An adjoint variable method for design sensitivity analysis of elastoplastic structures

1999 ◽  
Vol 13 (3) ◽  
Author(s):  
Tae Hee Lee
Keyword(s):  
Sensitivity Analysis ◽  
Design Sensitivity ◽  
Variable Method ◽  
Design Sensitivity Analysis ◽  
Adjoint Variable Method ◽  
Adjoint Variable

Parametric Design Sensitivity Analysis of High Frequency Structural-Acoustic Problems Using Energy Finite Element Method

2003 ◽  
Author(s):  
Kyung K. Choi ◽  
Jun Dong ◽  
Nickolas Vlahopoulos ◽  
Aimin Wang ◽  
Weiguo Zhang
Keyword(s):  
Finite Element Method ◽  
Sensitivity Analysis ◽  
Finite Element ◽  
High Frequency ◽  
Parametric Design ◽  
Design Sensitivity ◽  
Variable Method ◽  
Design Sensitivity Analysis ◽  
Adjoint Variable Method ◽  
Adjoint Variable

A design sensitivity analysis of high frequency structural-acoustic problem is formulated and presented. The Energy Finite Element Method (EFEM) is used to predict the structural-acoustic responses in high frequency range, where the coupling between the structural and acoustic domain are modeled by using radiation efficiency. The continuum design sensitivity formulation is derived from the governing equation of EFEM and the discrete method is applied in the variation of the structural-acoustic coupling matrix. The direct differentiation and adjoint variable method are both developed for the sensitivity analysis, where the difficulty of the adjoint variable method is overcome by solving a transposed system equation. Parametric design variables such as panel thickness and material damping are considered for sensitivity analysis, and the numerical sensitivity results show excellent agreement comparing with the finite difference results.

A Sequential Adjoint Variable Method in Design Sensitivity Analysis of NVH Problems

2001 ◽  
Author(s):  
N. H. Kim ◽  
K. K. Choi ◽  
J. Dong ◽  
C. Pierre ◽  
N. Vlahopoulos ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Boundary Element ◽  
Design Sensitivity ◽  
Variable Method ◽  
Design Sensitivity Analysis ◽  
Response Analysis ◽  
Adjoint Variable Method ◽  
Adjoint Variable ◽  
Structural Dynamic ◽  
Structural Part

Abstract A design sensitivity analysis of a sequential structural-acoustic problem is presented. A frequency response analysis is used to obtain the dynamic behavior of an automotive structure, while the boundary element method is used to solve the pressure response of an interior, acoustic domain. For the purposes of design sensitivity analysis, a direct differentiation method and an adjoint variable method are presented. In the adjoint variable method, an adjoint load is obtained from the acoustic boundary element re-analysis, while the adjoint solution is calculated from the structural dynamic re-analysis. The evaluation of pressure sensitivity only involves a numerical integration process for the structural part. The proposed sensitivity results are compared to finite difference sensitivity results with excellent agreement.

Second-Order Design Sensitivity Analysis of Mechanical System Dynamics by a Mixed Direct Differentiation Adjoint Variable Method

1998 ◽  
Author(s):  
Javier Urruzola ◽  
José Manuel Jiménez
Keyword(s):  
Sensitivity Analysis ◽  
Design Sensitivity ◽  
Second Order ◽  
Variable Method ◽  
Adjoint Variable Method ◽  
Adjoint Variable ◽  
Direct Differentiation ◽  
Design Variables ◽  
Adjoint Variables ◽  
Derivatives Of

Abstract This paper presents a new approach to second order sensitivity analysis of multibody dynamics. Adjoint variables together with direct differentiation are used to derive first- and second-order derivatives of measures of dynamic response with respect to design variables. It is shown that the proposed method can be compared advantageously to the fully adjoint variable method proposed by Haug in terms of simplicity and numerical cost. In order to validate the algorithm, a simple oscillator example proposed by Haug is solved analytically and by the mixed method, with identical results.

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.

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