Computational Technology Resources - CCP

Keywords: sandwich construction, buckling analysis, long cylindrical shells.

Summary

Sandwich construction has become increasingly very popular in the design of future transportation industry, especially aircraft. The paper deals with the theoretical prediction of buckling loads for sandwich long cylindrical shells with laminated facings and foam core. The loading is a uniform hydrostatic pressure, which means that the loading remains normal to the deflected surface during the buckling process. Several fiber materials are used in the laminated facings. The materials are: Boron/Epoxy, Graphite/Epoxy and Kevlar/Epoxy laminates with 0 orientation with respect to the hoop direction. These various materials are employed to provide comparative data that can be used in design. Results are generated by various theoretical solutions. Shell theory results are generated with and without accounting for the transverse shear effect [1,2]. Moreover, results based on three-dimensional elasticity [3] are also generated for comparison purposes. The facings are 2.54mm thick and the core is 25.4mm thick; therefore, the total thickness is 30.48mm.

Four values of the ratio of mean radius to total thickness, , are used in order to assess the effect of transverse shear: = 30, 60, 120 and 240. The effect of transverse shear appears to be more pronounced for the construction corresponding to facings made out of Boron/Epoxy. This effect decreases as we deal with Graphite/Epoxy facings and it is much smaller for the case of Kevlar/Epoxy facings. As expected, the transverse shear effect is very large for = 30, for all three facing materials. When comparing the buckling pressure, as computed according to [1], to the classical value [1,2], it is 30% for Boron/Epoxy, 34% for Graphite/Epoxy and 51% for Kevlar/Epoxy. As increases to 120, the effect reduces considerably for all three facing materials. For this value of , the critical pressure is 87%, 89% and 95% respectively. At = 240, the effect is virtually nonexistent.

When computing critical pressure by the three-dimensional elasticity solution, the results are slightly higher than those computed by the procedure of [1]. Both procedures will be presented with details in the full paper, as well as the numerical results and the discussion of the findings.

As far as the authors know, there are no analyses and no results published in the literature with regard to buckling of pressure loaded sandwich shells. Although the results are for very long shells (ring behavior), the study will be next extended to finite length cylinders, similar to [2].

Acknowledgement

The financial support of the Office of Naval Research, Ship Structures and Systems, S & T Division, Grants N00014-90-J-1995 and N00014-0010323, and the interest and encouragement of the Grant Monitor, Dr. Y.D.S. Rajapakse, are both gratefully acknowledged.

References

1: C.V. Smith, Jr. and G.J. Simitses, "Effect of Shear and Load Behavior on Ring Stability" ASCE, Journal of the EM Division, 95, EM 3, pp. 559-569, 1969.
2: G.J. Simitses, and M. Aswani, "Buckling of Cylinders Under Uniform Lateral Loading" ASME, Journal of Applied Mechanics, 41, 3, 827-829, 1974.
3: G.A. Kardomateas, "Buckling of Thick Orthotropic Cylindrical Shells Under External Pressure", ASME Journal of Applied Mechanics, 60, 1,. 195-202, 1993. doi:10.1115/1.2900745

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £125 +P&P)

	Computational & Technology Resources an online resource for computational, engineering & technology publications
	not logged in - login
Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 75 PROCEEDINGS OF THE SIXTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and Z. Bittnar Paper 140 Buckling of Long, Sandwich Cylindrical Shells under Pressure G.A. Kardomateas+ and G.J. Simitses* +Georgia Institute of Technology, Atlanta, Georgia, United States of America University of Cincinnati, Cincinnati, Ohio, United States of America doi:10.4203/ccp.75.140 purchase the full-text of this paper Full Bibliographic Reference for this paper G.A. Kardomateas, G.J. Simitses, "Buckling of Long, Sandwich Cylindrical Shells under Pressure", in B.H.V. Topping, Z. Bittnar, (Editors), "Proceedings of the Sixth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 140, 2002. doi:10.4203/ccp.75.140 Keywords:* sandwich construction, buckling analysis, long cylindrical shells. Summary Sandwich construction has become increasingly very popular in the design of future transportation industry, especially aircraft. The paper deals with the theoretical prediction of buckling loads for sandwich long cylindrical shells with laminated facings and foam core. The loading is a uniform hydrostatic pressure, which means that the loading remains normal to the deflected surface during the buckling process. Several fiber materials are used in the laminated facings. The materials are: Boron/Epoxy, Graphite/Epoxy and Kevlar/Epoxy laminates with 0 orientation with respect to the hoop direction. These various materials are employed to provide comparative data that can be used in design. Results are generated by various theoretical solutions. Shell theory results are generated with and without accounting for the transverse shear effect [1,2]. Moreover, results based on three-dimensional elasticity [3] are also generated for comparison purposes. The facings are 2.54mm thick and the core is 25.4mm thick; therefore, the total thickness is 30.48mm. Four values of the ratio of mean radius to total thickness, , are used in order to assess the effect of transverse shear: = 30, 60, 120 and 240. The effect of transverse shear appears to be more pronounced for the construction corresponding to facings made out of Boron/Epoxy. This effect decreases as we deal with Graphite/Epoxy facings and it is much smaller for the case of Kevlar/Epoxy facings. As expected, the transverse shear effect is very large for = 30, for all three facing materials. When comparing the buckling pressure, as computed according to [1], to the classical value [1,2], it is 30% for Boron/Epoxy, 34% for Graphite/Epoxy and 51% for Kevlar/Epoxy. As increases to 120, the effect reduces considerably for all three facing materials. For this value of , the critical pressure is 87%, 89% and 95% respectively. At = 240, the effect is virtually nonexistent. When computing critical pressure by the three-dimensional elasticity solution, the results are slightly higher than those computed by the procedure of [1]. Both procedures will be presented with details in the full paper, as well as the numerical results and the discussion of the findings. As far as the authors know, there are no analyses and no results published in the literature with regard to buckling of pressure loaded sandwich shells. Although the results are for very long shells (ring behavior), the study will be next extended to finite length cylinders, similar to [2]. Acknowledgement The financial support of the Office of Naval Research, Ship Structures and Systems, S & T Division, Grants N00014-90-J-1995 and N00014-0010323, and the interest and encouragement of the Grant Monitor, Dr. Y.D.S. Rajapakse, are both gratefully acknowledged. References 1 C.V. Smith, Jr. and G.J. Simitses, "Effect of Shear and Load Behavior on Ring Stability" ASCE, Journal of the EM Division, 95, EM 3, pp. 559-569, 1969. 2 G.J. Simitses, and M. Aswani, "Buckling of Cylinders Under Uniform Lateral Loading" ASME, Journal of Applied Mechanics, 41, 3, 827-829, 1974. 3 G.A. Kardomateas, "Buckling of Thick Orthotropic Cylindrical Shells Under External Pressure", ASME Journal of Applied Mechanics, 60, 1,. 195-202, 1993. doi:10.1115/1.2900745 purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £125 +P&P)
Back to top	©Civil-Comp Limited 2023 - terms & conditions