Dynamic Behaviour Characterization of a Brake Disc by Means of Electronic Speckle Pattern Interferometry Measurements

2005 ◽  
Author(s):  
Alessandro Zanarini
Keyword(s):  
Speckle Pattern ◽  
Low Frequency ◽  
Harmonic Excitation ◽  
Electronic Speckle Pattern Interferometry ◽  
Brake Disc ◽  
Full Field ◽  
Resonance Frequencies ◽  
Displacement Maps ◽  
Bending Modes

A complete experimental approach is here carried out to obtain the dynamic characterization of an automotive brake disc fixed on its grounded knuckle. The operative deflection shapes (ODS) were measured under harmonic excitation in the 1–23 kHz frequency range. Electronic Speckle Pattern Interferometry (ESPI) [1, 2] technology was exploited to measure high spatially defined full field displacement maps at each frequency by means of optical non-contact techniques. The harmonic excitation source was an electrodynamic shaker. The displacement maps acquired depict the dynamic behavior of the brake disc with high accuracy in the whole range, from the global bending modes at low frequency to the arising of small lobes at high frequency, with particular attention paid to the transition over resonance frequencies. Results are reported and discussed in detail.

Damage Location Assessment in a Composite Panel by Means of Electronic Speckle Pattern Interferometry Measurements

2005 ◽  
Author(s):  
Alessandro Zanarini
Keyword(s):  
Structural Damage ◽  
Speckle Pattern ◽  
Harmonic Excitation ◽  
Speckle Interferometry ◽  
Composite Panel ◽  
Electronic Speckle Pattern Interferometry ◽  
Full Field ◽  
Damage Location ◽  
Displacement Maps ◽  
Non Destructive

The assessment of structural damage location in composite honeycomb sandwich panels is here pursued by means of a complete experimental non-destructive approach on a pre-damaged sample. In the experiments proposed full field displacement maps were acquired by means of optical non-contact Electronic Speckle Pattern Interferometry (ESPI) technology [1, 2], in order to obtain high spatial definition and locate small defects on the sample, like debondings, material separations, voids, cracks and delaminations. When dealing with holographic/speckle interferometry it is important to find the stressing technique able to produce singularities in the state of the object surface. Four different loading approaches were taken to detect the flaws: acoustic, thermal, static and harmonic excitation. The displacement maps acquired depict with high accuracy the inhomogeneous local behavior of the structure induced by the defects. Results are reported from the different loading approaches and discussed in detail.

Electronic Speckle Pattern Interferometry Applied to the Displacement Measurement of Sandwich Plates with Single ‘Fully Potted’ Insert

2004 ◽  
Vol 20 (4) ◽  
pp. 273-276 ◽  
Author(s):  
S. J. Huang ◽  
H. L. Lin
Keyword(s):  
Speckle Pattern ◽  
Fem Analysis ◽  
Electronic Speckle Pattern Interferometry ◽  
Sandwich Plates ◽  
Destructive Testing ◽  
Displacement Fields ◽  
Full Field ◽  
Out Of Plane ◽  
Plane Displacement ◽  
Non Destructive

AbstractThe construction and operation of electronic speckle pattern interferometer (ESPI) applied to single-inserted sandwich plates have been earliest presented in this paper. Proposed ESPI has advantages of full-field and non-destructive testing, which can measures microscopic out-of-plane displacement in the elastic region without wasting specimen. For validation purpose, the finite element method (FEM) analysis was conducted. By comparing the results of ESPI and FEM displacement fields around the inserts that a convincing agreement is revealed. The effect of potting material diameter on the displacement of single-inserted sandwich plates was obtained by the ESPI and FEM.

A study of brake disc modal behaviour during squeal generation using high-speed electronic speckle pattern interferometry and near-field sound pressure measurements

2000 ◽  
Vol 214 (3) ◽  
pp. 285-296 ◽  
Author(s):  
M Reeves ◽  
N Taylor ◽  
C Edwards ◽  
D Williams ◽  
C. H. Buckberry
Keyword(s):  
High Speed ◽  
Sound Pressure ◽  
Surface Deformation ◽  
Speckle Pattern ◽  
Near Field ◽  
Electronic Speckle Pattern Interferometry ◽  
Brake Disc ◽  
Pressure Measurements ◽  
Near Field Sound ◽  
Field Sound

The out-of-plane surface vibration of a brake disc during naturally excited squeal has been investigated using a combination of high-speed electronic speckle pattern interferometry (ESPI) and near-field sound pressure measurements. Both techniques provide visualization and quantification of the time-resolved surface velocity. A mathematical description of disc brake squeal modal behaviour is proposed that predicts accurately all of the experimentally observed interferometry and sound field measurements. The complex mode description proposed here is in agreement with that proposed by others for drum brake squeal. This assumes that two identical diametral modes are excited simultaneously, identical except for a spatial and temporal phase shift. The use of a near-field microphone array provided a convenient multipoint, non-contacting vibration probe which may find use in the study of other vibrations characterized by high surface amplitudes and efficient sound radiation. The high-speed ESPI provided a real-time visualization of surface deformation analogous to double- pulsed holographic interferometry, with the benefit of giving a true time series of the surface deformation during a single vibration cycle.

Study on Fracture Properties of Mortar Based on Electronic Speckle Pattern Interferometry

2017 ◽  
Vol 893 ◽  
pp. 405-409
Author(s):  
Hong Niao Chen ◽  
Ray Kai Leung Su ◽  
Jia Jian Chen
Keyword(s):  
Process Zone ◽  
Speckle Pattern ◽  
Electronic Speckle Pattern Interferometry ◽  
Displacement Curve ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Full Field ◽  
Fracture Properties ◽  
Point Bend ◽  
Crack Tip Opening

With high resolution, electronic speckle pattern interferometry (ESPI) technique can be useful in measuring full-filed deformation of laboratory specimens. In this study, ESPI was applied to measure the full-field displacements of mortar beam subjected to three-point bend. Load-displacement curves measured by ESPI were compared to that measured by clip gauge and LVDTs. Satisfactory agreement was observed in all the comparisons, demonstrating the effectiveness and accuracy of ESPI measurement. Furthermore, load versus crack tip opening displacement curve was obtained from ESPI results. Finally, extent of the fracture process zone and neutral axis of the mortar beam were analyzed based on full-filed displacement contour measured by ESPI.

Full-Field Laser Vibrometer for Instantaneous Vibration Measurement and Non-Destructive Inspection

2010 ◽  
Vol 437 ◽  
pp. 407-411 ◽  
Author(s):  
James M. Kilpatrick ◽  
Vladimir B. Markov
Keyword(s):  
High Speed ◽  
Fiber Optic ◽  
Speckle Pattern ◽  
Vibration Measurement ◽  
Electronic Speckle Pattern Interferometry ◽  
Laser Vibrometer ◽  
Full Field ◽  
The Matrix ◽  
Interferometric Sensor ◽  
Non Destructive

We describe a system for real-time, full-field vibrometry, incorporating features of high-speed electronic speckle pattern interferometry (ESPI) and laser Doppler velocimetry (LDV). Based on a 2D interferometric sensor array, comprising 16×16 parallel illumination and detection channels, the matrix laser vibrometer (MLV), captures full-field data instantaneously, without beam scanning. The instrument design draws on the advantages of scale offered by modern telecommunications fiber optic and digital electronics. The resulting architecture, comprising a compact measurement probe linked by fiber optic umbilical to a remote electronics unit, facilitates practical application to the full-field study of transient vibrations and rapid non-destructive inspection of composite materials.

scholarly journals Re-Anchorage of a Ruptured Tendon in Bonded Post-Tensioned Concrete Beams: Model Validation

2013 ◽  
Vol 569-570 ◽  
pp. 302-309 ◽  
Author(s):  
Amged O. Abdelatif ◽  
John S. Owen ◽  
Mohammed F.M. Hussein
Keyword(s):  
Speckle Pattern ◽  
Concrete Strength ◽  
Concrete Surface ◽  
Concrete Bridges ◽  
Electronic Speckle Pattern Interferometry ◽  
Full Field ◽  
Experimental Programme ◽  
Structural Capacity ◽  
Wide Range ◽  
Post Tensioned

Many post-tensioned concrete bridges have been reported to have ruptured tendons due to corrosion [1] and the assessment of their residual structural capacity has to account for the possibility of re-anchorage of failed tendons. This paper presents an experimental programme to validate a numerical model developed by the authors for the re-anchorage of a ruptured tendon in post-tensioned concrete [2]. The experimental programme considered 33 post-tensioned concrete prisms, in which the rupture of tendon was simulated by releasing the tendon at one end. The full field displacement at concrete surface after release was measured using 3D Electronic Speckle Pattern Interferometry (ESPI). A wide range of parameters: tendon diameter, duct material, grout strength, concrete strength and shear reinforcement were investigated to validate the proposed model, which is found to be suitable for use in assessing post-tensioned concrete bridges with damaged tendons.

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