Browsing by Author "He, Shun"

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    Identification of the key design inputs for the FEM-based preliminary sizing and mass estimation of a civil aircraft wing box structure
    (Elsevier, 2021-12-14) You, Chao; Yasaee, Mehdi; He, Shun; Yang, Daqing; Xu, Yigeng; Dayyani, Iman; Ghasemnejad, Hessam; Guo, Shijun; Webb, Phil; Jennings, James; Federico, Giovanni
    FEM-based preliminary structural sizing has been successfully carried out for a typical single-aisle wing box structure using MSC Nastran, by considering various load cases representing typical aircraft manoeuvres, engine loads, landing and ground handling conditions. The strength, buckling and fatigue criteria have been applied as the design constraints for sizing. The resultant total mass and the structural (static and modal) behaviour of the sized wing box model have been verified against a validated high-fidelity wing box model. A sensitivity analysis has been performed to evaluate the influence of the number of design fields and the selected design inputs (i.e. load cases and design constraints) on the accuracy of sizing and mass estimation of the wing box. This sensitivity analysis has also been extended to the static and modal behaviour of the wing box structure obtained from sizing. It provides an insight into the significance of considering the buckling and fatigue constraints, aircraft rolling loads, engine loads and landing loads in sizing, in addition to the commonly-applied 2.5 g aircraft pull-up loads under the strength constraint. The findings of this study highlight the trade-off between the sizing efficiency and accuracy of a civil aircraft wing for modelling purposes.
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    Nonlinear aeroelastic behavior of an airfoil with free-play in transonic flow
    (Elsevier, 2019-12-16) He, Shun; Guo, Shijun; Li, Wenhao; Yang, Daqing; Gu, Yingsong; Yang, Zhichun
    An investigation has been made into the nonlinear aeroelastic behavior of an airfoil system with free-play nonlinear stiffness in transonic flow. Computational Fluid Dynamics (CFD) and Reduced Order Model (ROM) based on Euler and Navier-Stokes equations are implemented to calculate unsteady aerodynamic forces. Results show that the nonlinear aeroelastic system experiences various bifurcations with increasing Mach number. Regular subcritical bifurcations are observed in low Mach number region. Subsequently, complex Limit Cycle Oscillations (LCOs) and even non-periodic motions appear at specific airspeed regions. When the Mach number is increased above the freeze Mach number, regular subcritical bifurcations occur again. Comparisons with inviscid solutions are used to identify and elaborate the effect of viscosity with the help of aeroelastic analysis techniques, including root locus, Single Degree of Freedom (SDOF) flutter and aerodynamic influence coefficient (AIC). For low Mach numbers in the transonic regime, the viscosity has little effect on the linear flutter characteristic because of limited influence on AIC, but a remarkable impact on the nonlinear dynamic behavior due to the sensitivity of the nonlinear structure. As the Mach number increases, the viscosity becomes significantly important due to the existence of shock-boundary layer interaction. It affects the unstable mechanism of linear flutter, impacts the aerodynamic center and hence the snap-through phenomenon, influences the AIC and consequently the nonlinear aeroelastic response. When the Mach number is increased further, the shock wave dominates the air flow and the viscosity is of minor importance.
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    Nonlinear magnetic-coupled flutter-based aeroelastic energy harvester: modeling, simulation and experimental verification
    (Kui Li, Zhichun Yang, Yingsong Gu, et al., Nonlinear magnetic-coupled flutter-based aeroelastic energy harvester: modeling, simulation and experimental verification. Smart Materials and Structures, Volume 28, Issue 1, 2018, Article number 051020, 2018-11-29) Li, Kui; Yang, Zhichun; Gu, Yingsong; He, Shun; Zhou, Shengxi
    Aeroelastic energy harvesting can be used to power wireless sensors embedded into bridges, ducts, high-altitude buildings, etc. One challenging issue is that the wind speed in some application environments is low, which leads to an inefficiency of aeroelastic energy harvesters. This paper presents a novel nonlinear magnetic-coupled flutter-based aeroelastic energy harvester (FAEH) to enhance energy harvesting at low wind speeds. The presented harvester mainly consists of a piezoelectric beam, a two-dimensional airfoil, two tip magnets and two external magnets. The function of magnets is to reduce the cut-in wind speed of the FAEH and enhance energy harvesting performance at low wind speeds. A theoretical model is deduced based on Hamilton's principle, theory of aeroelasticity, Kirchhoff's laws and experimental measurements, etc. A good agreement is found between numerical simulation and experimental results, which verifies the accuracy of the theoretical model. Stability analysis is provided to determine the characteristics of the presented harvester. More importantly, it is numerically and experimentally verified that the presented harvester has a much lower cut-in wind speed (about 1.0 m s−1) and has a better energy harvesting performance at a low wind speed range from 1.0 m s−1 to 2.9 m s−1, when compared with traditional FAEHs.
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    Passive gust alleviation of a flying-wing aircraft by analysis and wind-tunnel test of a scaled model in dynamic similarity
    (Elsevier, 2021-03-29) He, Shun; Guo, Shijun; Liu, Ying; Luo, Wukui
    An investigation was conducted to evaluate the effectiveness of a passive gust alleviation device (PGAD) installed in a flying-wing aircraft of 62.3m wing span at large swept back angle. It was performed by numerical analysis and validated by wind-tunnel test of a 1:25 reduced scale physical model of dynamic similarity to the full-scale aircraft. The 1-cosine gust model with a range of gust parameters specified in the airworthiness regulation CS-23 was taken in the gust response analysis that led to 7~9% gust alleviation results by employing the PGAD. The gust response dominated by the first three modes of the aircraft was most critical in the frequency close to the first bending mode of the wing. The wind-tunnel test model was designed and manufactured based on dynamic scaling law, and proved to be of excellent dynamic similarity by the deviation of less than 5.5% between the first three modes of the physical model measured by vibration test and the full-scale aircraft model. The wind tunnel test results show that the gust response of the model in the specified range was reduced by 8.3~14.3% according to the measured wing tip deflection associated with the PGAD oscillation amplitude at 4.0°~15.5°. The present study shows that the numerical analysis of gust response and alleviation of a full-scale aircraft installed with PGAD can be validated by wind tunnel test of a scaled physical model with dynamic similarity.
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    Strength enhancement of bonded composite laminate joints reinforced by composite pins
    (Elsevier, 2020-01-10) Li, Wenhao; Guo, Shijun; Giannopoulos, Ioannis K.; He, Shun; Liu, Yiding
    This paper presents an experimental and numerical investigation in the static strength enhancement of composite laminate Single Lap bonded Joints (SLJ), reinforced by pins made of Uni-Directional (UD) fibre reinforced plastic composite materials. Bonded lap joint specimens were experimentally tested in tension to obtain the failure loads and failure modes. The specimens were subsequently benchmarked against the hybrid version of the joint resulted from the introduction of composite Pins. The Pin reinforcement enhanced the hybrid single lap joint strength by an average of 19.1% increase. Numerical models generated were used for correlation with the experimental results. Numerical and experimental results observation indicated that increased strength of the hybrid bonded/Pinned joint was partly attributed to the load sharing between the adhesive and the Pin past the adhesive failure initiation as well as to the enhanced out-of-plane bending stiffness after the Pin introduction on the lap joint. Numerical investigations were performed as well with hybrid SLJ reinforced by composite pins versus designs employing metallic Pins. The simulations showed that for the investigated lap joint design parameters, the hybrid metallic pin joint failed at a higher failure load. Nevertheless, the hybrid joint utilizing the composite Pin could benefit from the enhanced corrosion resistance properties. In the case of applying a larger composite Pin diameter and/or rearranging the fibre orientation in the Pin, the hybrid SLJs could potentially achieve higher strength characteristics before the adhesive bond ultimate failure in relation to the steel Pin, as well as resulting to additional weight saving up to 46.9%.
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    Structure health monitoring of a composite wing based on flight load and strain data using deep learning method
    (Elsevier, 2022-01-29) Lin, Minxiao; Guo, Shijun; He, Shun; Li, Wenhao; Yang, Daqing
    An investigation was made into a method for Structural Health Monitoring (SHM) of a composite wing using Convolutional Neural Network (CNN) model. In this method, various aerodynamic loads of an aircraft during flight and corresponding strain data were used for CNN model training. The proposed method was demonstrated by numerical simulation using vortex lattice method for aerodynamic loads of an A350-type aircraft in over a thousand flight conditions and a Finite Element (FE) model as a digital twin of the full-scale composite wing. To represent the measurement of 324 sensors mounted in the 18 skin-rib joints of the inboard wing, strain data from the 18x18 elements of the FE model in the sensor locations were calculated corresponding to the flight loadings. The strain data from the original structure FE model were employed to train a CNN model that was classified as healthy samples. Damaged elements were then introduced in random locations to produce data samples corresponding to the same set of flight loads for the CNN model training. In the subsequent damage detection process using the trained CNN model, confusion matrix, uncertainty and sensitivity analysis were evaluated. The study results show that robust damage detection results can be obtained with 99% accuracy without noise and 97% accuracy with 2% Gaussian noise. In the damage localization process, threshold value was set at 1.5, 2 or 2.5, and 83% overall accuracy was achieved using the CNN model when the threshold value was 1.5. The study demonstrated that the proposed method is efficient, accurate and robust.
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    Transonic flutter characteristic of an airfoil with morphing devices
    (Sage, 2020-08-30) He, Shun; Guo, Shijun; Li, Wenhao
    An investigation into transonic flutter characteristic of an airfoil conceived with the morphing leading and trailing edges has been carried out. Computational fluid dynamics (CFD) is used to calculate the unsteady aerodynamic force in transonic flow. An aerodynamic reduced order model (ROM) based on autoregressive model with exogenous input (ARX) is used in the numerical simulation. The flutter solution is determined by eigenvalue analysis at specific Mach number. The approach is validated by comparing the transonic flutter characteristics of the Isogai wing with relevant literatures before applied to a morphing airfoil. The study reveals that by employing the morphing trailing edge, the shock wave forms and shifts to the trailing edge at a lower Mach number, and aerodynamic force stabilization happens earlier. Meanwhile, the minimum flutter speed increases and transonic dip occurs at a lower Mach number. It is also noted that leading edge morphing has negligible effect on the appearance of the shock wave and transonic flutter. The mechanism of improving the transonic flutter characteristics by morphing technology is discussed by correlating shock wave location on airfoil surface, unsteady aerodynamics with flutter solution