Natural Frequency Based Topology Optimization of an Aircraft Engine Support Frame

2020 ◽  
Author(s):  
Braden T. Warwick ◽  
Chris K. Mechefske ◽  
Il Yong Kim
Keyword(s):  
Topology Optimization ◽  
Natural Frequency ◽  
Design Space ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Aircraft Engine ◽  
Problem Statement ◽  
Support Frame ◽  
Engine Excitation ◽  
Initial Geometry

Abstract The multi-stage design space refinement (MSDSR) technique increases the likelihood of convergence of topology optimization (TO) with large volume fraction constraints. This work considers MSDSR TO of an aircraft engine support frame with a natural frequency-based objective function. The problem statement maximized the first natural frequency, effectively maximizing the stiffness to mass ratio of the frame. The problem statement considered natural frequency constraints, which eliminated all natural frequencies within 5% of the engine excitation frequency times a safety factor of two. The design space did not consider the initial geometry; therefore, allowing for the determination of the optimal stiffener location on the initial geometry. The results of this work increased the first natural frequency of the engine support frame by 25.9%, eliminated all natural frequencies within 11.3% of the engine excitation frequency, and added only 0.253 kg of mass to the frame. The results of this work further demonstrate the advantages of MSDSR TO and the impact that it can have on the aerospace industry. Specifically, the design space considered in this work allows for the structural reinforcement of a pre-existing design, which is easier to implement and easier to regulate than similar results from the literature.

Natural frequency modulation of a kinematically redundant planar parallel robot

2021 ◽  
pp. 095440622110524
Author(s):  
Jiawei Gu ◽  
Zhijiang Xie ◽  
Jian Zhang ◽  
Yangjun Pi
Keyword(s):  
Natural Frequency ◽  
Frequency Modulation ◽  
Natural Frequencies ◽  
Vibration Suppression ◽  
Excitation Frequency ◽  
Parallel Robot ◽  
Modulation Method ◽  
Kinematic Redundancy ◽  
Resonance Amplitude ◽  
Searching Method

When a parallel robot is equipped with kinematic redundancy, it has sufficient capabilities of natural frequency modulation through adjusting geometric configuration. To reduce resonance of a mechanism, this paper investigates the natural frequency modulation of a kinematically redundant planar parallel robot. A double-threshold searching method is proposed for controlling the inverse kinematics solution and keeping the natural frequencies away from the excitation frequency. The effectiveness of modulating the natural frequencies is demonstrated by comparing it with a non-modulation method. The simulation results indicate that, in all directions, the responses are coupled, and every order should be taken into consideration during natural frequency modulation. Compared to the non-modulation method, the proposed method can reduce the resonance amplitude to a certain extent, and the effect of vibration suppression is remarkable.

Control Research on Construction Excitation Frequency of Resonant Rubblization Machine

2011 ◽  
Vol 305 ◽  
pp. 394-397
Author(s):  
Xin Qiu ◽  
Qing Yang ◽  
Lan Yun Chen
Keyword(s):  
Natural Frequency ◽  
Elastic Foundation ◽  
Thin Plate ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Research Results ◽  
Vibration Theory ◽  
Fundamental Natural Frequency ◽  
Control Research

Based on the assumption of thin plate of elastic foundation and vibration theory, a method for calculating the fundamental natural frequency of cement slab is presented and the influence of slab dimension and foundation reaction modulus on the fundamental natural frequency of cement slab is discussed. As well, according to the analysis results of fundamental natural frequencies of typical cement pavements of China, the selected proposals of the excitation frequency of the resonant rubblization machine are presented. The research results provide a theory support to popularize resonant rubblization technology in overlaying and rebuilding engineering of the existed cement pavements in China.

Mechanics Mechanism Analysis of Concrete Pavement Resonant Rubblization

2015 ◽  
Vol 667 ◽  
pp. 365-369
Author(s):  
Peng Chen ◽  
Xin Qiu ◽  
Qing Zhu ◽  
Chan Chan Ouyang
Keyword(s):  
Boundary Condition ◽  
Natural Frequency ◽  
Elastic Foundation ◽  
Thin Plate ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Concrete Pavement ◽  
Mechanism Analysis ◽  
Vibration Theory ◽  
Fundamental Natural Frequency

Based on the assumption of thin plate of elastic foundation and vibration theory, a method for calculating the fundamental natural frequency of cement slab is presented and the certain relationship between the fundamental natural frequency of cement slab and cement slab boundary condition is discussed. As well, according to the analysis results of fundamental natural frequencies of the typical cement pavements of China, the selected proposals of the excitation frequency of the resonant rubblization machine are presented .The research results provide a theory support to popularize resonant rubblization technology in overlaying and rebuilding engineering of the existed cement pavements in China.

scholarly journals Static and Dynamic Analysis of Vibro Fluidized Bed Dryer using Finite Element Method

2018 ◽  
Vol 73 ◽  
pp. 05029
Author(s):  
Yohana Eflita ◽  
Haryanto Ismoyo ◽  
Dwiputra Muhamad Adrian ◽  
Luqmanul H Yusuf
Keyword(s):  
Dynamic Analysis ◽  
Fluidized Bed ◽  
Natural Frequency ◽  
Maximum Stress ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Enzymatic Oxidation ◽  
Static And Dynamic Analysis ◽  
Fluidized Bed Dryer ◽  
Working Principle

Vibro Fluidized bed dryer is a widely used tea dryer now. Its function is to stop the enzymatic oxidation process and decrease water content up to 2,8-3,8%. The working principle is to use the vibrations generated by the eccentric motor so that the tea powder that runs on the bed will vibrate. The purpose of this research is to model, static and dynamic of vibro fluidized bed dryer. The analysis was to determine the maximum stress and natural frequency of the vibro fluidized bed dryer to the variation of green tea mass being processed. Using dynamic analysis the obtained first three natural frequencies of the vibro fluidized bed dryer were 5,8876 Hz, 9,5267 Hz, and 10,512 Hz. The results showed that at 695 kg tea mass the natural frequency has the same as the excitation frequency. In this case, the safety factor of the vibro fluidized bed dryer is 27.6. It can be concluded that the maximum capacity of the vibro fluidized bed dryer is 695 kg..

Nonlinear Resonances in a Flexible Cantilever Beam

1994 ◽  
Vol 116 (4) ◽  
pp. 480-484 ◽  
Author(s):  
T. J. Anderson ◽  
B. Balachandran ◽  
A. H. Nayfeh
Keyword(s):  
Natural Frequency ◽  
Cantilever Beam ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Continuous Systems ◽  
Modal Interactions ◽  
The Third ◽  
First Case ◽  
Second Mode ◽  
Band Limited

An experimental investigation into the response of a nonlinear continuous systems with many natural frequencies in the range of interest is presented. The system is a flexible cantilever beam whose first four natural frequencies are 0.65 Hz, 5.65 Hz, 16.19 Hz, and 31.91 Hz, respectively. The four natural frequencies correspond to the first four flexural modes. The fourth natural frequency is about fifty times the first natural frequency. Three cases were considered with this beam. For the first case, the beam was excited with a periodic base motion along its axis. The excitation frequency fe was near twice the third natural frequency f3, which for a uniform isotropic beam corresponds to approximately the fourth natural frequency f4. Thus the third mode was excited by a principal parametric resonance (i.e., fe ≈ 2f3) and the fourth mode was excited by an external resonance (i.e., fe ≈ f4) due to a slight curvature in the beam. Modal interactions were observed involving the first, third, and fourth modes. For the second case, the beam was excited with a band-limited random base motion transverse to the axis of the beam. The first and second modes were excited through nonlinear interactions. For the third case, the beam was excited with a base excitation along the axis of the beam at 138 Hz. The corresponding response was dominated by the second mode. The tools used to analyze the motions include Fourier spectra, Poincare´ sections, and dimension calculations.

Topology Optimization in Structural Design of a LP Turbine Guide Vane: Potential of Additive Manufacturing for Weight Reduction

2014 ◽  
Author(s):  
Joona Seppälä ◽  
Andreas Hupfer
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Weight Reduction ◽  
Design Space ◽  
Guide Vane ◽  
Aircraft Engine ◽  
Optimization Methods ◽  
Optimization Constraints ◽  
Turbine Guide Vane ◽  
Optimal Material

A low pressure turbine guide vane of an aircraft engine is structurally redesigned for additive manufacturing (AM). AM is known to provide more design freedom than conventional manufacturing methods, which encourages the implementation of numerical optimization methods in the design process in order to reduce weight by eliminating unneeded material. One such method is called topology optimization (TO), which finds the optimal material distribution inside a fixed design space. Using commercial software, TO is conducted to find the optimal geometry. The guide vane is subject to gas loads. During optimization, constraints for bending deformation and Eigen frequencies are applied. The design space consists of the airfoil interior and the shrouds, leaving aerodynamic surfaces untouched. Several TO approaches are examined and the result is preliminarily evaluated in a stationary coupled temperature-displacement FEA with take-off loading conditions. The results indicate a potential weight reduction of 19% but with a rise in temperature gradients. An enlarged shroud geometry would enable even greater weight reduction.

scholarly journals Effects of Elliptical Hole on the Correlation of Natural Frequency with Buckling Load of Basalt Laminates Composite Plates

2020 ◽  
Vol 27 (1) ◽  
pp. 216-225
Author(s):  
Buntheng Chhorn ◽  
WooYoung Jung
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Basalt Fiber ◽  
Orientation Angle ◽  
Elliptical Hole ◽  
Composite Plates ◽  
Buckling Load ◽  
Mode Shapes ◽  
Geometric Ratio

AbstractRecently, basalt fiber reinforced polymer (BFRP) is acknowledged as an outstanding material for the strengthening of existing concrete structure, especially it was being used in marine vehicles, aerospace, automotive and nuclear engineering. Most of the structures were subjected to severe dynamic loading during their service life that may induce vibration of the structures. However, free vibration studied on the basalt laminates composite plates with elliptical cut-out and correlation of natural frequency with buckling load has been very limited. Therefore, effects of the elliptical hole on the natural frequency of basalt/epoxy composite plates was performed in this study. Effects of stacking sequence (θ), elliptical hole inclination (ϕ), hole geometric ratio (a/b) and position of the elliptical hole were considered. The numerical modeling of free vibration analysis was based on the mechanical properties of BFRP obtained from the experiment. The natural frequencies as well as mode shapes of basalt laminates composite plates were numerically determined using the commercial program software (ABAQUS). Then, the determination of correlation of natural frequencies with buckling load was carried out. Results showed that elliptical hole inclination and fiber orientation angle induced the inverse proportion between natural frequency and buckling load.

scholarly journals A Vibration-Based Structural Health Monitoring System for Transmission Line Towers

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 515 ◽  
Author(s):  
Long Zhao ◽  
Xinbo Huang ◽  
Ye Zhang ◽  
Yi Tian ◽  
Yu Zhao
Keyword(s):  
Structural Health Monitoring ◽  
Transmission Line ◽  
Natural Frequency ◽  
Health Monitoring ◽  
Structural Changes ◽  
Natural Frequencies ◽  
Transmission Tower ◽  
Health Monitoring System ◽  
Wind Speeds ◽  
Before And After

In this paper, we present a vibration-based transmission tower structural health monitoring system consisting of two parts that identifies structural changes in towers. An accelerometer group realizes vibration response acquisition at different positions and reduces the risk of data loss by data compression technology. A solar cell provides the power supply. An analyser receives the data from the acceleration sensor group and calculates the transmission tower natural frequencies, and the change in the structure is determined based on natural frequencies. Then, the data are sent to the monitoring center. Furthermore, analysis of the vibration signal and the calculation method of natural frequencies are proposed. The response and natural frequencies of vibration at different wind speeds are analysed by time-domain signal, power spectral density (PSD), root mean square (RMS) and short-time Fouier transform (STFT). The natural frequency identification of the overall structure by the stochastic subspace identification (SSI) method reveals that the number of natural frequencies that can be calculated at different wind speeds is different, but the 2nd, 3rd and 4th natural frequencies can be excited. Finally, the system was tested on a 110 kV experimental transmission line. After 18 h of experimentation, the natural frequency of the overall structure of the transmission tower was determined before and after the tower leg was lifted. The results show that before and after the tower leg is lifted, the natural frequencies of each order exhibit obvious changes, and the differences in the average values can be used as the basis for judging the structural changes of the tower.

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