Physical Parameter Identification of Laminates Based on Thermal Deformation Measurements

1995 ◽  
Author(s):  
Werner Konrad ◽  
Bernd Caesar
Keyword(s):  
Parameter Identification ◽  
Physical Parameter ◽  
High Precision ◽  
Model Updating ◽  
Nodal Point ◽  
Design Parameters ◽  
Physical Parameters ◽  
Spherical Mirror ◽  
Load Case ◽  
Space Applications

Abstract High precision structures, as telescope mirrors for space applications, require high thermal stability and structural stiffness combined with low weight. Laminate structures with their special properties can satisfy these stringent requirements. Model updating and physical parameter identification on the basis of measurements can be applied to optimize such structures or define correction measures w.r.t. manufacturing inaccuracies. In classic update procedures correction factors are used to improve physical parameters. The definition of correction differences which are suitable for parameters with zero starting values or values changing from positive to negative as it may be the case for the layer orientations of a laminate is presented. High precision structures require high accurate measuring methods for the test. Thermal deformations can be measured by holographic, interferometric methods with high precision in the μm range. An interferometric contour map can be compared with the nodal point displacements of a Finite Element model by special spline functions called Zernike’s polynomials. The equations to determine the various design parameters or material properties may not be linear independent, depending on the applied thermal load case. The degree of correlation between the various parameters is investigated. The results are used to optimize the load case selection and to improve error localization methods. The proposed method is applied to a segment of a high stability spherical mirror plate with real measuring data.

Development of Physical-Parameter Identification Procedure for Energy-Dissipated Buildings with Symmetric Ductile Braces

2013 ◽  
Vol 479-480 ◽  
pp. 1149-1154
Author(s):  
Ming Chih Huang ◽  
Yen Po Wang ◽  
Tzu Kang Lin ◽  
Jer Fu Wang
Keyword(s):  
System Identification ◽  
Parameter Identification ◽  
Physical Parameter ◽  
Primary Structure ◽  
Substantial Reduction ◽  
Physical Parameters ◽  
Hysteretic Model ◽  
Identification Procedure ◽  
Restoring Force ◽  
Energy Dissipated

In this paper, a pseudo-single-degree-of-freedom system identification procedure is developed to investigate the dynamic characteristics of energy-dissipated buildings equipped with symmetric ductile braces (SDBs). The primary structure is assumed to be linear on account of substantial reduction of seismic forces due to the installation of SDBs for which a bilinear hysteretic model is considered. The hysteretic model is in turn characterized by a backbone curve by which the multi-valued restoring force is transformed into a single-valued function. With the introduction of backbone curves, the system identification analysis of inelastic structures is significantly simplified. The proposed algorithm extracts individually the physical parameters of each primary structure and each energy-dissipation device that are considered useful information in the structural health monitoring. A numerical example is conducted to demonstrate the feasibility of using the proposed technique for physical parameter identification of partially inelastic energy-dissipated buildings.

Structural Physical Parameter Identification of Nonlinear Parametric System in Time Domain

2011 ◽  
Vol 94-96 ◽  
pp. 1040-1043
Author(s):  
Xiang Jian Wang ◽  
Jie Cui
Keyword(s):  
Singular Value Decomposition ◽  
Parameter Identification ◽  
Physical Parameter ◽  
High Precision ◽  
Time Domain ◽  
Singular Value ◽  
Parametric System ◽  
Levenberg Marquardt ◽  
Shear Type ◽  
Value Decomposition

The modified Levenberg-Marquardt (mLM) method is introduced for nonlinear parametric system, such as stiffness proportional damping and Rayleigh proportional damping. Since the mLM method is sensitive to the initial values of parameter, a SVD-mLM method is proposed with combination of singular value decomposition (SVD). Parameter identification of five-storey shear-type is simulated with incomplete output. The results show that the identified parameters have high precision, and the proposed method is effective and robust on noise.

Structural Physical Parameter Identification Based on Empirical Genetic-Simplex Algorithm and Structural Dynamic Response

2011 ◽  
Vol 94-96 ◽  
pp. 1998-2004
Author(s):  
Li Ping Jiang ◽  
Wei Liu ◽  
Lei Shi ◽  
Yan Liu
Keyword(s):  
Genetic Algorithm ◽  
Dynamic Response ◽  
Parameter Identification ◽  
Physical Parameter ◽  
Degrees Of Freedom ◽  
Simplex Algorithm ◽  
Physical Parameters ◽  
Running Speed ◽  
Structural Dynamic ◽  
Calculation Step

In the complex conversion analysis of multi-degrees of freedom，large calculation count needed in each calculation step of Genetic Algorithm limits the running speed of genetic algorithm. So the positive calculation count to be reduced is an effective method to enlarge the range of GA’s application. Empirical Genetic-Simplex Algorithm (EGSA) proposed in this paper is one of the effective methods to solve the problem. This method is applied to structural physical parameters identification based on the structural dynamic response. The result shows that EGSA has many advantages on precision, efficiency in searching, strong to resist the noise, and good adaptation to the incomplete information.

Structural Parameter Identification Based on Equivalent Single Degree Systems

2010 ◽  
Vol 450 ◽  
pp. 510-513
Author(s):  
Yan Wei Wang ◽  
Zi Fa Wang ◽  
Rui Zhi Wen
Keyword(s):  
Numerical Simulation ◽  
Differential Evolution ◽  
Parameter Identification ◽  
Physical Parameter ◽  
Optimization Algorithm ◽  
New Method ◽  
Structural Parameter ◽  
Physical Parameters ◽  
Single Degree

In order to solve the problems of optimization algorithm used to identify the physical parameters of structures, a new method based on a series of equivalent single degree systems is proposed in this paper. The key idea of the method is that a multi-degree system can be represented by a series of single degree systems that can be identified one by one to perform the identification of the whole system. This method can not only decrease the dimensions of optimization algorithm, but also reduce the amount of estimation work in searching for the bound of parameters, and at the same time improve the identification results when parameters might suddenly change. In the numerical simulation of the physical parameter identification of a multi-degree system, Differential evolution is one of the optimization algorithm methods which are used to identify a series of equivalent single degree systems instead of the multi-degree system they represent, and the identification results prove that the method proposed in this paper is valid.

Benefits of Model Updating: A Case Study Using the Micro-Precision Interferometer Testbed

1997 ◽  
Author(s):  
Sanjay S. Joshi ◽  
James W. Melody ◽  
Gregory W. Neat ◽  
Andrew Kissil
Keyword(s):  
Physical Parameter ◽  
Transfer Functions ◽  
Model Updating ◽  
Integrated Model ◽  
Scale Model ◽  
Physical Parameters ◽  
Optical Elements ◽  
Optomechanical System ◽  
Modal Test

Abstract This paper presents a case study on the benefits of model updating using the Micro-Precision Interferometer (MPI) testbed, a full-scale model of a future spaceborne optical interferometer located at JPL. The MPI testbed is composed of several active and passive optical elements distributed across a 7 m × 7 m × 6.5 m truss structure. Successful operation of this complex optomechanical system requires positional stabilities of these optical elements down to the ten-nanometer level. Design of such systems for space requires a disturbance modeling capability that integrates optical modeling, structural modeling and control system design. An integrated model of MPI was built in parallel with the testbed, enabling a unique model updating and validation opportunity. Physical parameters of the structural finite element model were updated based on two separate modal tests: a comprehensive modal test of the base structure alone and an in situ component modal test. This paper quantifies the effect of these physical parameter updates on MPI integrated model prediction capability. Specifically, the paper compares three sets of disturbance-input to optical-output transfer functions: (1) measured data from the testbed, (2) predictions from a high-fidelity model without any parameter updates, and (3) similar predictions for the model with updated physical parameters. Results from this study indicate that physical parameter updating has provided little benefit for disturbance modeling on the MPI testbed. These results will have significant impact on the modeling strategy adopted for the Spaceborne Interferometer Mission (SIM).

scholarly journals A New Physical Parameter Identification Method for Two-Axis On-Road Vehicles: Simulation and Experiment

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Minyi Zheng ◽  
Peng Peng ◽  
Bangji Zhang ◽  
Nong Zhang ◽  
Lifu Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Parameter Identification ◽  
Physical Parameter ◽  
Mass Matrix ◽  
Estimation Method ◽  
Least Square Method ◽  
Least Square ◽  
Percentage Error ◽  
Physical Parameters ◽  
Identification Method

A new physical parameter identification method for two-axis on-road vehicle is presented. The modal parameters of vehicle are identified by using the State Variable Method. To make it possible to determine the matricesM,C, andKof the vehicle, a known mass matrixΔMis designed to add into the vehicle in order to increase the number of equations ensuring that the number of equations is more than the one of unknowns. Therefore, the physical parameters of vehicle can be estimated by using the least square method. To validate the presented method, a numerical simulation example and an experiment example are given in this paper. The numerical simulation example shows that the largest of absolute value of percentage error is 1.493%. In the experiment example, a school bus is employed in study for the parameter identification. The simulation result from full-car model with the estimated physical parameters is compared with the test result. The agreement between the simulation and the test proves the effectiveness of the proposed estimation method.

LED MODULE WITH ELECTRONIC ILLUMINATION CONTROL

2019 ◽  
Vol 1 (12) ◽  
pp. 146-154
Author(s):  
V. Lisovenko ◽  
D. Lisovenko ◽  
O. Bazyk
Keyword(s):  
High Precision ◽  
Single Point ◽  
Dynamic Control ◽  
Directional Pattern ◽  
Current Strength ◽  
Design Parameters ◽  
Light Sources ◽  
Computer Design ◽  
Light Power ◽  
Electron Dynamic

Many energy saving tasks can be solved thanks to the current advances in LED technology in the production of semiconductor light sources. Modern production of solid-state LEDs guarantees high-precision compliance with the calculated design parameters of illumination devices. This opens up wide opportunities for high-precision control of the lighting parameters of a multicomponent module: light power, a directional pattern and a distribution of illumination. Today, the methodical issues of the preliminary modeling of LED illumination devices with the given parameters are fundamentally solved. There is a shift from manual calculations to computer design and need to develop and select the most effective mathematical modeling methods. The paper presents a consistent approach to the modeling of the distribution of illumination on a horizontal plane from the planar LED module, based on the Lambert type of radiation of a single point source. Simple mathematical expressions, programmed on a personal computer, are obtained. The example of a 25-LED floodlight has shown the ability of dynamic control the lighting characteristics of the module. Connecting patterns of separate LEDs or their groups allow to change the direction pattern of the lamp by the appropriate way of switching diodes with different aperture of radiation. The lighting power can be controlled within the linearity of the ampere-brightness characteristics by changing the current strength through the LED. The static selection of characteristics is controlled by the geometry of the location of discrete sources. The formation of uniform illumination of the plane is graphically illustrated. The electron-dynamic way of controlling the lighting parameters of the LED floodlight is confirmed by the inventor’s certificate.

scholarly journals Physical Parameter Identification Algorithm Modeling for Complex Microsystem via Triangulation Functions

2018 ◽  
Vol 7 (4.36) ◽  
pp. 962
Author(s):  
Elena N. Meshcheryakova ◽  
. .
Keyword(s):  
Parameter Identification ◽  
Physical Parameter ◽  
Delaunay Triangulation ◽  
Model Development ◽  
Physical Object ◽  
Identification Algorithm ◽  
Classification Analysis ◽  
Advantages And Disadvantages ◽  
Object Parameters ◽  
D Model

This article describes the possibility of triangulation function use for the classification, analysis and identification of complex microsystem physical object parameters. They analyzed the existing methods and identification algorithms, their advantages and disadvantages are highlighted. The existing methods of triangulation are considered, the possibility of Delaunay triangulation is described for surfactant signal 3-D model development and analysis. They developed the algorithm to identify the state of an object using the triangulation function that takes into account the change of node coordinates and the length of the triangulation grid edges. They presented the visual UML model. The conclusions are drawn about the possibility of triangulation function use for the analysis of complex microsystem state.  

A Dynamic Model for the Design of Methanol to Hydrogen Steam Reformers for Transportation Applications

2004 ◽  
Vol 126 (2) ◽  
pp. 149-158 ◽  
Author(s):  
Gregory L. Ohl ◽  
Jeffrey L. Stein ◽  
Gene E. Smith
Keyword(s):  
Response Time ◽  
Dynamic Model ◽  
First Principles ◽  
Initial Conditions ◽  
Design Parameters ◽  
Physical Parameters ◽  
Steam Reformer ◽  
Powerful Means ◽  
Steam Reformers ◽  
Transportation Applications

As an aid to improving the dynamic response of the steam reformer, a dynamic model is developed to provide preliminary characterizations of the major constraints that limit the ability of a reformer to respond to the varying output requirements occurring in vehicular applications. This model is a first principles model that identifies important physical parameters in the steam reformer. The model is then incorporated into a design optimization process, where minimum steam reformer response time is specified as the objective function. This tool is shown to have the potential to be a powerful means of determining the values of the steam reformer design parameters that yield the fastest response time to a step input in hydrogen demand for a given set of initial conditions. A more extensive application of this methodology, yielding steam reformer design recommendations, is contained in a related publication.

A Method for Identifying Parameters of Mechanical Joints

1990 ◽  
Vol 57 (2) ◽  
pp. 337-342 ◽  
Author(s):  
J. Wang ◽  
P. Sas
Keyword(s):  
Physical Parameter ◽  
Mechanical Systems ◽  
Degree Of Freedom ◽  
Modal Testing ◽  
Physical Parameters ◽  
Mechanical Joints ◽  
Joint Parameters

A method for identifying the physical parameters of joints in mechanical systems is presented. In the method, a multi-d.o.f. (degree-of-freedom) system is transformed into several single d.o.f. systems using selected eigenvectors. With the result from modal testing, each single d.o.f. system is used to solve for a pair of unknown physical parameters. For complicated cases where the exact eigenvector cannot be obtained, it will be proven that a particular physical parameter has a stationary value in the neighborhood of an eigenvector. Therefore, a good approximation for a joint physical parameter can be obtained by using an approximate eigenvector and the exact value for the joint parameters can be reached by carrying out this process in an iterative way.

Sign in / Sign up

Export Citation Format

Share Document