scholarly journals Damage Detection of Bridges Using Vibration Data by Adjoint Variable Method

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Akbar Mirzaee ◽  
Mohsenali Shayanfar ◽  
Reza Abbasnia
Keyword(s):  
Finite Element ◽  
Damage Detection ◽  
Numerical Study ◽  
Relative Effectiveness ◽  
Computational Cost ◽  
Variable Method ◽  
Main Concern ◽  
Element Formulation ◽  
Adjoint Variable Method ◽  
Adjoint Variable

This research entails a theoretical and numerical study on a new damage detection method for bridges, using response sensitivity in time domain. This method, referred to as “adjoint variable method,” is a finite element model updating sensitivity based method. Governing equation of the bridge-vehicle system is established based on finite element formulation. In the inverse analysis, the new approach is presented to identify elemental flexural rigidity of the structure from acceleration responses of several measurement points. The computational cost of sensitivity matrix is the main concern associated with damage detection by these methods. The main advantage of the proposed method is the inclusion of an analytical method to augment the accuracy and speed of the solution. The reliable performance of the method to precisely identify the location and intensity of all types of predetermined single, multiple, and random damages over the whole domain of moving vehicle speed is shown. A comparison study is also carried out to demonstrate the relative effectiveness and upgraded performance of the proposed method in comparison to the similar ordinary sensitivity analysis methods. Moreover, various sources of errors including the effects of noise and primary errors on the numerical stability of the proposed method are discussed.

Design Optimization for Structural-Acoustic Problems Using FEA-BEA With Adjoint Variable Method

2003 ◽  
Vol 126 (3) ◽  
pp. 527-533 ◽  
Author(s):  
Jun Dong ◽  
Kyung K. Choi ◽  
Nam H. Kim
Keyword(s):  
Finite Element ◽  
Design Optimization ◽  
Boundary Element ◽  
Design Sensitivity ◽  
Variable Method ◽  
Adjoint Variable Method ◽  
Adjoint Variable ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Structural Part

A noise-vibration-harshness (NVH) design optimization of a complex vehicle structure is presented using finite element and boundary element analyses. The steady-state dynamic behavior of the vehicle is calculated from the frequency response finite element analysis, while the sound pressure level within the acoustic cavity is calculated from the boundary element analysis. A reverse solution process is employed for the design sensitivity calculation using the adjoint variable method. The 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 over the structural part where the design variable is defined. A design optimization problem is formulated and solved, where the structural weight is reduced while the noise level in the passenger compartment is lowered.

scholarly journals Parameter Identification on Flexible Multibody Models Using the Adjoint Variable Method and Flexible Natural Coordinate Formulation

2020 ◽  
Vol 15 (7) ◽  
Author(s):  
Simon Vanpaemel ◽  
Frank Naets ◽  
Martijn Vermaut ◽  
Wim Desmet
Keyword(s):  
Parameter Identification ◽  
Computational Cost ◽  
Variable Method ◽  
System Level ◽  
Model Parameters ◽  
Adjoint Variable Method ◽  
Adjoint Variable ◽  
Component Level ◽  
Flexible Multibody

Abstract This work proposes a methodology for in situ parameter identification using system-level measurements of (flexible) multibody systems, opposed to dedicated component-level identification. The sensitivity information employed for the optimization is obtained using the adjoint variable method (AVM). This method has the advantage of obtaining sensitivity information at a computational cost independent of the amount of model parameters. The underlying flexible multibody formulation employed is a novel approach called the flexible natural coordinates formulation (FNCF). This formulation combines the advantageous properties of the floating frame of reference formulation (FFRF) and the generalized component mode synthesis (GCMS) methods and results in a constant mass and stiffness matrix with quadratic constraint equations. This work shows how the specific structure of equations obtained through FNCF drastically reduces the complexity of the AVM as the simulation derivatives can be readily obtained and are of limited order. The proposed approach has been implemented in an in-house object-oriented matlab multibody code. The methodology is illustrated by identifying 13 model parameters of a MacPherson suspension model, in situ and using system-level measurements.

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.

Adjoint variable method for two-dimensional plasmonic structures

2012 ◽  
Vol 37 (16) ◽  
pp. 3453 ◽  
Author(s):  
O. S. Ahmed ◽  
M. H. Bakr ◽  
X. Li ◽  
T. Nomura
Keyword(s):  
Variable Method ◽  
Two Dimensional ◽  
Adjoint Variable Method ◽  
Adjoint Variable ◽  
Plasmonic Structures
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