Novel method for forecasting calendar life of metal structure of aging aircraft

Abstract

A novel method for forecasting a calendar life of a metal structure of an aging aircraft. The method comprises five steps of: S1, establishing a prior-corroded metal material fatigue property S-N-t curve surface representation model; S2, according to a relative coefficient optimization method, establishing a prior-corroded metal material fatigue property S-N-t curve surface parameter fitness method; S3, establishing a prior-corroded metal material fatigue S-N-t curve surface model in a random stress ratio; S4, establishing a calendar life calculating formula for the metal structure of the aging aircraft under a spectrum load; and S5, substituting material fatigue properties with different prior-corrosion life limits, which are measured by testing, and a fatigue load spectrum counting processing result into the calendar life calculating formula to determine the calendar life of the metal structure of the aging aircraft. The novel method is simple and practical; a small number of model parameters need to be measured by testing; and the calendar life of the metal structure of the aging aircraft can be determined only by substituting the material corrosion fatigue properties with different prior-corrosion life limits and fatigue load spectrum data into the calendar life calculating formula.

Description

Technical field [0001] The invention provides a new method for predicting the calendar life of an aged aircraft metal structure, and belongs to the technical field of fatigue life determination of metal structures. Background technique [0002] As the service life continues to increase, the problem of environmental corrosion of aging aircraft structures has become increasingly prominent. Therefore, the calendar life assessment of their metal structures has become very important. For a long time, a large number of studies have been conducted on the corrosion fatigue of metal structures of aging aircraft at home and abroad, aiming to study the influence of corrosive environment on the fatigue characteristics of metal structures and the failure mechanism, and establish an accurate calendar life assessment method for metal structures of aging aircraft. At present, the evaluation method of fatigue life of old aircraft metal structure in corrosive environment is mainly from the perspec...

AI Technical Summary

Problems solved by technology

At present, the evaluation method of fatigue life of aging aircraft metal structures in corrosive environments is mainly based on the perspective of metal corrosion damage evolution, using the method of fracture mechanics to predict and evaluate the fatigue life of materials and structures in corrosive environments. Some deficiencies: (1) There are many material parameters to be measured, not only the number, depth, shape, etc. crack growth rate), (2) the predicted corrosion fatigue life of metal structures often only considers the fracture and failure process of a certain key corrosion pit, and ignores the interaction between corrosion pits, which is inconsistent with the actual situation

In fact, a considerable number of aircraft (such as rescue and special aircraft, etc.) have low flight intensity and are parked on the ground most of the time during their service, which is vulnerable to corrosion by the corrosive environment. It has a weak impact on the fatigue performance of the structure. The damage mode of its metal structure is an alternating process of corrosion damage on the ground and fatigue damage in flight. Therefore, it is necessary to establish a simple and practical The calendar life assessment method of

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