Method used for determining low-load truncation limiting value of flight-by-flight load spectrum

Abstract

The invention discloses a method used for determining the low-load truncation limiting value of a flight-by-flight load spectrum. The method comprises the following steps of: designing a test piece; compiling a plurality of flight-by-flight load spectrums corresponding to a plurality of truncation levels; aiming at each truncation level to independently carry out a crack propagation test on the text piece; taking the truncation levels as independent variables and crack propagation service life as a dependent variable to carry out exponential fitting; according to an exponential fitting formula, calculating a crack propagation service life increment coefficient corresponding to each truncation level; and taking the truncation levels as the independent variables and the crack propagation service life increment coefficients as the dependent variables to carry out polynomial fitting, and determining the low-load truncation limiting value. By use of the method, on a premise of guaranteeing the precision and the accuracy of a full-size fatigue test, a great quantity of small load cycles which slightly affect structure fatigue damages can be effectively truncated, test time is shortened, test cost is lowered, and the method has the advantages of being simple, practical, convenient in operation and high in damage precision, and time and resources are saved.

Description

technical field [0001] The invention relates to the field of aircraft fatigue tests, in particular to a method for determining the low-load cut-off limit value of the continuous flight load spectrum used in aircraft full-scale fatigue tests. Background technique [0002] Compiling the continuous flight load spectrum to simulate the load situation encountered in the real environment is a necessary condition for the full-scale fatigue test of the aircraft. The continuous flight load spectrum is compiled based on the load statistical data. The smaller the load, the higher the probability of occurrence. Therefore, there are infinitely many cycles of small loads in the load spectrum in theory, which makes the load spectrum unable to be compiled completely according to the theoretical situation. In order to compile the load spectrum, a low load cut-off limit must be set, and all loads smaller than the limit are cut off. [0003] The setting of low load cut-off limit has significa...

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is to overcome the difficulty of accurately determining the low-load cut-off limit for the full-scale fatigue test of the aircraft in the prior art, which leads to the difficulty of improving the test efficiency, reducing resource consumption and ensuring the accuracy of the test in the fatigue test deficiencies, propose a method for determining low-load cut-off limits for the continuous flight load spectrum

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