CN1945269A - Method for predicting life and life consumption of high temperature member material - Google Patents

Abstract

The method of predicting the life and life consumption of high temperature member material features that based on the experiment data distribution of enduring quality, the reliable life of high temperature member material is predicted and the life consumption at certain reliability is calculated. The present invention makes it possible to obtain reliability analysis result in reliably high confidence by using the enduring quality data under different temperatures and stresses so as to realize the reliability prediction on high temperature life and life consumption in high precision. The method of the present invention is suitable for high temperature members.

Description

The life-span of high temperature construction material and the Forecasting Methodology of life consumption

Technical field

The invention belongs to the life prediction field, relate to the service life of prediction high-temperature component materials used and the method for life consumption, specially refer to life value and the life consumption of calculating under certain fiduciary level.

Background technology

Consider that in devices such as nuclear power, generating set, high-speed aircraft, gas turbine and high-temperature high-voltage reaction the elevated temperature strength factor carries out structural design and become more and more important.The creep rupture strength of high-temperature material is that it is the most basic, also is most important performance.And be to estimate other mechanical behavior under high temperature, as the basis of high temperature low-cycle fatigue, creeping crack expansion, stress relaxation etc.The design of high-temperature service must be carried out according to the long-term creep rupture strength of material, and critical component then requires creep rupture strength with high confidence level, high reliability as design considerations.In addition, consideration actual and economically requires lengthening the life of member, and the danger that this needs assessment is lengthened the life and may be brought.

In the predicting residual useful life and the assessment of lengthening the life, because the difficulty of test is inferred long-term creep rupture strength according to creep in short-term or enduring quality data on the engineering mostly.Monkman-Grant relation obtains the expression formula of tr creep rupture life according to the relation of steady state creep speed and temperature T, stress:

$\frac{1}{t_r}\∝{\stackrel{\·}{\mathrm{\ϵ}}}_s={\mathrm{A\σ}}^n\exp (-\frac{Q_c}{\mathrm{RT}})---\left(1\right)$

And people such as Larson-Miller, Manson-Haferd, Pueraria lobota front yard flint and Doan have proposed temperature-time parameter P (σ)=f (T, t based on separately model _r), utilize temperature-time comprehensive parameters to put the parameter extrapolation method of creep rupture life in order, thereby make A can put in order in the data scope, or represent with a principal curve in bigger stress, enduring quality data in the temperature range.Utilize this method extrapolation, for example the extrapolation of Larson-Miller method has become the representation commonly used of many engineering alloy enduring quality data.

Robinson life-span mark rule is regarded the accumulation of damage as a linear process.Independently suppose based on following 2: promptly under certain temperature and stress, the rupture life mark of creep impairment and consumption is proportional, and each loading period, caused creep impairment was independent of each other.Obtain:

$\underset{i}{\mathrm{\Σ}}\frac{t_i}{t_{\mathrm{fi}}}=1---\left(2\right)$

Robinson life-span mark rule shows when the accumulation of the left-hand component of formula (2) equals 1, destroys producing.Said method all shows for precise dose, stress and material property value, life-span of prediction and determined by the numerical value of loss.

In addition, in Chinese invention patent CN 1010130B, United States Patent (USP) 3950985, United States Patent (USP) 5042295, component's life can accurately be calculated after the service condition that accurately obtains temperature, stress.Yet, because aging, the damage of engineering component, losing efficacy is subjected to the influence of numerous uncertain factors at random, for example equipment in manufacture process or the size of the defective that produces in the military service process, orientation and pattern etc. often have uncertain at random character; Perhaps because aspects such as metallurgy can cause discontinuity of materials; Even the material that the trade mark of the same race, same stove are smelted, its mechanical property also often has bigger dispersiveness.These all cause life prediction result's uncertainty.Because the enduring quality experiment need be carried out under certain temperature and stress condition, therefore, the data volume under same experimental conditions is fewer, and the accuracy of statistic analysis result is limited to.For most of materials, obtain the rupture life DATA DISTRIBUTION under same experimental conditions, be to require a great deal of time and financial resources, the difficulty of enforcement is bigger.

Summary of the invention

The invention provides and a kind ofly can effectively utilize experimental data to carry out the method for the reliability prediction in high temperature construction material life-span, a kind of method of the life consumption based on the Calculation of Reliability high temperature construction material also is provided.

The scheme of technical solution problem of the present invention is as follows:

Determine the service life and the life consumption of high temperature construction material under certain fiduciary level, comprising: determine the rupture life value of material under set point of temperature and regulation stress, determine data area creep rupture life according to certain temperature-time comprehensive parameters; Utilize the principal curve of least square method specified data; Calculate the degree that above-mentioned enduring quality data depart from principal curve; Come the distribution curve of specified data according to deviation value; Determine corresponding numerical value according to distribution curve according to fiduciary level; According to the service life that is converted at the numerical value under each fiduciary level under temperature, the military service stress under arms; According to calculating the life consumption that produces at interval at the fixed time at the service life of setting under the fiduciary level.

Effect of the present invention and benefit are: can make full use of the enduring quality data under different temperatures and stress, obtain the fail-safe analysis result of high confidence, realize the high-temperature duration life of degree of precision and the reliability prediction of life consumption.The method that is proposed is applicable to the life appraisal of high-temperature component and the analysis of lengthening the life.

Description of drawings

Use of the present invention and step and further purpose and advantage can better be understood with reference to the following drawings.

Fig. 1 is stress σ and temperature-time parameter synoptic diagram.Can see with stress σ and temperature-time parameter P (σ)=f (T, t _r) related enduring quality DATA DISTRIBUTION is in a data tape, solid line is the principal curve that returns according to data, can be expressed as polynomial expression:

P(σ)＝Z ₀+C ₁logσ+C ₂log ²σ+C ₃log ³σ (3)

Wherein: P (σ)=f (T, t _r) be temperature-time parameter;

σ is a stress, and T is a temperature, Z ₀, C ₁, C ₂, C ₃Be constant.

In some cases, use formula (3) may cause producing unusual deviation at low stress side principal curve, thereby produces wrong life prediction result, so the principal curve that the enduring quality data return also can be represented with following formula:

P(σ)＝Z ₀+Alogσ+Bσ (4)

Wherein: P (σ)=f (T, t _r) be temperature-time parameter;

σ is a stress, and T is a temperature, Z ₀, A, B be constant.

Fig. 2 is the distribution plan that data point departs from the principal curve distance, and wherein horizontal ordinate Z represents that data point departs from the distance of principal curve, and the calculating of Z is represented with following formula:

Z＝Z ₀+C ₁logσ+C ₂log ²σ+C ₃log ³σ-P(σ) (5)

Perhaps, be expressed as for principal curve under the situation of formula (4), the calculating of Z is represented with following formula:

Z＝Z ₀+Alogσ+Bσ-P(σ) (6)

Generally, the numerical value Normal Distribution of Z.

According to the distribution of Fig. 2, can obtain the value of parameter Z under Different Reliability.On the basis that obtains Z value under the Different Reliability, can calculate in temperature T based on formula (5) or formula (6) _i, stress σ _iUnder life-span t _Ri

With reference to above result, in temperature T _i, stress σ _iUnder time interval Δ t _i, at the life consumption Δ D that sets under the fiduciary level _iCan calculate by following formula:

ΔDi＝Δt _i/t _ri (7)

Embodiment

Be described in detail specific embodiments of the invention below in conjunction with technical scheme and accompanying drawing.

Fig. 3 is the result according to the data preparation of 5Cr0.5Mo heat-resisting steel enduring quality, temperature wherein-time parameter P (σ)=T (20+lgt _r), principal curve is expressed as among the figure:

P＝17.56+11.4logσ-7.16log ²σ+0.95log ³σ (8)

And departing from the degree of principal curve, data point can be expressed as:

Z＝17.56+11.4logσ-7.16log ²σ+0.95log ³σ-10 ³×T(20+lgtr) (9)

Fig. 4 is the distribution plan that the data point of 5Cr0.5Mo departs from the Z value of principal curve, and the distribution Normal Distribution is learnt in check.

According to the fiduciary level 95%, 99% and 99.9% that sets, calculating the corresponding Z value is 0.3222,0.44020 and 0.5754, can calculate the life value t under set point of temperature T and stress σ _r

For example based on above result, calculating is at temperature 773K, under the stress 70MPa, set fiduciary level and be 95%, 99% and the relation of 99.9% o'clock life consumption and active time as shown in Figure 5, can see the life consumption value of different active times and the substantial connection between the fiduciary level.

Claims (7)

1. the Forecasting Methodology of the life-span of a high temperature construction material and life consumption is characterized in that utilizing reliability to come bimetry and life consumption, and implementation step comprises:

A. determine the rupture life value of material under set point of temperature and regulation stress;

B. determine the enduring quality data area according to temperature-time comprehensive parameters, and definite principal curve;

C. determine the distribution curve of enduring quality data;

D. the fiduciary level of setting according to distribution curve is calculated the life-span under set point of temperature, regulation stress;

E. predetermined time interval produces loss value divided by the life-span of setting under the fiduciary level, and loss value is illustrated in sets the life consumption in the predetermined time interval under the fiduciary level.

2. the Forecasting Methodology of the life-span of high temperature construction material as claimed in claim 1 and life consumption is characterized in that the degree of utilizing the enduring quality data to depart from principal curve comes the distribution curve of specified data.

3. the Forecasting Methodology of the life-span of high temperature construction material as claimed in claim 1 and life consumption is characterized in that utilizing and sets the value that the pairing data of fiduciary level depart from principal curve, calculates the life value under set point of temperature, the regulation stress.

4. the Forecasting Methodology of the life-span of high temperature construction material as claimed in claim 1 and life consumption, it is characterized in that predetermined time interval divided by the loss value that produces by the resulting life value of claim 3, be illustrated in and set the life consumption in the predetermined time interval under the fiduciary level.

5. the Forecasting Methodology of the life-span of high temperature construction material as claimed in claim 1 and life consumption, it is characterized in that determining stress, the temperature of data area employing creep rupture life test condition, the rupture life under the calculating setting fiduciary level then uses temperature and the stress under the actual service condition.

6. the distribution curve of specified data as claimed in claim 2 is characterized in that the degree that the enduring quality data depart from principal curve represents with following formula:

Z＝Z ₀+C ₁logσ+C ₂log ²σ+C ₃log ³σ-P(σ)

Wherein: Z departs from the degree of principal curve for the enduring quality data;

P (σ)=f (T, t _r) be temperature-time parameter;

P (σ)=Z ₀+ C ₁Log σ+C ₂Log ²σ+C ₃Log ³σ represents the principal curve of enduring quality data area;

σ is a stress, and T is a temperature, Z ₀, C ₁, C ₂, C ₃Be constant.

7. the distribution curve of specified data as claimed in claim 2 is characterized in that the degree that the enduring quality data depart from principal curve also can be represented by the formula:

Z＝Z ₀+Alogσ+Bσ-P(σ)

Wherein: Z departs from the degree of principal curve for the enduring quality data;

P (σ)=f (T, t _r) be temperature-time parameter;

P (σ)=Z ₀+ Alog σ+B σ represents the principal curve of enduring quality data area;

σ is a stress, and T is a temperature, Z ₀, A, B be constant.

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