scholarly journals Structure Dynamic Response of Amphibious Aircraft Induced by Water-Taxiing

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jihang Lyu ◽  
Rong Yang ◽  
Lingcai Huang
Keyword(s):  
Dynamic Response ◽  
Water Surface ◽  
Aerodynamic Force ◽  
Coupling Effect ◽  
Elastic Response ◽  
Structural Vibration ◽  
Approximation Formula ◽  
Response Analysis ◽  
Single Wave ◽  
Added Water

The significant dynamic response under the combined impact of aerodynamic and hydrodynamic forces could be likely to appear because of the structural flexibility, when taxiing on the water surface for amphibious aircraft. Meanwhile, the modal characteristics of the structure are also affected by the additional motion of water. These require that the influence of the structural elasticity and the coupling effect between water and structure should be considered in dynamic response analysis of water-taxiing. According to the peculiarities of the amphibious aircraft, structural dynamics model is based on the distribution of stiffness and mass, Virtual Mass Theory is utilized to solve the wet modes on the water surface, rational function approximations of unsteady aerodynamic force in time-domain are constructed by the Minimum-State Approximation Formula, and loose coupling method is employed to simulate the hydrodynamic elastic response under the encounter of amphibian with single wave and repeated waves, respectively. Analysis of dynamic characteristics during the water-taxiing of the amphibious aircraft has been achieved in this work. The results show that wet natural frequencies of the aircraft have different degrees of decline compared with the dry frequencies because of the influence of added water on the hull, and the response amplitude of dynamic loads obtained by using the wet modes have some certain extent decrease compared with the dry modes. The dynamic amplitude of different locations changes in different degree relatives to the center of gravity position, which reflects the influence of structural elasticity. Due to the excitation of single wave and repeated waves, the structural vibration amplitude will increase rapidly, but the amplitude shows a certain divergence trend under the action of repeated waves with a given oscillation frequency, which is more severe for structural strength design.

Response Characteristics of Semisubmersible-Type-Megafloat in Waves and Accuracy of Hydroelastic Response Analysis Program VODAC

2002 ◽  
Author(s):  
Hideyuki Suzuki ◽  
Koichiro Yoshida ◽  
Kazuhiro Iijima ◽  
Kentaro Kobayashi
Keyword(s):  
Dynamic Response ◽  
Elastic Response ◽  
Scale Model ◽  
Design Parameters ◽  
Accurate Estimation ◽  
Response Analysis ◽  
Functional Requirements ◽  
Analysis Program ◽  
Floating Structure ◽  
Response Characteristics

Technical feasibility and practical design method of SSMF, a Semi-Submersible-Type-Megafloat, was studied under research funding from Corporation for Advanced Transport and Technology. A SSMF which serves as a airport for local air transportation of isolated islands was assumed in the research. Typical deck size of the SSMF is 2200m long, 300m wide and 9m deep. In the design of the SSMF, column supported type structure was chosen to satisfy the strength and functional requirements in the environmental condition around Japanese islands in the pacific ocean. The deck structure is supported by 320 columns with draft of 16m. In the design of structural dynamics of the SSMF, a computer code VODAC was adopted to calculate hydro-elastic response. VODAC is an analysis program of hydro-elastic response of Very Large Floating Structure (VLFS) which has been developed in University of Tokyo. This paper presents a series of experiments and calculations carried out to investigate response characteristics of SSMF and to confirm capability and accuracy of VODAC. Basin experiments were carried out using a scale model, which is elastically and dynamically similar to the designed SSMF airport, and the response characteristics were clarified. A simple numerical model was also proposed as a simplified model of dynamic response of VLFS. This model is a simple beam on elastic foundation, but it is shown that basic response characteristics of the structure can be relatively accurately expressed by this model. Design parameters were discussed using this model. Relationships between major design parameters and dynamic response characteristics were clarified. Furthermore it was shown that this model is not just a qualitative model but gives relatively accurate estimation of the response. It is shown that this model gives upper limits of response of real structure and a good safe side estimation.

Thermal and structural response of aerospike mounted on blunt-nose body

2020 ◽  
pp. 095441002097648
Author(s):  
Zhang ZhunHyok ◽  
Won CholJin ◽  
Ri CholUk ◽  
Kim CholJin ◽  
Kim RyongSop
Keyword(s):  
Aerodynamic Force ◽  
Coupling Effect ◽  
Angle Of Attack ◽  
Structural Response ◽  
Response Characteristic ◽  
Wave Drag ◽  
Hypersonic Vehicle ◽  
Loosely Coupled ◽  
Calculation Results ◽  
Blunt Nose

The inclusion of aerospike on blunt nose body of hypersonic vehicle has been considered to be the simplest and most efficient technique for a concurrent reduction of both aeroheating and wave drag due to hypersonic speed. However, the thermal and mechanical behavior of aerospike structure under the coupling effect of aerodynamic force and aeroheating remains unclear. In this study, the thermal and structural response of aerospike mounted on the blunt nose body of hypersonic vehicle was numerically simulated by applying 3 D fluid-thermal-structural coupling method based on loosely-coupled strategy. In the simulation, the angle-of-attack and the spike’s length and diameter are differently set as α = 0°–10°, L/D = 1–2 and d/D = 0.05–0.15, respectively. Through the parametric study, the following results were obtained. Firstly, the increase of vehicle’s angle-of-attack and spike’s length unfavorably affect the thermal and structural response of aerospike. Secondly, the increase of spike’s diameter can improve its structural response characteristic. Finally, the aerospike with the angle-of-attack of 0° and the length and diameter of L/D = 1 and d/D = 0.15, respectively, is preferred in consideration of the effect of flight angle-of-attack and spike’s geometrical structure on the thermal and structural response of spike and the drag reduction of vehicle. The numerical calculation results provide a technical support for the safe design of aerospike.

Dynamic Response Analysis of Butt Joint of HTS-A Steel Considering Welding Residual Stresses

2013 ◽  
Vol 423-426 ◽  
pp. 944-950
Author(s):  
Wei Shen ◽  
Ren Jun Yan ◽  
Lin Xu ◽  
Kai Qin ◽  
Xin Yu Zhang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Dynamic Response ◽  
Hot Spot ◽  
Time History ◽  
High Strength ◽  
Simulation Method ◽  
Butt Joint ◽  
Welding Residual Stress ◽  
Response Analysis ◽  
Hull Structure

This paper uses both numerical simulation method and experimental research method to study on welding residual stress of high-strength steel of the cone-cylinder hull. Welding is often accompanied by a larger welding residual stress, which directly affects the safety and service life of the hull structure. In order to obtain the distribution of the welding residual stress, the welding procedure was developed by its parameter language by using FE analysis software in this paper. Then the welding residual stress of hot spot region was measured through X-ray nondestructive testing method, and compared it with simulation results. Finally, considering the residual stress as the initial stress, this paper analyzed dynamic response process of the welding structure under combined actions of the welding residual stress and multiaxial loads, which could more accurately determine the stress of welding structure and the location of fatigue risk point. According to the amplitude of damage parameters and strain time-history curve, we can estimate the fatigue life of structure by selecting the corresponding damage models.

Dynamic Response of Spiral Cantilever Undergoing Magnetic Coupling

2014 ◽  
Vol 14 (08) ◽  
pp. 1440021
Author(s):  
Xiaoling Bai ◽  
Yumei Wen ◽  
Ping Li ◽  
Jin Yang ◽  
Xiao Peng ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Cantilever Beam ◽  
Magnetic Force ◽  
Coupling Effect ◽  
Magnetic Coupling ◽  
Resonant Frequencies ◽  
Energy Harvesters ◽  
Magnetic Transducer ◽  
Underlying Mechanisms ◽  
Tip Mass

Cantilever beams have found intensive and extensive uses as underlying mechanisms for energy transduction in sensors as well as in energy harvesters. In magnetoelectric (ME) transduction, the underlying cantilever beam usually will undergo magnetic coupling effect. As the beam itself is either banded with magnetic transducer or magnets, the dynamic motion of the cantilever can be modified due to the magnetic force between the magnets and ME sensors. In this study, the dynamic response of a typical spiral cantilever beam with magnetic coupling is investigated. The spiral cantilever acts as the resonator of an energy harvester with a tip mass in the form of magnets, and a ME transducer is positioned in the air gap and interacts with the magnets. It is expected that this spiral configuration is capable of performing multiple vibration modes over a small frequency range and the response frequencies can be magnetically tunable. The experimental results show that the magnetic coupling between the magnets and the transducer plays a favorable role in achieving tunable resonant frequencies and reducing the frequency spacings. This will benefits the expansion of the response band of a device and is especially useful in energy harvesting.

scholarly journals Dynamic response analysis for multi-degrees-of-freedom parallel mechanisms with various types of three-dimensional clearance joints

2021 ◽  
Vol 18 (3) ◽  
pp. 172988142110177
Author(s):  
Jia Yonghao ◽  
Chen Xiulong
Keyword(s):  
Dynamic Response ◽  
Multibody Systems ◽  
Parallel Mechanism ◽  
Three Dimensional ◽  
Response Analysis ◽  
Parallel Mechanisms ◽  
Dynamics Model ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Spatial Parallel Mechanism

For spatial multibody systems, the dynamic equations of multibody systems with compound clearance joints have a high level of nonlinearity. The coupling between different types of clearance joints may lead to abundant dynamic behavior. At present, the dynamic response analysis of the spatial parallel mechanism considering the three-dimensional (3D) compound clearance joint has not been reported. This work proposes a modeling method to investigate the influence of the 3D compound clearance joint on the dynamics characteristics of the spatial parallel mechanism. For this purpose, 3D kinematic models of spherical clearance joint and revolute joint with radial and axial clearances are derived. Contact force is described as normal contact and tangential friction and later introduced into the nonlinear dynamics model, which is established by the Lagrange multiplier technique and Jacobian of constraint matrix. The influences of compound clearance joint and initial misalignment of bearing axes on the system are analyzed. Furthermore, validation of dynamics model is evaluated by ADAMS and Newton–Euler method. This work provides an essential theoretical basis for studying the influences of 3D clearance joints on dynamic responses and nonlinear behavior of parallel mechanisms.

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