Benchmark for identification of structural modifications and inelastic impacts
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SHM benchmark

G. Suwała & Ł. Jankowski

A benchmark for identification of structural modifications and inelastic impacts

Contents

Introduction

Originally, the benchmark has been described in:
G. Suwała, Ł. Jankowski, A benchmark for identification of structural modifications and inelastic impacts: the structure, test data and an example solution, Proc. of the 5th ECCOMAS Thematic Conference on Smart Structures and Materials (SMART'11), 6-8 July 2011, Saarbrcken, Germany [PDF downloads: paper, slides].

You are invited to download the files and test your identification algorithms. If you do so, please drop me an email, so that I can inform you of updates and corrections (if any). If you share the results of your identification, you will obtain the actual numbers, and if you prefer, your results will be evaluated with respect to other results and listed in this page. The evaluation criteria are described in the slides.

The structure

The benchmark uses a commercial construction system of nodes and tubes (MeroForm M12). The catalogue with detailed technical specifications of all elements can be downloaded here or here. The structure is 4 m x 0.5 m x 0.354 m and consists of
  • 26 steel nodes (element ID: 20055000), 
  • 1 aluminum element of 0.5 m (element ID: 20185000): dotted black element in Figure 1,
  • 8 steel elements of 0.707 m (element ID: 20091000): blue diagonal elements in Figure 1,
  • 61 steel elements of 0.5 m (element ID: 20088000): all other elements.

Figure 1. Scheme of the benchmark structure (click to enlarge)


Figure 2. The benchmark structure (click to enlarge)


Figure 3. The benchmark structure (click to enlarge)


Figure 4. A node of the benchmark structure (click to enlarge)


Figure 5. Orientation of axes

Experimental characteristics of the unmodified structure

The benchmark is purely experimental. That is, only experimental characteristics of the benchmark structure are provided. There is no "official" parametric numerical model. The experimental characteristics of the original unmodified structure consist of measured quasi impulse responses:
  • excitations with a modal hammer: nodes M1 to M6 (xyz-directions) and nodes E1 to E4 (z-direction),
  • measured responses: nodes M1 to M6 (xyz-directions) and nodes S1 to S3 (z-direction).
Each quasi impulse response has been repeated and measured three times. Compressed measurements can be downloaded here: unmodified.7z [136 MB]. After unpacking you will obtain a set of files:
  • File naming convention: "(impacted node)(impact direction)_(measurement node)(measurement direction)_Test_N.txt", where N=1,2,3 is the test number. 
  • Each file contains the data in four columns: time [s], force [N], displacement [m], acceleration [m/s2]. Acceleration is directly measured, while the displacement is computed internally by the measurement system.

Identification cases

The following identification cases are provided as yet:

Single nodal mass modification

An unknown additional mass has been attached (fixed) to a single node. Experimental characteristics of the modified structure are given by a set of quasi impulse responses:
  • excitations with a modal hammer: nodes E1 to E4 (z-direction),
  • measured responses: nodes S1 to S3 (z-direction).
Each quasi impulse response has been repeated and measured three times. Three subcases are available:
After unpacking you will obtain a set of files:
  • File naming convention: "(affected node)_(impacted node)(impact direction)_(measurement node)(measurement direction)_Test_N.txt", where N=1,2,3 is the test number. 
  • Each file contains the data in four columns: time [s], force [N], displacement [m], acceleration [m/s2]. Acceleration is directly measured, while the displacement is computed internally by the measurement system.

Modification of two nodal masses

Two unknown additional masses have been attached (fixed) to two selected node. Experimental characteristics of the modified structure are given by a set of quasi impulse responses:
  • excitations with a modal hammer: nodes E1 to E4 (z-direction),
  • measured responses: nodes S1 to S3 (z-direction).
Each quasi impulse response has been repeated and measured three times. Three subcases are available:
After unpacking you will obtain a set of files:
  • File naming convention: "(affected node1)-(affected node2)_(impacted node)(impact direction)_(measurement node)(measurement direction)_Test_N.txt", where N=1,2,3 is the test number. 
  • Each file contains the data in four columns: time [s], force [N], displacement [m], acceleration [m/s2]. Acceleration is directly measured, while the displacement is computed internally by the measurement system.

Inelastic impact

Inelastic impact is simulated by a quasi imulsive excitation (z-direction) of an additional mass attached (fixed) in a selected node. Experimental characteristics of the modified structure are given by a set of the responses to the simulated impact measured in nodes S1 to S3 (z-direction). To increase the accuracy of identification, each impact has been simulated three times. Three subcases are available:
After unpacking you will obtain a set of files:
  • File naming convention: "(impacted node)_(impacted node)(impact direction)_(measurement node)(measurement direction)_Test_N.txt", where N=1,2,3 is the test number. 
  • Each file contains the data in four columns: time [s], force [N], displacement [m], acceleration [m/s2]. Acceleration is directly measured, while the displacement is computed internally by the measurement system

IPPT PAN
Adaptronica
EACS 2020