CN105574307A - Judgment method of dual adaptation critical point of expansion direction connection structure DFR (Detail Fatigue Rating) - Google Patents

Abstract

The invention provides a judgment method of a dual adaptation critical point of expansion direction connection structure DFR (Detail Fatigue Rating). The judgment method comprises the following steps: (1) determining an expansion direction connection structure DFR value: obtaining the DFR value according to a formula DFR=DFRbase*A*B*C*C*D*E*Rc; and (2) calculating ([Tau]s/[Delta]g)*(ts/tp): aiming at the specific position of the calculated expansion direction connection structure in an airplane, calculating to obtain the fatigue stress spectra of the position, extracting DFR reference stress [Delta]g, shearing stress [Tau]s in the spectra corresponding to the DFR reference stress [Delta]g, the basic thickness ts of a wallboard and the thickness tsp of the wallboard boss of a connection position, and calculating to obtain the numerical value of the ([Tau]s/[Delta]g)*(ts/tp).

Description

A kind of exhibition is to the determination methods of the two-way correction critical point of syndeton DFR

Technical field

The exhibition that patent of the present invention provides is to the determination methods of the two-way correction critical point of DFR of syndeton.

Background technology

Exhibition is a kind of syndeton common in aircaft configuration to syndeton.

Because exhibition is to syndeton physical presence three-dimensional stress, after calculating DFR value by exhibition to syndeton DFR computing method, often need the two-way correction carrying out DFR according to Subjected To Biaxial Loading joint.But existing method is to when needing two-way correction (namely comprising the critical relation that the structural parameters such as thickness, diameter fastener, securing member spacing and stress intensity parameter and DFR are revised) not define, cannot judge whether before correction to need to revise, after correction work can be caused to complete, discovery is in fact without the need to revising the appearance of situation, wastes unnecessary manpower and material resources.

Existing Patents document does not relate to problem of the present invention.

Therefore, development one is needed can to judge fast the need of two-way correction to syndeton DFR exhibition, the quick judgment method of namely two-way correction critical point.

Summary of the invention

The present invention provides the determination methods of a kind of exhibition to the two-way correction critical point of syndeton DFR, it is characterized in that, efficiently can solve and cannot judge critical point in existing method and the problem of the unnecessary correction caused, and easy to use, practical.

Comprise the following steps:

(1) determine to open up the DFR value to syndeton:

According to formula DFR=DFR _baseaBCDER _cobtain DFR value.

(2) calculate

For calculated exhibition to the concrete position of syndeton in aircraft, calculate the Simulating of Fatigue Stress Spectra at this position, extract DFR Reference Stress σ _g, and shear stress τ in corresponding spectrum _s, the basic thickness t of wallboard _s, connecting portion wallboard boss thickness t _sp, calculate numerical value.

(3) p/d is calculated:

The exhibition of getting calculates the securing member spacing p at position to syndeton, and diameter fastener d, calculates the numerical value of p/d.

(4) t is calculated _sp/ d:

Get the diameter fastener d of calculated exhibition to syndeton position, and the wall panel thickness t of fastener connection section position _sp, calculate t _spthe numerical value of/d.

(5) set up coordinate axis to carry out judging whether to need two-way correction:

With numerical value is as the horizontal ordinate of coordinate axis, and using p/d as the ordinate of coordinate axis, rule of thumb data are carried out process of fitting treatment and obtained different t _spthe curve of/d in coordinate axis region, obtains according to step 2 numerical value looks into the horizontal ordinate of coordinate axis, and the p/d obtained according to step 3 looks into the ordinate of coordinate axis, according to the t that step 4 obtains _sp/ d numerical value looks into corresponding t _spthe curve that/d parameter is corresponding, checks whether the point of above-mentioned three groups of data composition drops on corresponding t _spthe right side of/d curve, if the right side dropping on curve, then the DFR value that must obtain step 1 carries out two-way correction; Otherwise, then without the need to two-way correction.

(6) to the DFR result of the two-way correction of needs that step 5 is determined, carry out two-way correction by " civil aircraft structures permanance and damage tolerance design handbook " fatigue design and analysis chapter 5 relevant portion, calculate stress parameters used when determining two-way correction factor two-way correction factor therefore two-way revised DFR is obtained _bifor:

Symbol description used is as follows above:

The tired ratings of DFR---CONSTRUCTED SPECIFICATION;

DFR _base---the basic value of detail fatigue rating;

DFR _bi---two-way revised DFR value;

A---hole coefficient of admission;

B---alloy and surface treatment coefficient;

C---immerse oneself in depth coefficient;

D---material laminate thickness coefficient;

E---bolt clamping coefficient;

R _c---the specified coefficient of component fatigue;

σ _g---calculate position exhibition to stretching Reference Stress;

τ _s---calculate position exhibition to the shear stress corresponding to stretching Reference Stress;

T _s---the basic thickness of wallboard;

T _sp---connecting portion wallboard boss thickness;

P---securing member spacing;

D---diameter fastener.

---two-way correction factor.

Further, after step 6 completes, to the DFR result not needing two-way correction that step 5 is determined, in order to verify that whether conclusion is correct, still carry out two-way correction according to the method described in step 6, if correction factor namely error is less than 3%, then prove the two-way correction critical point that step 5 proposes judges it is correct.

The invention solves the problem of exhibition to the two-way correction critical point of syndeton DFR, before exhibition is revised to syndeton DFR value, can judge fast the need of correction (critical point namely revised), thus save unnecessary man power and material, realize the efficient calculation of exhibition to syndeton DFR.

Accompanying drawing explanation

Fig. 1 opens up to syndeton schematic diagram,

Fig. 2 is two-way correction critical point judgment curves figure.

Embodiment

Given two groups of different parameters:

a)t _s＝6.6mm,t _sp＝8.0mm,d＝8.0mm,p＝32mm，σ _g＝120.5MPa,τ _s＝35.8MPa；

b)t _s＝6.3mm,t _sp＝7.6mm,d＝8.0mm,p＝32mm，σ _g＝118.1MPa,τ _s＝6.8MPa。

Respectively above-mentioned two groups of parameters are calculated by described concrete technical scheme above, thus determine whether to need to carry out two-way correction.

1, determine to open up the DFR value to structure as shown in Figure 1:

DFR＝DFR _base·A·B·C·D·E·R _C

DFR computation process is completely the same with " civil aircraft structures permanance and damage tolerance design handbook " existing method herein.The DFR only providing two groups of parameters corresponding is respectively: a) DFR=115MPa; B) DFR=120MPa.

2, calculate

For calculated exhibition to the concrete position of syndeton in aircraft, calculate the Simulating of Fatigue Stress Spectra at this position, extract DFR Reference Stress σ _g, and shear stress τ in corresponding spectrum _s.Calculate above-mentioned two groups of parameters corresponding numerical value is respectively: a) $\frac{{\mathrm{\τ}}_s}{{\mathrm{\σ}}_g}\·\frac{t_s}{t_{\mathrm{sp}}}=0.245;$ b) $\frac{{\mathrm{\τ}}_s}{{\mathrm{\σ}}_g}\·\frac{t_s}{t_{\mathrm{sp}}}=0.048.$

3, p/d is calculated:

The exhibition of getting calculates the securing member spacing p at position to syndeton, and diameter fastener d, and the p/d numerical value calculating above-mentioned two groups of parameters corresponding is respectively: a) p/d=4.0; B) p/d=4.0.

4, t is calculated _sp/ d:

Get the diameter fastener d of calculated exhibition to syndeton position, and the wall panel thickness t of fastener connection section position _sp.Calculate the t that above-mentioned two groups of parameters are corresponding _spthe numerical value of/d is respectively: a) t _sp/ d=1.0; B) t _sp/ d=0.95.

5, undertaken judging whether to need two-way correction by Fig. 2:

Substitute into that the 2nd step obtains numerical value looks into the horizontal ordinate of Fig. 2 bottom side, and the p/d of the 3rd step looks into the p/d on the left of Fig. 2, the t that the 4th step obtains _sp/ d numerical value looks into Fig. 2 top t _spthe curve that/d parameter is corresponding, checks whether the point of three data compositions that above-mentioned two groups of parameters are corresponding drops on the right side of response curve: right side a) dropping on curve; B) left side of curve is dropped on.Therefore, two-way correction must be carried out to a) organizing DFR corresponding to parameter, b) organizing DFR corresponding to parameter then without the need to two-way correction.

6, to DFR result a) organizing parameter that the 5th step is determined, two-way correction is carried out by " civil aircraft structures permanance and damage tolerance design handbook " fatigue design and analysis chapter 5 relevant portion.Stress parameters used when determining correction factor two-way correction factor φ=1-0.45 ω ^1.4=0.918.Therefore two-way revised DFR is obtained _bifor: DFR _bi=DFR × φ=115 × 0.918=105.6MPa.Two-way correction factor φ=0.918 < 1, then prove that two-way correction is on the impact of DFR comparatively large (revised change number percent is 8.17%).

That 7, determines the 5th step does not need the b of two-way correction) organize DFR result corresponding to parameter, in order to verify that whether conclusion is correct, still two-way correction is carried out, if correction factor by " civil aircraft structures permanance and damage tolerance design handbook " fatigue design and analysis chapter 5 relevant portion then prove the two-way correction critical point that the present invention provides judges it is correct.Stress parameters used when first determining correction factor two-way correction factor φ=1-0.45 ω ^1.4=0.992.Therefore two-way revised DFR is obtained _bifor: two-way correction factor then showing that two-way correction is on the impact of DFR little (revised change number percent is 0.83%<3%), without the need to revising, then proving the two-way correction critical point that the present invention provides judges it is correct.

Claims (1)

1. exhibition is to a determination methods for the two-way correction critical point of syndeton DFR, it is characterized in that,

(1) determine to open up the DFR value to syndeton:

According to formula DFR=DFR _baseaBCDER _cobtain DFR value;

(2) calculate

For calculated exhibition to the concrete position of syndeton in aircraft, calculate the Simulating of Fatigue Stress Spectra at this position, extract DFR Reference Stress σ _g, and shear stress τ in corresponding spectrum _s, the basic thickness t of wallboard _s, connecting portion wallboard boss thickness t _sp, calculate numerical value;

(3) p/d is calculated:

The exhibition of getting calculates the securing member spacing p at position to syndeton, and diameter fastener d, calculates the numerical value of p/d;

(4) t is calculated _sp/ d:

Get the diameter fastener d of calculated exhibition to syndeton position, and the wall panel thickness t of fastener connection section position _sp, calculate t _spthe numerical value of/d;

(5) set up coordinate axis to carry out judging whether to need two-way correction:

With numerical value is as the horizontal ordinate of coordinate axis, and using p/d as the ordinate of coordinate axis, rule of thumb data are carried out process of fitting treatment and obtained different t _spthe curve of/d in coordinate axis region, obtains according to step 2 numerical value looks into the horizontal ordinate of coordinate axis, and the p/d obtained according to step 3 looks into the ordinate of coordinate axis, according to the t that step 4 obtains _sp/ d numerical value looks into corresponding t _spthe curve that/d parameter is corresponding, checks whether the point of above-mentioned three groups of data composition drops on corresponding t _spthe right side of/d curve, if the right side dropping on curve, then the DFR value that must obtain step 1 carries out two-way correction; Otherwise, then without the need to two-way correction;

(6) to the DFR result of the two-way correction of needs that step 5 is determined, carry out two-way correction by " civil aircraft structures permanance and damage tolerance design handbook " fatigue design and analysis chapter 5 relevant portion, calculate stress parameters used when determining two-way correction factor two-way correction factor therefore two-way revised DFR is obtained _bifor: