Failure Analysis of Low-density Polymer Foam Core Sandwich Structures under Three-point Bending Loading

In this study, low-density polymer foam core sandwich beams, non-existent in the literature, havingwoven carbon/epoxy face sheets in different core thicknesses and specimen lengths were fabricated andthen subjected to three-point bending tests. The bending behavior of the sandwich beams were scrutinizedexperimentally. The effects of both core thickness and specimen length were revealed. As the ratio of facesheet to core decreases, transferring of shear forces between the face sheets decreases and the face sheetsalso become weaker. Hence, the failure mode changes from core shearing to indentation and thesandwiches have become tendency to fail by indentation. The theoretical models available in the literaturewas also utilized to predict the failure mode and collapse forces. The results indicated that both analyticalcalculations and experimental findings are compatible with each other

Üç Nokta Eğilme Yüklemesi Altındaki Düşük Yoğunluklu Polimer Köpük Sandviç Yapıların Hasar Analizi

Bu çalışmada, örgü dokuma karbon/epoksi yüzeylere sahip, literatürde yer almayan, düşük yoğunluklu polimer köpük çekirdek sandviç kirişler, farklı uzunluk ve çekirdek kalınlıklarında üretilmiş üç nokta eğilme testlerine tabi tutulmuştur. Sandviç kirişlerin deneysel olarak eğilme davranışları incelenmiştir. Hem numune uzunluğunun hem de çekirdek kalınlığının etkisi ortaya çıkarılmıştır. Yüzey tabaka kalınlığının çekirdek kalınlığına oranı azaldıkça, yüzeyler arasındaki kayma kuvvetlerinin transferi azalmaktadır ve yüzeyler de zayıflamaktadır. Bu yüzden, hasar modu çekirdek kayması hasarından batma hasarına doğru değişmektedir ve sandviçler batma şeklindeki hasara uğramaya meyilli olmaktadır. Hasar modunu ve çökme kuvvetlerini tahmin etmek için literatürde mevcut bulunan teorik modellerden de faydalanılmıştır. Sonuçlar, hem analitik hesapların hem de deneysel bulguların birbirleriyle uyumlu olduğunu göstermiştir.

PDF

___

1. Ashby, M.F., 2011. Materials Selection in Mechanical Design. Elsevier, 4th Edition, The Netherlands.

2. Gibson, R.F., 2012. Principles of Composite Material Mechanics. 3rd Edition, CRC Press, USA.

3. Liu, C., Zhang, Y.X., Heslehurst, R., 2014. Impact Resistance and Bonding Capability of Sandwich Panels with Fibre-Metal Laminate Skins and Aluminium Foam Core. Journal of Adhesion Science and Technology, 28(24), 2378-2392.

4. Mallick, P.K., 2007. Fiber-Reinforced Composites: Materials, Manufacturing, and Design. CRC Press.

5. Basturk, S.B., Tanoglu, M., 2011. Mechanical and Energy Absorption Behaviors of Metal/Polymer Layered Sandwich Structures. Journal of Reinforced Plastics and Composites, 30(18), 1539-1547.

6. Xu, J., Liu, J., Gu, W., Wang, Z., Liu, X., Cao, T., 2018. Effect of Cell Size on the Energy Absorption of Closed-Cell Aluminum Foam. Materials Testing, 60, 583-590.

7. Harte, A.M., Fleck, N.A., Ashby, M.F., 2000. Sandwich Panel Design Using Aluminum Alloy Foam. Advanced Engineering Materials, 2(4), 219-222.

8. Ashby, M.F., Evans, A.G., Fleck, N.A., Gibson, L.J., Hutchinson, J.W., Wadley, H.N.G., 2000. Metal Foams: a Design Guide. London: Butterworth, Heinemann, 251.

9. Daniel, I.M., Gdoutos, E.E., Wang, K.A., Abot, J.L., 2002. Failure Modes of Composite Sandwich Beams. International Journal of Damage Mechanics, 11, 309-334.

10.Carlsson, L.A., Kardomateas, G.A., 2011. Structural and Failure Mechanics of Sandwich Composites, Springer, USA.

11. Styles, M., Compston, P., Kalyanasundaram, S., 2007. The Effect of Core Thickness on the Flexural Behaviour of Aluminium Foam Sandwich Structures. Composite Structures, 80(4), 532-538.

12. Kabir, K., Vodenitcharova, T., Hoffman, M., 2014. Response of Aluminium Foam-Cored Sandwich Panels to Bending Load. Composites Part B-Engineering, 64, 24-32.

13.Jiang, B.H., Li, Z.B., Lu, F.Y., 2015. Failure Mechanism of Sandwich Beams Subjected to Three-Point Bending. Composite Structures, 133, 739-745.

14. Lim, T.S., Lee, C.S., Lee, D.G., 2004. Failure Modes of Foam Core Sandwich Beams under Static and Impact Loads. Journal of Composite Materials, 38(18), 1639-1662.

15. Technical Data Sheet, Dost Kimya Inc., 2014. Carbon Fabric-200gr/sqm 3K Plain. Rev.2.2, Turkey, 1.

16. Technical Data Sheet, 2011. Universal Structural Foam: Airex C70. 3A Composites.

17. Technical Data Sheet, 2009. Laminating Resin MGSTM L160 and Hardener H160, Hexion, The Netherlands, 10.

18. McDonough, W.G., Dunkers, J.P., Flynn, K.M., Hunston, D.L., 2004. A Test Method to Determine the Fiber and Void Contents of Carbon/Glass Hybrid Composites. Journal of ASTM International, 1(3), 1-15.

19. ASTM C393/C393M-11, 2011. Standard Test Method for Core Shear Properties of Sandwich Constructions by Beam Flexure. Annual Book of ASTM Standards, ASTM International, West Conshohocken, USA, 8.

20. ASTM D7249/D7249M-12, 2012. Standard Test Method for Facing Properties of Sandwich Constructions by Long Beam Flexure. Annual Book of ASTM Standards, ASTM International, West Conshohocken, USA, 9.

21. Kaw, A.K., 2006. Mechanics of Composite Materials, CRC Press, 2nd Edition, USA, 457.

22. Steeves, C.A., Fleck, N.A., 2004. Collapse Mechanisms of Sandwich Beams with Composite Faces and a Foam Core, Loaded in Three-Point Bending. Part II: Experimental Investigation and Numerical Modelling. International Journal of Mechanical Sciences, 46(4), 585-608.

23. Sadeghian, P., Hristozovand, D., Wroblewski, L., 2018. Experimental and Analytical Behavior of Sandwich Composite Beams: Comparison of Natural and Synthetic Materials. Journal of Sandwich Structures and Materials, 20(3), 287-307.

24.Bezazi, A., Mahi, A., Berthelot, J.M., Bezzazi, B., 2007. Experimental Analysis of Behavior and Damage of Sandwich Composite Materials in Three-Point Bending. Part 1. Static Tests and Stiffness Degradation at Failure Studies. Strength of Materials, 39(2), 170-77.