A Hybrid Approach to Test-Analysis-Model Development for Large Space Structures

1991 ◽  
Vol 113 (3) ◽  
pp. 325-332 ◽  
Author(s):  
D. C. Kammer
Keyword(s):  
Model Development ◽  
Hybrid Approach ◽  
Element Model ◽  
Space Structure ◽  
Mode Shapes ◽  
Analysis Model ◽  
Large Space ◽  
Test Analysis ◽  
Test Mode ◽  
Analysis Mode

A new finite element model (FEM) reduction method is presented for use in the generation of Test-Analysis-Models (TAM) in test-analysis correlation. The method addresses the concern that some current TAM methodologies, specifically the Modal TAM, are overly sensitive to differences between test mode shapes and analysis mode shapes. This sensitivity can result in large off-diagonal terms within the orthogonality and cross-orthogonality matrices used for test-analysis mode shape correlation. It has been hypothesized that the sensitivity is due to the Modal TAM’s poor representation of residual mode shapes and frequencies which are modes that are not targeted for identification. In many cases it has been observed that the less accurate static TAM often gives better off-diagonal correlation results. A new Hybrid TAM methodology is developed to combine the exact representation of the FEM target modes from the Modal TAM with the more accurate static TAM representation of the residual modes. The superior residual dynamics representation of the Hybrid TAM is demonstrated for both a simple spacecraft and a much more detailed representation of a Large Space Structure. Simulated test-analysis correlation results are presented for both examples where test mode shapes are represented by FEM target modes with noise modeled as a random linear combination of all FEM modes. Analysis indicates that the Hybrid TAM’s improved residual representation results in reduced sensitivity of the test-analysis correlation to model error.

scholarly journals Mathematical modeling of transformable space structure dynamics

2019 ◽  
Vol 221 ◽  
pp. 01018 ◽  
Author(s):  
Vladimir Zimin ◽  
Alexey Krylov ◽  
Sergey Churilin ◽  
Zikun Zhang
Keyword(s):  
Strain State ◽  
Element Model ◽  
Space Structure ◽  
Space Structures ◽  
Elastic Rod ◽  
Stress Strain ◽  
Large Space ◽  
Structure Dynamics ◽  
Stress Strain State ◽  
Large Space Structure

Today large space structures are in focus of attention of engineers and designers of rocket and space equipment. In ground-based experiments, it is not always possible to carry out complex tests of large space structure functionality. Therefore, the development of mathematical models describing properly the transformable structure dynamics when they opened from the densely packed transport state to the operating position in the orbit becomes very important. To determine the stress-strain state of the frame elements when it is unfolding the shape of the framework is taken at the moments when relative velocities of the adjacent sections are maximal. Supposed, that at these moments the frame elements are getting on the stops limiting their relative angular displacements, and the structure behaves as an elastic rod with specified characteristics. Numerical analysis of the stress-strain state in the framework is carried out by means of a finite element model. Therefore, the represented mathematical model can be effectively used to predict the functional suitability of such transformable space structures already on the early stages of their development.

An effective method for damage assessment based on limited measured locations in skeletal structures

2020 ◽  
Vol 24 (1) ◽  
pp. 183-195 ◽  
Author(s):  
Parsa Ghannadi ◽  
Seyed Sina Kourehli
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Damage Detection ◽  
Degrees Of Freedom ◽  
Truss Structures ◽  
Mode Shapes ◽  
Analysis Model ◽  
Test Analysis ◽  
Modal Test ◽  
Artificial Neural

This article proposes a new damage detection method using Modal Test Analysis Model and artificial neural networks. A challenge in damage detection problems is lack of measured degrees of freedom, as well as limitations of attached sensors. Modal Test Analysis Model has been used in order to estimate unmeasured degrees of freedom. An experimental cantilever beam was used to show Modal Test Analysis Model’s efficiency in estimation of unmeasured mode shapes. To solve the inverse problem of damage detection, mode shapes estimated by Modal Test Analysis Model were used as inputs, and characteristics of the damage served as outputs of the artificial neural network. The sensitivity analysis carried out for each example showing the performance of artificial neural network after mode shape expansion was efficiently improved. Three numerical examples for plane and space truss structures are considered, in order to verify effectiveness of the proposed method. Results demonstrate a high accuracy of Modal Test Analysis Model and artificial neural network for structural damage detection.

Geometric Mistuning Reduced-Order Model Development Utilizing Bayesian Surrogate Models for Component Mode Calculations

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Joseph A. Beck ◽  
Jeffrey M. Brown ◽  
Alex A. Kaszynski ◽  
Emily B. Carper ◽  
Daniel L. Gillaugh
Keyword(s):  
Periodic Structures ◽  
Model Development ◽  
Element Model ◽  
Forced Response ◽  
Mode Shapes ◽  
Order Model ◽  
Mode Localization ◽  
Reduced Order ◽  
Structural Periodicity ◽  
Computationally Intensive

AbstractIntegrally bladed rotors (IBRs) are meant to be rotationally periodic structures. However, unique variations in geometries and material properties from sector-to-sector, called mistuning, destroy the structural periodicity. This results in mode localization that can induce forced response levels greater than what is predicted with a tuned analysis. Furthermore, mistuning and mode localization are random processes that require stochastic treatments when analyzing the distribution of fleet responses. Generating this distribution can be computationally intensive when using the full finite element model (FEM). To overcome this expense, reduced-order models (ROMs) have been developed to accommodate fast calculations of mistuned forced response levels for a fleet of random IBRs. Usually, ROMs can be classified by two main families: frequency-based and geometry-based methods. Frequency-based ROMs assume mode shapes do not change due to mistuning. However, this assumption has been shown to cause errors that propagate to the fleet distribution. To circumvent these errors, geometry-based ROMs have been developed to provide accurate predictions. However, these methods require recalculating modal data during ROM formulations. This increases the computational expense in computing fleet distributions. A new geometry-based ROM is presented to reduce this cost. The developed ROM utilizes a Bayesian surrogate model in place of sector modal calculations required in ROM formulations. The method, surrogate modal analysis for geometry mistuning assessments (SMAGMA), will propagate uncertainties of the surrogate prediction to forced response. ROM accuracies are compared to the true forced response levels and results computed by a frequency-based ROM.

A Hybrid Approach for Quantifying the Winding Process and Material Effects on Sheet Coil Deformation

2004 ◽  
Vol 126 (3) ◽  
pp. 303-313 ◽  
Author(s):  
Shunping Li ◽  
Jian Cao
Keyword(s):  
Hybrid Approach ◽  
Material Model ◽  
Element Model ◽  
Equivalent Material ◽  
Analysis Model ◽  
Engineering Design Process ◽  
Radial Stiffness ◽  
Gravitational Loading ◽  
Laminate Sheet ◽  
Winding Tension

Excessive coil deformation can complicate normal handling of a wound or rolled coil, cause difficulties in mass production, and introduce undesirable variations in the subsequent manufacturing processes. Four critical factors for coil deformation have been identified, i.e., radial stiffness of the coil material, winding tension, stiffness of the core which supports the coil, and lubrication. In this paper, we advance the understanding of coil deformation by developing an equivalent material model based on the internal stress distribution obtained from a two-dimensional winding-analysis model. The proposed material model is then implemented in a multi-layer finite element model to study the coil deformation under gravitational loading. This proposed framework can quantify the contribution of each factor in the coil deformation and thereby provide more scientific base in the engineering design process. The approach is used to analyze the deformation of laminate sheet coils.

Geometric Mistuning Reduced Order Model Development Utilizing Bayesian Surrogate Models for Component Mode Calculations

2019 ◽  
Author(s):  
Joseph A. Beck ◽  
Jeffrey M. Brown ◽  
Alex A. Kaszynski ◽  
Emily B. Carper ◽  
Daniel L. Gillaugh
Keyword(s):  
Periodic Structures ◽  
Model Development ◽  
Element Model ◽  
Forced Response ◽  
Mode Shapes ◽  
Order Model ◽  
Mode Localization ◽  
Reduced Order ◽  
Structural Periodicity ◽  
Computationally Intensive

Abstract By design, Integrally Bladed Rotors (IBRs) are meant to be tuned, rotationally periodic structures. However, unique variations in geometries and material properties from sector-to-sector, referred to as mistuning, destroy the structural periodicity. This results in mode localization that can induce forced response levels greater than what is predicted with a tuned-structure analysis. Furthermore, mistuning and mode localization are random processes that require stochastic treatments when analyzing the distribution of fleet responses. Generating this distribution can be computationally intensive when using the full finite element model. To overcome this expense, Reduced Order Models (ROMs) have been developed to accommodate fast calculations of mistuned forced response levels for a fleet of random IBRs. Usually, ROMs can be classified by two main families: frequency-based and geometry-based methods. Frequency-based ROMs assume mode shapes do not change due to mistuning. However, this assumption has been shown to cause errors that propagate to the fleet distribution. To circumvent these errors, geometry-based ROMs have been developed to provide accurate predictions. However, these methods require recalculating modal data during ROM formulations. This increases the computational expense in computing fleet distributions. A new geometry-based ROM is presented to reduce this cost. The developed ROM utilizes a Bayesian surrogate model in place of sector modal calculations required in ROM formulations. This method, referred to as the Surrogate Modal Analysis for Geometry Mistuning Assessments (SMAGMA), will propagate the uncertainties of the surrogate prediction to the forced response. Assessments of the ROM accuracy are made by comparing results to the true forced response levels and results computed by a frequency-based ROM.

Integrated Controls-Structures Optimization of a Large Space Structure

1990 ◽  
Author(s):  
SHARON PADULA ◽  
JOANNE WALSH ◽  
CHRIS SANDRIDGE ◽  
RAPHAEL HAFTKA
Keyword(s):  
Space Structure ◽  
Large Space ◽  
Large Space Structure
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