Flexural Performance of the Sandwich Structures Having Aluminum Foam Core with Different Thicknesses

The structures obtained with the use of sandwich technologies combine low weight with high energy absorbing capacity and load carrying capacity. Hence, there is a growing and markedly interest in the use of sandwiches with aluminum foam core because of very good properties such as flexural rigidity and energy absorption capability. In the current investigation, the static threepoint bending tests were carried out on the sandwiches with aluminum foam core and glass fiber reinforced polymer (GFRP) skins at different values of support span distances aiming the analyses of their flexural performance. The influence of the core thickness and the GFRP skin type was reported in terms of peak load and energy absorption capacity. For this purpose, the skins with two different types of fabrics which have same thickness value and the aluminum foam core with two different thicknesses were bonded with a commercial polyurethane based flexible adhesive in order to combine the composite sandwich panels. The main results of the bending tests are: force-displacement curves, peak force values, absorbed energy, collapse mechanisms and the effect of the support span length and core thickness. The results of the experimental study showed that the sandwich with the skins made of S-Glass Woven fabrics and with the thicker foam core presented higher mechanical values such as load carrying and energy absorption capacities. The increment of the support span distance generated the decrease of the mechanical values for each type of panels, as expected, because of the inverse proportion between the force and span length. The most common failure types of the sandwiches are debonding of the lower skin and the core shear. The obtained results have particular importance for applications that require lightweight structures with a high capacity of energy dissipation, such as the transport industry (automotive, aerospace, shipbuilding and marine industry), where the problems of collision and crash have increased in the last years.

Authors:

• Emre Kara
• Ahmet F. Geylan
• Kadir Koç
• Şura Karakuzu
• Metehan Demir
• Halil Aykul

Keywords:

• Aluminum foam
• Composite panel
• Flexure
• Transport application.

References:

[1] S. Belouettar, A. Abbadi, Z. Azari, R. Belouettar, P. Freres,
“Experimental investigation of static and fatigue behaviour of composite
honeycomb materials using four point bending tests”, Composite
Structures, vol. 87, no. 3, pp. 265-273,2008.
[2] V. Crupi, G. Epasto, E. Guglielmino, “Impact response of aluminium
foam sandwiches for light-weight ship structures”, Metals, vol. 1, pp.
98-112, 2011.
[3] W. J. Cantwell, G. R. Villanueva, “The high velocity impact response of
composite and FML-reinforced sandwich structures”, Composite
Science and Technology, vol. 64, pp. 35-54, 2004.
[4] J. Banhart, “Manufacture, characterisation and application of cellular
metals and metal foams”, Progress in Material Science, vol. 46, no. 6,
pp. 559–632, 2001.
[5] H. P. Degischer, B. Kriszt, Handbook of cellular metals: production,
processing, applications. Weinheim: Wiley-VCH Verlag, 2002, ch. 4.
[6] L. J. Gibson, M. F. Ashby, Cellular solids: structure and properties.
Oxford: Pergamon Press, 1997.
[7] M. F. Ashby, A. G. Evans, N. A. Fleck, L. J. Gibson, J. W. Hutchinson,
H. N. G. Wadley, Metal foams: a design guide. Boston: Butterworth-
Heinemann, 2000. [8] T. M. McCormack, R. Miller, O. Kesler, L. J. Gibson, “Failure of
sandwich beams with metallic foam cores”, International Journal of
Solids and Structures, vol. 38, pp. 4901–4920, 2001.
[9] H. Bart-Smith, J. Hutchinson, A. Evans, “Measurement and analysis of
the structural performance of cellular metal sandwich construction”,
International Journal of Mechanical Sciences, vol. 43, no. 8, pp. 1945–
1963, 2001.
[10] J. Yu, E. Wang, J. Li, Z. Zheng, “Static and low-velocity impact
behaviour of sandwich beams with closed-cell aluminum foam core in
three-point bending”, International Journal of Impact Engineering, vol.
35 , no. 8, pp. 885–894, 2008.
[11] K. Mohan, Y. T. Hon, S. Idapalapati, H. P. Seow, “Failure of sandwich
beams consisting of alumina face and aluminum foam core in bending”,
Materials Science and Engineering: A, vol. 409, pp. 292–301, 2005.
[12] C. Chen, A. M. Harte, N. A. Fleck, “The plastic collapse of sandwich
beams with a metallic foam core”, International Journal of Mechanical
Sciences, vol. 43, no. 6, pp. 1483–1506, 2001.
[13] Y. Shenhar, Y. Frostig, E. Altus, “Stresses and failure patters in the
bending of sandwich beams with transversely flexible cores and
laminated composite skins”, Composite Structures, vol. 35, pp. 143–152,
1996.
[14] M. Kampner, J. L. Grenestedt, “On using corrugated skins to carry shear
in sandwich beams”, Composite Structures, vol. 85, pp. 139–148, 2007.
[15] G. Reyes, “Mechanical behavior of thermoplastic FML-reinforced
sandwich panels using an aluminum foam core: experiments and
modelling”, Journal of Sandwich Structures and Materials, vol. 12, pp.
81 – 96, 2010.
[16] O. Kesler, L. J. Gibson, “Size effects in metallic foam core sandwich
beams”, Materials Science and Engineering:A, vol. 326, no. 2, pp. 228–
234, 2002.
[17] V. Crupi, R. Montanini, “Aluminium foam sandwiches collapse modes
under static and dynamic three-point bending”, International Journal of
Impact Engineering, vol. 34, pp. 509 – 521, 2007.