Vibration frequency of modified wave beam guardrail based on collision simulation and vibration acceleration analysis

2021 ◽  
Author(s):  
Jin Jiang ◽  
Yun-wei Meng ◽  
Jian Liao ◽  
Guang-yan Qing ◽  
Qing Yang
Keyword(s):  
Vibration Frequency ◽  
Wave Beam ◽  
Vibration Acceleration ◽  
Acceleration Analysis

scholarly journals A Novel High-Frequency Vibration Error Estimation and Compensation Algorithm for THz-SAR Imaging Based on Local FrFT

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2669
Author(s):  
Yinwei Li ◽  
Li Ding ◽  
Qibin Zheng ◽  
Yiming Zhu ◽  
Jialian Sheng
Keyword(s):  
Error Estimation ◽  
Vibration Frequency ◽  
High Frequency ◽  
Motion Platform ◽  
Vibration Acceleration ◽  
High Frequency Vibration ◽  
Compensation Algorithm ◽  
Sar Imaging ◽  
Vibration Error ◽  
Novel Algorithm

Compared with microwave synthetic aperture radar (SAR), terahertz SAR (THz-SAR) is easier to achieve ultrahigh-resolution image due to its higher frequency and shorter wavelength. However, higher carrier frequency makes THz-SAR image quality very sensitive to high-frequency vibration error of motion platform. Therefore, this paper proposes a novel high-frequency vibration error estimation and compensation algorithm for THz-SAR imaging based on local fractional Fourier transform (LFrFT). Firstly, the high-frequency vibration error of the motion platform is modeled as a simple harmonic motion and THz-SAR echo signal received in each range pixel can be considered as a sinusoidal frequency modulation (SFM) signal. A novel algorithm for the parameter estimation of the SFM signal based on LFrFT is proposed. The instantaneous chirp rate of the SFM signal is estimated by determining the matched order of LFrFT in a sliding small-time window and the vibration acceleration is obtained. Hence, the vibration frequency can be estimated by the spectrum analysis of estimated vibration acceleration. With the estimated vibration acceleration and vibration frequency, the SFM signal is reconstructed. Then, the corresponding THz-SAR imaging algorithm is proposed to estimate and compensate the phase error caused by the high-frequency vibration error of the motion platform and realize high-frequency vibration error estimation and compensation for THz-SAR imaging. Finally, the effectiveness of the novel algorithm proposed in this paper is demonstrated by simulation results.

scholarly journals МЕТРОЛОГИЧЕСКОЕ ОБЕСПЕЧЕНИЕ КАЛИБРОВКИ КАНАЛОВ КОНТРОЛЯ ВИБРАЦИИ В СОСТАВЕ РЕГУЛЯТОРА АВИАДВИГАТЕЛЯ

2019 ◽  
pp. 151-156
Author(s):  
Анна Григорьевна Буряченко
Keyword(s):  
Vibration Frequency ◽  
Primary Transducer ◽  
Vibration Acceleration ◽  
Measuring Systems ◽  
Information Measuring ◽  
Predetermined Level ◽  
Normative Documentation ◽  
Vibration Measuring ◽  
Electric Signals

There are shown the normative documentation requirements concerning complete and element wise calibration of the information-measuring systems measuring channels. It is about requirements, which are applicable for tests area of aviation turbo-engines and their componentry, including the electronic regulators FADEC-type. There are given short information concerning the experience of JSC "Element" – certificated developer and manufacturer of such regulators – on providing of calibration (testing) of measuring channels with the use of imitators of electric signals of engine transducers. There is given the information concerning the ranges of measuring of vibrating accelerations and vibrating frequencies, which are required for providing of the engine vibrating monitoring and the information about the extreme high magnitudes of vibrating acceleration, which is interesting for the developer of the engine. There are covered the problems, which the developer of regulators deals with necessary to execute complete calibration of vibration measuring channels (jointly with a primary transducer), including the limitations laid on by the possibilities of accessible facilities of creation of vibration with the controlled magnitudes of vibration acceleration and vibration frequency in the required ranges of measuring. There are described the workplaces organized in JSC "Element" at the methodical help of SE "Ukrmetrteststandard" for providing of complete calibration of vibration measuring channels in laboratory terms at the enterprise-manufacturer, including the workplace with the resonator, which was specially developed and made. There are brought the results over of development, making and uses of the resonator, which provides controlled vibrations with the extreme level of vibration acceleration – 400 g and more at the predetermined level of vibration frequency.There is shown the expediency of element wise measuring channels calibration with the use of imitators of sensors signals for serial producing of regulators. There is explained the necessity to organize workplaces for the realization of complete calibration on enterprise-developer of FADEC regulators, which provide verification results got with imitators.

Structure Sensitivity Analysis and Dynamic Performance Optimization of Marine Gearbox

2017 ◽  
Author(s):  
Tengjiao Lin ◽  
Daokun Xie ◽  
Ziran Tan ◽  
Bo Liu
Keyword(s):  
Sensitivity Analysis ◽  
Performance Optimization ◽  
Optimization Design ◽  
Dynamic Performance ◽  
Structure Sensitivity ◽  
Superposition Method ◽  
Structure Parameters ◽  
Analysis Model ◽  
Vibration Acceleration ◽  
Response Optimization

The aim of this paper is to investigate the influence of structure parameters on the vibration characteristics and improve the dynamic performance of marine gearbox. A finite element model was established to solve the dynamic response by using modal superposition method. Based on the theory of multi-objective optimization design, the structure sensitivity analysis model of marine gearbox was established, which takes the structure parameters of the housing as design variables. The modal and response sensitivity was obtained by using the optimal gradient method. According to the results of sensitivity analysis, a modal and response optimization model of marine gearbox was established. The objective was to avoid natural frequencies from the excitation frequencies and minimize the root mean square of vibration acceleration of the evaluating points on the surface of housing. Then the modal optimization and response optimization of gearbox were carried out by using zero-order and first-order optimization method. The results indicate that the dynamic optimization of the gearbox can be achieved. After optimization, the amplitude of vibration acceleration of the evaluating points on the housing surface has been reduced and the resonance of marine gearbox can be avoided.

Conceptual design and numerical studies of active flow control aerofoil based on shape-memory alloy and macro fibre composites

2021 ◽  
Vol 125 (1287) ◽  
pp. 830-846
Author(s):  
W. Zhang ◽  
X.T. Nie ◽  
X.Y. Gao ◽  
W.H. Chen
Keyword(s):  
Shape Memory Alloy ◽  
Flow Control ◽  
Shape Memory ◽  
Vibration Frequency ◽  
Active Flow Control ◽  
Flow Characteristics ◽  
Hybrid Design ◽  
Numerical Studies ◽  
Fibre Composites ◽  
Active Flow

ABSTRACTActive flow control for aerofoils has been proven to be an effective way to improve the aerodynamic performance of aircraft. A conceptual hybrid design with surfaces embedded with Shape-Memory Alloy (SMA) and trailing Macro Fibre Composites (MFC) is proposed to implement active flow control for aerofoils. A Computational Fluid Dynamics (CFD) model has been built to explore the feasibility and potential performance of the proposed conceptual hybrid design. Accordingly, numerical analysis is carried out to investigate the unsteady flow characteristics by dynamic morphing rather than using classical static simulations and complicated coupling. The results show that camber growth by SMA action could cause an evident rise of Cl and Cd in the take-off/landing phases when the Angle-of-Attack (AoA) is less than 10°. The transient tail vibration behaviour in the cruise period when using MFC actuators is studied over wide ranges of frequency, AoA and vibration amplitude. The buffet frequency is locked in by the vibration frequency, and a decrease of 1.66–2.32% in Cd can be achieved by using a proper vibration frequency and amplitude.

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