Localized Effects near Non-vertical Core Junctions in Sandwich Panels

Abstract

The article investigates the role of localized effects in the vicinity of junctions between core materials of different stiffness when these joints are non-vertical and may take any shape. The mathematical formulation uses a variational approach, and the proposed analysis incorporates the effects of the vertical flexibility of the core following the high-order sandwich panel theory (HSAPT) approach. The proposed analysis is geometrically non-linear. The presented study examines various joint types in the vicinity of the boundaries between cores of different stiffness in the load introduction zone, including: straight vertical (traditional ‘butt’ junction), straight non-vertical with different inclination angles, a double line joint, and finally a double line joint with extremely large difference between the stiffness properties of the joined cores. The response is described in terms of deflections and stress resultants in the face sheets, as well as in terms of the interfacial stresses at the upper and lower face-core interfaces near the edges of the stiffened core. The concept of equivalent modulii for the modulus of elasticity and the shear modulus of the core is presented and validated through numerical examples. It is shown that the stress concentrations induced near junctions between core materials of different stiffness can be reduced significantly, if non-vertical junctions are used instead of the traditional vertical (‘butt’) junctions.

Keywords

localized effects sandwich structures high-order theory reinforced core load introduction zone junctions between cores of different stiffness

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References

Allen, H.G. (1969). Analysis and Design of Structural Sandwich Panels, Pergamon Press, London .

Plantema, F.J. (1966). Sandwich Construction, John Wiley and Sons, New York .

Zenkert, D. (1995). An Introduction to Sandwich Construction, Chameleon Press Ltd., London .

Vinson, J.R. (1999). The Behavior of Sandwich Structures of Isotropic and Composite Materials, Technomic Publishing Co. Inc., Lancaster .

Smith, C.S. (1990). Design of Marine Structures in Composite Materials, Elsevier, London .

Shenoi, R.A. and Wellicome, J.F. (eds), (1993). Composite Materials in Maritime Structures, University Press, Cambridge .

Gay, D. , Hoa, S.V. and Tsai, S.N. (2003). Composite Materials: Design and Applications, CRC Press, New York .

Zenkert, D. (ed.) (1997). The Handbook of Sandwich Construction, EMAS Publishing, London .

Clarke, J.L. (ed.) (1996). Structural Design of Polymer Composites, EUROCOMP Design Code and Handbook, E &! FN Spon., London .

10.

Thomsen, O.T. (1997). Sandwich Plates with Through-the-Thickness and Fully-Potted Inserts: Evaluation of Differences in Structural Performance , Composite Structures, 40(2): 159-174 .

11.

Adams, R.D. and Wake, W.C. (1984). Structural Adhesive Joints in Engineering, Elsevier, London .

12.

Zenkert, D. (1992). Effect of Manufacture-Induced Flaws on the Strength of Foam Core Sandwich Beams , In: Proceedings of the International Symposium on Damage Detection and Quality Assurance in Composite Materials, ASTM Special Technical Publication, 1128, pp. 137-151 .

13.

Zenkert, D. , Schubert, O. and Burman, M. (1997). Fracture Initiation in Foam-Core Sandwich Structures due to Singular Stresses at Corners of Flawed Butt Junctions , Mechanics of Composite Materials and Structures, 4(1): 1-21 .

14.

Noor, A.K. , Burton, W.S. and Bert, C.W. (1996). Computational Models for Sandwich Panels and Shells , Applied Mechanics Review, 49(3): 155-199 .

15.

Skvortsov, V. and Thomsen, O.T. (2002). Analytical Estimates for Stresses in Face Sheets of Sandwich Panel at the Junction of Two Core Materials, Report No. 113, Institute of Mechanical Engineering, Aalborg University .

16.

Skvortsov, V. and Thomsen, O.T. (2003). Analytical Estimates for the Stresses in Face Sheets of Sandwich Panels at Junctions between Different Core Material , In: Proceedings of the 6th International Conference on Sandwich Structures (ICSS-6), Fort Lauderdale, USA, FL, pp. 551-559 .

17.

Bozhevolnaya, E. , Thomsen, O.T. , Kildegaard, A. and Skortsov, V. (2003). Local Effects across Core Junctions in Sandwich Panels , Composites, Part B: Engineering, 34(6): 509-517 .

18.

Bozhevolnaya, E. , Lyckegaard, A. , Thomsen, O.T. and Skvortsov, V. (2003). Local Effects in the Vicinity of Inserts in Sandwich Panels, In: Rajapakse, Y. (ed.), Composites Part B: Engineering, (Special Issue, ONR), Vol. 35(6-8), pp. 619-627.

19.

Bozhevolnaya, E. and Lyckegaard, A. (2005). Structurally Graded Core Inserts in Sandwich Panels , Composite Structures, 68(1): 23-29 .

20.

Bozhevolnaya, E. and Thomsen, O.T. (2005). Structurally Graded Core Junctions in Sandwich Panels: Quasi Static Loading Conditions , Composite Structures, 70(1): 1-11 .

21.

Bozhevolnaya, E. and Thomsen, O.T. (2005). Structurally Graded Core Junctions in Sandwich Panels: Fatigue Loading Conditions , Composite Structures, 70(1): 12-23 .

22.

Thomsen, O.T. , Bozhevolnaya, E. and Lyckegaard, A. (2005). Structurally Graded Core Junctions in Sandwich Elements , Composites Part A: Applied Science and Manufacturing, 36(10): 1397-1411 .

23.

Sankar, B.V. (2001). An Elasticity Solution for Functionally Graded Beams , Composite Science and Technology, 61(5): 689-696 .

24.

Apetre, N.A. and Sankar, B.V. (2003). Composite Sandwich Plates with Functionally Graded Cores , In: Vinson, G.R. and Carlson, L. (eds), Proceedings of the Sixth International Conference on Sandwich Structures (ICSS-6), CRC Press, pp. 227-239 .

25.

Frostig, Y. and Rabinovitch, O. (July 2000). Behavior of Unidirectional Sandwich Panels with a Multi-Skin Construction or a Multi-Layered Core Layout - High-Order Approach , Journal of Sandwich Structures and Materials, 2(3): 181-213 .

26.

Frostig, Y. , Baruch, M. , Vilnay, O. and Sheinman, I. (May 1992). A High Order Theory for the Bending of Sandwich Beams with a Flexible Core , Journal of the ASCE, EM Division, 118(5): 1026-1043 .

27.

Thomsen, O.T. and Frostig, Y. (January 1997). Localized Bending Effects in Sandwich Panels: Photoelastic Investigation versus High-Order Sandwich Theory Results , Composite Structures, 37(1): 97-108 .

28.

Swanson, S.R. (Feb.-Mar. 1999). An Examination of a High-Order Theory for Sandwich Beams , Composite Structures, 44(2-3): 169-177 .

29.

Petras, A. and Sutcliffe, M.P.F. (Dec. 1999). Indentation Resistance of Sandwich Beams , Composite Structures, 46(4): 413-424 .

30.

Petras, A. and Sutcliffe, M.P.F. (Nov. 2000). Indentation Failure Analysis of Sandwich Beams , Composite Structures, 50(3): 311-318 .

31.

Stoer, J. and Bulirsch, R. (1980). Introduction to Numerical Analysis, Springer Verlag, New York .

Localized Effects near Non-vertical Core Junctions in Sandwich Panels - A High-order Approach

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