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Stiffness behavior of hybrid laminated composites with surface crack

100%

Güneş A. , Şahin Ö. A.

tom Vol. 80, nr 2

49--52

Purpose: The purpose of this paper investigates to stiffness behavior of hybrid laminated composites with surface crack. Design/methodology/approach: Hybrid laminated composites has 18 layers and 90x25 mm size with two different layers line up. The low velocity impact test of hybrid laminated composites carried on 3 m/sec with a/t=0.4 and a/c=0.4 surface crack parameters. Findings: The results are presented as the change of force-time and force-displacement graphs. As a result of this study, effects of stacking sequence on hybrid composite plates were analysed. Research limitations/implications: The research of stiffness behavior or dynamic response of hybrid laminated composites can contribute to developing new composite materials. Practical implications: These hybrid laminated composites materials could be used for different aviation areas. Originality/value: This paper is based on studies from Selçuk University and all the experiments and results were conducted by me.

Detection of damages in hybrid composite plates with the use of elastic waves generated by PZT active sensors

100%

Barski M. , Pająk P.

tom Vol. 24, No. 2

17--24

The presented article is devoted to the problem of detection and localization of damages occurring in components of structures, which are made of hybrid composite materials. The subject of the work is a square plate consisting of a single layer made of aluminum alloy and several layers made of glass fibres (glass fabric) and epoxy resin. On the surface, which is made of composite, 12 piezoelectric elements are installed. These elements sequentially, one by one, generates a signal that is further recorded by the remaining piezoelectric elements. Picked up signal for the selected pair of activator – sensor is compared with the reference signal. The reference signal corresponds to the intact structure. This kind of approach is known as the pitch – catch configuration. In situations when the signal obtained for interrogated structure and reference one differs significantly, this may indicate that a damage exists between the activator and the sensor. Next, taking into account the information obtained from the other sensors, it is possible not only to detect but also to determine the approximate location of the flaw and to estimate its size. In order to visualize the obtained results, an especially dedicated software is developed according to the algorithms available in the literature – probability ellipse. Several computer simulations of wave propagation are performed using the finite element method. The proposed procedure is also tested experimentally. The presented approach makes it possible to detect both single and multiple damages.

Development Of Multistitched Three-Dimensional (3D) Nanocomposite And Evaluation Of Its Mechanical And Impact Properties

84%

Bilisik K. , Ozdemir H. , Kaya G.

Autex Research Journal

2017

tom Vol. 17, no. 3

238--249

Multistitched three-dimensional (3D) woven E-glass/polyester/nanosilica composite (MNS) was developed. Its mechanical and impact performances were characterized for particular end-use applications. It was found that the warp-weft directional tensile strength and modulus of MNS structure were higher than those of the off-axis directions. In addition, there was not a big difference between warp and weft directional bending and short beam strengths of MNS structure. The MNS structure had a small damaged area under low velocity impact load. The failure was confined at a narrow area because of multistitching and nanomaterial and resulted in the catastrophic fiber breakages in the normal direction of the applied load of the structure. The results from the study indicated that the multistitching and the addition of nanosilica in the composite structure improved its damage tolerance.

Experimental Investigation on the Impact Behaviour of Composite Laminate

67%

Azzam A. , Li W.

tom Vol. 23, no. 1 (109)

77--84

The impact response of a composite laminate structure was investigated by subjecting several stacking sequences of a composite laminate structure to low velocity impact loading using a Drop-Weight Machine (CEAST 9350 drop tower) and three-point bending using an electronic universal tester (Type: WDW-20) machine. The air-coupled ultrasonic C-scan technique (NAUT21) was selected in order to characterise the impact damage size, delamination, flaw detection, and damage in composite laminate structures. The failure processes of damaged specimens for impact energy (5 J) were evaluated by comparing load-displacement curves and images of damaged samples taken from impacted sides through a C-scan.

Badano odpowiedź na udar struktury laminatów kompozytowych. Zastosowano kilka sekwencji udarów charakteryzujących się małą prędkością. Stosowano specjalną maszynę umożliwiającą opadanie obciążenia (wieża udarowa). Zginanie następowało w systemie trzech punktów podparcia. Zastosowano sprzężoną technikę ultradzwiękowego skanowania dla scharakteryzowania wielkości uszkodzeń w wyniku udaru, delaminację warstw i zmiany strukturalne. Dla scharakteryzowania uszkodzeń materiału badawczego powstałych przy energii udaru 5J wykorzystano porównanie wykresów obciążenie-przesunięcie i zdjęć uszkodzonych próbek.