CN104316457A - Method for determining reliability of calendar life of airplane structure protection system - Google Patents

Abstract

The invention discloses a method for determining the reliability of the calendar life of an airplane structure protection system. The method includes the following steps that firstly, a relation model of the corrosion damage amount of a structure base body and the corrosion time is established; secondly, a corrosion test of a protection system test piece is conducted, and a calendar safe service life expression of the protection system is established; thirdly, a relation model of the maintenance cost and the reliability is established, and the reliability value enabling the air fleet maintenance cost to be the lowest is solved; fourthly, the limiting conditions of the reliability are determined. The method has the advantages that the method for determining the reliability of the calendar life of the airplane structure protection system lays a foundation for reasonably determining the calendar safe life of the airplane structure protection system and has significance on reducing of the maintenance cost of an airplane and keeping of the combat readiness rate of equipment on the premise that the structural safety of the airplane is ensured.

Description

The defining method of aircaft configuration protection system calendar life fiduciary level

Technical field

The present invention relates to a kind of defining method of aircaft configuration protection system calendar life fiduciary level, belong to aircaft configuration and determine longevity technical field.

Background technology

The life-span of aircraft refers to aircraft term of life from the retired grounding of coming into operation under normal service state, refer generally to the structural life-time of airframe, there are two leading indicators: one is consider that flight alternate load is to the fatigue lifetime of structure influence, characterizes with pilot time number or the number of times that rises and falls; Two is consider that environmental corrosion is to the calendar life of structure influence, characterizes with tenure of use.

Determine the fatigue lifetime in longevity for aircaft configuration, do not refer to life-span when aircaft configuration destroys, but a safe life limits value with high-reliability, i.e. the fatigue safety life-span.Such as, if aircraft structure fatigue life-span obeys logarithm normal distribution, usually will provide the fatigue safety life-span of satisfied 0.999 fiduciary level and 0.90 confidence level, corresponding tired dispersion coefficient gets 4.

Determine the calendar life in longevity for aircaft configuration, the calendar of present stage is determined the longevity and is directly provided by analysis of experiments result, wherein there is not the process of statistical study.And in fact, the calendar life of aircaft configuration is also a probable value, the time of real aircraft structure generation corrosion failure has dispersiveness, namely there is the concept of calendar safe life.

The calendar safe life of aircaft configuration protection system is that aircaft configuration is under environment for use and service condition, can complete the calendar service time of its using function according to the determined aircaft configuration protection system of safe-life design criterion, the aircaft configuration protection system namely obtained by fail-safe analysis has the calendar life restriction of particular etch failure probability.

The calendar safe life of aircaft configuration protection system is not only relevant with the environment for use of protection system itself and aircraft, also relevant with the fiduciary level chosen.If it is on the low side that fiduciary level is chosen, have more structural shielding system when then arriving protection system calendar safe life to lose efficacy, more structural matrix material is caused to corrode, thus need to place under repair to more position when aircraft overhaul, some position even may cause structure to change part owing to failing to be repaired in time after protection system inefficacy, adds the working service cost of aircraft; If it is higher that fiduciary level is chosen, by partially short for the protection system calendar safe life causing determining thus, make structure overhaul relatively frequent, not only make the Inspection and maintenance cost of aircraft increase, also can affect the Operational Ready Rate of aircraft; In addition, choosing of structural shielding system calendar life fiduciary level, also must will guarantee that structural matrix did not lose efficacy within the calendar cycle that this fiduciary level is corresponding.

In order to reasonably determine aircaft configuration protection system calendar safe life, the defining method of a kind of aircaft configuration protection system of necessary proposition calendar life fiduciary level.

Summary of the invention

The object of the present invention is to provide a kind of defining method of aircaft configuration protection system calendar life fiduciary level, under the prerequisite ensureing structural safety, make the maintenance cost of structure minimum, for reasonably determining aircaft configuration protection system calendar safe life, aircaft configuration is used to provide Theories and methods support economically and safely.

In order to realize above-mentioned target, the present invention adopts following technical scheme:

A defining method for aircaft configuration protection system calendar life fiduciary level, is characterized in that, comprise the following steps:

Step 1: according to the corrosion damage type of structural matrix, carry out structural matrix simulating piece accelerated corrosion test under experimental conditions, testpieces is divided into many groups, each group is experienced different abrasion cycles and determines the structure erosion amount of damage after different abrasion cycle, and set up the average corrosion amount of damage of structural matrix and the relational model of etching time, foregoing model is:

h＝f(t)(1)

In formula (1), h is average corrosion amount of damage, and t is equivalent etching time;

Step 2: carry out the corrosion test of protection system testpieces under equivalent accelerated corrosion environment, according to the criterion of protection system calendar to the longevity, obtain equivalent etching time when different tests part reaches failure criteria, according to the regularity of distribution of test findings determination protection system calendar life, obtain the calendar safe life expression formula of protection system:

$N_{\mathrm{\α}}=\stackrel{\‾}{N}-k_{\mathrm{\α}}\·S---\left(2\right)$

In formula (2), N _αfor the protection system calendar safe life under fiduciary level α, N is the mean value testing the protection system calendar life obtained, k _αfor meeting the monolateral tolerance factor of fiduciary level α and given confidence level, S is the standard deviation testing the protection system calendar life obtained;

Step 3: suppose that the expense that structure economics is repaired is C ₀, the expense that structure changes part is C ₁, the other fees of Aviation Fleet Maintenance are C ₂, the maintenance total expenses of whole group of planes m part structure is C, then supposes a fiduciary level α ', is reaching calendar safe life N _αm (1-α) part protection system failure structure in, have the matrix of m (1-α ') part structure at least under corrosion environment, to experienced by t _cthe long time, existence function relation between fiduciary level α ' and fiduciary level α:

α′＝g(α) (8)

Selected fiduciary level α determines the calendar safe life of protection system, then Aviation Fleet Maintenance total expenses C when reaching protection system calendar safe life is:

C＝C ₀·{m(1-α)-0.5m[1-g(α)]}+C ₁·0.5m[1-g(α)]+C ₂ (9)

A group of planes is often on active service the overhaul cost C apportioned by a year _afor:

$C_a=\frac{C}{N_{\mathrm{\α}}}=\frac{C}{\stackrel{\‾}{N}-k_{\mathrm{\α}}\·S}---\left(10\right)$

The derivative of formula (10) is got 0, obtains making the value of the fiduciary level α that Aviation Fleet Maintenance cost is minimum;

Step 4: suppose a fiduciary level β, is reaching calendar safe life N _αm (1-α) part protection system failure structure in, have the matrix of m (1-β) part structure at least under corrosion environment, to experienced by t _βthe long time, existence function relation between fiduciary level β and fiduciary level α:

β＝l(α) (13)

Then the fiduciary level λ of structural matrix is:

$\mathrm{\λ}=1-\frac{0.5m(1-\mathrm{\β})}{m}=0.5[1+l\left(\mathrm{\α}\right)]---\left(14\right)$

If the actual fiduciary level of the structural matrix determined by α value meets structural reliability requirement, then this α value selected is as the fiduciary level of protection system calendar life;

If can not meet, then require to determine protection system calendar life fiduciary level α by counter the pushing away of formula (17) according to the fiduciary level of structure:

α＝l ^-1(2λ-1) (17)。

The defining method of aforesaid aircaft configuration protection system calendar life fiduciary level, it is characterized in that, in step (1), aforementioned structure matrix simulating piece is without surfacecti proteon system and can reflect the local feature of structural matrix, and preceding experimental conditions can reflect the actual Service Environment of aircaft configuration and have clear and definite equivalent relation.

The defining method of aforesaid aircaft configuration protection system calendar life fiduciary level, is characterized in that, in step (2), for the k under normal distyribution function _αvalue, try to achieve by formula (4) is approximate:

$k_{\mathrm{\α}}=\frac{{\mathrm{\μ}}_{\mathrm{\α}}+{\mathrm{\μ}}_{\mathrm{\γ}}\sqrt{\frac{1}{n}[1-\frac{{\mathrm{\μ}}_{\mathrm{\γ}}^2}{2(n-1)}]+\frac{{\mathrm{\μ}}_{\mathrm{\α}}^2}{2(n-1)}}}{1-\frac{{\mathrm{\μ}}_{\mathrm{\γ}}^2}{2(n-1)}}---\left(4\right)$

In formula (4), n is the number of testpieces, μ _αthe standard normal deviator relevant to fiduciary level α, μ _γthe standard normal deviator relevant to degree of confidence γ.

Usefulness of the present invention is: the defining method that The present invention gives aircaft configuration protection system calendar life fiduciary level, for reasonably determining that aircaft configuration protection system calendar safe life is laid a good foundation, under the prerequisite ensureing aircaft configuration security, to reducing the maintenance cost of aircraft and keeping the Operational Ready Rate of equipment significant.

Embodiment

Choosing of aircaft configuration protection system calendar life fiduciary level, closely related with the corrosion damage rule of structural matrix, the fiduciary level chosen not only will ensure the safety of structure, also will, from the angle of economy, make the working service cost of aircraft minimum.

Elaborate below in conjunction with the defining method of specific embodiment to aircaft configuration protection system calendar life fiduciary level of the present invention.

The defining method of aircaft configuration protection system calendar life fiduciary level of the present invention, specifically comprises the steps:

Step 1: the relational model setting up structural matrix corrosion damage amount and etching time

The type of impairment that aircaft configuration matrix occurs under corrosion environment has a variety of, as the not contingent spot corrosion of loaded structure, degrades, the contingent corrosion fatigue of loaded structure, stress corrosion crack etc.

According to the corrosion damage type of structural matrix, carry out structural matrix simulating piece accelerated corrosion test in laboratory conditions.Require testpieces without surfacecti proteon system in process of the test and can reflect the local feature of structural matrix, test condition (corrosion environment and load environment) can reflect the actual Service Environment of aircaft configuration and have clear and definite equivalent relation.Testpieces is divided into many groups, and each group different abrasion cycle of experience also determines the structure erosion amount of damage after different abrasion cycle, and sets up the average corrosion amount of damage of structural matrix and the relational model of etching time, and this model is:

h＝f(t) (1)

In formula (1), h is average corrosion amount of damage, and namely fiduciary level is the corrosion damage amount of 50%; T is equivalent etching time; F (t) is the funtcional relationship of average corrosion amount of damage and matrix corrosion time.

According to the residual intensity requirement of aircaft configuration requirement for major repairs and structure, determine that structure reaches the damage critical value h changing part requirement _cthe damage critical value h scrapping requirement is reached with structure _b.

When structural damage amount reaches the damage critical value h changing part requirement _ctime, namely think that uneconomical or after repairing the structure of structure repair can not ensure flight safety, need the replacing carrying out structure;

When structural damage amount reaches the damage critical value h scrapping requirement _btime, namely think that structure can not continue to use again, as re-used the danger by there being fracture suddenly.

Step 2: the corrosion test of carrying out protection system testpieces, sets up the calendar safe life expression formula of protection system

Carry out the corrosion test of protection system testpieces under equivalent accelerated corrosion environment, according to the criterion of protection system calendar to the longevity, obtain equivalent etching time when different tests part reaches failure criteria, i.e. the calendar life of different tests part, is designated as Ni by the calendar life of i-th testpieces.

According to the calendar life testing the different tests part obtained, calculate the mean value of protection system calendar life

$\stackrel{\‾}{N}=\frac{1}{n}\·\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{N}_i---\left(3\right)$

N is the number of testpieces.

According to testing the calendar life of different tests part and the mean value of protection system calendar life that obtain, calculate the standard deviation S testing the calendar life obtained:

$S=\sqrt{\frac{1}{n-1}\·\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(N_i-\stackrel{\‾}{N})}^2}---\left(5\right).$

According to above test findings and result of calculation, determine the regularity of distribution of protection system calendar life, and obtain the calendar safe life expression formula of protection system with this:

$N_{\mathrm{\α}}=\stackrel{\‾}{N}-k_{\mathrm{\α}}\·S---\left(2\right)$

In formula (2), N _αfor the protection system calendar safe life under fiduciary level α, k _αfor meeting the monolateral tolerance factor of fiduciary level α and given confidence level.

Monolateral tolerance factor k _αobtain, for the k under normal distyribution function by consulting handbook _αvalue, can try to achieve by formula (4) is approximate:

$k_{\mathrm{\α}}=\frac{{\mathrm{\μ}}_{\mathrm{\α}}+{\mathrm{\μ}}_{\mathrm{\γ}}\sqrt{\frac{1}{n}[1-\frac{{\mathrm{\μ}}_{\mathrm{\γ}}^2}{2(n-1)}]+\frac{{\mathrm{\μ}}_{\mathrm{\α}}^2}{2(n-1)}}}{1-\frac{{\mathrm{\μ}}_{\mathrm{\γ}}^2}{2(n-1)}}---\left(4\right)$

In formula (4), μ _αthe standard normal deviator relevant to fiduciary level α, μ _γthe standard normal deviator relevant to degree of confidence γ.

If the quantity of structure is m part in an actual group of planes, then arrive calendar safe life N _αtime, having the degree of confidence of γ to think has the protection system of m (1-α) part structure to lose efficacy at the most.

Equally, for arbitrary fiduciary level α ', when reaching the calendar safe life N determined with this fiduciary level _{α '}time, having the degree of confidence of γ to think has the protection system of m (1-α ') part structure to lose efficacy at the most.

Step 3: the relational model setting up maintenance cost and fiduciary level, tries to achieve the reliability value making Aviation Fleet Maintenance cost minimum

Suppose that the expense that structure economics is repaired is C ₀, the expense that structure changes part is C ₁, the other fees of Aviation Fleet Maintenance (as disassemble, transport etc.) are C ₂, the maintenance total expenses of whole group of planes m part structure is C.

It is h that structure reaches the damage critical value of changing part requirement _c, the average corrosion amount of damage of structural matrix and the relational model of etching time are h=f (t), this means that the structural matrix that protection system lost efficacy experienced by t _c=f ^-1(h _c) after the time, nearly half needs to carry out changing part.Suppose a fiduciary level α ', reach calendar safe life N _αm (1-α) part protection system failure structure in, have the matrix of m (1-α ') part structure at least under corrosion environment, to experienced by t _cthe long time, then N _α-N _{α '}=t _c, wherein, N _{α '}for the calendar safe life determined by fiduciary level α '.At calendar safe life N _αtime, arrive the damage critical value h changing part requirement _cstructure number of packages be 0.5m (1-α ').Therefore, equation can be obtained:

$\begin{array}{c}{N}_{\mathrm{\α}}-N_{{\mathrm{\α}}^{\′}}=(\stackrel{\‾}{N}-k_{\mathrm{\α}}\·S)-(\stackrel{\‾}{N}-k_{{\mathrm{\α}}^{\′}}\·S)\\ =(k_{{\mathrm{\α}}^{\′}}-k_{\mathrm{\α}})\·S\\ =f^{-1}\left(h_C\right)\end{array}---\left(6\right)$

That is:

$k_{{\mathrm{\α}}^{\′}}=\frac{f^{-1}\left(h_C\right)}{S}+k_{\mathrm{\α}}---\left(7\right)$

Visible, existence function relation between fiduciary level α ' and fiduciary level α, can be write as:

α′＝g(α) (8)

Therefore, if selected fiduciary level α determines the calendar safe life of protection system, then Aviation Fleet Maintenance total expenses C when reaching protection system calendar safe life is:

C＝C ₀·{m(1-α)-0.5m[1-g(α)]}+C ₁·0.5m[1-g(α)]+C ₂ (9)

Only still can not weigh the overhaul economy of a group of planes in total life cycle by the maintenance total expenses of a group of planes when an overhaul.If the protection system calendar life fiduciary level chosen is very high, a group of planes can be made very low in the expense of single overhaul, but can maintenance frequency be increased; Cultivate greatly from all in group of planes total life cycle, its expense sum may be very high.Therefore, the overhaul cost C that often should be on active service apportioned by a year with a group of planes _aweigh overhaul economy.

$C_a=\frac{C}{N_{\mathrm{\α}}}=\frac{C}{\stackrel{\‾}{N}-k_{\mathrm{\α}}\·S}---\left(10\right)$

In formula (9) and formula (10), m, C ₀, C ₁, C ₂, s is known quantity, and therefore, the overhaul cost of a group of planes is the function of protection system calendar life fiduciary level α.

The derivative of formula (10) is got 0, can obtain making the value of the fiduciary level α that Aviation Fleet Maintenance cost is minimum.

Step 4: the restrictive condition determining fiduciary level

The fiduciary level α making Aviation Fleet Maintenance cost minimum can be determined after have passed through step 3, but still can not determine that this fiduciary level is exactly the protection system calendar life fiduciary level that will choose.From the angle of safety of structure, the protection system calendar life fiduciary level chosen must ensure that aircaft configuration has very high fiduciary level and failure fracture do not occur simultaneously, and namely the fiduciary level of protection system calendar safe life is subject to the restriction of safety of structure.

It is h that structure reaches the damage critical value of scrapping requirement _b, the structural matrix that namely protection system lost efficacy experienced by t _b=f ^-1(h _b) after the time, nearly half needs to scrap.Suppose a fiduciary level β, reach calendar safe life N _αm (1-α) part protection system failure structure in, have the matrix of m (1-β) part structure at least under corrosion environment, to experienced by t _βthe long time, then N _α-N _β=t _β, wherein, N _βfor the calendar safe life determined by fiduciary level β; At calendar safe life N _αtime, arriving the structure number of packages scrapping the damage critical value of requirement is 0.5m (1-β).Therefore, equation can be obtained:

$N_{\mathrm{\α}}-N_{\mathrm{\β}}=(\stackrel{\‾}{N}-k_{\mathrm{\α}}\·S)-(\stackrel{\‾}{N}-k_{\mathrm{\β}}\·S)$

＝(k _β-k _α)·S

＝f ^-1(h _B) (11)

That is:

$k_{\mathrm{\β}}=\frac{f^{-1}\left(h_B\right)}{S}+k_{\mathrm{\α}}---\left(12\right)$

Visible, existence function relation between fiduciary level β and fiduciary level α, can be write as:

β＝l(α)(13)

Then the fiduciary level λ of structural matrix is:

$\mathrm{\λ}=1-\frac{0.5m(1-\mathrm{\β})}{m}=0.5[1+l\left(\mathrm{\α}\right)]---\left(14\right)$

If the actual fiduciary level of the structural matrix determined by α value meets structural reliability requirement, then this α value selected is as the fiduciary level of protection system calendar life; If can not meet, then need to require to determine protection system calendar life fiduciary level α by counter the pushing away of formula (17) according to the fiduciary level of structure:

α＝l ^-1(2λ-1) (17)。

Below for the protection system of certain type military airframe bulkhead, further illustrate the deterministic process of aircaft configuration protection system calendar life fiduciary level.

By test the structural parameters determined and known related data as follows:

(1) relational model of structural matrix corrosion damage amount and etching time

Corrosion test by experiment under the acceleration environment of room, determine that the maximum corrosion depth of bulkhead matrix material with the Changing Pattern of equivalent etching time is:

h＝0.08t+0.28 (15)

Formula (15) fitting precision R=0.994, engineering demands, data reliability is 50%.In formula (15), h is the maximum corrosion depth of bulkhead matrix material, and unit is mm, t is equivalent etching time, and unit is year.

(2) according to the requirement of structure repair level and residual intensity, structure reaches the damage critical value h changing part requirement _c=0.6mm; Structure reaches the damage critical value h scrapping requirement _b=1.0mm.

(3) corrosion test of n=30 part protection system testpieces under equivalent accelerated corrosion environment has been carried out, the aluminium coating that protection system calendar is matrix surface to the criterion in longevity corrodes, and obtains the equivalent etching time (calendar life) when different tests part reaches failure criteria.

By the existing method determining Data distribution8 rule, learn the calendar life Normal Distribution of protection system, and obtain the mean value of protection system calendar life year, calendar life standard deviation S=1.5.

(4) in a group of planes, the number of packages of bulkhead structure is m=1000 part, and the economic repair expense of bulkhead is C ₀=1 ten thousand yuan/part, changing part expense is C ₁=30 ten thousand yuan/part, the other fees total value that a group of planes is repaired is C ₂=3,000 ten thousand yuan.

According to formula (6) and formula (7), k _{α '}=k _α+ 2.66.According to formula (9) and formula (10), when reaching protection system calendar safe life, the annual apportioned overhaul cost of a group of planes is:

$C_a=\frac{18500-1000\mathrm{\α}-14500g\left(\mathrm{\α}\right)}{12-1.5k_{\mathrm{\α}}}---\left(16\right)$

Due to g (α), k _αexpression formula more complicated, cause above formula to be not easy to differentiate, C can be carried out by computer software _asolving of minimum value.Getting degree of confidence is 0.90, tries to achieve the maintenance cost C that a group of planes is shared every year _aminimum value be 308.1 ten thousand yuan/year, corresponding fiduciary level α is 0.661, and protection system calendar safe life is 11 years.

According to formula (12) to formula (14), the structural reliability of protection system calendar life fiduciary level α=0.661 correspondence is 0.99999999, that is, consider from the angle of calendar safe life, substantially can not lose efficacy reaching overhaul pre-structure.

By above-mentioned analysis, this type can be defined as 0.661 in the protection system calendar life fiduciary level at this position.

If the calendar life fiduciary level of protection system is taken as 0.999 according to existing fatigue life reliability, then the protection system calendar safe life that the present embodiment is corresponding is 6.4 years, the maintenance cost C that the group of planes obtained is shared every year _abe 472.5 ten thousand yuan/year, this not only adds the expense of maintenance, also have impact on the Operational Ready Rate of aircraft.

As can be seen here, the defining method of the aircaft configuration protection system calendar life fiduciary level that the present invention provides, for reasonably determining that aircaft configuration protection system calendar safe life is laid a good foundation, under the prerequisite ensureing aircaft configuration security, to reducing the maintenance cost of aircraft and keeping the Operational Ready Rate of equipment significant.

It should be noted that, above-described embodiment does not limit the present invention in any form, the technical scheme that the mode that all employings are equal to replacement or equivalent transformation obtains, and all drops in protection scope of the present invention.

Claims (3)

1. the defining method of aircaft configuration protection system calendar life fiduciary level, is characterized in that, comprise the following steps:

Step 1: according to the corrosion damage type of structural matrix, carry out structural matrix simulating piece accelerated corrosion test under experimental conditions, testpieces is divided into many groups, each group is experienced different abrasion cycles and determines the structure erosion amount of damage after different abrasion cycle, and set up the average corrosion amount of damage of structural matrix and the relational model of etching time, described model is:

h＝f(t) (1)

In formula (1), h is average corrosion amount of damage, and t is equivalent etching time;

Step 2: carry out the corrosion test of protection system testpieces under equivalent accelerated corrosion environment, according to the criterion of protection system calendar to the longevity, obtain equivalent etching time when different tests part reaches failure criteria, according to the regularity of distribution of test findings determination protection system calendar life, obtain the calendar safe life expression formula of protection system:

$N_{\mathrm{\α}}=\stackrel{\‾}{N}-k_{\mathrm{\α}}\·S---\left(2\right)$

In formula (2), N _αfor the protection system calendar safe life under fiduciary level α, for testing the mean value of the protection system calendar life obtained, k _αfor meeting the monolateral tolerance factor of fiduciary level α and given confidence level, S is the standard deviation testing the protection system calendar life obtained;

Step 3: suppose that the expense that structure economics is repaired is C ₀, the expense that structure changes part is C ₁, the other fees of Aviation Fleet Maintenance are C ₂, the maintenance total expenses of whole group of planes m part structure is C, then supposes a fiduciary level α ', is reaching calendar safe life N _αm (1-α) part protection system failure structure in, have the matrix of m (1-α ') part structure at least under corrosion environment, to experienced by t _cthe long time, existence function relation between fiduciary level α ' and fiduciary level α:

α′＝g(α) (8)

Selected fiduciary level α determines the calendar safe life of protection system, then Aviation Fleet Maintenance total expenses C when reaching protection system calendar safe life is:

C＝C ₀·{m(1-α)-0.5m[1-g(α)]}+C ₁·0.5m[1-g(α)]+C ₂ (9)

A group of planes is often on active service the overhaul cost C apportioned by a year _afor:

$C_a=\frac{C}{N_{\mathrm{\α}}}=\frac{C}{\stackrel{\‾}{N}-k_{\mathrm{\α}}\·S}---\left(10\right)$

The derivative of formula (10) is got 0, obtains making the value of the fiduciary level α that Aviation Fleet Maintenance cost is minimum;

Step 4: suppose a fiduciary level β, is reaching calendar safe life N _αm (1-α) part protection system failure structure in, have the matrix of m (1-β) part structure at least under corrosion environment, to experienced by t _βthe long time, existence function relation between fiduciary level β and fiduciary level α:

β＝l(α) (13)

Then the fiduciary level λ of structural matrix is:

$\mathrm{\λ}=1-\frac{0.5m(1-\mathrm{\β})}{m}=0.5[1+l\left(\mathrm{\α}\right)]---\left(14\right)$

If the actual fiduciary level of the structural matrix determined by α value meets structural reliability requirement, then this α value selected is as the fiduciary level of protection system calendar life;

If can not meet, then require to determine protection system calendar life fiduciary level α by counter the pushing away of formula (17) according to the fiduciary level of structure:

α＝l ^-1(2λ-1) (17)。

2. the defining method of aircaft configuration protection system calendar life fiduciary level according to claim 1, it is characterized in that, in step (1), described structural matrix simulating piece is without surfacecti proteon system and can reflect the local feature of structural matrix, and described experiment condition can reflect the actual Service Environment of aircaft configuration and have clear and definite equivalent relation.

3. the defining method of aircaft configuration protection system calendar life fiduciary level according to claim 1, is characterized in that, in step (2), for the k under normal distyribution function _αvalue, try to achieve by formula (4) is approximate:

$k_{\mathrm{\α}}=\frac{{\mathrm{\μ}}_{\mathrm{\α}}+{\mathrm{\μ}}_{\mathrm{\γ}}\sqrt{\frac{1}{n}[1-\frac{{\mathrm{\μ}}_{\mathrm{\γ}}^2}{2(n-1)}]+\frac{{\mathrm{\μ}}_{\mathrm{\α}}^2}{2(n-1)}}}{1-\frac{{\mathrm{\μ}}_{\mathrm{\γ}}^2}{2(n-1)}}---\left(4\right)$

In formula (4), n is the number of testpieces, μ _αthe standard normal deviator relevant to fiduciary level α, μ _γthe standard normal deviator relevant to degree of confidence γ.