Design Sensitivity Analysis of Structure-Induced Noise and Vibration

1997 ◽  
Vol 119 (2) ◽  
pp. 173-179 ◽  
Author(s):  
K. K. Choi ◽  
I. Shim ◽  
S. Wang
Keyword(s):  
Sensitivity Analysis ◽  
Numerical Method ◽  
Variational Equation ◽  
Adjoint Operator ◽  
Design Sensitivity ◽  
Design Sensitivity Analysis ◽  
Adjoint Variable ◽  
Element Analysis ◽  
Modal Frequency ◽  
Noise And Vibration

A continuum design sensitivity analysis (DSA) method for dynamic frequency responses of structural-acoustic systems is developed using the adjoint variable and direct differentiation methods. A variational approach with a non-self-adjoint operator for complex variables is used to retain the continuum elasticity formulation throughout derivation of design sensitivity results. It is shown that the adjoint variable method is applicable to the variational equation with the non-self-adjoint operator. Sizing design variables such as the thickness and cross-sectional area of structural components are considered for the design sensitivity analysis. A numerical implementation method of continuum DSA results is developed by postprocessing analysis results from established finite element analysis (FEA) codes to obtain the design sensitivity of noise and vibration performance measures of the structural-acoustic systems. The numerical DSA method presented in this paper is limited to FEA and boundary element analysis (BEA) is not considered. A numerical method is developed to compute design sensitivity of direct and modal frequency FEA results. For the modal frequency FEA method, the numerical DSA method provides design sensitivity very efficiently without requiring design sensitivities of eigenvectors. The numerical method has been tested using passenger vehicle problems. Accurate design sensitivity results are obtained for analysis results obtained from established FEA codes.

Adjoint Design Sensitivity Analysis of Molecular Gas Film Lubrication Sliders

2002 ◽  
Vol 125 (1) ◽  
pp. 145-151 ◽  
Author(s):  
Sang-Joon Yoon ◽  
Dong-Hoon Choi
Keyword(s):  
Sensitivity Analysis ◽  
Design Sensitivity ◽  
Design Sensitivity Analysis ◽  
Finite Difference Approximation ◽  
Molecular Gas ◽  
Air Bearings ◽  
Adjoint Variable ◽  
Topological Parameters ◽  
Molecular Gas Film Lubrication ◽  
Film Lubrication

This paper proposes an analytical design sensitivity analysis (DSA) to topological parameters of MGL (molecular gas film lubrication) sliders by introducing an adjoint variable method. For the analysis of slider air bearings, we used the spatial discretization of the generalized lubrication equation based on a control volume formulation. The residual functions for inverse analysis of the slider are considered as the equality constraint functions. The slider rail heights of all grid cells are chosen as design variables since they are the topological parameters determining air bearing surface (ABS). Then, a complicated adjoint variable equation is formulated to directly handle the highly nonlinear asymmetric coefficient matrix and vector in the discrete system equations of slider air bearings. An alternating direction implicit (ADI) scheme is utilized to efficiently solve large-scale problem in special band storage. The simulation results of DSA are directly compared with those of finite-difference approximation (FDA) to show the effectiveness and accuracy of the proposed approach. The overall sensitivity distribution over the ABS is reported, and clearly shows to which section of the ABS the special attention should be given during the manufacturing process. It is demonstrated that the proposed method can reduce more than 99 percent of the CPU time in comparison with FDA, even though both methods give the same results.

Development of a Design Sensitivity Analysis Technique for Explicit Finite Element Software With Applications in Crashworthiness

2000 ◽  
Author(s):  
Douglas W. Stillman
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Time Integration ◽  
Design Sensitivity ◽  
Design Sensitivity Analysis ◽  
Element Analysis ◽  
Automotive Safety ◽  
Explicit Finite Element ◽  
Finite Element Software ◽  
Analysis Technique

Abstract Design Sensitivity Analysis (DSA) is a widely used technique in many areas of finite element analysis, but one that hasn’t yet become available for industrial problems in crashworthiness and automotive safety. In the following effort, an implementation of DSA in the automotive safety simulation program, Radioss, is described. Radioss is a non-linear structures program using an explicit time integration method. A full set of DSA equations are developed and integrated into Radioss so that the design sensitivities can be computed directly and accurately as a result of a single crashworthiness simulation. Some validation results are included. The resulting methodology promises to be an extremely useful tool for engineers involved in the design of safety and crashworthiness of automobiles.

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