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composite structures based on multiwavelet analysis of modal shapes . Indian Journal of Engineering and Materials Sciences 22: pp. 451-459. [15] Wronkowicz A., Dragan K., Lis K. (2018): Assessment of uncertainty in damage evaluation by ultrasonic testing of composite structures . Composite Structures 203, pp. 71-84. [16] Wronkowicz A. (2018): Non-destructive evaluation of composite aircraft elements based on ultrasonic testing and image analysis . Rozprawa doktorska. Politechnika Śląska, Gliwice. [17] Katunin A. (2015): Stone impact damage identification in composite

Experimental investigation on effective detection of delamination in gfrp composites using taguchi method

Detection of delamination defect in glass fiber reinforced plastics (GFRP) by using ultrasonic testing has been a challenging task in industry. The properties of the constituent materials, fiber orientation and the stacking sequence of laminated composite materials could cause high attenuation of ultrasound signals. Ultrasonic testing is based on the interpretation of the reflected ultrasound signals when a transducer imposes ultrasound waves (pulse) to a material. It is difficult to differentiate if the reflected signal is induced from the defects, fiber content or the intermediate layers of GFRP composites. Most of the time, the drastic attenuation of signals could enshroud the modest changes in the reflected signals from defects. The purpose of this paper is to investigate the influence of fiber orientation, thickness and delamination of GFRP composites on the rise time, pulse duration and attenuation ratio of the reflected ultrasound signal. The rise time, pulse duration and attenuation ratio of A-scan data was observed with respect to different positions of damage (delamination), thickness and stacking sequence of the lamina. It is essential to identify the significant factors that contribute to the abnormal characteristics of the reflected signals in which the defect is identified. Moreover, this paper presents the application of Taguchi method for maximizing the detection of defect in GFRP composites influenced by delamination. The optimum combination of the significant contributing factor for the signal’s abnormal characteristics and its effect on damage detection was obtained by using the analysis of signal-to-noise ratio. The finding of this study revealed that delamination is the most influential factor on the attenuation ratio.

Abstract

Following the damage tolerance philosophy in aircraft design and operation, one of the most significant stages of maintenance is non-destructive testing of structures. It is, therefore, essential to use testing methods sensitive to particular damage types occurring in aircraft structures during operation. In this paper, the authors present a study on selection and comparison of methods of information fusion applied to testing the results of inspection of composite structures used in aircraft elements, obtained using various ultrasonic methods. The presented approach of fusion of ultrasonic scans allows for enhancement of damage detection and identification due to the presence of different parts of information about detected damage obtained from different initial information sources in a single resulting set. Such an approach can be helpful at the decision-making stage during inspection of aircraft elements and structures. Besides the methodology, the GUI-based software for performing fusion of various types of ultrasonic data is presented.

Abstract

This paper is devoted to the application of ultrasonic wave propagation phenomena for the diagnostics of prestressed, concrete, bridge T-beams. A multi-point damage detection system is studied with use of numerically obtained data. The system is designed to detect the presence of the material discontinuities as well as their location.

Density and Ultrasonic Characterization of Oil Palm Trunk Infected by Ganoderma Boninense Disease

Oil palm trunks infected by Ganoderma boninense disease have been studied using density and ultrasonic characterizations. The ultrasonic characterizations have been performed using a commercial ultrasonic instrument at the frequency of 54 kHz. The measurements have been done in 3 zones: inner zone, central zone and peripheral zone. It was found that the stem density of the oil palm infected by Ganoderma boninense disease was reduced by 50% in comparison to the original healthy trunk. From this effect the velocity of the ultrasonic wave propagated through the Longitudinal, Radial, and Tangential directions is lower for the trunk infected by Ganoderma boninense disease compared to a healthy trunk. For the 10 cm thickness of samples, the ultrasonic velocity for all transit directions was in range of 260 - 750 ms-1 for the infected sample, whereas for healthy samples was in the range of 460 - 900 ms-1. These results are very useful for the detection of the area which has been affected by the disease.

Abstract

The application of small-sized metal fillers (SMF) provides a combination of high bulk density, increased durability and ferromagnetic properties of composite materials on the cement basis. However, the total strength of the composite can be compromised by poor adhesion of metal particles with the cement matrix. The use of versatile additives like microsilica and metakaolin is able to improve the structural integrity and mechanical properties of heavy concretes. The paper considers the results of a study using specimens of heavy concretes with SMF aiming to estimate its strength, structural features and ultrasonic parameters. It was found that the contact of SMF particles with the cement was not perfect, since the voids appeared between them and the cement matrix during the cement hydration process (exothermal reaction). Due to the border porosity, the specimens with the metal fillers have lower compressive strength, lower ultrasound velocity and increased frequency slope of attenuation. Microsilica and metakaolin additives facilitate better contact zone between the cement matrix and metal fillers.

Abstract

In this article we studies BVP’s that can not be solved as P.V.I or BVP with Matlab solvers ODExx or BVPxx since the solutions do not have limit in 0. We propose a numerical algorithm based on Cubic-spline written in Maple 16 [4].

BIBLIOGRAPHY [1] Wiśniowski W., 2014, „Specjalizacje Instytutu Lotnictwa – Przegląd i Wnioski’’ [”Specialisations of Institute of Avition – Review and Results”], Prace Instytutu Lotnictwa [Works of Institute of Avition], 2 (235), pp. 7-16. [2] http://www.kompozyty.milar.pl/strona-prepegs-2-13 . [3] http://www.hexcel.com/resources/datasheets/brochure-data-sheets/pre-impregnate_technology.pdf [4] Mackiewicz S., Góra G., 2005, Ultradźwiękowe badania konstrukcji kompozytowych w przemyśle lotniczym [Ultrasonic tests of composite structures in aviation], „ XI

time measurements”, Nondestructive Testing and Evaluation, vol. 23, No. 4, pp. 241-255, December 2008. [8] V.V., Dzenis, V.H. Lapsa, Ultrasonic testing of hardening concrete . Leningrad: Strojizda (Publishing House for the construction), 1972. [In Russian]. [9] M.F. Kaplan, “Compressive Strength and Ultrasonic Pulse Velocity Relationships for Concrete in Columns”, ACI Journal, vol. 29 (54-37), 675, 1958. [10] LVS EN 12504-4:2004 A. Testing concrete - Part 4: Determination of ultrasonic pulse velocity, LVS, 2004. [11] BS 1881: Part 203: 1986. Testing Concrete

Abstract

The article is focused on the possibilities of ultrasound surfaces control on metallic materials by conventional ultrasonic techniques. Physical principles, types of ultrasonic waves to be used for surface control are described in the theoretical part. Three surface control techniques are listed in the experimental part of article. The first technique is a common control by angle ultrasonic probe with using transverse waves. The second technique is surface control by 30-70-70 creep waves and third techniques is surface testing by Rayleigh waves. Practical examples of ultrasonic testing for all techniques are illustrated. The conclusion of the article is devoted to the advantages and limitations of the individual testing methods.