scholarly journals Optimum Design of a Gearbox for Low Vibration

1993 ◽  
Vol 115 (4) ◽  
pp. 1002-1007 ◽  
Author(s):  
K. Inoue ◽  
D. P. Townsend ◽  
J. J. Coy
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Shell Element ◽  
Optimization Method ◽  
Vibration Energy ◽  
Nasa Lewis Research ◽  
Element Analysis ◽  
Constant Weight ◽  
Triangular Shell Element ◽  
Exciting Frequency

A computer program was developed for designing a low vibration gearbox. The code 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 method, the overall vibration energy of the gearbox is used as the objective function and is minimized at the exciting frequency by varying the finite element thickness. Modal analysis is used to derive the sensitivity of the vibration energy with respect to the design variable. The sensitivity is representative 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. The computer code is applied to a design problem derived from an experimental gearbox in use at the NASA Lewis Research Center. The top plate and two side plates of the gearbox are redesigned and the contribution of each surface to the total vibration is determined. Results show that even the optimization of the top plate alone is effective in reducing total gearbox vibration.

scholarly journals Optimum Design of a Gearbox for Low Vibration

1992 ◽  
Author(s):  
Katsumi Inoue ◽  
Dennis P. Townsend ◽  
John J. Coy
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Optimization Method ◽  
Vibration Energy ◽  
Nasa Lewis Research ◽  
Analysis Method ◽  
Element Analysis ◽  
Constant Weight ◽  
Triangular Shell Element ◽  
Exciting Frequency

Abstract A computer program was developed for designing a low vibration gearbox. The code is based on a finite element shell analysis method, a modal analysis method, and a structural optimization method. In the finite element analysis, a triangular shell element with 18 degrees-of-freedom is used. In the optimization method, the overall vibration energy of the gearbox is used as the objective function and is minimized at the exciting frequency by varying the finite element thickness. Modal analysis is used to derive the sensitivity of the vibration energy with respect to the design variable. The sensitivity is representative 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. The computer code is applied to a design problem derived from an experimental gearbox in use at the NASA Lewis Research Center. The top plate and two side plates of the gearbox are redesigned and the contribution of each surface to the total vibration is determined. Results show that optimization of the top plate alone is effective in reducing total gearbox vibration.

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.

Verification of a Finite Element Analysis Procedure for Modeling the Nonlinear, Monotonic In-Plane Behavior of 4 Inch, Schedule 10, Stainless Steel, 90° Elbows

2003 ◽  
Author(s):  
James K. Wilkins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stainless Steel ◽  
Nonlinear Behavior ◽  
Shell Element ◽  
Analysis Procedure ◽  
Hoop Strain ◽  
Element Analysis ◽  
Butt Welding ◽  
Strain Data

A project has been conducted to verify a finite element analysis procedure for studying the nonlinear behavior of 90°, stainless steel, 4 inch schedule 10, butt welding elbows. Two displacement controlled monotonic in-plane tests were conducted, one closing and one opening, and the loads, displacements, and strains at several locations were recorded. Stacked 90° tee rosette gages were used in both tests because of their ability to measure strain over a small area. ANSYS shell element 181 was used in the FEA reconciliations. The FEA models incorporated detailed geometric measurements of the specimens, including the welds, and material stress-strain data obtained from the attached straight piping. Initially, a mesh consisting of sixteen elements arrayed in 8 rings was used to analyze the elbow. The load-displacement correlation was quite good using this mesh, but the strain reconciliation was not. Analysis of the FEA results indicated that the axial and hoop strain gradients across the mid-section of the elbow were very high. In order to generate better strain correlations, the elbow mesh was refined in the mid-section of the elbow to include 48 elements per ring and an additional six rings, effectively increasing the element density by nine times. Using the refined mesh produced much better correlations with the strain data.

Analysis and Optimization of Bellows With General Shape

1998 ◽  
Vol 120 (4) ◽  
pp. 325-333 ◽  
Author(s):  
B. K. Koh ◽  
G. J. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Beam Theory ◽  
Inequality Constraints ◽  
Shell Element ◽  
Scalar Function ◽  
Programming Algorithm ◽  
Multiple Objective ◽  
Axially Symmetric ◽  
Element Analysis

A bellows is a component in piping systems which absorbs mechanical deformation with flexibility. Its geometry is an axially symmetric shell which consists of two toroidal shells and one annular plate or conical shell. In order to analyze the bellows, this study presents the finite element analysis using a conical frustum shell element. A finite element analysis program is developed to analyze various bellows. The formula for calculating the natural frequency of bellows is made by the simple beam theory. The formula for fatigue life is also derived by experiments. A shape optimal design problem is formulated using multiple objective optimization. The multiple objective functions are transformed to a scalar function with weighting factors. The stiffness, strength, and specified stiffness are considered as the multiple objective function. The formulation has inequality constraints imposed on the natural frequencies, the fatigue limit, and the manufacturing conditions. Geometric parameters of bellows are the design variables. The recursive quadratic programming algorithm is utilized to solve the problem.

The Finite Element Modal Analysis of Spur Gear Based on Patran

2014 ◽  
Vol 962-965 ◽  
pp. 2957-2960
Author(s):  
Qian Peng Han ◽  
Bo Peng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Modal Analysis ◽  
Spur Gear ◽  
Parametric Model ◽  
Parametric Modeling ◽  
Element Analysis ◽  
General Process

This article summarized the general process of parametric modeling and finite element analysis of spur gear,PRO/E used to create parametric model,and Patran used to finite element analysis.Parametric modeling can reduce design period of the similar products,and modal analysis provide the basis for the selection and optimization of gear.

Control Effectiveness of Segmented Actuators Laminated on Ring-Shells

1997 ◽  
Author(s):  
R. Ye ◽  
H. Bahrami ◽  
H. S. Tzou
Keyword(s):  
Finite Element ◽  
Distributed Control ◽  
Piezoelectric Actuators ◽  
Shell Element ◽  
Circular Ring ◽  
Control Effectiveness ◽  
Triangular Shell Element ◽  
Circular Ring Shell ◽  
System Equations ◽  
Ring Shell

Abstract Distributed control effectiveness of ring-shells laminated with segmented actuators is investigated in this paper. A new laminated quadratic piezoelastic triangular shell FE is developed using the layerwise constant shear angle theory. Element and system equations are also derived. The developed piezoelastic triangular shell element is used to model a semi-circular ring shell with various segments of distributed piezoelectric actuators. Finite element (triangular shell FE) solutions are compared with the theoretical, experimental, and finite element first. Natural frequencies and distributed control effects of the ring shell with different length of piezoelectric actuators are also studied. Control effectiveness is evaluated and optimal length of the actuator is recommended.

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