CN108910081A - A kind of metal structure defect tolerance stress and cycle-index relationship determine method - Google Patents
A kind of metal structure defect tolerance stress and cycle-index relationship determine method Download PDFInfo
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- CN108910081A CN108910081A CN201810676634.7A CN201810676634A CN108910081A CN 108910081 A CN108910081 A CN 108910081A CN 201810676634 A CN201810676634 A CN 201810676634A CN 108910081 A CN108910081 A CN 108910081A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
- B64F5/00—Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
- B64F5/60—Testing or inspecting aircraft components or systems
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- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
The present invention provides a kind of metal structure defect tolerance stress and cycle-index relationship to determine method, is related to helicopter structure fatigue design field.Make the first tangent line of high all defect tolerance mean stress-cycle-index curves the method includes crossing starting point, intersect at the curve, and the first relation curve is constituted, to the stress of first relation curve multiplied by the stress reduction factor of metal structure, obtain the second relation curve；To the cycle-index of first relation curve divided by the factor of life scatter of metal structure, third relation curve is obtained；Take the envelope of second relation curve and the third relation curve as metal structure defect tolerance stress and cycle-index relation curve.The present invention can be established the gamut defect tolerance safe stress-cycle-index curve for adapting to safety indexes, be met the requirement of defect tolerance design and verifying based on existing high all defect tolerance stress-cycle-index curvilinear equations.
Description
Technical field
The present invention relates to helicopter structure fatigue design fields, and in particular to a kind of metal structure defect tolerance stress with follow
Ring number relationship determines method.
Background technique
The verifying of helicopter structure defect tolerance is the new demand of airworthiness regulation clause " fatigue assessments of 29.571 structures ", is lacked
Falling into tolerance stress-cycle-index curve is one of the design of helicopter structure defect tolerance and the important input of verifying.Because of safety
The difference of index, traditional fatigue stress-cycle-index curve are different from defect tolerance stress-cycle-index curve.
Summary of the invention
To solve the above-mentioned problems, the present invention provides a kind of metal structure defect tolerance stress and cycle-index relationship are true
Determine method, including：
Step 1: building plane coordinate system, the plane coordinate system abscissa are cycle-index, ordinate is answered for tolerance
Power, and high all defect tolerance mean stress-cycle-index curves are generated under shown plane coordinate system；
Step 2: crossing the first tangent line that starting point makees high all defect tolerance mean stress-cycle-index curves, the curve is met at
Point of contact, then averagely answered by the straightway of starting point to point of contact and by point of contact to all defect tolerances of height between the cycle-index upper limit
Power-cycle-index curve collectively forms the first relation curve, and the starting point is the point under coordinate system where yield limit value；
Step 3: the stress of first relation curve is obtained second and is closed multiplied by the stress reduction factor of metal structure
It is curve；
Step 4: to the cycle-index of first relation curve divided by the factor of life scatter of metal structure, the is obtained
Three relation curves；
Step 5: the envelope of second relation curve and the third relation curve is taken to hold as metal structure defect
Limit stress and cycle-index relation curve.
Preferably, the envelope includes：
The starting point for crossing third relation curve does the second tangent line of third relation curve, institute in the starting point and step 1
The abscissa for stating starting point is identical；
The first turning point is taken on the second tangent line, does the third tangent line of second relation curve, with second relationship
Curve meets at the second turning point；
Then the envelope includes by the first line segment of starting point to the first turning point, by the first turning point to the second turnover
Point second line segment and collectively formed by the second turning point to the second relation curve between the cycle-index upper limit.
Preferably, first line segment is identical as the second line segment length by length.
It is an advantage of the invention that：It can establish and adapt to based on existing high all defect tolerance stress-cycle-index curvilinear equations
Gamut defect tolerance safe stress-cycle-index curve of safety indexes meets the requirement of defect tolerance design and verifying.
Detailed description of the invention
Fig. 1 is the preferred implementation that method is determined according to metal structure defect tolerance stress of the present invention and cycle-index relationship
The curvilinear motion relation schematic diagram of example.
Specific embodiment
To keep the purposes, technical schemes and advantages of the invention implemented clearer, below in conjunction in the embodiment of the present invention
Attached drawing, technical solution in the embodiment of the present invention is further described in more detail.In the accompanying drawings, identical from beginning to end or class
As label indicate same or similar element or element with the same or similar functions.Described embodiment is the present invention
A part of the embodiment, instead of all the embodiments.The embodiments described below with reference to the accompanying drawings are exemplary, it is intended to use
It is of the invention in explaining, and be not considered as limiting the invention.Based on the embodiments of the present invention, ordinary skill people
Member's every other embodiment obtained without creative efforts, shall fall within the protection scope of the present invention.Under
Face is described in detail the embodiment of the present invention in conjunction with attached drawing.
Metal structure defect tolerance stress of the present invention and cycle-index relationship determine method, including：
Step 1: building plane coordinate system, the plane coordinate system abscissa are cycle-index, ordinate is answered for tolerance
Power, and high all defect tolerance mean stress-cycle-index curves are generated under shown plane coordinate system；
Step 2: crossing the first tangent line that starting point makees high all defect tolerance mean stress-cycle-index curves, the curve is met at
Point of contact, then averagely answered by the straightway of starting point to point of contact and by point of contact to all defect tolerances of height between the cycle-index upper limit
Power-cycle-index curve collectively forms the first relation curve, and the starting point is the point under coordinate system where yield limit value；
Step 3: the stress of first relation curve is obtained second and is closed multiplied by the stress reduction factor of metal structure
It is curve；
Step 4: to the cycle-index of first relation curve divided by the factor of life scatter of metal structure, the is obtained
Three relation curves；
Step 5: the envelope of second relation curve and the third relation curve is taken to hold as metal structure defect
Limit stress and cycle-index relation curve.
In the present embodiment, the envelope includes：
The starting point for crossing third relation curve does the second tangent line of third relation curve, institute in the starting point and step 1
The abscissa for stating starting point is identical；
The first turning point is taken on the second tangent line, does the third tangent line of second relation curve, with second relationship
Curve meets at the second turning point；
Then the envelope includes by the first line segment of starting point to the first turning point, by the first turning point to the second turnover
Point second line segment and collectively formed by the second turning point to the second relation curve between the cycle-index upper limit.
In the present embodiment, first line segment is identical as the second line segment length by length.
The embodiment of the present invention is described in detail with reference to the accompanying drawing.
As shown in Figure 1, its key step is as follows：
A most upper curve, specific practice include first relation curve of step 2 building as shown in figure 1：
Determine gamut defect tolerance mean stress-cycle-index curve：Cross starting point PmB(0.001,R02) make high all defects
Tolerance mean stress-cycle-index curveTangent line, meet at point of contact PmA(NmA,SmA), then straightway
PmBPmA(SmA< S≤R02) and curve(S∞mf< S≤SmA) constitute the first relation curve；Wherein R02It is in the wrong
The limit is taken, S is alternating load amplitude, and N is destruction recurring number (unit 10 corresponding with S value6It is secondary), S∞mfFor defect tolerance
Mean fatigue lixnit, Af, α f are respectively defect tolerance stress-cycle-index profile shape parameter.
In step 3, determine that gamut defect tolerance reduces stress-cycle-index curve：The curve that step 2 is determined
Stress multiplied by stress reduction factor kS, then gamut defect tolerance decrement stress-cycle-index curve, i.e. the second relationship are obtained
Curve, with reference to thicker dotted line intermediate in Fig. 1；
In step 4, gamut defect tolerance stress-decrement cycle-index curve is determined：The curve that step 2 is determined
Cycle-index divided by factor of life scatter kN, then gamut defect tolerance stress-decrement cycle-index curve, i.e. third is obtained
Relation curve, with reference to thinner dotted line intermediate in Fig. 1；
In step 5, gamut defect tolerance safe stress-cycle-index curve is determined：Determine that step 3 and step 4 are bent
The envelope of knot fruit --- straightway PsCPsB(SsB< S≤SsC)、PsBPsA(SsA< S≤SsB) and curve(S∞sf< S≤SsA), that is, constitute gamut defect tolerance safe stress-cycle-index curve.
Note：Signified straightway is all made of logarithmic coordinates system in above-mentioned steps, and wherein abscissa is lgN.
It is described using certain metal structure as specific example.The present embodiment is based on existing high week scratch defect tolerance and answers
Power-cycle-index curvilinear equation, which is characterized in that scratch defect tolerance stress-cycle-index curve and (scratch defect comprising low week
Tolerance stress-cycle-index curve) determine step it is as follows：
Step 2: determining that gamut scratches defect tolerance mean stress-cycle-index curve：Cross starting point PmB(0.001,
R02) make high all defect tolerance mean stress-cycle-index curvesTangent line, meet at point of contact PmA
(0.00689,155.8), then straightway PmBPmA(155.8 < S≤R02) and curve(68.7 < S≤
155.8) gamut defect tolerance mean stress-cycle-index curve is constituted；Wherein R02For 237.6MPa；
In step 3, determine that gamut scratches defect tolerance decrement stress-cycle-index curve：The song that step 2 is determined
The stress of line then obtains gamut defect tolerance decrement stress-cycle-index curve multiplied by stress reduction factor 0.661；
In step 4, determine that gamut scratches defect tolerance stress-decrement cycle-index curve：The song that step 2 is determined
The cycle-index of line then obtains gamut defect tolerance stress-decrement cycle-index curve divided by factor of life scatter 7；
In step 5, determine that gamut scratches defect tolerance safe stress-cycle-index curve：It determines Step 3: four is bent
The envelope of knot fruit --- straightway PsCPsB(120.0 S≤155.2 <), PsBPsA(83.9 S≤120.0 <) and curve(45.4 S≤83.9 <), as gamut scratch defect tolerance safe stress-cycle-index curve；
Wherein PsC(0.001,155.2) intersection point of the curve and straight line N=0.001 determined for step 4, PsCPsBIt is determined with step 4
Contact of a curve；Cross PsB(0.00230,120) make curveTangent line, point of contact PsA(0.0158,
83.9)。
Certain aluminium alloy scratches defect tolerance stress-cycle-index parameter of curve and is shown in Table 1.
Certain aluminium alloy of table 1 scratches defect tolerance stress-cycle-index parameter of curve
| Parameter name | Parameter value |
| Yield limit R02, MPa | 237.6 |
| Defect tolerance mean fatigue lixnit S∞mf, MPa | 68.7 |
| Defect tolerance stress-cycle-index profile shape parameter Af | 0.113 |
| Defect tolerance stress-cycle-index profile shape parameter α f | 0.486 |
| Stress reduction factor kS | 0.661 |
| Factor of life scatter kN | 7 |
| The safe fatigue limit S of defect tolerance∞sf, MPa | 45.4 |
It is an advantage of the invention that：It can establish and adapt to based on existing high all defect tolerance stress-cycle-index curvilinear equations
Gamut defect tolerance safe stress-cycle-index curve of safety indexes meets the requirement of defect tolerance design and verifying.
It is last it is to be noted that：The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations.To the greatest extent
Present invention has been described in detail with reference to the aforementioned embodiments for pipe, those skilled in the art should understand that：It is still
It is possible to modify the technical solutions described in the foregoing embodiments, or part of technical characteristic is equally replaced
It changes；And these are modified or replaceed, the essence for technical solution of various embodiments of the present invention that it does not separate the essence of the corresponding technical solution
Mind and range.
Claims (3)
1. a kind of metal structure defect tolerance stress and cycle-index relationship determine method, which is characterized in that including：
Step 1: building plane coordinate system, the plane coordinate system abscissa is cycle-index, and ordinate is tolerance stress, and
High all defect tolerance mean stress-cycle-index curves are generated under shown plane coordinate system；
Step 2: crossing the first tangent line that starting point makees high all defect tolerance mean stress-cycle-index curves, described first is cut
Line and described high all defect tolerance mean stress-cycle-index curve intersection in point of contact, then by the straightway of starting point to point of contact with
And the first relationship is collectively formed by point of contact to all defect tolerance mean stress-cycle-index curves of height between the cycle-index upper limit
Curve, the starting point are the point under coordinate system where yield limit value；
Step 3: it is bent to be obtained the second relationship multiplied by the stress reduction factor of metal structure for the stress of first relation curve
Line；
Step 4: obtaining third and closing the cycle-index of first relation curve divided by the factor of life scatter of metal structure
It is curve；
Step 5: second relation curve and the envelope of the third relation curve is taken to answer as metal structure defect tolerance
Power and cycle-index relation curve.
2. metal structure defect tolerance stress as described in claim 1 and cycle-index relationship determine method, which is characterized in that
The envelope includes：
The starting point for crossing third relation curve does the second tangent line of third relation curve, and the starting point rises with described in step 1
The abscissa of point is identical；
The first turning point is taken on the second tangent line, does the third tangent line of second relation curve, with second relation curve
Meet at the second turning point；
Then the envelope includes by the first line segment of starting point to the first turning point, by the first turning point to the second turning point
It second line segment and is collectively formed by the second turning point to the second relation curve between the cycle-index upper limit.
3. metal structure defect tolerance stress as claimed in claim 2 and cycle-index relationship determine method, which is characterized in that
First line segment is identical as the second line segment length by length.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110884685A (en) * | 2019-12-04 | 2020-03-17 | 中国直升机设计研究所 | Load monitoring method for helicopter blade |
| CN111046547A (en) * | 2019-12-04 | 2020-04-21 | 中国直升机设计研究所 | Method for rapidly calculating high-cycle life of rectangular composite flexible beam of helicopter |
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| CN1587967A (en) * | 2004-08-10 | 2005-03-02 | 东华大学 | Measuring device for flexural fatigue property of flexible material |
| CN102854252A (en) * | 2012-09-10 | 2013-01-02 | 北京理工大学 | Method and system used for detecting metal material fatigue state |
| CN102854245A (en) * | 2011-06-27 | 2013-01-02 | 霍尼韦尔国际公司 | Structural damage index mapping system and method |
| CN103380057A (en) * | 2010-09-29 | 2013-10-30 | 航空机器股份有限公司 | Novel systems and methods for non-destructive inspection of airplanes |
| CN106596301A (en) * | 2016-11-30 | 2017-04-26 | 中国直升机设计研究所 | Method for determining inspection period of metal structure defects of helicopter |
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Patent Citations (5)
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|---|---|---|---|---|
| CN1587967A (en) * | 2004-08-10 | 2005-03-02 | 东华大学 | Measuring device for flexural fatigue property of flexible material |
| CN103380057A (en) * | 2010-09-29 | 2013-10-30 | 航空机器股份有限公司 | Novel systems and methods for non-destructive inspection of airplanes |
| CN102854245A (en) * | 2011-06-27 | 2013-01-02 | 霍尼韦尔国际公司 | Structural damage index mapping system and method |
| CN102854252A (en) * | 2012-09-10 | 2013-01-02 | 北京理工大学 | Method and system used for detecting metal material fatigue state |
| CN106596301A (en) * | 2016-11-30 | 2017-04-26 | 中国直升机设计研究所 | Method for determining inspection period of metal structure defects of helicopter |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110884685A (en) * | 2019-12-04 | 2020-03-17 | 中国直升机设计研究所 | Load monitoring method for helicopter blade |
| CN111046547A (en) * | 2019-12-04 | 2020-04-21 | 中国直升机设计研究所 | Method for rapidly calculating high-cycle life of rectangular composite flexible beam of helicopter |
| CN110884685B (en) * | 2019-12-04 | 2022-06-21 | 中国直升机设计研究所 | Load monitoring method for helicopter blade |
| CN111046547B (en) * | 2019-12-04 | 2022-09-16 | 中国直升机设计研究所 | Method for rapidly calculating high-cycle life of rectangular composite flexible beam of helicopter |
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Inventor after: Yu Jianjian Inventor after: Cui Wei Inventor after: Chen Yaping Inventor after: Xu Chaoliang Inventor after: Liu Wenqi Inventor after: Zhang Junnan Inventor after: Hu Lei Inventor after: Zou Jing Inventor after: Xiong Xin Inventor after: Gao Ya Inventor before: Yu Jianjian Inventor before: Chen Yaping Inventor before: Zhang Junnan Inventor before: Hu Lei Inventor before: Zou Jing Inventor before: Xiong Xin Inventor before: Gao Ya Inventor before: Cui Wei |
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