Outline

  • Abstract
  • Keywords
  • 1. Introduction
  • 2. Theory
  • 2.1. Mode Shape Condensation
  • 2.2. Element Damage Equations
  • 2.3. Optimization Function
  • 3. Parameterized Stiffness Matrix
  • 4. Numerical Verification
  • 4.1. Noise Free Data
  • 4.1.1. Truss
  • 4.1.2. Frame
  • 4.2. Noisy Measurements
  • 5. Conclusion
  • References
  • Vitae

رئوس مطالب

  • چکیده
  • کلید واژه ها
  • 1. مقدمه
  • 2. نظریه
  • 2.1. تراکم شکل مود
  • 2.2. معادلات تخریب المان
  • 2.3. تابع بهینه سازی
  • 3. ماتریس سفتی پارامتری شده
  • 4. تایید عددی
  • 4.1. داده های بی اختلال
  • 4.1.1. خرپا
  • 4.1.2. قاب
  • 4.2. اندازه گیری های شلوغ و با اختلال
  • 5. نتیجه گیری

Abstract

This paper presents a global algorithm for damage assessment of structures, based on a parameter estimation method, using the finite element and measured modal response of the structure. Damage is considered as a localized reduction in structural stiffness. Unmeasured parts of the mode shapes of a structure are characterized as a function of the structural parameter and measured parts of the mode shape. Elemental damage equations, which relate the partially measured mode shapes of a damaged structure to a change in structural parameters, are developed using incomplete measured mode shapes. These equations are solved to find the changes in structural parameters, utilizing an optimization method. Noise polluted data are used through Monte Carlo simulation to investigate the sensitivity of the proposed method to errors present in the measured modal data. The algorithm is verified in a numerical simulation environment using a planer truss and frame. Results show the good ability of this method to detect any damage of structures in the presence of errors in the acquired data.


Conclusions

This paper presents an approach to damage detection in structures utilizing incomplete measured mode shapes and natural frequencies. The unmeasured part of the mode shapes of a structure is characterized as a function of structural stiffness parameters and measured modal displacements. More equations have been obtained, using element damage equations, which need complete mode shapes. This drawback is solved by presenting mode shape equations and dividing structural degrees of freedom into measured and unmeasured parts. An optimal criterion is used to solve these sets of equations to obtain changes in structural parameters. Results of bowstring truss and planer frames represent the ability of this method to evaluate the severity and location of damage, using exact and noise polluted data. Additionally, results demonstrate that this method is capable of detecting structural damage using less modal data and measurement effort.

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