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«DESIGN OF AN INTEGRAL THERMAL PROTECTION SYSTEM FOR FUTURE SPACE VEHICLES By SATISH KUMAR BAPANAPALLI A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL ...»

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11. The trusses closer to the panel edges experienced a disproportionately high amount of load when compared to the trusses close to the center of the panel. Other truss-core geometries (arrangement of trusses with respect to the face sheet) need to be explored so as to distribute the loads more evenly among the trusses.

Some material trade-off studies for corrugated-core ITPS were carried out during the preliminary stages of the ITPS design process. The results were not presented in the dissertation because the input parameters for the designs were altered significantly as the design process evolved. In the light of these different input parameters the results of older designs would not appear coherent. A companion study [62] used the code developed for this research work to carry out a more meaningful material trade-off study. However, this study did not take the deflection and stress constraints into consideration for the optimization process. Some of the conclusions that can be drawn from these combined studies are presented below.

12. Beryllium alloys are superior to Aluminum alloys in all aspects. Use of Beryllium alloys also facilitates in designing a much lighter ITPS. Therefore, in spite of the toxicity concerns of Beryllium, it is worthwhile to use Beryllium alloys in the ITPS designs.

13. Titanium alloys have excellent high temperature properties and are suitable for top face sheet and web material. However, the service temperature of these alloys limits their use to low heat flux regions.

14. Inconel alloys, with a higher service temperature than titanium alloys, allow ITPS design for higher heat flux. However, high density of inconel leads to prohibitively high ITPS weight in corrugated-core structures.

15. Ceramic matrix composites, for example Nextel-718/Alumina Silicate, have many superior properties like low density, high service temperature, stiffness comparable to aluminum, low thermal conductivity and low coefficient of thermal expansion. However, very low tensile strength of these materials is their “Achilles’ heel”. Otherwise, these materials are the most suitable for ITPS designs for top face sheet and web.

–  –  –

Now that a general framework for the ITPS design has been established with this research work, new structure geometries need to be explored. Corrugated-core structure design provides a lot of insight into the factors affecting typical ITPS designs. It is necessary to build on these to improve the structure geometry for a lighter ITPS. A drastic change like a transition to truss-core structures should be avoided. Instead, the active constraints in the corrugated-core designs should be studied and step-wise changes in geometry should be implemented.

The excessive thermal deflection of the webs, due to thermal gradients, causes large stresses in the webs and bottom face sheet. A classic technique to relieve thermal stresses is to provide local provisions for expansion of the structure so as not to accumulate high stresses. One of the changes that need to be immediately explored is to divide each web in the length-direction.

If the web in Figure 5-6 were to be split into two parts along the centerline (dotted line in Figure 5-6), and a small gap provided between the two partitions, then the thermal deflection can be cut into half. This will reduce the stresses considerably while not adversely affecting the load carrying capacity of the panel.

Buckling of the edges is another major factor influencing the design. For example, buckling of the web-edges close to the panel edges is one of the first buckling modes. By tactically placing stiffeners in the webs and face sheets, such buckling modes can be prevented.

Stiffeners do not add to the weight or heat conduction path of the ITPS significantly, while drastically improving the buckling resistance of the structure. Therefore, this line of design improvement has a potential for reducing the ITPS weight considerably.

Although truss-core geometries considered for this research did not yield a feasible structure, other geometries need to be explored that can distribute the thermal stresses more evenly over all the trusses. In the truss-cores used for this research, the trusses close to the panel edges experienced large loads due to the top face sheet expansion, while the trusses close to the center of the panel experienced very small loads. One of the suggestions to improve this design is to arrange all the trusses so that they tilt towards the center point of the panel. This will impart more loads to the interior trusses. Stress concentration in the top face sheet will still be a problem in these structures. There is a need to device a method to overcome the stress concentrations that arise as a result of FE modeling. In practice, these stresses will be much lower due to the manner in which the trusses are attached to the face sheets. A method to overcome the stress singularities in the beam-plate models for truss-core structures can help reduce the cost of FE calculations to a large extent.

In this research work, heat flux loads for a Space Shuttle-like vehicle were considered.

Most future space vehicles are likely to be space capsules like Apollo. The heat loads for space capsules are many times higher than the loads on the Shuttle. As of now there are no materials that have service temperature to withstand these loads. Therefore, ablative materials have to be used to provide thermal protection. It would be very interesting to combine the ablative materials with ITPS structures so that the ablative material thickness controls the amount of heat flowing into the structure.





The number of FE experiments carried out to obtain the response surface approximations was manageable for the corrugated-core design. However, as the design gets complicated, the number of design variable will increase. Therefore, methods to reduce the number of FE analyses need to be explored in future. One of the suggestions is to couple approximate analytical formulas with the accurate FE analysis to carry out a multi-fidelity optimization procedure.

–  –  –

1. Futron Corporation, “Space Transportation Costs: Trends in Price Per to Orbit 1990 – 2000,” White Paper, September 6, 2002.

(http://www.google.com/search?q=cache:Y_XJTWtXyJ:www.futron.com/pdf/FutronLaunchCostWP.pdf+cost+of+payload&hl=en&gl=us&ct=c lnk&cd=5&client=firefox-a. Last accessed on Decemeber 25, 2006).

2. Bekey, I., Powell, R., Austin, R., “NASA Studies Access to Space,” Aerospace America, Vol. 32, No. 5, May 1994, pp. 38-43.

3. Lee, G., “Ablation Effects on Apollo Afterbody Heat Transfer,” AIAA Journal, Vol. 7, No.

8, 1969, pp. 1616-1618.

4. Boynton, J. H., and Kleinknecht, K. S., “Systems Design Experience from Three Manned Space Programs,” Journal of Spacecraft (and Rockets), Vol. 7, No. 7, 1970, pp. 770 – 784.

5. Erb, R. B., Greenshields, D. H., Chauvin, L. T., Pavlosky, J. E., and Statham, C. L, “Apollo Thermal-Protection System Development,” Journal of Spacecraft (and Rockets), Vol. 7, No. 6, June 1970, pp. 727-734.

6. Bartlett, E. P., Anderson, L. W., and Curry, D. M., “An Evaluation of Ablation Mechanisms for the Apollo Heat Shield Material,” Journal of Spacecraft (and Rockets), Vol. 8, No. 5, May 1971, pp. 463-469.

7. Braun, R. D., Powell, R. W., Evans Lyne, J., “Earth Aerobraking Strategies for Manned Return from Mars,” Journal of Spacecraft and Rockets, Vol. 29, No. 3, May-June 1992, pp. 297-304.

8. Lyne, J. E., Tauber, M. E., Braun, R. D, “Parametric Study of Manned Aerocapture. 1.

Earth Return from Mars,” Journal of Spacecraft and Rockets, Vol. 29, No. 6, Nov-Dec 1992, pp. 808-813.

9. Williams, S. D., Curry, D. M., Bouslog, S. A., Rochelle, W. C., “Thermal Protection System-Design Studies for Lunar Crew Module,” Journal of Spacecraft and Rockets, Vol.

32, No. 3, May-Jun 1995, pp. 456-462.

10. Cooper, P. A., and Holloway, P. F., “The Shuttle Tile Story,” Astronautics and Aeronautics, Jan 1981, pp. 24-34.

11. Blosser, M. L., “Advanced Metallic Thermal Protection Systems for Reusable Launch Vehicles,” Ph.D. Dissertation, University of Virginia, May 2000.

12. Poteet, C. C., Abu-Khajeel, H., and Hsu, S.-Y., “Preliminary Thermal-Mechanical Sizing of a Metallic Thermal Protection System,” Journal of Spacecraft and Rockets, Vol. 41, No.

2, Mar-Apr 2004, pp. 173-182.

13. Dorsey, J. T., Poteet, C. C., Wurster, K. E., and Chen, R. R., “Metallic Thermal Protection System Requirements, Environments, and Integrated Concepts,” Journal of Spacecraft and Rockets, Vol. 41, No. 2, Mar-Apr 2004, pp. 162-172.

14. Blosser, M. L., Chen, R. R., Schmidt, I. H., Dorsey, J. T., Poteet, C. C., Bird, R. K., and Wurster, K. E., “Development of Advanced Metallic Thermal-Protection-System Prototype Hardware,” Journal of Spacecraft and Rockets, Vol. 41, No. 2, Mar-Apr 2004, pp. 183-194.

15. Blosser, M. L., “Fundamental Modeling and Thermal Performance Issues for Metallic Thermal Protection System Concept,” Journal of Spacecraft and Rockets, Vol. 41, No. 2, Mar-Apr 2004, pp. 195-206.

16. Blosser, M. L., “Development of Metallic Thermal Protection Systems for the Reusable Launch Vehicle,” NASA TM-110296, Oct 1996.

17. Glass, D. E., Camarda, C. J., “Preliminary Thermal/Structural analysis of a CarbonCarbon/Refractory-Metal Heat-Pipe-Cooled Wing Leading Edge, Thermal Structures and Materials for High Speed Flight,” edited by E. A. Thornton, Vol. 140, Progress in Astronautics and Aeronautics, AIAA, Washington D.C., 1992, pp. 301-322.

18. Shideler, J. L., Kelly, H. N., Avery, D. E., Blosser, M. L., Adelman, H. M., “Multiwall TPS – An Emerging Concept,” Journal of Spacecraft and Rockets, Vol. 19, No. 4, Jul-Aug 1982, pp. 358-365.

19. Grallert, H., Keller, K., “Metallic Thermal Protection Concept for Hypersonic Vehicles,” Journal of Aircraft, Vol. 28, No. 6, 1991, pp. 410-416.

20. Bohon, H. L., Shildeler, J. L., and Rummler, D. R., “Radiative Metallic Thermal Protection Systems: A Status Report,” Journal of Spacecraft and Rockets, Vol. 12, No. 10, Oct 1977, pp. 223-227.

21. Zhu, H., “Design of Metallic Foams as Insulation in Thermal Protection Systems,” PhD Disseration, University of Florida, Dec 2004.

22. Zhu, H., Sankar, B. V., Haftka, R. T., Venkataraman, S., Blosser, M., “Optimization of Functionally Graded Metallic Foam Insulation Under Transient Heat Transfer,” Structural and Multidisciplinary Optimization,Vol. 28, No. 5, Nov. 2004, pp. 349-355.

23. Zhu, H., Sankar, B. V., “Analysis of Sandwich TPS Panel with Functionally Graded Foam Core by Galerkin Method,” Composite Structures, Vol. 77, No. 3, Feb 2007, pp. 280-287.

24. Wicks, N., Hutchinson, J. W., “Optimal Truss Plates,” International Journal of Solids and Structures, Vol. 38, 2001, pp. 5165-5183.

25. Wicks, N., Hutchinson, J. W., “Performance of Sandwich Plates with Truss Cores,” Mechanics of Materials, Vol. 36, 2004, pp. 739-751.

26. Liu, J.-S., Lu, T. J., “Multi-Objective and Multi-Loading Optimization of Ultralightweight Truss Materials,” International Journal of Solids and Structures, Vol. 41, 2004, pp. 619Liu, T., Deng, Z. C., Lu, T. J., “Design Optimization of Truss-Cored Sandwiches with Homogenization,” International Journal of Solids and Structures, Vol. 43, 2006, pp. 7891Zok, F. W., Rathbun, H. J., Wei, Z., Evans, A. G., “Design of Metallic Textile Core Sandwich Panels,” International Journal of Solids and Structures, Vol. 40, 2003, pp. 5707Hyun, S., Karlsson, A. M., Torquato, S., Evans, A. G., “Simulated Properties of Kagome and Tetragonal Truss Core Panels,” International Journal of Solids and Structures, Vol.

40, 2003, pp. 6989-6998.

30. Valdevit, L., Hutchinson, J. W., Evans, A. G., “Structurally Optimized Sandwich Panels with Prismatic Cores,” International Journal of Solids and Structures, Vol. 41, 2004, pp.

5105-5124.

31. Rathbun, H. J., et al, “Measurement and Simulation of the Performance of a Lightweight Metallic Sandwich Structure with a Tetrahedral Truss Core,” Journal of Applied Mechanics-Transaction of ASME, Vol. 71, May 2004, pp. 368-374.

32. Rathbun, H. J., Zok, F. W., Evans, A. G., “Strength Optimization of Metallic Sandwich Panels Subject to Bending,” International Journal of Solids and Structures, Vol. 42, 2005, pp. 6643-6661.

33. Wei, Z., Zok, F. W., Evans, A. G., “Design of Sandwich Panels with Prismatic Cores,” Journal of Engineering Materials and Technology – Transactions of ASME, Vol. 128, April 2006, pp. 186-192.

34. Valdevit, L., Wei, Z., Mercer, C., Zok, F. W., Evans, A. G., “Structural Performance of Near-Optimal Sandwich Panels with Corrugated Cores,” International Journal of Solids and Structures, Vol. 43, 2006, pp. 4888-4905.

35. Gu, S., Lu, T. J., Evans, A. G., “On the Design of Two-Dimensional Cellular Metals for Combined Heat Dissipation and Structural Load Capacity,” International Journal of Heat and Mass Transfer, Vol. 44, 2001, pp. 2163-2175.

36. Sobieszczanski-Sobieski, J., Haftka, R. T., “Multidisciplinary Aerospace Design Optimization: Survey of Recent Developments,” Review Article, Structural Optimization, Vol. 14, 1997, pp. 1-23.

37. Guruswamy, G. P., Obayashi, S., “Study on the Use of High-Fidelity Methods in Aeroelastic Optimization,” Journal of Aircraft, Vol. 41, No. 3, May-Jun 2004, pp. 616Adelman, H. M., Mantay, W. R., “Integrated Multidisciplinary Design Optimization of Rotorcraft,” Journal of Aircraft, Vol. 28, No. 1, Jan 1991, pp. 22-28.

39. Kirsch, U., “Reduced Basis Approximations of Structural Displacements for Optimal Design,” AIAA Journal, Vol. 29, No. 10, Oct 1991, pp. 1751-1758.

40. Hutchinson, M. G., Unger, E. R., Mason, W. H., Grossman, B., Haftka, R. T., “VariableComplexity Aerodynamic Optimization of a High-Speed Civil Transport Wing,” Journal of Aircraft, Vol. 31, No. 1, Jan-Feb 1994, pp. 110-116.

41. Huang, X., Dudley, J., Haftka, R. T., Grossman, B., Mason, W. H., “Structural Weight Estimation for Multidisciplinary Optimization of a High-Speed Civil Transport,” Journal of Aircraft, Vol. 33, No. 3, May-Jun 1996, pp. 608-616.



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