SkyScan User Meeting 2011

Transcription

1 SkyScan User Meeting 2011 A paper can be submitted for an oral presentation or a poster presentation. You will receive the approval and selection of the presentation type by March 4, All the approved papers will be put in the meeting book. As a support for the SkyScan users who are willing to submit a paper SkyScan will be pleased to offer the presenting authors their hotel accommodation (3 nights). Also poster presenters will be supported, we offer them 1 night at the chosen hotel filled in on your hotel reservation form. We want to thank you already for the effort and hope to welcome you all in Leuven! Please send your papers before February 4, 2011 to usermeeting@skyscan.be Paper Title: Composite Impact Damage Investigation with Micro-CT Presenting Author: Sinan Fidan Organization: Address: KOCAELI UNIVERSITY SCHOOL OF CIVIL AVIATION Kocaeli Üniversitesi Sivil Havacılık Yüksekokulu Arslanbey Yerleşkesi Kocaeli / TURKEY sinan_fidan@hotmail.com Choice of presentation: (highlight the type you prefer) Oral Presentation - Poster Presentation

2 Composite Impact Damage Investigation with Micro-CT Sinan Fidan 1, Egemen Avcu 2, Tamer Sınmazçelik 2,3 1 Kocaeli University, School of Civil Aviation, Arslanbey Campus, 41285, Izmit/ Turkey, sinan_fidan@hotmail.com ; sfidan@kocaeli.edu.tr 2 Kocaeli University, Mechanical Eng. Dept. Umuttepe Campus, 41380, Izmit/TURKEY. 3 TUBITAK-MRC, Po.Box. 21, Materials Institute, 41470, Gebze/Turkey Aims The present study investigated experimentally damage process in polymer composites under the low velocity impact loading. After low velocity impact, internal damages (like delaminations) occurred inside the composite is hard to visualize with classical non-destructive inspection techniques. As an alternative method Micro-Ct was used to visualize the internal damage zones with Skyscan 1173 Micro-CT. Inspection of internal damage mechanisms in composites after low velocity impact loading with using Micro-CT has not been reported in literature. Method Performances of composite materials have shown their superiority over metals in many applications, such as in aircraft and automobile industries, requiring high mechanical properties as well as low weight. The laminated fiber-reinforced composite plates are known to be susceptible to damage resulting from accidental impact of foreign objects. The behavior of composites under impact has been of significant concern in many advanced engineering structure and components [1-3]. Further developing the understanding of composite materials behavior under impulsive loading conditions is crucial for applications such as transportation of explosive material, collision, and use as armor. Common methods of dynamically loading composite materials are shock wave loading by use of explosives [4] and shock tubes [5-7], high velocity impact loading [8-10], and drop weight impact tests [11,12]. The tested material is a glass fibre reinforced polyester matrix composite produced by TeknoMa in one stacking sequence namely [0/90] s. The volume fraction is approximately 60% in fibres. (0/90) s oriented cross-ply E-glass/polyester laminated composites of 5 mm nominal thickness are used for low velocity drop weight impact testing. The cross-ply laminated specimens are prepared by cutting out 100 mm x 100 mm. In this study it is aimed to investigate the relationship between the damaged area/volume and impact energies by using damaged impact (front) face, back face dimensions and volumes of the damage cone. This will be an interesting point, because in daily use, engineers should get more knowledge about damaged structure without using none-destructive testing devices at their first inspections after impact. At this point the key question is which sign will give more meaningful knowledge about the damage level of composite sample at visual inspection?. In order to understand the damage volume correctly, a new method of non-destructive

3 technique has to be used. We thought Micro-CT visualization of composite will be a good alternative. Figure 1: Impact cone cross section Micro-Ct image of composite specimen. For investigation of internal damage occurred in composite after low velocity impact SkyScan 1173 high-energy micro-ct images were taken as slices. In Figure 1 the mid-point micro-ct image of impacted composite is seen. Damage cone geometry and fiber breakages with inter-laminar delaminations can be seen clearly. Damage cone geometry and settlement gave a lot of information about effect of low velocity impact loading. Figure 2: 3D image of impacted composite obtained with CtVox. Slices of micro-ct images taken from impacted composite were connected with image processing program CtVox and 3D model image of composite specimen was gained as seen in Figure 2. This 3D realistic model of impacted composite gives a lot of information about the damage mechanisms and also detailed maps of delaminations occurred. Impacted face and back face of specimen also can be seen clearly with this 3D realistic model and give us a chance of building a relationship between the impact energies and resultant damage cone occurred.

4 Figure 3: Back face image of impacted composite obtained with CtVox. In figure 3, back face of impacted specimen can be seen. Here, fibers those were bended due to low velocity impact and deflection of matrix can be seen clearly. Figure 4: Micro-CT realistic model of repeatedly impacted glass fibre-reinforced composite. Results It is fully understood that Micro-CT images of a damaged composite give a lot of information about damage mechanisms. In addition, micro-ct images have great resolution values which can t be achieved by other non-destructive inspection techniques. Capability of building a 3D model from micro-ct images is another important advantage which can t be done with other imagining techniques. Conclusion Using micro-ct in materials and mechanical engineering applications will be very helpful in future. No other inspection technique can give such detailed map of internal structure of a material except micro-ct.

5 References: [1] Rydin RW, Locurcio A, Karbhari VM. Influence of reinforcing layer orientation on impact response of plain weave RTM composites. J Reinf Plast Comp 1995; 14: [2] Wu E, Chang LC. Loading rate effect on woven glass laminated plates by penetration force. J Compos Mater 1998; 32: [3] Wisheart M, Richardson MOW. Low velocity response of simple geometry pultruded glass/polyester composite. J Mater Sci 1992; 34: [4] Mouritz AP. The effect of underwater explosion shock loading on the flexural properties of grp laminates. Int J Impact Eng 1996; 18: [5] Stoffel M, Schmidt R, Weichert D. Shock wave-loaded plates. Int J Solids Struct 2001; 38: [6] Leblanc J, Shukla A, Rousseau C, Bogdanovich A. Shock loading of threedimensional woven composite materials. Compos Struct 2007; 79: [7] Stoffel M. A measurement technique for shock wave-loaded structures and its application. Exp Mech 2006; 46: [8] Zaretsky E, debotton G, Perl M. The response of a glass fibers reinforced epoxy composite to an impact loading. Int J Solids Struct 2004; 41: [9] Dandekar DP, Hall CA, Chhabildas LC, Reinhart WD. Shock response of a glassfiber reinforced polymer composite. Compos Struct 2003; 61: [10] Boteler JM, Rajendran AM, Grove D. Shock wave profiles in polymer matrix composites. Aip Conf Proc Presented at [11] Shah Khan MZ, Simpson G, Gellert EP. Resistance of glass-fibre reinforced polymer composites to increasing compressive strain rates and loading rates. Compos Part A-Apply S 2000; 31: [12] Ku H, Cheng YM, Snook C, Baddeley D. Drop weight impact test fracture of vinyl ester composites: micrographs of pilot study. J Compos Mater 2005; 39: