cyclic stress accelerated life test
采用脑机接口技术的医疗器械 术语及定义204年版
脑机接口技术的医疗器械的术语和定义1 范围本文件界定了采用脑机接口技术的医疗器械的术语和定义，并对其进行了分类。
本文件适用于采用脑机接口技术的医疗器械2 规范性引用文件本文件没有规范性引用文件。
3 术语和定义下列术语和定义适用于本文件。
3.1老化因子/加速因子 accelerated aging factor一个估计的或计算出的与植入体内后的脑机接口医疗器械植入体达到同样水平的物理性能变化的时间比率。
注：温度增加或降低10℃的老化因子Q10 是一个保守估计的加速老化因子。
[来源：YY 0681.1-2018，3.2，有修改]3.2加速寿命测试accelerated life testing用于确定未来可能发生故障的一种测试和分析方法。
通常用于当不能等待故障以正常速率发生，需要加速时间分析故障在未来可能如何发生的方法。
3.33.4 附件accessory与设备一起使用的附加部分，用来：——达到预期用途；——使设备适合一些特定用途；——便于设备的使用；——增强设备的性能；或——启用某些功能，以便其他设备的某些功能集成。
[来源：GB9706.1-2020，3.3]随附文件accompany ing document随ME 设备、ME 系统或附件所带的文件，其内容包含了为责任方或操作者提供的信息，特别是关于基本安全和基本性能。
[来源：GB9706.1-2020，3.4] 3.5动作电位action potential；AP神经元膜上突然的、快速的、短暂的、扩张性的电极化变化，它是由膜电位的快速上升和下降引起的。
3.6主动式脑机接口医疗器械active BCI-ME需要使用者有意识地改变大脑活动的脑机接口医疗器械范式或系统。
3.7自适应学习Adaptive Learning根据用户的反馈和历史交互数据，动态调整和优化LLM 模型，提高响应的准确性和相关性。
3.8环境温度ambient temperature代表模拟植入体内脑机接口医疗器械设备的实际老化时间样品的测试温度。
加速寿命试验
1.MTBF測試原理
1.1.9 反乘冪法則(Inverse Power Law)適用於金屬和非金 屬材料,軸承和電子裝備等. 1.1.10.復合模式(Combination Model)適用於同時考慮溫度 與電壓作為環境應力的電子材料,如電容. 1.1.11.一般情況下,主動電子零件完全適用阿氏模型,而電子 和資訊類成品也可適用阿氏模型,原因是成品類的失效 模式是由大部分主動式電子零件所構成.因此,阿氏模 型,廣泛應用於電子﹑資訊行業.
1.MTBF測試原理
1.2.2. 加速因子
加速因子即為產品在使用條件下的壽命和高測試應力條件下 的壽命的比值.
如果產品壽命適用於阿氏模型,則其加速因子為:
Vu為使用條件下的絕對溫度 Va為加速條件下的絕對溫度 B=EA/K
1.MTBF測試原理
1.2.3.加速因子中活化能Ea的計算 活化能是分子與化學或物理作用中需具備的能量,單位 是電子伏特Ev. 當試驗的溫度與使用溫度差距範圍不大時, 則Ea可設為常數. Ea= K* (Inλa – Inλn)/(1/Tn-1/Ta) λa為加速溫度時的失效率 λn為正常溫度時的失效率 Tn, Ta均為絕對溫度0K λa和λn可以以試驗的方式的得出,但需要較長的試驗時 間.而且新機種的失效率很難在短時間內得出.
MTB F 計算方法概論
CASS工艺运行原理
CASS工艺运行原理CASS（Cyclic Accelerated Stress Screening）工艺是一种应用在电子产品生产中的可靠性测试方法。
它主要通过快速循环的加速应力进行产品筛选，以提高产品的可靠性和稳定性。
CASS工艺的原理是利用产品在加速应力下可能出现的故障，通过循环的加速应力施加和故障检测，将这些潜在故障尽早暴露出来，并对其进行修复或排除。
CASS主要通过速热速冷的循环，在短时间内进行高温和低温的交替应力加载。
这种温度变化会导致产品内部材料的热膨胀和收缩，从而引起应力的变化。
通过加速应力加载，潜在缺陷部位可能会发生裂纹扩展或断裂，从而可通过故障检测手段进行定位和修复。
CASS工艺运行的主要步骤包括：1. 组装和校准：首先，将产品组装并进行校准，以确保其正常运行。
2. 预热和冷却：接下来，将产品置于高温环境中进行预热，通常为85℃，并在一定时间后将其迅速冷却到低温环境（通常为-40℃）。
3. 切换和加载：循环的高温和低温操作会造成产品内部应力的变化。
这个过程会反复进行，通常持续数百至数千个循环，以确保产品在应力加载下的稳定性。
4. 故障检测：在CASS工艺的每个循环结束后，使用故障检测设备对产品进行测试，以检测可能出现的故障和缺陷。
5. 故障修复和排除：一旦故障被检测到，需要对其进行修复或排除，以确保产品的可靠性和稳定性。
CASS工艺的优势在于能够在较短的时间内对产品进行可靠性测试，尽早发现潜在故障和缺陷。
通过循环的应力加载和故障检测，可以提高产品的质量和可靠性。
另外，CASS工艺还可以辅助产品设计和工艺改进，以提升产品的性能和可靠性。
总之，CASS工艺通过循环的加速应力施加和故障检测，可以提高产品的可靠性和稳定性。
它是电子产品生产中常用的可靠性测试方法之一，对于提高产品质量和可靠性具有重要作用。
CASS（Cyclic Accelerated Stress Screening）工艺是一种应用在电子产品生产中的可靠性测试方法。
食品储存期加速测试及其应用
食品储存期加速测试及其应用Accelerated Shelf Life Testing（ASLT）and application摘要：利用化学动力学的原理，改变储存环境来缩短食品储存期，从而在短时间内可得到长寿食品（一年以上）的储存期，以及应用于食品稳定性的测试，确保食品的商业储存期。
Abstract: using the principle of chemical kinetics, change the storage conditions to shorten the shelf life of food, and in a short time can get the shelf life of long life foods at normal condition, and apply in stability test for food, to insure the commercial shelf life of foods.A．基本原理食品储存期加速测试的原理就是利用化学动力学来量化外来因素如温度、湿度、气压和光照等对变质反应的影响力。
通过控制食品处于一个或多个外在因素高于正常水平的环境中，变质的速度将加快或加速，在短于正常时间内就可判定产品是否变质。
因为影响变质的外在因素是可以量化的，而加速的程度也可以计算得到，因此可以推算到产品在正常储存条件下实际的储存期。
由于许多包装食品通常可以储存超过一年，评价对储存期产生影响的外在因素，如产品本身配料的改变（采用新的抗氧化剂或增稠剂），加工过程的改变（采用不同消毒时间或温度），或包装材料的改变（采用新的聚合体薄膜），都会希望储存期尽可能持续到产品所要求的时间（商业储存期）。
但许多公司都等不起这么长的时间来知道这些新产品/新加工过程/新包装材料能否提供足够的储存期，因为会影响到其他决定（如新工厂的合同，采购新设备，或者安排供应新包装材料等都有时间限制）。
高速加速生命测试与高速加速压力屏测方法说明书
What We DoHALT – Highly Accelerated Life TestHASS – Highly Accelerated Stress Screen . . . . . . . . . . . . . . 3An Advanced System For Accelerated Testing . . . . . . . . . . 3How We Do ItThe Elements of a SuccessfulAccelerated Stress Test (AST) Program . . . . . . . . . . . . . . . . . 4Goals, Budgets, and ROI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Testing and Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Knowledge Support for AST Program Success . . . . . . . . . . . . 4Solutions GroupESPEC Solutions Group (ASK) . . . . . . . . . . . . . . . . . . . . . . . . . . 5Fixture Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Testing Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Hobbs Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5OverviewThe QFusion System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6The Typhoon Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6The Inferno System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6HawQ (Patent Pending) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6The OVTT Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Mechanical Halt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6HALT/HASS Reliability Testing SystemsQFusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Typhoon 8.0+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Typhoon 4.0+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Typhoon 3.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Typhoon 2.5+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Typhoon 2.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Typhoon 1.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13HawQ™ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Typhoon 4.0+ Inferno . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Typhoon 2.5+ Inferno . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15OVTT18 and OVTT24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Mechanical Halt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17World’s Largest HALT/HASS ProviderESPEC North America is the largest manufacturer of AST (Accelerated Stress Testing)equipment worldwide. The Qualmark brand HALT (Highly Accelerated Life Test) and HASS (Highly Accelerated Stress Screen) testing technology has been recognized as one of the fastest and most e ective disciplines for design reliability testing and production screening for electronics and electromechanical devices.Innovative System TechnologyThe Qualmark brand pioneered accelerated stress test technology in the early 1990s and has since consistently led the market in technology innovation. In 2009 thebrand introduced the next generation vibration table – the xLF2™. The xLF2 provides the rst and only “ eld maintainable” PSD (Power Spectral Density) table, allowing for simple maintenance procedure to restore the table to Factory PSD.Accelerated Testing Knowledge LeaderThe Qualmark brand o ers a wide range of Applications support, Skills, and Knowledge (ASK) speci cally designed so that best practices are applied to HALT/ HASS system use for maximum returns. The ESPEC Solutions Group adds to the value derived from accelerated testing by customizing services to target customer speci c program optimization. The educational value of the ESPEC Solutions Group can dramatically improve reliability program outcomes and deliver faster product pro tability. It’s never too early or late to “ASK” the ESPEC Solutions Group for the expert support you need.LN 2 InfrastructureLN 2 Infrastructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Qualmark L N 2 Eciency . . . . . . . . . . . . . . . . . . . . . . . . 19Vacuum Jacketed (VJ) Piping . . . . . . . . . . . . . . . . . . . . . . . . 19LN 2 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Typhoon MVIP TM Dewar KitTyphoon — 2.5/3.0 3 Position MVIP Dewar Kit . . . . . . . . . . . . 20Modular Vacuum Insulated Pipe MVIP — Superiority Through Experience . . . . . . . . . . . . . . . . . 21VJ Manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21System Con guration OptionsTable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Certi ed European (CE) Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Additional Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Safety Enhancements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23L iquid Nitrogen Delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23AccessoriesData Acquisition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Monitor And Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Fixturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Spares Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25UpgradesPLC Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25xLF2 Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Service ProgramsAnnual Technical Support Plan . . . . . . . . . . . . . . . . . . . . . . . . 26Extended Parts Warranty Program . . . . . . . . . . . . . . . . . . . . 26Preventative Maintenance & Calibration Services Program . . . 26 Annual Maintenance Program . . . . . . . . . . . . . . . . . . . . . . . . 27Tech Enhancement and Maintenance Program . . . . . . . . . . . . . 272Table of Contents1HALT – Highly Accelerated Life TestHASS – Highly Accelerated Stress ScreenHALT and HASS, collectively referred to as AcceleratedStress Testing (AST), subject a product to a series of stresses, e ectively forcing product weak links to emerge by accel-erating fatigue. Unlike traditional single axis vibration test methods or thermal only methods, an AST program requires specialized HALT/HASS equipment to render the required stresses – random six-degree-of-freedom vibration and rapid thermal change rates – in the combined environment necessary to drive out latent failure modes.In HALT and HASS, stresses are applied in a controlled, in-cremental fashion while the unit under test is continuously monitored for failures. Once the weaknesses of the product are uncovered and corrective actions taken, the limits of the product are clearly understood and the operating margins have been extended as far as possible. The result? A more mature product can be introduced much more quickly with a higher degree of reliability.ESPEC – Accelerating Product ReliabilityBecause we focus on the way rapid shock technology can be utilized to support business goals, ESPEC forms strategic partnerships, provides expert services, and o ers profession-al programs designed to deliver maximum value delivery.Starting with client needs, ESPEC envisions the entire prod-uct testing life cycle and then o ers a solution to deliver maximum tangible return on investment (ROI). ESPEC’s product design and process management solutions help increase productivity, stimulate growth and build com-petitive advantages – measurable business values for your enterprise.Qualmark Testing Technology –An Advanced System For Accelerated TestingQualmark testing technology is speci cally engineered to reduce the total cost of developing and supporting product throughout its lifecycle – from prototype testing, through production, and during warranty. Since pioneering thetechnology, the Qualmark brand has been the market leader in delivering accelerated stress test technology for perform-ing HALT (Highly Accelerated Life Tests) and HASS (Highly Accelerated Stress Screens) that:• Shorten (DVT) Design Veri cation Time and expense • Remove costly manufacturing defects • Boost product reliability • Reduce warranty costs• Increase brand quality recognitionQualkmark Brand accelerated stress test systems, with their powerful thermal performance and six-degree-of-freedom (6DoF) repetitive-shock vibration, drives out design aws fast while conserving energy consumption. Our vibration system delivers low frequency energy for penetrating complex products, while retaining the high frequency en-ergy that is so e ective at exposing weak solder joints and surface mount weaknesses. The advanced engineering that goes into the Qualmark Typhoon series leads the industry in ful lling the complex task of providing e ective excitation of high and low frequency modes while simultaneouslydelivering rotation (roll, pitch and yaw) around three axes (X, Y and Z) vibration. The system’s air ow technology delivers superior rapid temperature cycling – reaching set points faster and delivering stability during cold/hot dwells and ramps that out-perform other systems.Advanced Technology . . . Faster TestingQualmark Brand ProvidesFaster Time to Market • Shorter DVT and expense Increase Revenues• Beat competition to market Reduced Product Failures • More rugged designReduced Costs• Fewer service & warranty claims Improved Customer Satisfaction • Dependable productProtect Brand Value •A recent study showed that 32% of failure modes would have been missed without the combined stresses of Qualmark’saccelerated reliability testing technology.Eliminate 32% of your product’s failure modes andrecalculate your product’s protability!Graph and data proprietary to ESPEC North America. No portion may be copied,modied, distributed, or published without the express written permission of ESPEC.Failures Found by Stress Type2008 Failures by Stress TypeClick Here For Full White Paper3What We DoHALTHASSProof of ScreenA n n u al M a int e n a n c e P r o g r a m W a r r a n t y – S ys t e m &C o m p o n e n t sA p p l i c a t i on T r a in i ng O p e r a t or T r a i n i ngVisit the ESPEC website to learn more about Accelerated Stress Testing (AST) Programs, and howthey can help you complete testing in 1/5 th the time!Hobbs Engineering KnowledgeHobbs Engineering is an independent Knowledge and accelerated testing by tailoring services to deliver customer-speci c program optimization. The educational value of the ESPEC Solutions Group can dramatically improve reliability program outcomes that will quickly drive increases in product pro tability.accelerated testing by tailoring servPart Number: 971-7000 Standard Features High Rate, High FlowPart Number: 971-4008 Standard FeaturesPart Number: 971-4006 Standard FeaturesHigh Rate, High Flow Typhoon Thermal System xLF2 Vibration Table with PSD Management Vacuum Jacketed ManifoldPart Number: 971-4030 Standard FeaturesHigh Rate, High Flow Typhoon Thermal System xLF2 Vibration Table with PSD Management Vacuum Jacketed ManifoldPart Number: 971-4020 (Single Phase) 971-4022 (3 Phase) Standard FeaturesHigh Rate, High FlowTyphoon Thermal SystemxLF2 Vibration Table withPSD ManagementReview Con guration Options and available Accessories with your ESPEC representativePart Number: 971-4250Part Number: 971-4300OVTT18 — Part Number: 971-5001 OVTT24 — Part Number: 971-5200 Standard FeaturesOVTT18 and 24 Base AssemblyWork Space Outer DimensionsOVTT 18OVTT 24Part Number: EQGNZ2.5-Rxx Standard FeaturesRefrigerationESPEC Cascade refrigerationBoost LN2 injection - optional Controls:ESPEC integrated P-300controller with color touch screen xLF2 Vibration TableSafety Features for Battery Testing:Contact FactorySee Con guration Options on page 22 and Accessories on page 26) storage timum HALT/HASS system performance and test results,LN 2 Pipe Outer Pipe Non-Conductive Spacers Vacuum Cavity Microbulk Solution – Cost E ective AlternativeYou must order two (2) VJ Clamps and two (2) O-rings whenordering the kit. These two items are sold separately.750-0303 Clamp, VJ, 1/2”, MVIP Bayonet 760-0273 O-Ring, VJ, 1/2”, MVIP Bayonetst order two (2) VJ Clamps and two (2) O-rings when TO DEWAR TANKSTO TOP OF CHAMBERex Hose (P/N 442-0034)Categories Pro1. Easy – Use the online Modulator to con gure, price and deliver your VIP modulesTop Three Bene tsand accessories.2. Reliable – Long-term maintenance-free reliability that will not degrade, drip or leakMAWP*Installation ConsiderationReusabilityBellows to allow for up to 400°Finternal / external di erentialDesign PlatformMaterialVacuum gauge and retention testprior to shipment* MAWP = Maximum Allowable Working PressureVJ ManifoldVJ Manifold – Part Number: 410-0131• Standard on all chambers except Typhoon 1.5 and 2.0.*• Supports patented dissimilar metal (Invar 36), provides superior seal• Supports dual seats, provides secondary sealingMVIP INLET18”* Optional Vacuum Jacketed Manifold for Typhoon 1.5 and Typhoon 2.0Part number:785-3171 factory installed785-3206 eld retro tElevation StandRaises system 11¾” o oorTyphoons 2.5+ . . . . . . . . . . . . . . . . . . . . . . . . . 785-3005 Typhoons 3.0 . . . . . . . . . . . . . . . . . . . . . . . . . 785-1590 Safety EnhancementsAir Purge KitThe Qualmark air purge system safeguards operators from invisible nitrogen by providing su cient air purge and oxygen normalization before automatically trigger-ing the pneumatic door interlocks allowing the system doors to be opened.Typhoon 4.0+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . .785-2090 Typhoon 4.0+ Inferno . . . . . . . . . . . . . . . . . . . . .785-2119 Typhoon 8.0+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . .785-1763 Air Purge Door Lock KitThe Qualmark air purge door lock system safeguards operators from invisible nitrogen by establishing oxygen normalization before automatically triggering the pneu-matic door interlocks and allowing the system doors to be opened.Typhoon 2.5+/3.0 . . . . . . . . . . . . . . . . . . . . . 785-1668 QFusion 300 . . . . . . . . . . . . . . . . . . . . . . . . . . 785-2672 Door Lock Kit (Typhoons 2.0 &1.5)The Qualmark door interlock system safeguards opera-tors from being able to open the Typhoon door while the system is in operation.Typhoons 2.0, 1.5 . . . . . . . . . . . . . . . . . . . . . . . . . .785-1689 Door Override Typhoon 4.0+ . . . . . . . . . . . . . . 785-2418 SSR Thermal Monitoring AlarmAvailable on all Typhoon models, the thermal alarm monitors the electrical panel and displays a warning light should temperature reach +60ºC and shuts down the system and provides an audible alarm at +80ºC. 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Acceleration life test
3. 加速寿命试验(ALT)提供了产品预期磨损机理的有价值数据，这在当今的市场上是很关键的， 因为越来越多的消费者对其购买的产品提出了使用寿命要求。估计使用寿命仅仅是加速寿命试 验的用处之一。它能使设计者和生产者对产品有更全面的了解，识别出关键的元器件、材料和 工艺，并根据需要进行改进及控制。另外试验得出的数据使生产厂商对产品有充分的信心。 4. 加速寿命试验的对象是抽样产品。 5. 在物理与时间上,加速产品的劣化因子,以较短的时间试验来推定产品在正常使用状态的寿命或 失效率.但基本条件是不能破坏原有设计特性.
如果导入湿度因子: 正常使用条件的湿度为50%RH,加速湿度条件为90%RH, 那么加速因子为 AF=(90/50)3 AF=5.83, 如果温湿度因子同时导入,那么AF=5.83*1.88=10.9
可信度系数
可信度系数A •测试时间＝A×MTBF, 根据给定的MTBF值,确定出可信度系数A,就可算出需测试的时间了. •A＝0.5*χ2（1-a，2(r+1)） •X2（1-a，2(r+1)）是自由度为2(r+1)的X平方分布的1-a的分位数； •a 是要求的信心度； r 是允许的失效数，由你自己决定 •For example : 某种产品，要求在90%的信心度,允许失效1个下的可信度系数A? •通过查表 X2（0.1，4）=7.78 •允许失效1次时，A=0.5*7.78＝3.89
MTBF (Mean Time Between Failure)
MTBF,即平均无故障时间，英文全称是“Mean Time Between Failure”。是衡量一个产品（尤其是电器产品）的可靠性指标。单位为“小 时”。它反映了产品的时间质量，是体现产品在规定时间内保持功能的一种能力。具体来说，是指相邻两次故障之间的平均工作时 间，也称为平均故障间隔。它仅适用于可维修产品。同时也规定产品在总的使用阶段累计工作时间与故障次数的比值为MTBF。 MTBF and POH Formulas: •Where: T = Power On Hours (Total of Accelerated + Non Accelerated) • C = Confidence Level • 2 = Chi Squared distribution • r = # of Failures • 2r+2 = Degrees of Freedom This formula assumes an exponential distribution and a constant failure rate. This assumption is valid, since we do not exercise electrical or mechanical items to the wear out stage. MTBF Calculation Example: What is the demonstrated MTBF for 80 units with 2000 POH each and 1 failure? •(Confidence level => C = 90%, T = 2000 x 80 = 160,000. Expected service calls (failures) = 1: r = 1). •MTBF = (2 * 160,000)/ [X2 (90%, 2 r + 2)] -> r=1, -> Utilize the Chi Square Table in Appendix B to find a corresponding value for v=4(left column), at C=0.1 (top row) •The resultant value (X2) = 7.78; MTBF = (320,000)/7.78 = 41,131 hours. POH Calculation Example: What is the POH required to achieve a 87,600 MTBF given the following: •(Confidence level => C = 90%, MTBF = 87,600(10 years). Expected service calls (failures) = 1, therefore r = 1, #units = 20) •T = [(87,600 * X2 (90%, 2 r + 2)] / 2 -> r=1, -> Utilize the Chi Square Table in Appendix B to find a corresponding value for v=4(left column), at C=0.1 (top row) •The resultant value (X2) = 7.78; T (POH) = (87,600*7.78)/2 = 340,764 POH •With 20 units with an average of 22 power on hours per day, the POH per unit will be 340,764/20 = 17038 POH. Since these are accelerated Power On Hours, dividing this value by the acceleration factor of 10.9 (for 35ºC/90%RH) •The actual POH is 17038/10.9= 1703 or 70 days.
accelerated tests名词解释
accelerated tests名词解释
Accelerated tests（加速测试）是一种用于评估产品可靠性和寿命的测试方法。
这种测试方法通过在短时间内模拟产品在长时间使用过程中可能遇到的各种环境和应力条件，来推断产品的寿命和可靠性。
加速测试的原理是将产品暴露在高温、低温、高湿度、振动、电磁场等各种环境和应力条件下，模拟产品在实际使用中可能遇到的各种情况，比如高温会加速材料老化，振动会加速零部件磨损等。
通过观察产品在这些条件下的表现和损耗程度，来推断产品在实际使用中的寿命和可靠性。
加速测试可用于各种产品的可靠性评估，比如电子产品、汽车、航空航天设备、医疗设备等。
加速测试可以帮助厂商在产品上市前发现潜在的问题，进行改进和修正，从而提高产品的可靠性和寿命，减少售后维修和召回的成本。
Accelerated Life Test
6/13/2016
Product Life Model
• Products behave through its life in a “bathtub” characteristic. • Three areas of survival are recognized: – Infant Mortality.
number of units to survive a time t
• f(t) Probability Density Function (PDF). Probability of failing at an
instant (time that is infinitesimally small).
– Cumulative Distribution Function: – Linear form of the Cumulative Distribution Function: – Probability Density Function – Failure Rate
6/13/2016
Life Test Concepts
Fail Time 0.1 1 2 3 6 16 17 18 21 44 Fail. Occurr. 9 6 2 2 1 1 1 2 3 3 Acc Test Cum. Time Failures 6 60 120 180 360 960 1020 1080 1260 2640 9 15 17 19 20 21 22 24 27 30
Field Failed units/year 30 7 4 3 2 2 1 1 1 1 1
-4 .5
Reg ress ion 95 % CI -5 .0 2 3 4 5 6 7 8 95 % PI
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Study of Decoupling Control for Airborne Hydraulic Pumpin the Cyclic Stress Accelerated Life TestMingxia Wang 1 Zhaoqin Peng 1 Yongling Fu 1 Xin Wang 21. School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China2. School of Information Technology,Easten LiaoNing University,Dandong 118003,ChinaEmail:small_135@Abstract –Based on the characteristics of stress change for the cyclic stress accelerated life testing (ALT) for the airborne hydraulic and ensured the accuracy acceleration model is established based on the pressure stress; the coupling relationship between the pressure subsystem and the rotation speed subsystem is analyzed.The coupling relationship will have cause a problem on the rotation speed with the pressure changes and bring a non-accuracy acceletation model is established based on the pressure stress, which eventually bring about the impact of life estimation; the principle of the single neuron PID decoupling controller is studied. The simulation results shows that the coupling relations is solved and the accuracy acceletation model is established to ensure by using the decoupling controller .Keywords –airborne hydraulic pump,cyclic stress,accelerated life test,decoupling control.I. INTRODUCTIONIn order to ascertain the distribution of product’s life, eatimate the reliability index of products and research the failure mechanism of products,life test should be carried out. Accelerated life test(ALT) can be defined as: a test that conducted in a worse environmental condition speeds up the failure of products and shortens the testing time. The stress level is brought beyond the normal size. The reliability characters of the products in normal stress level are deducedby accelerated life test model based on the failure data [1]. Accelerated life testing of hydraulic components are widely used in the reliability analysis of hydraulic components and the assessment of new product quality and life [2]. According the different spectrum of test stress imposed on products, ALT can be divided into four types: constant stress ALT, step stress ALT, progressive stress ALT and variable stress ALT [3].ALT for the airborne hydraulic pump(AHP) is a good way to obtain the reliability of airborne hydraulic pump under a more severe environment in a short period of test time,which can provide the reliable experimental data for developing AHP with excellent performance (high output pressure and great flow).In order to ensure the same failure mechanism, when the stress test carried out to maximize and the sufficient failure number of product isn’t yet obtained, the product has not yet expired continue to test under the repeated cyclic stress. The above-mentioned test method known as the circular stress ALT. Its’ stress is based on a certain cycle and amplitude (eg sine curve) to change, forexample, imposed on the insulator voltage is low or high cycle changes [4]. A hydraulic pump failure mode of sensitive critical stress——pressure, speed and temperature was introduced in literature [5]. In circular stress ALT for AHP, pressure acts as accelerated stress,the proportional relief valve is used to adjust system pressure changes in accordance with the sine curve. The tested pump is connected with the output shaft of the DC motor, circular pressure changes will cause some changes in the rotation speed.If the change rate of the rotation speed is greater than zero, then it will also play a role in accelerating [6]. To get an accurate test results, speed can not great change with the pressure changes in ALT, otherwise it will has an impact on the life estimates and changes the failure mechanism.In order to eliminate the coupling relationship between pressure and rotation speed ,the single neuron PID decoupling methods has been projected, the simulation results shows that the decoupling method can reduce the coupling impact of the pressure and the rotation speed.This paper will be structured as follows; In Section II he working principle of the ALT system is presented; In Section III the coupling relation between the pressure and the rotation speed is analyzed. In Section Č, the single neuron PID decoupling controller is designed. In Section č, the model in Matlab/Simulink is shown .Then the simulation results and discussion are presented. Finally, a brief conclusion is given in Section Ď..Ċ. SYSTEM DESCRIPTIONThe hydraulic schematic diagram of ALT system considered in this paper is shown in figure.1.The system generally consists of replenishing pressure subsystem, driving subsystem and load subsystem. The replenishing pressure subsystem provides low-pressure great-flow hydraulic oil for the driving subsystem,the aim of the replenishing pressure subsystem is only used to increase inlet pressure of pump (about 0.2-0.4MPa) and prevent creating cavity. The AHP is a variable-displacement pump mounted in the driving subsystem. It is served as a tested element, which is driven by a DC motor. The DC motor with two output shafts is adopted in the ALT system and this special structure is used to connect hydraulic motor and AHP. So the hydraulic power that recovered by the hydraulic motor can be transmitted to the DC motor in form of the mechanical coupling,the recovered energy can be reused again. A DC speed regulator controls the speed of the DC motor,which meet3-690_____________________________978-1-4244-3864-8/09/$25.00 ©2009 IEEEthe need of the extreme speed ALT.The proportional relief valve in the load subsystem served as a constant pressure valve can set system’s pressure according to the need of the extreme pressure ALT. The study in thispaper is based on the cyclic stress ALT.Fig.1. Schematic of the ALT systemċ. COUPLING RELATION ANALYSE According to the literature [7], the mathematical model of the pressure adjustment subsystem and speed adjustment subsystem is established in the ATL system is shown in figure1.Then the model is expressed as the form of block diagram after appriate simplification and sorting,as shown in figure2. It’s demonstrated by Figure.2 that the part of i p ̚s p corresponds to the pressure adjustment control subsystem, and the part of i Z ̚e Z corresponds to the speed adjustment control subsystem.The meaning of symbols in Figure.2 can be explained as:)(1s G is the transfer function of the pressure adjustment control subsystem ,)(2s Gis the transfer function of the speed adjustment control subsystem;p D is displacement of pump,m 3;g i is the growth rate of the gear box; e J is the motor inertia,2m Kg ;e B is the friction coefficient,rad s m N .g p s l i D p T is the loadtorque of the electric motor;g p e s i D Q Z is the flow disturbance of the proportional relief valve;1K is the speed sensor feedback coefficient,)(s rad V ;2K is the pressure sensor feedback coefficient,Pa V ;e c K 1is the main valve Equivalent flow-pressure coefficient,dimensionless;s Z is the turning frequency of thecontrolled Pressure chamber, s rad ;p u is the expect pressure voltage,V;n u is the expect speed voltage,V .Fig.2. block diagram of the ALT’s control systemFrom figure2, the coupling relationship between the pressure adjustment subsystem and speed adjustmentsubsystem is existence. Two subsystems is coupled through the torque l T and flow s Q ˈand l T and s Q are closely related to s p and e Z .So the change of s p would affect the stability of e Z . The impact of results will be introduced in the next simulation analysis. Č. DESIGN THE DECOUPLING CONTROLLER Neural network is widely used,which is not depend on the control object model, easy control the uncertain model and nonlinear system and solves a number of inextricable problems adopting classical control and modern control method [8]. In this paper, a arithmetic of decoupling control based on single neuron is proposed according to the above mentioned features of neural network .A. Decoupling controller structureIn this paper, the coupling problem between thepressure adjustment subsystem and speed adjustment subsystem serves as the research object. The structure of single neuron PID decoupling controller is shown in Figure.3. In the Figure.3,the reference input vector of the system is Ti ip ][Z ,the output vector isT s e p ][Z ,Two controllers are common PIDcontroller.In the single neuron PID decoupling controller, a neuron is placed in each of the input/output channels, each neuron has two inputs to accept the output control signal '1u and '2u of the two PID controllers. The output3-691of each neuron )2,1( i u i as a control signal is sent to the coupling system, the coupling problem is solvedthrough modifing the weights of neurons.Fig.3. block diagram of the control system with single neurondecoupling controllerB. The principle of decoupling controller The algorithm of the single neuron decouplingcontroller [9] in the figure.3 as follows:°°¯°°®' ¦ )()()1()()(21't w t w t w t u w t u ijij ij j j ij i )2,1( i (1)The initial network weights in the Formula (1) is¯®z )(0)(1j i w j i w ijij (2)ij w 'is weight correction,K is learn efficiency.The assumptin that transfer function matrix of the controlled object as follows:»¼º«¬ª»¼º«¬ª »¼º«¬ª2122211211u u g g g g p s e Z (3)The assumption that neurons controller input-output matrix as follows:»¼º«¬ª»¼º«¬ª »¼º«¬ª'2'12221121121u u w w w w u u (4)According to formula (3) and formula (4) the system’stransfer function matrix after adding decoupling controller as fllows ˖»¼º«¬ª »¼º«¬ª»¼º«¬ª»¼º«¬ª »¼º«¬ª'2'1'2'12221121122211211u u E u u w w w w g g g g p s e Z (5) So the training goal of this series neurons decouplingcontroller is to make the matrix E in the formula (5) into adiagonal matrix, which the purpose of decoupling is achieved. The performance index function of the single neuron decoupling controller is>@21)()(21t t J e i Z Z (6)>@22)()(21t p t p J s i(7) In order to obtain the minimun of 1J and 2J ,the gradient descent algorithm for searching a set of the optimized weight parameters was used. Finally, ij w 'asfollows °°¯°°® 'z ' 'z ')2(1)2)(())()(()()1(1)1)(())()(()(2'221'11j w j t u t p t p t w j w j t u t t t w j s i j j e i j K Z Z K (8)According to the formula (8), the deviation of )()(t t e i Z Z or )()(t p t p s i is exist so that theneurons will continue to adjust the weights until the output meet the expectations, and ultimately the decoupling was achieved.č. SIMULATION STUDYThe whole system model is established inMATLAB/SIMULINK environment. The simulink model of the coupling sysytem is shown in figure 4. The simulation method combines SIMULINK module and function files, and the main program is realized in SIMULINK, the single neuron PID decoupling controller is given by using function file. Simulation results are given in this paper. The simulation curves of proportional relief valve output pressure in the cyclic stress ALT is shown in figure 5.Fig.4. Coupling system simulink model3-692Fig.5. Pressure response curveView from figure 5, the given signal of the proportional relief valve is 1Hz frequency and 2~5v amplitude sine curve ,then the pressure is similar to 1Hz frequency and 20~38Mpa amplitude sine curve.The cyclic fluctuation of pressure for the circular stress ALT is achieved.Let the pressure change in accordance with 1Hz sine wave when the speed is 1500min /r . Figure 6 showsthe response curve of the rotation speed.Fig.6. Rotation speed response curveView from Figure 6, without the single neuron PID decoupling controller, when the system pressure changes the rotation speed is greatly affected. The rotation speed changes from 1450min /r ~1800min /r , then the change rate of the rotation speed is 20%. However, adding decoupling controller, the change rate of the rotation speed is 6%, the stability of the rotation speed is significantly improved.Ď. CONCLUSIONThe coupling relationship between the pressure adjustment subsystem and speed adjustment subsystem has been found during the circular stress ALT for the airborne hydraulic pump. The existence of coupling will damage the stability of the rotation speed and bring the influence for the life evaluation. The paper focuses on the analysis of the decoupling method. A single neuron PID decoupling controller has been projected. The simulation results show that this method is indeed reducing couplinginfluence and improving the stability of the rotation speed.ACKNOWLEDGMENTTeachers and classmates in department 303 of Beihang University (Beijing, P.R. China) are gratefully acknowledged by the first author.REFERENCES[1] Zhang Chunhua,Wen Xisen,Chen Xun.“A compehensive reviewof accelerated life testing”. Acta Armamentarii ,Vol. 25, No. 4, pp. 485-490, Jul. 2006[2] Bai uochang,Wang Zhanlin,Qi Xiaoye.“The design ofaccelerated life test-bed for aero hydraulic pump with variable load”. Chinese Hydraulics & Pneumatics ,No.3,pp.47-50,Mar.2006[3] Zhao Sijun,Wang Shaoping, Shi Jian, Li Lan. “Development ofAccelerated Life Test”. Robotics, Automation and Mechatronics, 2008 IEEE Conference . pp. 1071- 1074,Sept. 2008.[4] Chen Juan. “Research on pneumatic product accelerated life testmethod”.Beijng:Beihang University,2005[5] Wang Shaoping,Li Peiqiong. “Synthetic Stress Life Testing forHydraulic Pump”.Journal of Beihang University .Vol. 26,No. 1, pp. 38-40, Feb. 2000[6] Xu Yaoming.“Hydraulic pressure reliability projectfoundation”.Harbin: Harbin Institute of Technology Press,1991[7] Sang Yong.“Research on Key Technology of Accelerated LifeTesting Bed For Airborne Hydraulic Pump With Variable Loadings”.BeiJing:BeiHang University,2007[8] Liu Jinkun.“Advanced PID control MATLAB simulation”Beijing:Electronics industry Press,2004[9] Gao Ximing, Meng Yanjing. “Arithmetic of decoupling controlbased on neural cell”. Journal of Shanxi University of Science and Technology . Vol. 27, No. 1, pp. 110-113, Feb. 2009.3-693。