numerical models of steel-UHPC-steel slab were established by Abaqus/Explicit, which considered the material damage and element deletion. The applicability of the finite element method was verified by comparing load-deflection curves and failure characteristics with the test results. On this basis, the influence of the arrangement of shear connectors on the mechanical performances of the steel-UHPC-steel slab was analyzed and discussed. Combining all the cases, flexural-slippage failure and punching shear failure were proposed according to the different composite action caused by shear connectors. Finally, the design method was enhanced, which predicted the ultimate capacity of steel-UHPC-steel composite slabs under concentrated loads. Design recommendation was provided for the arrangement of shear connectors based on controlling the failure modes. [ABSTRACT FROM AUTHOR]