Non-Destructive Dielectric Assessment of Water Permeation in Composite Structures

1999 ◽  
Vol 591 ◽  
Author(s):  
P. Boinard ◽  
E. Boinard ◽  
R.A. Pethrick ◽  
W.M. Banks ◽  
R.L. Crane
Keyword(s):  
Time Domain ◽  
Dielectric Spectroscopy ◽  
High Frequency ◽  
Composite Structures ◽  
Frequency Domain Analysis ◽  
Adhesively Bonded ◽  
Water Permeation ◽  
Reinforced Plastic ◽  
Carbon Fibre Reinforced Plastic ◽  
Non Destructive

ABSTRACTOver the last ten years, the application of high frequency dielectric spectroscopy techniques for the assessment of composite structures has been investigated. Novel approaches to assess non-destructively the evolution during ageing of adhesively bonded carbon fibre reinforced plastic (CFRP) structures and bulk glass fibre reinforced plastic (GRP) structures are presented in this paper and the results are critically assessed.The applicability and limitations of dielectric measurements, in both frequency and time domain, to the monitoring of water ingress at 30°C and 60°C are examined. The correlation between gravimetric and high frequency dielectric spectroscopy data demonstrates the suitability of the techniques regarding the assessment of water uptake in composites structures and illustrates its potential as a non-destructive evaluation (NDE) technique. The dielectric time domain response (TDR) study of adhesively bonded structures indicates a new way to assess such structures. The approach for frequency domain analysis of bulk GRP using a coaxial probe technique indicates the potential portability of the technique for in-situ measurements.

Non-destructive examination of adhesively bonded structures using dielectric techniques: Review and some results

2000 ◽  
Vol 214 (1) ◽  
pp. 87-102 ◽  
Author(s):  
S Affrossman ◽  
W. M. Banks ◽  
D Hayward ◽  
R. A. Pethrick
Keyword(s):  
Carbon Fibre ◽  
Time Domain ◽  
High Frequency ◽  
Prolonged Exposure ◽  
Dielectric Measurements ◽  
Adhesively Bonded ◽  
Joint Structure ◽  
Time Domain Data ◽  
Non Destructive ◽  
Adhesively Bonded Structures

The use of high-frequency dielectric measurements is described for the non-destructive evaluation of adhesively bonded structures. Frequency domain measurements have been used to monitor the ingress of moisture into the joint structure. A good correlation has been observed between the data obtained from gravimetric and dielectric measurements. On prolonged exposure to water, changes occur to the surface oxide in the case of aluminium/aluminium joints to produce a surface hydroxide. The conversion process of oxide to hydroxide has a distinct dielectric signature. A correlation is observed between the changes in the failure mechanism and the variation in the dielectric profile. Time domain data have been used to investigate the integrity of the pristine bonded structure and the changes that occur on ageing. Examples of the application of the technique to both the aluminium and to carbon fibre/carbon fibre bonded structures are presented. The sensitivity of the technique to the occurrence of defects is critically discussed. A method for the study of bonds using a non-contacting method is outlined.

Systematic Process Chain Creation for CFRP Structures in Early Product Development Stages

2016 ◽  
Vol 1140 ◽  
pp. 328-334
Author(s):  
Matthias Behr ◽  
Carsten Schmidt
Keyword(s):  
Composite Structures ◽  
Production Costs ◽  
Preliminary Design ◽  
Process Chain ◽  
Whole Process ◽  
Reinforced Plastic ◽  
Building Process ◽  
Process Chains ◽  
Carbon Fibre Reinforced Plastic ◽  
Specific Sequences

A planning method is presented which allows to systematically building process chains based on a preliminary design of composite structures. The method utilises the specific sequences of procedural steps that occur in the production of carbon fibre reinforced plastic (CFRP) structures, to build sub process chains for each component of the structure. Process restrictions are considered to evaluate the suitability of different production processes. To obtain the whole process chain of the structure, different joining methods are applied in addition to combine the components and its sub process chains. The results of the presented method are used in an overarching development procedure to investigate resulting impacts on the solution. Possible impacts could be the production costs or the material characteristics.

Numerical Procedures for Damage Mechanisms Analysis in CFRP Composites

2013 ◽  
Vol 569-570 ◽  
pp. 111-118 ◽  
Author(s):  
Francesco Caputo ◽  
Di Felice Gennaro ◽  
Giuseppe Lamanna ◽  
Antonio Lefons ◽  
Aniello Riccio
Keyword(s):  
Safety Margin ◽  
Matrix Cracking ◽  
Interface Debonding ◽  
Low Velocity ◽  
Destructive Testing ◽  
Damage Mechanisms ◽  
Reinforced Plastic ◽  
Live Loads ◽  
Carbon Fibre Reinforced Plastic ◽  
Non Destructive

Damage after impact often involves aeronautic structures. The aircraft can be involved in impacts during the assembly stage and operative life. Typical impacts can be related to falling tools, hailstones, debris on the take-off strip thrown against the aircraft by the rolling tyres, maintenance operations. There are two categories of damage impact: Low and High Velocity Impact (LVI, HVI). Damages coming from low velocity impacts are difficult to identify because they are often within the composite structure and the use of non-destructive testing, e.g. ultrasonic test, is not convenient. In order to prevent catastrophic events the designers must increase the safety margin and thereby the weight of the aircraft. The present study shows two different numerical procedures based on finite elements method to investigate on some damage mechanisms of a carbon fibre reinforced plastic (CFRP) structures (e.g. interface debonding, fibre or matrix cracking) and the residual strength of such structures under live loads.

Advanced debonding detection technique for aerospace composite structures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Assunta Sorrentino ◽  
Fulvio Romano ◽  
Angelo De Fenza
Keyword(s):  
High Frequency ◽  
Composite Structures ◽  
Guided Waves ◽  
Plastic Material ◽  
Impact Damage ◽  
Small Scale ◽  
Content Type ◽  
Stiffened Panels ◽  
Reinforced Plastic ◽  
Debonding Detection

Purpose The purpose of this paper is to introduce a methodology aimed to detect debonding induced by low impacts energies in typical aeronautical structures. The methodology is based on high frequency sensors/actuators system simulation and the application of elliptical triangulation (ET) and probability ellipse (PE) methods as damage detector. Numerical and experimental results on small-scale stiffened panels made of carbon fiber-reinforced plastic material are discussed. Design/methodology/approach The damage detection methodology is based on high frequency sensors/actuators piezoceramics system enabling the ET and the PE methods. The approach is based on ultrasonic guided waves propagation measurement and simulation within the structure and perturbations induced by debonding or impact damage that affect the signal characteristics. Findings The work is focused on debonding detection via test and simulations and calculation of damage indexes (DIs). The ET and PE methodologies have demonstrated the link between the DIs and debonding enabling the identification of position and growth of the damage. Originality/value The debonding between two structural elements caused in manufacturing or in-service is very difficult to detect, especially when the components are in low accessibility areas. This criticality, together with the uncertainty of long-term adhesive performance and the inability to continuously assess the debonding condition, induces the aircrafts’ manufacturers to pursuit ultraconservative design approach, with in turn an increment in final weight of these parts. The aim of this research’s activity is to demonstrate the effectiveness of the proposed methodology and the robustness of the structural health monitoring system to detect debonding in a typical aeronautical structural joint.

scholarly journals High-frequency electromagnetic non-destructive evaluation for high spatial resolution, using metamaterials

2012 ◽  
Vol 468 (2146) ◽  
pp. 3080-3099 ◽  
Author(s):  
Raimond Grimberg ◽  
Gui-Yun Tian
Keyword(s):  
Spatial Resolution ◽  
High Frequency ◽  
Printed Circuit Boards ◽  
Carbon Fibres ◽  
Circuit Boards ◽  
Non Destructive Evaluation ◽  
Low Energies ◽  
Metallic Strip ◽  
Carbon Fibre Reinforced Plastic ◽  
Non Destructive

This study presents a new high-frequency electromagnetic method for a non-destructive evaluation of metallic strip gratings from printed circuit boards and of some carbon-fibre-reinforced plastic composites, allowing the detection of small defects. The electromagnetic transducer is based on a metamaterial lens realized with two conical Swiss rolls, that allows the transmission and intensification of purely evanescent modes generated in the slits of metallic strip gratings and in the dielectric that insulate the carbon fibres between them. The method and the transducer used allow the localization of metallic strip interruptions whose widths are greater than 0.2 mm, the non-alignment of carbon fibres, the breaking of carbon fibres, the lack of resin or delaminations due to impact at low energies, with spatial resolution being greater than 0.1 mm.

Sign in / Sign up

Export Citation Format

Share Document