Accurate characterization of the frictional behavior at the bead–rim interface of aircraft tires is essential for predicting tire service performance. Aircraft tires are subjected to high torque loads during landing impact and braking, which can readily induce relative slip between the tire and the rim. The interference fit between the tire and the rim generates extremely high contact pressure, while the interfacial friction coefficient exhibits significant pressure-dependent variation, which substantially affects the slip resistance of the interface. However, research on interfacial friction behavior under high-contact-pressure conditions remains relatively limited, and the underlying mechanisms are still not well understood. In this paper, an experimental setup is developed to evaluate the slip resistance of aircraft tires under static radial loads. Combined with numerical simulation methods, the friction coefficient at the bead–rim interface under high-contact-pressure conditions is calculated. The results indicate that as the contact pressure increases, the friction force between the bead and the rim decreases significantly, exhibiting a pronounced pressure-dependent characteristic. Through finite element analysis, the effects of bead wire type, bead heel profile, wire width, and bead interference on the contact pressure distribution are investigated. This study reveals the intrinsic mechanisms governing tire–rim frictional behavior and provides an important basis for optimizing tire–rim slip resistance design.
Aircraft nose landing gear shimmy is a self-excited instability that threatens ground handling safety and structural reliability. To address the limitations of conventional hydraulic and magnetorheological dampers, this paper presents a passive electromagnetic damper integrated into a nose wheel steering actuator platform. An analytical damping torque model is established based on electromagnetic induction and the skin effect, clarifying the inherent dependence of damping behavior on air-gap length and stator disk material properties. The proposed damper inherently delivers high damping at low shimmy velocities while exhibiting natural attenuation at higher speeds, which is beneficial for balancing shimmy suppression and steering performance. An electromagnetic–thermal coupled finite element model is developed to evaluate damping characteristics and temperature rise, and the simulation results are validated through prototype experiments. The measured equivalent damping coefficients meet shimmy suppression requirements, demonstrating the engineering feasibility of the proposed solution.
The assembly quality of aircraft skin rivets directly affects aerodynamic performance and structural integrity, particularly in high-speed aircraft and stealth fighters. Consequently, rivet flushness measurement is a critical aspect of aircraft assembly inspection. However, existing methods often suffer from high computational complexity, poor noise resistance, and redundant feature extraction, which limits measurement accuracy and efficiency. To address these limitations, this paper proposes a density-geometry collaborative constraint method that integrates geometric feature analysis with an optimization algorithm. Specifically, in the data preprocessing stage, a lightweight contour extraction method is developed to reduce the processed data volume to 3.5–6.8% of the original scale, thereby mitigating the computational burden and eliminating feature redundancy. In the rivet feature screening stage, a density-geometry dual screening strategy is proposed to precisely eliminate abnormal clusters via a dual-threshold filtering mechanism, enhancing antinoise capability. In the quantitative evaluation stage, a circular model reconstruction method combining probability sampling and dynamic weight optimization is developed to accurately identify and locate the circular contour of the rivet head. The proposed method enables rapid and accurate rivet feature identification and flushness measurement.
This paper validates OpenFOAM, an open-source computational fluid dynamics (CFD) software, for modeling separated flows relevant to aircraft aerodynamics with high-lift wing configurations. Reynolds-averaged Navier–Stokes (RANS) simulations of flow past the Common Research Model (CRM) in its High-Lift configuration were performed in two stages. The first stage focused on aerodynamic coefficients near the stall angle of attack as part of a grid refinement study, comparing results with those from other participants in the High-Lift Prediction Workshop who used various CFD codes. The second stage validated OpenFOAM against wind-tunnel data and workshop CFD results across a sequential buildup of configuration complexity, from wing–fuselage only to the full configuration including flaps, slats, and engine nacelles with pylons. Particular attention was paid to using RANS modeling in OpenFOAM to obtain multiple flow solutions for high-lift configurations. The results showed that OpenFOAM’s RANS predictions aligned more closely with wind-tunnel data than those of other workshop participants and revealed static hysteresis over a wide range of angles of attack, driven by distinct flow separation structures. These findings encourage the use OpenFOAM for aerodynamics prediction of high-lift configurations and support its growing adoption in both academia and industry.
This work is a study of stochastic ship deck motions and how to land on them. The emphasis is on the minimum tools that are necessary and sufficient to carry out the task. A U.S. Navy–provided dataset is used to develop a ship-deck dynamics model whose frequency spectrum and statistical behavior match those of a generic DDG-51-class ship. The model drives a Stewart platform that reproduces this motion in the laboratory. Drawing on the operating principle of the beartrap recovery system, it is shown that only the surge and sway motions of the deck need to be tracked for landing. A fiducial-based monocular vision system is then developed that can estimate the deck position to within 1.2 cm. An in-house-fabricated quadrotor aircraft fitted with this vision system is used to demonstrate that a single camera (with a cooperative fiducial on deck) and a 0.15 Hz bandwidth control system are all that is needed to land on stochastic ship decks. This is a proof-of-concept work in a laboratory environment; validation on a real-ship deck is deferred to future work.
