JPS6234900A - Mechanical strength estimation method during aircraft operation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for estimating mechanical strength during aircraft operation, and in particular, a method that applies the AE phenomenon (acoustic emission) to estimate the mechanical strength during aircraft operation. ) on how to monitor.

(Conventional technology) (a) Conventionally, ground maintenance inspections before and after aircraft operation have mainly been based on visual inspections. Non-destructive testing using flaw detectors is partially carried out.

(b) Accumulative deterioration of adult plants over time is a problem, but in the past, repeated load tests were carried out using an indoor experimental machine as a representative example, and a relational expression between the number of repetitions and fatigue fracture strength was determined, and then used. We check the actual usage time and number of times the aircraft has been used to estimate the degree of deterioration and conduct periodic inspections.

(c) Regarding pilot training, there is no quantitative method to point out poor or inappropriate pilot performance, and the training relies solely on instructors' practical guidance.

(d) When carrying out emergency flights such as typhoon observation or work flights through typhoons, pilots have traditionally relied on their intuition, and have focused their efforts on cultivating that intuition.

(e) During experimental flight operations, there was no way to predict dangers due to unstable loads such as flying or hanging, which sometimes caused pilots to feel uneasy.

(Problem to be solved by the invention) (b) Speed up ground maintenance inspections and improve operational efficiency.

(b) Simplify and improve the accuracy of the method for estimating aging of the aircraft, and quickly and appropriately prepare for periodic inspections.

(c) Contribution to pilot education.

(d) Establishment of environmental monitoring methods during emergency flights.

(e) Danger limit monitor during test and experiment flights.

(Means and effects for solving the problem) The present invention addresses the above points, and provides an AE sensor (a pickup for detecting ultrasonic waves generated by the aircraft) in the body of the aircraft, so that the AE sensor during flight The above-mentioned problems were solved by measuring the phenomenon (a phenomenon in which an object generates ultrasonic waves when a mechanical force is applied to it) and estimating the ultimate safety strength of the aircraft. This paper attempts to provide an intensity estimation method.

In the present invention, for example, AE sensors are affixed to several important locations on the aircraft, and AE phenomena are automatically measured in real time during flight operations at the required locations or in a wider area, and the results are transmitted to the cockpit of the aircraft. Above is the AE occurrence curve (with time on the horizontal axis and the event incidence rate of AE phenomena on the vertical axis)
and an amplitude distribution curve (indicating the frequency distribution of the maximum amplitude of an event) and a slope value (details will be described later).

For each curve and slope value, safe, caution, and danger areas are indicated by color, for example.

The pilot flies while monitoring this, confirms the safety strength, and continues flying.The pilot also automatically records the results (using magnetic disks, etc.), and automatically organizes and analyzes them using Kenpo. This will be used as material for short-term maintenance and long-term periodic inspections based on aging deterioration.

(Example) Hereinafter, an example of the method for estimating mechanical strength during aircraft operation according to the present invention will be described with reference to the drawings.

(1) First, we conducted an experimental study of the AE generation phenomena leading up to their failure through fracture strength tests on aircraft materials and partial models, and examined the characteristics of the AE event occurrence rate and the pattern of amplitude distribution.

FIG. 1 shows the change in the incidence of AE events in repeated load tests of riveted aluminum plates used as aircraft materials. In the figure, the horizontal axis is time (0 seconds to 2000 seconds)
, the vertical axis is the number of events per second (number of events). Here, the event consists of multiple ultrasound pulses.

Figure 2 (A) is a logarithmic representation of the maximum amplitude value A and the number of events shown by each of the AE events in Figure 1, where the horizontal axis represents the maximum amplitude value A in dB, and the vertical axis represents the number of events. It is a common logarithmic display.

It can be seen that in this strength test, the slope value of this material is designated by m, and at the verge of failure is designated by J. That is, the m value of 3.4 is the basic safety limit for this test and the material, and if it is smaller than this, there is an abnormality in strength, and if it is 0.6 or less, it will immediately break.

FIG. 2(B) is an example of μ values showing strength changes in tensile tests of aircraft aluminum materials.

In this figure as well, the horizontal axis is the maximum amplitude value A in dB, and the vertical axis is the common logarithm of the number of events. In the tensile test, the slope value of this material is given in ml, and on the verge of failure it is 1
112. The m value of 1.5 is the basic safety limit for this test and for the material; anything smaller than this indicates an abnormality in strength, and anything less than 0.7 indicates immediate destruction.

(2) Operation status and AE of large and small aircraft in practical use, mainly Safir type and C-1 type transport islands.
It was clarified that there is a characteristic relationship between the developmental phenomena.

Figure 3 shows A during the period from takeoff to air glide of the C-1 aircraft.
E is a record of events, the horizontal axis is time (0 seconds to 2000 seconds), and the vertical axis is the number of events per second (number of events).

Figure 4 is a record of AE$ events corresponding to the operational status of the C-1 aircraft, and the horizontal axis is time (1300 seconds to 3300 seconds).
, the vertical axis is the number of events per second (number of events).

(3) As an example of a malfunction occurring in an actual aircraft, for the C-1 Airplane, if the rear door of the aircraft is opened during flight,
E occurrence status indicates an abnormality.

Figure tjS5 is a record of the AE$ event associated with the opening and closing of the rear door of the C-1 aviation rock (in the figure, M1 is open, M2 is closed, M is open, M is closed), and the horizontal axis is time (0 seconds to 1000 seconds), and the vertical axis is the number of events per second (number of events).

Figure 6 shows the number of events corresponding to Ml to M4 during the operation of the C-1 aircraft in Figure 5, a double logarithmic representation of the amplitude, and the slope value of the straight line 11.
11 to m, the horizontal axis is the maximum amplitude value A in dB, and the vertical axis is the common logarithm of the number of events. It can be seen that the odors at the curved points P1 to P of each straight line show an abnormality in intensity, and that the intensity needs to be checked at that sensor position.

If this condition is left as it is and the flight continues, it is inevitable that the aircraft will malfunction, and this will be considered a structural abnormality.
Looking at the AE occurrence status and amplitude distribution trends during that time, F
The trend is the same as in Figure A1 and Figures 2 (A) and (B), and in the case of Figure 6, the straight line group showing the slope value of the tooth product amplitude frequency distribution is revised and duplicated for each AE100 phenomenon. This shows a different feature from the one shown in the supplementary explanatory diagram (displayed) where the slope value is constant and no abnormality appears.

(4) From these experimental results, the deterioration of the aircraft structure and the limits of safety strength are determined depending on the focus point and maintenance purpose.

Then, the AE″Js event occurrence rate and the maximum amplitude A of that AE event
It can be determined by the slope value of the cumulative frequency distribution expressed in double logarithm.

(Effects of the Invention) As explained above, the method for estimating mechanical strength during aircraft operation according to the present invention can be applied to aircraft in operation and is useful for their safety. ! It is useful for speeding up maintenance inspections, and its effects are listed below.

(b) It is possible to quickly discover the necessary locations and extent of maintenance and repairs before and after aircraft transportation, shorten the time required for work, and quickly certify safety.

(b) By practicing Kempo all the time or repeatedly for a certain period of time, you can learn about sudden breakdowns and changes in the machine over time.
It is possible to clarify the necessity of periodic inspections and evaluate inspection results.

(c) By adopting Kenpo when carrying out training at flight schools, training centers, etc., the suitability of the trainee's movements can be quantitatively displayed and used for teaching purposes.

(d) By using Kenpo during emergency flights in special environments such as abnormal weather and monitoring environmental resistance, it is possible to know the safety limits and prevent dangers before they occur.

(e) Able to fly while confirming the safety of the main body during various dangerous tests and test flights.

[Brief explanation of drawings]

Figure 1 is a graph showing the transition of the AE event incidence rate in repeated load tests of riveted aluminum plates in an embodiment of the method for estimating mechanical strength during aircraft operation according to the present invention. Graph showing the maximum amplitude value A of each AE event in Figure 1 and logarithmic representation of the number of events, 2nd
Figure (B) is a graph showing strength changes in tensile tests of aircraft aluminum materials, Figure 3 is a graph showing records of AE$ events from takeoff to air glide of the C-1 aircraft, and Figure 4 is C-1. Figure 5 is a graph showing the record of AE events associated with the opening and closing of the rear door of the C-1 aircraft.
5J corresponding to M during operation of C-1 Aeroiso in the figure, thru M,
s quadrant, logarithmic display of amplitude, straight line slope value W, or In
4, and FIG. 7 is a supplementary explanatory graph in which straight line groups indicating the slope values of the cumulative amplitude frequency distribution are revised and displayed overlappingly for each AE100 phenomenon.

Claims (2)

[Claims] (1) A method for estimating mechanical strength during aircraft operation, characterized by arranging an AE sensor in the body of an aircraft, measuring AE phenomena during flight, and estimating the ultimate safety strength of the aircraft. (2) The mechanical strength estimating method during aircraft operation according to claim 1, wherein the limit of the safety strength of the aircraft body is estimated from the frequency distribution of the maximum amplitude of the event in the AE phenomenon.