Comparing Effectiveness of Measures That Improve Aircraft Structural Safety
Publication: Journal of Aerospace Engineering
Volume 20, Issue 3
Abstract
This paper aims to discover how the measures that improve aircraft structural safety compare with each other in terms of effectiveness. The safety measures we include here are a load safety factor of 1.5, conservative material properties, redundancy, certification tests, error reduction, and variability reduction. We consider a static point stress design with a simple redundancy model. We model individual errors in calculation (loads, stresses, failure) and in geometry and variability in loading, material properties, and geometry. We use a probabilistic model based on assumed uniform distribution for errors as we often have only upper limits on errors. For variabilities we also use some lognormal distributions. We find that error reduction is more effective than certification testing, which is more effective than using an extra load safety factor. Variability reduction is found to be a very effective way of reducing the probability of failure (more effective than error reduction), but it should be accompanied with an increased B-basis value. In addition, certification testing is found to be effective when errors are large, whereas structural redundancy is found to be more effective when errors are low. We also find that as safety measures are added and the probability of failure is reduced, the uncertainty in that probability of failure increases.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
This work was supported in part by NASA Cooperative Agreement No. NASANCC3-994, NASA University Research Engineering and Technology Institute (URETI), and NASA Langley Research Center Grant No. UNSPECIFIEDNAG1-03070.
References
Acar, E., Haftka, R. T., Sankar, B. V., and Qui, X. (2006). “Increasing allowable flight loads by improved structural modeling.” AIAA J., 44(2), 376–381.
Acar, E., Kale, A., Haftka, R. T., and Stroud, W. J. (2006). “Structural safety measures for airplanes.” J. Aircr., 43(1), 30–38.
Antonsson, E. K., and Otto, K. N. (1995). “Imprecision in engineering design.” J. Mech. Des., 117 B, 25–32.
ASTM. (2002). Composite materials handbook, Philadelphia.
Kale, A. and Haftka, R. T. (2007). “Tradeoffs of weight and inspection cost in reliability based structural optimization.” J. Aircr., in press.
Kale, A. A., and Haftka, R. T. (2005). “Effect of safety measures on reliability of aircraft structures subjected to damage growth.” 31st ASME Design and Automation Conf., Simulation Based Design under Uncertainty, Long Beach, Calif.
Lincoln, J. W. (1980). “Method for computation of structural failure probability for an aircraft.” ASD-TR-80-5035, Wright-Patterson Air Force Base, Ohio.
Long, M. W., and Narciso, J. D. (1999). “Probabilistic design methodology for composite aircraft structures.” FAA Final Rep. No. DOD/FAA/AR-99/2, Washington, D.C.
Melchers, R. E. (1999). Structural reliability: Analysis and prediction, 2nd Ed., Wiley, New York.
Nikolaidis, E., Chen, S., Cudney, H., Haftka, R. T., and Rosca, R. (2004). “Comparison of probability and possibility for design against catastrophic failure under uncertainty.” J. Mech. Des., 126, 386–394.
Oberkampf, W. L., DeLand, S. M., Rutherford, B. M., Diegert, K. V., and Alvin, K. F. (2000). “Estimation of total uncertainty in modeling and simulation.” Sandia National Laboratory Rep. No. SAND2000-0824, Albuquerque, N.M.
Oberkampf, W. L., Deland, S. M., Rutherford, B. M., Diegert, K. V., and Alvin, K. F. (2002). “Error and uncertainty in modeling and simulation.” Reliab. Eng. Syst. Saf., 75, 333–357.
Owen, D. B. (1956). “Tables for computing bivariate normal probabilities.” Ann. Math. Stat., 27, 1075–1090.
Qu, X., Haftka, R. T., Venkataraman, S., and Johnson, T. F. (2003). “Deterministic and reliability-based optimization of composite laminates for cryogenic environments.” AIAA J., 41(10), 2029–2036.
Smarslok, B. P., Haftka, R. T., and Kim, N. H. (2006). “Taking advantage of separable limit states in sampling procedures.” AIAA Paper No. 2006-1632, 47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conf., Newport, R.I.
Society of Automotive Engineers (SAE). (1997). “Integration of probabilistic methods into the design process.” Aerospace Information Rep. No. 5080, Warrendale, Pa.
Vanegas, L. V., and Labib, A. W. (2005). “Fuzzy approaches to evaluation in engineering design.” J. Mech. Des., 127, 24–33.
Wirsching, P. H. (1992). “Literature review on mechanical reliability and probabilistic design.” Probabilistic Structural Analysis Methods for Select Space Propulsion System Components (PSAM), NASA Contractor Report No. 189159, Vol. III, Washington, D.C.
Information & Authors
Information
Published In
Copyright
© 2007 ASCE.
History
Received: Mar 30, 2006
Accepted: Dec 8, 2006
Published online: Jul 1, 2007
Published in print: Jul 2007
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.