Muffler of High Quality and Efficiency Based on Structural Dynamic Optimization and the Modal Analysis

2013 ◽  
Vol 753-755 ◽  
pp. 1156-1160
Author(s):  
Xin Xiang Zhou ◽  
Da Meng Han ◽  
Xing Long Lei ◽  
Cheng Liu ◽  
Guang Yu Hu
Keyword(s):  
Modal Analysis ◽  
Dynamic Optimization ◽  
Noise Source ◽  
Peak Frequency ◽  
Optimization Method ◽  
Expansion Chamber ◽  
Structural Dynamic ◽  
Air Inlet ◽  
High Efficient ◽  
Inherent Frequency

According to the mechanism and spectrum characteristics of an oil-free air compressor noise source, determined the muffler installed at the air inlet. According to the characteristics of noise source, muffler is designed into type of expansion chamber, considering the structural dynamic parameters, by means of optimization method to determine the size, and the finite element modal analysis is conducted. By solving the muffler's inherent frequency and mode of vibration, knows weather each order natural frequency is away from the peak frequency, the structural dynamics of the muffler can be modification. Methods of structure modal analysis and dynamic optimization on the muffler provided reliable reference to design a high efficient new muffler.

The Rigid-Flexible Coupled Modeling and Dynamic Simulation of HP-20 Robot

2011 ◽  
Vol 101-102 ◽  
pp. 508-511
Author(s):  
Gang Zhang ◽  
Hai Bo Huang ◽  
Ting Zhang
Keyword(s):  
Modal Analysis ◽  
Dynamic Model ◽  
Dynamic Simulation ◽  
Dynamic Optimization ◽  
3D Modeling ◽  
Coupled Modeling ◽  
Structural Dynamic ◽  
Modeling Software ◽  
Multi Body ◽  
Body Dynamic

The rigid-flex coupled multi-body dynamic model of Motoman HP20 was built in this paper. The parts geometry shapes were modeled in 3D modeling software and imported into the multi-body platform. Then the joints were added to the parts. The arms were analyzed in FE software and modal neutral files were obtained. Then rigid parts were replaced by the modal neutral files. Driven curves of each arm joint were obtained by D-H method. The modal analysis of system was also made to analyze the robot dynamic characters. The results give some suggestions for robot motor selection and structural dynamic optimization.

A Study on Exhaust Muffler Using Counter-Phase Counteract

2014 ◽  
Vol 986-987 ◽  
pp. 810-813
Author(s):  
Ying Li Shao
Keyword(s):  
Mathematical Model ◽  
Experimental Validation ◽  
Noise Source ◽  
Low Frequency ◽  
Frequency Noise ◽  
Expansion Chamber ◽  
Band Noise ◽  
Exhaust Noise ◽  
Perforated Pipe ◽  
The Mathematical Model

The exhaust noise, which falls into low-frequency noise, is the dominant noise source of a diesel engines and tractors. The traditional exhaust silencers, which are normally constructed by combination of expansion chamber, and perforated pipe or perforated board, are with high exhaust resistance, but poor noise reduction especially for the low-frequency band noise. For this reason, a new theory of exhaust muffler of diesel engine based on counter-phase counteracts has been proposed. The mathematical model and the corresponding experimental validation for the new exhaust muffler based on this theory were performed.

scholarly journals Prediction of Vertical Tail Buffet Using CFD/CSD Coupling Method

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Bing Han ◽  
Min Xu
Keyword(s):  
Vortex Breakdown ◽  
Peak Frequency ◽  
Basis Functions ◽  
Resonance Phenomenon ◽  
Structural Dynamic ◽  
Flexible Tail ◽  
Bending Mode ◽  
Tail Structure ◽  
Tail Buffet ◽  
Modal Coordinates

The vertical tail buffet induced by the vortex breakdown flow is numerically investigated. The unsteady flow is calculated by solving the RANS equations. The structural dynamic equations are decoupled in the modal coordinates. The radial basis functions (RBFs) are employed to generate the deformation mesh. The buffet response of the flexible tail is predicted by coupling the three sets of equations. The results show that the presence of asymmetry flow on the inner and outer surface of the tail forced the structural deflection offsetting the outboard. The frequency of the 2nd bending mode of the tail structure meets the peak frequency of the pressure fluctuation upon the tail surface, and the resonance phenomenon was observed. Therefore, the 2nd bending responses govern the flow field surrounding the vertical tail. Finally, the displacement of the vertical tail is small, while the acceleration with a large quantitation forces the vertical tail undergoing severe addition inertial loads.

Stochastic Dynamic Analysis of Structures with Spatially Uncertain Material Parameters

2014 ◽  
Vol 14 (08) ◽  
pp. 1440029 ◽  
Author(s):  
Kheirollah Sepahvand ◽  
Steffen Marburg
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Polynomial Chaos ◽  
Element Model ◽  
Stochastic Dynamic ◽  
Stochastic Field ◽  
Structural Dynamic ◽  
Material Parameters ◽  
Material Uncertainties ◽  
Stochastic Dynamic Analysis

This paper investigates the uncertainty quantification in structural dynamic problems with spatially random variation in material and damping parameters. Uncertain and locally varying material parameters are represented as stochastic field by means of the Karhunen–Loève (KL) expansion. The stiffness and damping properties of the structure are considered uncertain. Stochastic finite element of structural modal analysis is performed in which modal responses are represented using the generalized polynomial chaos (gPC) expansion. Knowing the KL expansions of the random parameters, the nonintrusive technique is employed on a set of random collocation points where the structure deterministic finite element model is executed to estimate the unknown coefficients of the polynomial chaos expansions. A numerical case study is presented for a cantilever beam with random Young's modulus involving spatial variation. The proportional damping constants are estimated from the experimental modal analysis. The expected value, standard deviation, and probability distribution of the random eigenfrequencies and the damping ratios are evaluated. The results show high accuracy compared to the Monte-Carlo (MC) simulations with 3000 realizations. It is also demonstrated that the eigenfrequencies and the damping ratios are equally affected from material uncertainties.

scholarly journals Effects of upper body parameters on biped walking efficiency studied by dynamic optimization

2016 ◽  
Vol 14 (1) ◽  
pp. 172988141668270 ◽  
Author(s):  
Kang An ◽  
Chuanjiang Li ◽  
Zuhua Fang ◽  
Chengju Liu
Keyword(s):  
Body Length ◽  
Dynamic Optimization ◽  
Optimal Solution ◽  
Optimization Method ◽  
Step Length ◽  
Joint Torque ◽  
Upper Body ◽  
Walking Gait ◽  
Body Parameters ◽  
Walking Efficiency

Walking efficiency is one of the considerations for designing biped robots. This article uses the dynamic optimization method to study the effects of upper body parameters, including upper body length and mass, on walking efficiency. Two minimal actuations, hip joint torque and push-off impulse, are used in the walking model, and minimal constraints are set in a free search using the dynamic optimization. Results show that there is an optimal solution of upper body length for the efficient walking within a range of walking speed and step length. For short step length, walking with a lighter upper body mass is found to be more efficient and vice versa. It is also found that for higher speed locomotion, the increase of the upper body length and mass can make the walking gait optimal rather than other kind of gaits. In addition, the typical strategy of an optimal walking gait is that just actuating the swing leg at the beginning of the step.

Minimization of the Vibration Energy of Thin-Plate Structures

1992 ◽  
Author(s):  
Katsumi Inoue ◽  
Dennis P. Townsend ◽  
John J. Coy
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Thin Plate ◽  
Optimization Method ◽  
Optimum Shape ◽  
Vibration Energy ◽  
Plate Structures ◽  
Constant Weight ◽  
Exciting Frequency ◽  
The Given

Abstract An optimization method is proposed to reduce the vibration of thin-plate structures. The method is based on a finite-element shell analysis, a modal analysis, and a structural optimization method. In the finite-element analysis, a triangular shell element with 18 degrees of freedom is used. In the optimization, the overall vibration energy of the structure is adopted as the objective function, and it is minimized at the given exciting frequency by varying the thickness of the elements. The technique of modal analysis is used to derive the sensitivity of the vibration energy with respect to the design variables. The sensitivity is represented by the sensitivities of both eigenvalues and eigenvectors. The optimum value is computed by the gradient projection method and a unidimensional search procedure under the constraint condition of constant weight. A computer code, based on the proposed method, is developed and is applied to design problems using a beam and a plate as test cases. It is confirmed that the vibration energy is reduced at the given exciting frequency. For the beam excited by a frequency slightly less than the fundamental natural frequency, the optimized shape is close to the beam of uniform strength. For the plate, the optimum shape is obtained such that the changes in thickness have the effect of adding a stiffener or a mass.

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