Impact Induced Damage Detecting of Aircraft CFRP Covering by Acoustic Testing

NDT World ◽  
2015 ◽  
Vol 19 (4) ◽  
pp. 29-32 ◽  
Author(s):  
Самокрутов ◽  
Andrey Samokrutov ◽  
Шевалдыкин ◽  
Viktor Shevaldykin
Keyword(s):  
Composite Materials ◽  
Impact Damage ◽  
Point Contact ◽  
Complex Type ◽  
Active Thermography ◽  
Acoustic Methods ◽  
Periodic Monitoring ◽  
On Line ◽  
Contact Transducer ◽  
Acoustic Testing

Aircraft parts made of composite materials are susceptible to impact damage which can be negligible visually but significantly worsening their strength. Finding such damage requires periodic monitoring of large areas of the surface of the aircraft airframe. Fundamentally, such monitoring is possible by using active thermography or acoustic methods. Acceptable to practice, this task can be solved by scanning the surface with a rolling dry-point contact transducer array, and by analysis of Lamb wave signals propagating through the monitored material between the array adjacent transducers. This paper presents a device based on this principle, the signal analysis algorithm, and the images recomposed by the device during composite material testing. The developed equipment provides on-line inspection of impact-induced damage in aircraft covering made of composite materials. However, complex type of generated images requires constant monitoring of the covering state of each aircraft during its operation.

Investigation of the mechanical and forming behaviour of 3D warp interlock carbon woven fabrics for complex shape of composite material

2021 ◽  
pp. 152808372098410
Author(s):  
Mehmet Korkmaz ◽  
Ayşe Okur ◽  
Ahmad Rashed Labanieh ◽  
François Boussu
Keyword(s):  
Composite Materials ◽  
Complex Shape ◽  
Impact Damage ◽  
Woven Fabrics ◽  
Forming Process ◽  
Warp Yarn ◽  
Delamination Resistance ◽  
Fabric Architecture ◽  
Weave Pattern ◽  
Carbon Fabrics

Composite materials which are reinforced with 3D warp interlock fabrics have outstanding mechanical properties such as higher delamination resistance, ballistic damage resistance and impact damage tolerance by means of their improved structural properties. Textile reinforcements are exposed to large deformations in the production stage of composite materials which have complex shape. Although good formability properties of 3D warp interlock fabrics in forming process were already proven by recent studies, further information is needed to elucidate forming behaviours of multi-layer fabrics which is produced with high stiffness yarns like carbon. In this study, 3D warp interlock carbon fabrics were produced on a prototype weaving loom and the same carbon yarn was used in two fabric directions with equal number of yarn densities. Fabrics were differentiated with regard to the presence of stuffer warp yarn, weave pattern and parameters of binding warp yarn which are angle and depth. Therefore, the effect of fabric architecture on the mechanical and formability properties of 3D warp interlock carbon fabrics could be clarified. Three different breaking behaviours of fabrics were detected and they were correlated with crimp percentages of yarn groups. In addition, the bending and shear deformations were analysed in view of parameters of fabric architectures. Two distinct forming behaviours of fabrics were determined according to the distribution of deformation areas on fabrics. Moreover, the optimal structure was identified for forming process considering the fabric architecture.

scholarly journals Feedback cooling of cantilever motion using a quantum point contact transducer

2012 ◽  
Vol 101 (13) ◽  
pp. 133104 ◽  
Author(s):  
M. Montinaro ◽  
A. Mehlin ◽  
H. S. Solanki ◽  
P. Peddibhotla ◽  
S. Mack ◽  
...  
Keyword(s):  
Point Contact ◽  
Quantum Point Contact ◽  
Contact Transducer ◽  
Quantum Point

Enhancement Techniques for Ultrasonic Nondestructive Evaluation of Composite Materials

1990 ◽  
Vol 112 (2) ◽  
pp. 175-182 ◽  
Author(s):  
S. C. Wooh ◽  
I. M. Daniel
Keyword(s):  
Composite Materials ◽  
Impact Damage ◽  
Histogram Equalization ◽  
Matrix Cracking ◽  
Computer Data ◽  
Thermally Induced ◽  
Extraneous Noise ◽  
Suitable Combination ◽  
Contrast Stretching ◽  
Boundary Characteristics

Conventional ultrasonic C-scanning sometimes produces distorted and degraded images due to a variety of reasons, including surface roughness, beam dispersion, extraneous noise and imperfect fidelity of the total acquisition system. Enhancement techniques, using computer data acquisition and processing, can be used to enhance and restore the image. Enhancement techniques described include contrast stretching and median filtering, histogram equalization, thresholding, dynamic thresholding, thresholding depending on boundary characteristics, one-dimensional segmentation and intensity scans with hidden line removal. These enhancement techniques were applied and illustrated for five different types of damage in graphite/epoxy composite materials: (1) Embedded film patch in quasi-isotropic laminate; (2) impact damage in quasi-isotropic laminate; (3) matrix cracking due to static loading of crossply laminate; (4) fatigue damage in crossply laminate; and (5) thermally induced cracks in a thick crossply laminate. There is no single technique that is optimum in all cases. A suitable combination of techniques must be selected for optimum image quality.

scholarly journals Nondesructive Testing of Composite Materials of Aircraft Elements by Active Thermography

2018 ◽  
Vol 14 (2) ◽  
pp. 39-50
Author(s):  
E.Yu. Gordiyenko ◽  
◽  
M.I. Glushchuk ◽  
Yu.V. Fomenko ◽  
G.V. Shustakova ◽  
...  
Keyword(s):  
Composite Materials ◽  
Active Thermography

scholarly journals Damage detection in laminar thermoplastic composite materials by means of embedded optical fibers

2006 ◽  
Vol 60 (7-8) ◽  
pp. 176-179
Author(s):  
Aleksandar Kojovic ◽  
Irena Zivkovic ◽  
Ljiljana Brajovic ◽  
Dragan Mitrakovic ◽  
Radoslav Aleksic
Keyword(s):  
Composite Materials ◽  
Optical Fiber ◽  
Real Time ◽  
Optical Fibers ◽  
Impact Damage ◽  
Experimental Testing ◽  
Low Energy ◽  
Thermoplastic Composite ◽  
Woven Fabric ◽  
The Impact

This paper investigates the possibility of applying optical fibers as sensors for investigating low energy impact damage in laminar thermoplastic composite materials, in real time. Impact toughness testing by a Charpy impact pendulum with different loads was conducted in order to determine the method for comparative measurement of the resulting damage in the material. For that purpose intensity-based optical fibers were built in to specimens of composite materials with Kevlar 129 (the DuPont registered trade-mark for poly(p-phenylene terephthalamide)) woven fabric as reinforcement and thermoplastic PVB (poly(vinyl butyral)) as the matrix. In some specimens part of the layers of Kevlar was replaced with metal mesh (50% or 33% of the layers). Experimental testing was conducted in order to observe and analyze the response of the material under multiple low-energy impacts. Light from the light-emitting diode (LED) was launched to the embedded optical fiber and was propagated to the phototransistor-based photo detector. During each impact, the signal level, which is proportional to the light intensity in the optical fiber, drops and then slowly recovers. The obtained signals were analyzed to determine the appropriate method for real time damage monitoring. The major part of the damage occurs during impact. The damage reflects as a local, temporary release of strain in the optical fiber and an increase of the signal level. The obtained results show that intensity-based optical fibers could be used for measuring the damage in laminar thermoplastic composite materials. The acquired optical fiber signals depend on the type of material, but the same set of rules (relatively different, depending on the type of material) could be specified. Using real time measurement of the signal during impact and appropriate analysis enables quantitative evaluation of the impact damage in the material. Existing methods in most cases use just the intensity of the signal before and after the impact, as the measure of damage. This method could be used to monitor the damage in real time, giving warnings before fatal damage occurs.

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