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Repeated Loads Above the Proportional Limit on 24-ST Aluminum Alloy


Nelson, Conrad Nathaniel (1948) Repeated Loads Above the Proportional Limit on 24-ST Aluminum Alloy. Engineer's thesis, California Institute of Technology. doi:10.7907/V6ZX-5G92.


The purpose of this investigation was to study the effect of repeated tensile stresses above the proportional limit on 24ST aluminum alloy. The investigation consisted in obtaining data on prepared specimens of 24ST aluminum alloy in a machine capable of applying a pure tension stress, repeated many times a minute, without shock but with a high rate of loading. It was found that permanent deformation caused by overstressing is not a useful factor in forecasting the life expectancy of the specimen being tested. It was also found that the effects of "aging" (elapsed time between overstresses), initial stresses, and magnitude of overstresses applied, all have a definite influence on the ability of 24ST aluminum alloy to withstand further overstressing. However, these effects are so scattered between different specimens of the same material that they cannot be determined accurately, either qualitatively or quantitatively, without a thorough statistical survey. It is considered that this investigation merely points the way to a further study of the behavior of all aircraft materials above the proportional limit. The investigation was carried out at the Daniel Guggenheim Aeronautical Laboratory, California Institute of Technology, Pasadena, California. (referred to hereafter as GALCIT.)

Item Type:Thesis (Engineer's thesis)
Subject Keywords:Aeronautics
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Sechler, Ernest Edwin
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1948
Record Number:CaltechETD:etd-12192008-105659
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5079
Deposited By: Imported from ETD-db
Deposited On:15 Jan 2009
Last Modified:22 Mar 2023 18:06

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