CN106055790A - Optimization method and device of single-impact stress screening condition - Google Patents

Abstract

The invention discloses an optimization method and device of a single-impact stress screening condition. The method comprises the following steps: according to the failure threshold value of a product, establishing a reliability model of the product to obtain the operating life distribution function of a no-damage product and the operating life distribution function of a product which fails only due to impact stress in a use process; on the basis of the failure threshold value of the product, establishing a single-impact stress screening process model for a determined value to obtain the normalized life distribution function of a non-failure product after single-impact stress screening, wherein the product which does not have initial damage but has damages after screening and the product which has the initial damage but passes the screening have different life distribution functions; according to the expected life of the product, optimizing the normalized life distribution function of the product to obtain the optimized single-impact stress screening condition. The method can adapt to a situation that the product without initial damages and the product which is initially compact but has defects after screening have different life functions, and enriches an application scene of the single-impact stress screening condition.

Description

The optimization method of a kind of single-impact stress screening condition and device

Technical field

The present invention relates to reliability engineering technique field, particularly to the optimization side of a kind of single-impact stress screening condition Method and device.

Background technology

During product development, environmental stress screening test is that a kind of conventional rejecting product introduces in the fabrication process Potential defect, the effective means of damage.Such as, for aerospace electron product, before with satellite launch, often need to carry out device The environmental stress screenings at different levels such as level, plate level, unit level.Currently for choosing of environmental stress screening experimental condition, root often Determine according to engineering experience or all kinds of specification, seldom determine according to actual development, the applicable cases optimization of specific products.This ring The mode of choosing of border stress screening experimental condition there may be problems with: first, probably due to too high experimental condition causes There is defect, damage in the most intact product；Second, probably due to too much screening cause unnecessary testing expenses and time Between.

The research optimized currently, with respect to environmental stress screening Experiment Modeling and experimental condition is little, main in prior art For single-impact stress, carry out screening test condition to the research of the impact of life of product characteristic after test.Due to existing skill Art is, based on random this characteristic of product failure threshold value, the screening test condition of single-impact stress is launched research, thus Prior art utilize failure threshold carry out impact stress screening process modeling time, the product that do not lost efficacy being initially present defect obtained Product are identical with the lifetime function of the most intact but generation defect after screening the product that do not lost efficacy, i.e. prior art is only suitable for punching During hitting stress screening, it is initially present the product of defect and the most intact but produce the product of defect after screening and there is the identical longevity The scene of life function.But in Practical Project, as when sophisticated product being carried out impact stress screening, often existing and being initially present The product of defect is from the most intact but produce the product of defect after screening and have the average case of different lifetime function.

Summary of the invention

The invention provides optimization method and the device of a kind of single-impact stress screening condition, to solve in prior art Single-impact stress screening scheme be suitable for the problem that scene is limited.

For reaching above-mentioned purpose, the technical scheme is that and be achieved in that:

On the one hand, the invention provides the optimization method of a kind of single-impact stress screening condition, described method includes:

Failure threshold according to product sets up the reliability model of product, obtains the working life distribution letter of not damaged product Count and the most only because impact stress causes the working life distribution function of the product lost efficacy；

Failure threshold based on product is for determining that value sets up single-impact stress screening process model, and obtaining single-impact should Do not lost efficacy after power screening the normalizing life distribution function of product, and the product that do not lost efficacy after described single-impact stress screening includes: just Beginning not damaged and screening after do not exist the product of damage, initial not damaged but screening after there is the product of damage and be initially present damage Hinder but by the product of screening；Wherein initial not damaged but there is the product of damage after screening and be initially present damage but by sieve The product of choosing has different life distribution function；

Life expectancy according to product optimizes described normalizing life distribution function, the single-impact stress sieve after being optimized Condition, described screening conditions is selected to include screening stress.

Preferably, the working life distribution function of described not damaged product is specially

Described the most only because of impact stress cause lost efficacy product working life distribution function be specially

Wherein, T_NFor the life-span of not damaged product, T_EFor the most only causing the product longevity of inefficacy because of impact stress Life, r (x) is the substrate crash rate of not damaged product, the accumulative number of shocks that N (t) is suffered when being time t, W_iFor work process The lesion size that middle i & lt impact stress causes, W_MFor the original damage size of product, D_wFailure threshold for product.

Preferably, described failure threshold based on product is for determining that value sets up single-impact stress screening process model bag Include:

Failure threshold according to product carries out single-impact stress screening to product, obtains by single-impact stress screening After the product that do not lost efficacy, and calculate initial not damaged and screening after do not exist the product of damage, initial not damaged but screening after deposit Damage product and be initially present damage but by screening product all by single-impact stress screening after do not lost efficacy Product in shared ratio；

Longevity work life distribution function according to described not damaged product and described the most only lead because of impact stress Cause working life distribution function calculating every series products life distribution function in screening process of the product lost efficacy；

According to the ratio shared by every series products and the life distribution function in screening process thereof, set up single-impact stress Screening process model, the normalizing life distribution function of the product that do not lost efficacy after obtaining single-impact stress screening.

Preferably, there is not the ratio shared by product of damage and in screening process after described initial not damaged and screening In life distribution function be followed successively by respectively:

$P(T_{ESS}>t|Z=1)=\exp (-{\∫}_0^{t}r(x\left)dx\right);$

Described initial not damaged but screening after there is the ratio shared by product of damage and the life-span in screening process thereof Distribution function is followed successively by:

$P(T_{ESS}>t|Z=2)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s^{\&prime;}<D_w)P\left(N\right(t)=j);$

Described it is initially present damage but the ratio shared by product and life-span in making screening process thereof by screening is divided Cloth function is followed successively by:

$P(T_{ESS}>t|Z=3)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s+W_M<D_w)P\left(N\right(t)=j);$

Described single-impact stress screening process model is

Wherein, π is the ratio of initial not damaged product, and s is the value of screening stress, and ρ (s) is initial not damaged but screening The ratio of the rear product that there is damage, W_sThe lesion size caused for impact stress in screening process, W_s' it is the most undamaged Product screens the lesion size first caused, T because of impact stress_ESSThe use longevity for the product by single-impact stress screening Life.

Preferably, the described life expectancy according to product optimizes described normalizing life distribution function, the list after being optimized Secondary Shocks stress screening condition includes:

According to formulaDo not lost efficacy after optimizing described single-impact stress screening product Normalizing life distribution function；Or,

According to formulaDo not lost efficacy after optimizing described single-impact stress screening product The normalizing life distribution function of product；

Wherein, T_gLife expectancy for product.

On the other hand, present invention also offers the optimization device of a kind of single-impact stress screening condition, described device bag Include:

Reliability modeling unit, for setting up the reliability model of product according to the failure threshold of product, obtains not damaged The working life distribution function of product and the most only cause the working life distribution of the product lost efficacy because of impact stress Function；

Single-impact stress screening process model building unit, for failure threshold based on product for determining that value sets up single punching Hit stress screening process model, the normalizing life distribution function of the product that do not lost efficacy after obtaining single-impact stress screening, described list The product that do not lost efficacy after Secondary Shocks stress screening includes: there is not the product of damage, initial not damaged after initial not damaged and screening But there is the product of damage after Shai Xuan and be initially present damage but by the product of screening；Wherein initial not damaged but deposit after screening Product in damage has different life distribution function with being initially present damage by the product of screening；

Screening conditions optimize unit, optimize described normalizing life distribution function for the life expectancy according to product, obtain Single-impact stress screening condition after optimization, described screening conditions include screening stress.

Preferably, the working life distribution function of described not damaged product is specially

Described the most only because of impact stress cause lost efficacy product working life distribution function be specially

Wherein, T_NFor the life-span of not damaged product, T_EFor the most only causing the product longevity of inefficacy because of impact stress Life, r (x) is the substrate crash rate of not damaged product, the accumulative number of shocks that N (t) is suffered when being time t, W_iFor work process The lesion size that middle i & lt impact stress causes, W_MFor the original damage size of product, D_wFailure threshold for product.

Preferably, described single-impact stress screening process model building unit includes:

Ratio computing module, for product being carried out single-impact stress screening according to the failure threshold of product, is led to Cross the product that do not lost efficacy after single-impact stress screening, and there is not the product, just of damage after calculating initial not damaged and screening Beginning not damaged but there is the product of damage after screening and be initially present damage but rushed by single all by the product screened Ratio shared in the product not lost efficacy after hitting stress screening；

Life distribution function computing module, for according to longevity of described not damaged product work life distribution function and described Only the working life distribution function of the product lost efficacy is caused to calculate every series products in screening process because of impact stress during use In life distribution function；

Model building module, for being distributed letter according to the ratio shared by every series products and the life-span in screening process thereof Number, sets up single-impact stress screening process model, and the normalizing life-span of the product that do not lost efficacy after obtaining single-impact stress screening divides Cloth function.

Preferably, there is not the ratio shared by product of damage and in screening process after described initial not damaged and screening In life distribution function be followed successively by respectively:

$P(T_{ESS}>t|Z=1)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right);$

Described initial not damaged but screening after there is the ratio shared by product of damage and the life-span in screening process thereof Distribution function is followed successively by:

$P(T_{ESS}>t|Z=2)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s^{\&prime;}<D_w)P\left(N\right(t)=j);$

Described being initially present is damaged but by the ratio shared by product of screening and the distribution of the life-span in screening process thereof Function is followed successively by:

$P(T_{ESS}>t|Z=3)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s+W_M<D_w)P\left(N\right(t)=j);$

Described single-impact stress screening process model is

Wherein, π is the ratio of initial not damaged product, and s is the value of screening stress, and ρ (s) is initial not damaged but screening The ratio of the rear product that there is damage, W_sThe lesion size caused for impact stress in screening process, W_s' it is the most undamaged Product screens the lesion size first caused, T because of impact stress_ESSThe use longevity for the product by single-impact stress screening Life.

Preferably, described screening conditions optimize unit, specifically for according to formulaExcellent Do not lost efficacy after changing described single-impact stress screening the normalizing life distribution function of product；Or, according to formulaDo not lost efficacy after optimizing described single-impact stress screening product the normalizing life-span distribution Function；Wherein, T_gLife expectancy for product.

The embodiment of the present invention provides the benefit that: the present invention sets up the reliability mould of product according to the failure threshold of product Type, respectively obtains not damaged product and the most only because impact stress causes the working life distribution letter of the product lost efficacy Number；By failure threshold based on product be determine value set up single-impact stress screening process model so as to get single rush Do not lost efficacy after hitting stress screening in product, initial not damaged but there is the product of damage after screening and be initially present damage but pass through The product of screening has different screening life distribution function.Therefore, the screening technique of the present invention can be suitable for initial not damaged Product and the most intact but produce the product of defect after screening and have the average case of different lifetime function, enriches single-impact and answers The application scenarios of power screening；The present invention is always according to the product that do not lost efficacy after the life expectancy optimization single-impact stress screening of product Normalizing life distribution function such that it is able to the single-impact stress screening condition after being optimized, realizes above-mentioned average case Certain directive function is played in the screening conditions optimization of single-impact stress screening.

Accompanying drawing explanation

The optimization method flow chart of the single-impact stress screening condition that Fig. 1 provides for embodiment one；

Fig. 2 produces in screening process damage for the initial undamaged product that embodiment two provides increases with impact stress The probability curve diagram of wound；

In the case of the different impact stress that Fig. 3 provides for embodiment two, product is at T projected life_gTime reliability curves Figure；

The optimization apparatus structure block diagram of the single-impact stress screening condition that Fig. 4 provides for embodiment three.

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing to embodiment party of the present invention Formula is described in further detail.

Embodiment one

The optimization method flow chart of the single-impact stress screening condition that Fig. 1 provides for the present embodiment, as it is shown in figure 1, should Method includes:

S110, according to the failure threshold of product to setting up the reliability model of product, obtains the work longevity of not damaged product Order distribution function and the most only because impact stress causes the working life distribution function of the product lost efficacy.

In manufacture course of products, due to off-gauge material or other factors, may produce some exist latent defect, The product of damage (such as: micro-crack).These defective products, in use easily lose because of the damage of accumulation Effect, relative to there is not the product of latent defect, damage, just has a kind of extra failure mode because what accumulated damage lost efficacy Pattern, the product reliability model that therefore the present embodiment is set up distinguishes not damaged product and because impact stress causes the product of inefficacy Product, and obtain the working life distribution function of this two series products.

In the work process of product, it is frequently subjected to meet the impact of nonhomogeneous Poisson distribution under work condition environment, it is assumed that produce Accumulation number of shocks suffered in product working time t is N (t), and nonhomogeneous Poisson distribution intensity function is λ (t), there will be no latent It is denoted as T in defect, the product of damage, namely the life-span of lossless product_N, corresponding substrate crash rate is r (t).Further, this enforcement Official holiday is located in work condition environment, and impact stress can make the damaged products size that originally there is latent defect expand further until reaching To failure threshold D_w, and the product that originally there is not latent defect is insensitive to impact stress, i.e. will not be because of under work condition environment Impact stress cause the generation that damages accordingly, finally quit work because of other failure modes.

Based on foregoing description, working life distribution function the most following formula (1) institute of the not damaged product in the present embodiment Show:

$P(T_N>t)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)---\left(1\right)$

The substrate crash rate that r (x) is not damaged product in formula (1)；It should be noted that the base described in the present embodiment End crash rate is the crash rate not considering accumulated damage failure mode.

During product work time t, shown in the lesion size such as formula (2) of the product that originally there is latent defect:

$W\left(t\right)=\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_M---\left(2\right)$

W in formula (2)_iThe lesion size caused for i & lt impact stress in work process, W_MInitial damage for product Hinder size.

Can obtain according to formula (2), the most only cause the working life of the product lost efficacy because of impact stress Distribution function, concrete as shown in formula (3):

$\begin{array}{c}P(T_E>t)=P\left(W\right(t)<D_w)\\ =\underset{j=0}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_M<D_w)\&CenterDot;P\left(N\right(t)=j)\end{array}---\left(3\right)$

For ease of understand that the present embodiment formula (3) defines the most only because impact stress causes the product that lost efficacy The implication of working life distribution function, the present embodiment is illustrated by following specific implementation.

In this specific implementation, it is assumed that lesion size W that in work process, i & lt impact stress causes_iMeet all Value is μ, and variance is σ²Normal distribution, original damage size W_MMeeting average is μ_M, variance isNormal distribution time, above-mentioned Formula (3) can be derived as further:

$P(T_E>t)=\underset{N\left(t\right)=0}{\overset{\mathrm{\&infin;}}{\&Sigma;}}\mathrm{\&Phi;}\left(\frac{D_w-\left(N\right(t)\&CenterDot;{\mathrm{\&mu;}}_w+{\mathrm{\&mu;}}_M)}{\sqrt{N\left(t\right)\&CenterDot;{\mathrm{\&sigma;}}_w^2+{\mathrm{\&sigma;}}_M^2}}\right)\&CenterDot;\frac{{\left({\&Integral;}_0^t\mathrm{\&lambda;}\right(x\left)dx\right)}^{N\left(t\right)}}{N\left(t\right)!}\exp (-{\&Integral;}_0^t\mathrm{\&lambda;}(x\left)dx\right),t\&GreaterEqual;0---\left(4\right)$

The probability cumulative distribution function that Φ () is standard normal distribution in formula (4).

For a collection of product newly developed, it is assumed that the ratio of no defective product is π, the ratio of the most defective product is 1-π, is denoted as T by the life-span of product, then the working life distribution function of product is:

$P(T>t)=\mathrm{\&pi;}\&CenterDot;\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)+(1-\mathrm{\&pi;})\&CenterDot;\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;P(T_E>t),t\&GreaterEqual;0---\left(5\right)$

Formula (5) defines the product randomly selected from a collection of product produced life-span distribution letter in use Number.

S120, failure threshold based on product, for determining that value sets up single-impact stress screening process model, obtains single Do not lost efficacy after impact stress screening the normalizing life distribution function of product.

The product that do not lost efficacy after single-impact stress screening includes: do not exist after initial not damaged and screening damage product, Initial not damaged but there is the product of damage after screening and be initially present damage but by the product of screening；Wherein initial not damaged But the product that there is damage after Shai Xuan has different life distribution function with being initially present damage by the product of screening.

" failure threshold based on product is for determining that value sets up single-impact stress screening process model " tool in this step Body is:

Failure threshold according to product carries out single-impact stress screening to product, obtains by single-impact stress screening After the product that do not lost efficacy, and calculate initial not damaged and screening after do not exist the product of damage, initial not damaged but screening after deposit Product in damage passes through the product of screening with being initially present damage；

Longevity work life distribution function according to described not damaged product and described the most only lead because of impact stress Cause working life distribution function calculating every series products life distribution function in screening process of the product lost efficacy；

According to the ratio shared by every series products and the life distribution function in screening process thereof, set up single-impact stress Screening process model.

It should be noted that owing to when product is carried out single-impact stress screening, above-mentioned three types can be obtained Do not lost efficacy the life distribution function of product, for screening stress optimal during obtaining impact screening in subsequent treatment, this reality Execute example and the life distribution function of the product that do not lost efficacy of these three type is weighted summation process such that it is able to a life-span The expression formula of distribution function did not lost efficacy after representing screening the life distribution function of product；The i.e. distribution of normalizing life-span in present invention letter Number is diagrammatically only by with the life-span distribution of all kinds of products that do not lost efficacy after an expression formula statement screening, is not to all kinds of products that do not lost efficacy Life distribution function be normalized.

The method for building up of the single-impact stress screening process model for being more fully understood that in step S120, the present embodiment leads to Cross following implementation to illustrate.

In the impact stress screening test of this implementation, a magnitude is impact (the generally punching in work condition environment of s Hit the several times of stress intensity) put on each product participating in screening.

For original defective product, it is W that single-impact screening test is introduced into an extra size_sDamage, Its size increases and random increase with s.Additionally, the most intact product of a part creates scarce in impact stress screening test Fall into, the ratio of this portioned product is denoted as ρ (s), have 0≤ρ (s)≤1, and ρ (s) increases and random increase with s equally.Wherein, After impact stress screening test, the sample of inefficacy will be rejected, and the sample not lost efficacy then comes into operation.

This implementation terminate single-impact stress screening test after, the product not lost efficacy can be divided three classes: (1) just The product of damage is there is not after beginning not damaged and screening；(2) initial not damaged but there is the product of damage after screening；(3) initial There is damage but by the product of screening.

The most then having, the ratio shared by product that there is not damage after the initial not damaged of first kind product and screening is:

The initial not damaged of Equations of The Second Kind product but there is the ratio shared by product of damage after screening and be:

3rd series products is initially present damage but by the ratio shared by the product of screening is:

Working life distribution function P (T according to the not damaged product obtained in step S110_N＞ t) and in the process of use In only cause, because of impact stress, the working life distribution function P (T of product that lost efficacy_E＞ t) above-mentioned three series products can be obtained exist Life distribution function in screening process.

The life-span distribution in screening process of the product of damage is there is not after the initial not damaged of first kind product and screening Function is:

$P(T_{ESS}>t|Z=1)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)---\left(9\right)$

The initial not damaged of Equations of The Second Kind product but there is the product of the damage life-span distribution letter in screening process after screening Number is:

$P(T_{ESS}>t|Z=2)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s^{\&prime;}<D_w)P\left(N\right(t)=j)---\left(10\right)$

3rd series products is initially present damage but by the product of screening life distribution function in screening process is:

$P(T_{ESS}>t|Z=3)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s+W_M<D_w)P\left(N\right(t)=j)---\left(11\right)$

W in above-mentioned formula_s' screen, because of impact stress, the lesion size first caused for initial undamaged product.

When lesion size W that i & lt impact stress in work process causes_iMeeting average is μ, and variance is σ²Normal distribution, just The undamaged product that begins screens lesion size W first that causes because of impact stress_s' to meet average be μ '_s, variance isNormal distribution, Original damage size W_MMeeting average is μ_M, variance isNormal distribution, lesion size W that in screening process, impact stress causes_s Meeting average is μ_s, variance isNormal distribution time, in formula (10), In formula (11)

According to the ratio shared by above-mentioned three series products and the life distribution function in screening process thereof, single can be obtained Impact stress screening process model is:

T in above-mentioned formula_ESSFor the service life by the product after single-impact stress screening, correspond to respectively One series products, Equations of The Second Kind product and the 3rd series products.

S130, optimizes described normalizing life distribution function, the single-impact after being optimized according to the life expectancy of product Stress screening condition, described screening conditions include screening stress.

For the product developed, the reliability of the life expectancy of product is an important design objective, generally Wish the reliability of the life expectancy of improving product.

Step S130 is mainly by the normalizing longevity of the product that do not lost efficacy after following two schemes optimization single-impact stress screening Life distribution function:

The optimization of screening conditions is carried out, to obtain the screening conditions of optimum according to following formula:

$s^{*}=\underset{s}{\mathrm{argmax}}\&lsqb;P(T_{ESS}>T_g)\&rsqb;---\left(13\right)$

Or, carry out the optimization of screening conditions according to following formula, to obtain the screening conditions of optimum:

$s^{*}=\underset{s}{\mathrm{argmax}}\&lsqb;{\&Integral;}_0^{T_g}P(T_{ESS}>x)dx\&rsqb;---\left(14\right)$

Wherein, T_gLife expectancy for product.

It should be noted that formula (13) and formula (14) typically can be investigated at screening stress by the method for simulation calculation Scope possible for value s in the different reliability of product or the expectsted of working life, and finally choose optimal value.

The method of the present embodiment is particularly suited for the lesion size that impact stress causes and meets the product of normal distribution, this reality Execute example and set up the reliability model of product according to the failure threshold of product, respectively obtain not damaged product and the most only Because impact stress causes the working life distribution function of the product lost efficacy；Failure threshold based on product is for determining that value sets up single Impact stress screening process model so as to get single-impact stress screening after do not lost efficacy in product, initial not damaged but screening The rear product that there is damage has different screening life distribution function, therefore with being initially present damage by the product of screening The screening technique of the present invention can be suitable for initial not damaged product and the most intact but produce the product of defect after screening and have difference The situation of lifetime function, enriches the application scenarios of single-impact stress screening；The present invention is excellent always according to the life expectancy of product Change the normalizing life distribution function of the product that do not lost efficacy after single-impact stress screening such that it is able to the single-impact after being optimized Stress screening condition, certain guidance work is played in the screening conditions optimization that above-mentioned average case realizes single-impact stress screening With.

Embodiment two

The optimization method of the repeat impact stress screening condition in embodiment one is applicable to initial not damaged product with initial Intact but produce the product of defect after screening and have the average case of different lifetime function, it is particularly suited for the damage that impact stress causes Hinder size and meet the product of normal distribution.If the solder joint with micro-crack is during accepting external impact, crackle will gradually Extension, the fracture failure when crack size reaches a threshold value, thus the single-impact stress screening condition in embodiment one Optimization method can be used for the single-impact stress screening of solder joint.

When to single-impact stress screening process model building, it is assumed that substrate crash rate r (t)=0.001 of not damaged product, Nonhomogeneous Poisson distribution intensity function lambda (t)=0.001, failure threshold D_w=4, ratio π=0.7 of initial not damaged product, just Beginning not damaged but there is ratio ρ (the s)=1-exp [-0.001s], T projected life of product of product of damage after screening_g= 100。

Present embodiment assumes that lesion size W that in work process, i & lt impact stress causes_iMeeting average is μ=0.2, Variance is σ²The normal distribution of=0.2, initial undamaged product screens, because of impact stress, lesion size W first caused_s' symbol Conjunction average is μ '_s=0.1, variance isNormal distribution, original damage size W_MMeeting average is μ_M=0.8, variance ForNormal distribution, lesion size W that in screening process, impact stress causes_sMeeting average is μ_s=0.02s, side Difference isNormal distribution.

According to above-mentioned parameter, Fig. 2 gives initial undamaged product and increases with impact stress and produce in screening process The probability of raw damage, from figure 2 it can be seen that the most intact product is under the effect of impact stress, along with impact stress The probability increasing the most intact product generation damage is the biggest.

In the case of Fig. 3 gives different impact stress, product is at T projected life_gTime reliability.Can from Fig. 3 Go out, if according to maximizing the product criterion in projected life end reliability, the value s=of the optimum screening stress that should choose 158。

Embodiment three

The present embodiment uses the design concept identical with embodiment one, it is provided that a kind of single-impact stress screening condition Optimize device.

The optimization apparatus structure block diagram of the single-impact stress screening condition that Fig. 4 provides for the present embodiment, as shown in Figure 4, This device includes:

Reliability modeling unit 41, for setting up the reliability model of product according to the failure threshold of product, obtains lossless The working life distribution function of injured labor product and the most only cause the working life of the product lost efficacy to be divided because of impact stress Cloth function.

Wherein, the working life distribution function of not damaged product is specially

Described the most only because of impact stress cause lost efficacy product working life distribution function be specially

T in above-mentioned formula_NFor the life-span of not damaged product, T_EFor the most only causing losing efficacy because of impact stress Life of product, r (x) is the substrate crash rate of not damaged product, the accumulative number of shocks that N (t) is suffered when being time t, W_iFor The lesion size that in work process, i & lt impact stress causes, W_MFor the original damage size of product, D_wInefficacy threshold for product Value.

Single-impact stress screening process model building unit 42, for failure threshold based on product for determining that value sets up single Impact stress screening process model, the normalizing life distribution function of the product that do not lost efficacy after obtaining single-impact stress screening, described The product that do not lost efficacy after single-impact stress screening includes: there is not the product of damage, the most lossless after initial not damaged and screening Hinder but there is the product of damage after screening and be initially present damage but by the product screened；Wherein initial not damaged but after screening The product that there is damage has different life distribution function with being initially present damage by the product of screening.

In an implementation of the present embodiment, single-impact stress screening process model building unit 42 includes:

Ratio computing module, for product being carried out single-impact stress screening according to the failure threshold of product, is led to Cross the product that do not lost efficacy after single-impact stress screening, and there is not the product, just of damage after calculating initial not damaged and screening Beginning not damaged but there is the product of damage after screening and be initially present damage but rushed by single all by the product screened Ratio shared in the product not lost efficacy after hitting stress screening；

Life distribution function computing module, for according to longevity of described not damaged product work life distribution function and described Only the working life distribution function of the product lost efficacy is caused to calculate every series products in screening process because of impact stress during use In life distribution function；

Model building module, for being distributed letter according to the ratio shared by every series products and the life-span in screening process thereof Number, sets up single-impact stress screening process model, and the normalizing life-span of the product that do not lost efficacy after obtaining single-impact stress screening divides Cloth function.

Wherein, there is not the ratio shared by product of damage and the longevity in screening process thereof after initial not damaged and screening Life distribution function is followed successively by respectively:

$P(T_{ESS}>t|Z=1)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right);$

Initial not damaged but there is the ratio shared by product of damage and the life-span distribution in screening process thereof after screening Function is followed successively by:

$P(T_{ESS}>t|Z=2)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s^{\&prime;}<D_w)P\left(N\right(t)=j);$

It is initially present damage but by the ratio shared by product of screening and the life distribution function in screening process thereof It is followed successively by:

$P(T_{ESS}>t|Z=3)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s+W_M<D_w)P\left(N\right(t)=j);$

Single-impact stress screening process model is

π in above-mentioned formula is the ratio of initial not damaged product, and s is the value of screening stress, and ρ (s) is the most lossless Hinder but after screening, there is the ratio of the product of damage, W_sThe lesion size caused for impact stress in screening process, W_s' it is initial Undamaged product screens the lesion size first caused, T because of impact stress_ESSFor the product by single-impact stress screening Service life.

Screening conditions optimize unit 43, and screening conditions optimize unit, for returning according to the life expectancy optimization of product One life distribution function, the single-impact stress screening condition after being optimized, described screening conditions include screening stress.

In a preferred version of the present embodiment, screening conditions optimize unit 43, specifically for according to formulaOptimize the normalizing life distribution function of the product that do not lost efficacy after single-impact stress screening；Or Person, according to formulaOptimize the normalizing longevity of the product that do not lost efficacy after single-impact stress screening Life distribution function；Wherein, T_gLife expectancy for product.

The specific works mode of each unit module of apparatus of the present invention embodiment may refer to the embodiment of the method for the present invention, Do not repeat them here.

In sum, the invention provides optimization method and device, the present invention of a kind of single-impact stress screening condition Failure threshold according to product sets up the reliability model of product, respectively obtains not damaged product and the most only because of punching Hit stress and cause the working life distribution function of the product lost efficacy；By failure threshold based on product for determining that value sets up single Impact stress screening process model so as to get single-impact stress screening after do not lost efficacy in product, initial not damaged but screening The rear product that there is damage has different screening life distribution function with being initially present damage by the product of screening.Cause This, the screening technique of the present invention can be suitable for initial not damaged product and the most intact but produce the product of defect after screening and have not With the average case of lifetime function, enrich the application scenarios of single-impact stress screening；The present invention is always according to the expectation of product Life-span optimizes the normalizing life distribution function of the product that do not lost efficacy after single-impact stress screening such that it is able to the list after being optimized Secondary Shocks stress screening condition, the screening conditions optimization that above-mentioned average case realizes single-impact stress screening is played certain Directive function.

The foregoing is only presently preferred embodiments of the present invention, be not intended to limit protection scope of the present invention.All Any modification, equivalent substitution and improvement etc. made within the spirit and principles in the present invention, are all contained in protection scope of the present invention In.

Claims (10)

1. the optimization method of a single-impact stress screening condition, it is characterised in that described method includes:

Failure threshold according to product sets up the reliability model of product, obtain not damaged product working life distribution function and The most only cause the working life distribution function of the product lost efficacy because of impact stress；

Failure threshold based on product, for determining that value sets up single-impact stress screening process model, obtains single-impact stress sieve Do not lost efficacy after choosing the normalizing life distribution function of product, and the product that do not lost efficacy after described single-impact stress screening includes: initial nothing Do not exist after damage and screening the product of damage, initial not damaged but there is the product of damage after screening and be initially present damage but Product by screening；Wherein initial not damaged but there is the product of damage after screening and be initially present damage but by screening Product has different life distribution function；

Life expectancy according to product optimizes described normalizing life distribution function, the single-impact stress screening bar after being optimized Part, described screening conditions include screening stress.

Method the most according to claim 1, it is characterised in that the working life distribution function of described not damaged product is concrete For

Described the most only because of impact stress cause lost efficacy product working life distribution function be specially

Wherein, T_NFor the life-span of not damaged product, T_EFor the most only causing the life of product of inefficacy, r because of impact stress X () is the substrate crash rate of not damaged product, the accumulative number of shocks that N (t) is suffered when being time t, W_iFor in work process i-th The lesion size that Secondary Shocks stress causes, W_MFor the original damage size of product, D_wFailure threshold for product.

Method the most according to claim 2, it is characterised in that described failure threshold based on product is single for determining that value is set up Secondary Shocks stress screening process model includes:

Failure threshold according to product carries out single-impact stress screening to product, after obtaining by single-impact stress screening Do not lost efficacy product, and calculate initial not damaged and screening after do not exist the product of damage, initial not damaged but screening after exist damage The product of wound and be initially present damage but by the product of screening all by single-impact stress screening after the product that do not lost efficacy Ratio shared in product；

Longevity work according to described not damaged product orders distribution function and described the most only because impact stress causes losing The working life distribution function of the product of effect calculates every series products life distribution function in screening process；

According to the ratio shared by every series products and the life distribution function in screening process thereof, set up single-impact stress screening Process model, the normalizing life distribution function of the product that do not lost efficacy after obtaining single-impact stress screening.

Method the most according to claim 3, it is characterised in that

There is not the ratio shared by product of damage after described initial not damaged and screening and the life-span in screening process divides Cloth function is followed successively by respectively:

$P(T_{ESS}>t|Z=1)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right);$

Described initial not damaged but screening after exist damage the ratio shared by product and in screening process life-span distribution Function is followed successively by:

$P(T_{ESS}>t|Z=2)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+{W_s}^{\&prime;}<D_w)P\left(N\right(t)=j);$

Described being initially present is damaged but by the ratio shared by product of screening and the life distribution function in screening process thereof It is followed successively by:

$P\left(T_{ESS}>t|Z=3\right)=\exp \left(-{\&Integral;}_0^{t}r\left(x\right)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\mathrm{\&Sigma;}}}P\left(\underset{i=0}{\overset{N\left(t\right)}{\mathrm{\&Sigma;}}}{W}_i+W_s+W_M<D_w\right)P\left(N\left(t\right)=j\right);$

Described single-impact stress screening process model is

Wherein, π is the ratio of initial not damaged product, and s is the value of screening stress, and ρ (s) is initial not damaged but deposits after screening At the ratio of the product of damage, W_sThe lesion size caused for impact stress in screening process, W_s' for initial undamaged product Because impact stress screens the lesion size first caused, T_ESSService life for the product by single-impact stress screening.

Method the most according to claim 4, it is characterised in that the described life expectancy according to product optimizes the described normalizing longevity Life distribution function, the single-impact stress screening condition after being optimized includes:

According to formulaDo not lost efficacy after optimizing described single-impact stress screening the normalizing of product Life distribution function；Or,

According to formulaDo not lost efficacy after optimizing described single-impact stress screening product Normalizing life distribution function；

Wherein, T_gLife expectancy for product.

6. the optimization device of a single-impact stress screening condition, it is characterised in that described device includes:

Reliability modeling unit, for setting up the reliability model of product according to the failure threshold of product, obtains not damaged product Working life distribution function and the most only cause, because of impact stress, the working life distribution function of product that lost efficacy；

Single-impact stress screening process model building unit, for failure threshold based on product for determining that value is set up single-impact and answered Power screening process model, the normalizing life distribution function of the product that do not lost efficacy after obtaining single-impact stress screening, described single rushes The product that do not lost efficacy after hitting stress screening includes: there is not the product of damage, initial not damaged but sieve after initial not damaged and screening There is the product of damage after choosing and be initially present damage but by the product of screening；Wherein initial not damaged but exist after screening and damage The product of wound has different life distribution function with being initially present damage by the product of screening；

Screening conditions optimize unit, optimize described normalizing life distribution function for the life expectancy according to product, are optimized After single-impact stress screening condition, described screening conditions include screen stress.

Device the most according to claim 6, it is characterised in that the working life distribution function of described not damaged product is concrete For

Described the most only because of impact stress cause lost efficacy product working life distribution function be specially

Wherein, T_NFor the life-span of not damaged product, T_EFor the most only causing the life of product of inefficacy, r because of impact stress X () is the substrate crash rate of not damaged product, the accumulative number of shocks that N (t) is suffered when being time t, W_iFor in work process i-th The lesion size that Secondary Shocks stress causes, W_MFor the original damage size of product, D_wFailure threshold for product.

Device the most according to claim 7, it is characterised in that described single-impact stress screening process model building unit bag Include:

Ratio computing module, for product being carried out single-impact stress screening according to the failure threshold of product, obtains by list The product that do not lost efficacy after Secondary Shocks stress screening, and calculate initial not damaged and screening after there is not the product of damage, initial nothing The product that there is damage after damaging but screening is answered by single-impact all by the product screened with being initially present damage Ratio shared in the product not lost efficacy after power screening；

Life distribution function computing module, works for the longevity according to described not damaged product and orders distribution function and described in use During only because of impact stress cause lost efficacy product working life distribution function calculate every series products in screening process Life distribution function；

Model building module, for according to the ratio shared by every series products and the life distribution function in screening process thereof, builds Vertical single-impact stress screening process model, the normalizing life-span distribution letter of the product that do not lost efficacy after obtaining single-impact stress screening Number.

Device the most according to claim 8, it is characterised in that there is not the product of damage after described initial not damaged and screening Ratio shared by product and the life distribution function in screening process thereof are followed successively by respectively:

$P(T_{ESS}>t|Z=1)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right);$

Described initial not damaged but screening after exist damage the ratio shared by product and in screening process life-span distribution Function is followed successively by:

$P(T_{ESS}>t|Z=2)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+{W_s}^{\&prime;}<D_w)P\left(N\right(t)=j);$

Described being initially present is damaged but by the ratio shared by product of screening and the life distribution function in screening process thereof It is followed successively by:

$P(T_{ESS}>t|Z=3)=\exp (-{\&Integral;}_0^{t}r(x\left)dx\right)\&CenterDot;\underset{j=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}P(\underset{i=0}{\overset{N\left(t\right)}{\&Sigma;}}{W}_i+W_s+W_M<D_w)P\left(N\right(t)=j);$

Described single-impact stress screening process model is

Wherein, π is the ratio of initial not damaged product, and s is the value of screening stress, and ρ (s) is initial not damaged but deposits after screening At the ratio of the product of damage, W_sThe lesion size caused for impact stress in screening process, W '_sFor initial undamaged product Because impact stress screens the lesion size first caused, T_ESSService life for the product by single-impact stress screening.

Device the most according to claim 9, it is characterised in that described screening conditions optimize unit, specifically for according to public affairs FormulaDo not lost efficacy after optimizing described single-impact stress screening product the normalizing life-span distribution letter Number；Or, according to formulaDo not lost efficacy after optimizing described single-impact stress screening product The normalizing life distribution function of product；Wherein, T_gLife expectancy for product.