Removing the Ambiguity in Lamb Wave-Based Damage Localization

Proceedings of the Institution of Mechanical Engineers, Part C:

Kudela

et al. 2010

The aim of this article was a numerical and experimental study of the active damage detection methods based on piezoelectric elements attached to a composite laminate. In considered case, guided waves were excited and received in a structure using pulse-echo method. It means that after exciting a structure with a pulse, an array of sensors located on a structure was used to 'listen' for reflected waves coming from discontinuities. The main part of structural health monitoring system is signal-processing algorithms, which allow to detect and localize damage. Algorithm applied in this research results in special maps that indicate damage location. In this article, a damage localization algorithm was described and experimentally tested. The proposed method was successfully tested on a carbon-epoxy part of a helicopter.

Section: Introductionmentioning

confidence: 99%

Guided wave-based detection of delamination and matrix cracking in composite laminates

Wandowski

Proceedings of the Institution of Mechanical Engineers, Part C:

Kudela

et al. 2010

“…Up to now many research works focus on damage identification for structures made out of CFRP, but delaminations or cracks are the mainly considered damage cases [3,4]. In numerous examples guided elastic waves-based methods have been proven to be effective in damage detection, localization and quantification.…”

Section: Introductionmentioning

confidence: 99%

Characterization of CFRP Using Laser Vibrometry

Wandowski

Ostachowicz

2013

KEM

Self Cite

The investigation was focused on Carbon Fibre Reinforced Polymers (CFRP). In the first part of research the aim was the characterization of CFRP surfaces. These surfaces were influenced by release agent, hydraulic fluid, moisture and overheating. In the second part of research adhesive bond quality was investigated. Three different cases of possible weak bonds were focused on. Weak bond caused by release agent contamination, moisture contamination and poor curing of adhesive. The characterization was conducted using laser vibrometry used as NDT tools. An active element in the form of piezoelectric transducer was used to excite the samples made out of CFRP material. Laser vibroemter was used to register the surface response. Combining the piezoelectric excitation with laser sensing a tool was obtained to measure precisely the propagating elastic waves. The excited waves were measured in defined points by the vibrometer obtaining the wavefield. In order to characterize the surface and bonding quality an indicator was proposed based on propagating wave parameters. The guided elastic wave velocity depends material properties (Young modulus, density, Poisson ratio) and thickness of the sample. It was assumed that comparison of the velocities can provide an information about the bond condition. All the investigated scenarios showed deviation from the reference case.

“…In the case of EMI technique the research results show promising potential for damage detection and localization [1]. Also, the Lamb wave-based technique showed promising results for these tasks [2,3]. Mentioned techniques can be used for monitoring of many types of structures or structural elements such as beams, plates, pipes ,wind turbine blades and aircraft fuselage.…”

Section: Introductionmentioning

confidence: 99%

Application of Piezo Sensors in EMI and Guided Wave Techniques

Skarbek

Ostachowicz

2013

KEM

Self Cite

In reported research piezoelectric sensors were used for damage identicitaion purposes. Piezoelectric sensor was used for specimen excitation. Two techniques were investigated. The Electromechanical impedance (EMI) technique and guided wave based technique. The principle of EMI technique is based on measurement and analysis of impedance of piezoelectric transducers bonded on or embedded in investigated structure. It is assumed that structural change should influence the impedance characteristics of the transducers. The guided wave based technique is based on the guided elastic wave propagation phenomena. This type of waves can be used in order to obtain information about structure condition and possibly damaged areas. In reported investigation piezoelectric sensor was used to excite guided waves in chosen structural element. Dispersive nature of guided waves results in changes of velocity with the wave frequency, therefore a narrowband signal was used to minimize the dispersion phenomenon. The generated signal was amplified before applying it to the transducer in order to ensure measurable amplitude of excited guided wave. Measurement of the wave field was realized using laser scanning vibrometer that registered the velocity responses at a points belonging to a defined mesh. This non-contact tool allowed to investigate phenomena related to wave propagation. For both techniques numerical signals processing tools were developed. These numerical tools were designed to extract damage relevant features from EMI measurements and guided wave propagation measurements. The damage index (DI) was introduced on the basis of the extracted features.