Parametric Accelerated Life Testing (ALT) was used to improve the reliability of ice-maker system with a fractured helix upper dispenser in field. By using bond graphs and state equations, a variety of mechanical load...Parametric Accelerated Life Testing (ALT) was used to improve the reliability of ice-maker system with a fractured helix upper dispenser in field. By using bond graphs and state equations, a variety of mechanical loads in the assembly were analyzed. The acceleration factor was derived from a generalized life-stress failure model with a new load concept. To reproduce the failure modes and mechanisms causing the fracture, new sample size equation was derived. The sample size equation with the acceleration factor also enabled the parametric accelerated life testing to quickly reproduce early failure in field. Consequently, the failure modes and mechanisms found were identical with those of the failed sample. The design of this testing should help an engineer uncover the design parameters affecting the reliability of fractured helix upper dispenser in field. By eliminating the design flaws, gaps and weldline, the B1 life of the redesign of helix upper dispenser is now guaranteed to be over 10 years with a yearly failure rate of 0.1% that is the reliability quantitative test specifications (RQ).展开更多
针对以指挥信息系统为典型的复杂任务型软件试验鉴定领域中可靠性评估问题,在总结现有评价方法的基础上,提出了基于系统状态特征分析的可靠性评估方法。首先,从软件使命任务的角度解析系统的状态特征,设计充分覆盖系统典型应用样式及状...针对以指挥信息系统为典型的复杂任务型软件试验鉴定领域中可靠性评估问题,在总结现有评价方法的基础上,提出了基于系统状态特征分析的可靠性评估方法。首先,从软件使命任务的角度解析系统的状态特征,设计充分覆盖系统典型应用样式及状态特征的测试用例,通过定义“使用强度”,替代原有可靠性评价中“持续时间”指标,在此基础上收集可靠性失效数据,并给出软件可靠性增长模型(software reliability and growth model,SRGM)参数估计及可靠性评估过程。最后通过某任务型软件的可靠性评估试验,验证提出方法在工程实践中的可行性,同时给出了工程示例中收集的真实失效数据和SRGM参数估计结果,确保研究成果真实性和可复现性。展开更多
The energy expression is presented for a failure mechanism, and it is appliedin an Accelerated Life Test (ALT) and an Accelerated Reliability Growth Test (ARGT). The conditionsof the common failure mechanism are obtai...The energy expression is presented for a failure mechanism, and it is appliedin an Accelerated Life Test (ALT) and an Accelerated Reliability Growth Test (ARGT). The conditionsof the common failure mechanism are obtained. The essential relationship between the conditions andthe Accelerated Factor (A_f) is proposed by using the energy model.展开更多
高温可靠性测试如高温栅偏(High Temperature Gate Bias,HTGB)、高温反偏(High Temperature Reverse Bias,HTRB)、高温高湿反偏(High Humidity High Temperature Reverse Bias,H3TRB)是器件出厂和寿命评估必备的测试。然而,不同标准的...高温可靠性测试如高温栅偏(High Temperature Gate Bias,HTGB)、高温反偏(High Temperature Reverse Bias,HTRB)、高温高湿反偏(High Humidity High Temperature Reverse Bias,H3TRB)是器件出厂和寿命评估必备的测试。然而,不同标准的测试条件不尽相同,其对应的内在机理也不明确。为讨论测试条件的确定原则,首先从单个和耦合的温度、电场、湿度加速老化模型出发,论述了相关测试标准所用模型,分析了其应用范围和使用原则。进一步地,总结了现有各类标准下的测试条件,计算了电动汽车模块正常运行30年所需HTGB、HTRB、H3TRB加速老化时间分别为832 h、866 h、1038 h,测试的样本数均为70,并指出测试时间、样本数需根据实际工况决定。最后,基于以上分析,提出了一种加速老化时间、样本数可调的高温可靠性测试流程。展开更多
Based on Wiener process model, a new approach for reliability evaluation of cross-linked polyethylene(XLPE) is proposed to improve the lifetime evaluation reliability of XLPE under multi-stressing conditions and study...Based on Wiener process model, a new approach for reliability evaluation of cross-linked polyethylene(XLPE) is proposed to improve the lifetime evaluation reliability of XLPE under multi-stressing conditions and study the failure probability distribution. In this paper, two accelerated aging tests are carried out under combined thermal and vibration conditions. The volume resistance degradation data of XLPE samples are tested with a24 h interval under the accelerated stressing conditions at(130℃, 12 m/s^2) and(150℃, 8.5 m/s^2), respectively.Nonlinear degradation data obtained from the experiment are transformed to linear intermediate-variable values using time scaling function, and then linearized degradation data are calculated and evaluated on the basis of linear Wiener process model. Considering traditional Arrhenius equation and inverse power criterion, parameters of the linear Wiener model are estimated according to the maximum likelihood function. The relationship curves on probability density and reliability are given, and the lifetime distribution of XLPE under different stressing conditions is also obtained for evaluating the reliability of XLPE insulation. Finally, the life expectancy of XLPE is 17.9 a under an allowance temperature of 90℃ and an actual vibration acceleration of 0.5 m/s^2. The approach and results in this paper may be used for reliability assessment of high-voltage multiple samples or apparatuses.展开更多
文摘Parametric Accelerated Life Testing (ALT) was used to improve the reliability of ice-maker system with a fractured helix upper dispenser in field. By using bond graphs and state equations, a variety of mechanical loads in the assembly were analyzed. The acceleration factor was derived from a generalized life-stress failure model with a new load concept. To reproduce the failure modes and mechanisms causing the fracture, new sample size equation was derived. The sample size equation with the acceleration factor also enabled the parametric accelerated life testing to quickly reproduce early failure in field. Consequently, the failure modes and mechanisms found were identical with those of the failed sample. The design of this testing should help an engineer uncover the design parameters affecting the reliability of fractured helix upper dispenser in field. By eliminating the design flaws, gaps and weldline, the B1 life of the redesign of helix upper dispenser is now guaranteed to be over 10 years with a yearly failure rate of 0.1% that is the reliability quantitative test specifications (RQ).
文摘针对以指挥信息系统为典型的复杂任务型软件试验鉴定领域中可靠性评估问题,在总结现有评价方法的基础上,提出了基于系统状态特征分析的可靠性评估方法。首先,从软件使命任务的角度解析系统的状态特征,设计充分覆盖系统典型应用样式及状态特征的测试用例,通过定义“使用强度”,替代原有可靠性评价中“持续时间”指标,在此基础上收集可靠性失效数据,并给出软件可靠性增长模型(software reliability and growth model,SRGM)参数估计及可靠性评估过程。最后通过某任务型软件的可靠性评估试验,验证提出方法在工程实践中的可行性,同时给出了工程示例中收集的真实失效数据和SRGM参数估计结果,确保研究成果真实性和可复现性。
基金supported by Aeronautical Science Foundation(Grant No.00B53010)Astronautical Base Science Foundation(Grant No.2003CH0502)Natural Science Foundation of Shaanxi Province(Grant No.2003CS0501).
文摘The energy expression is presented for a failure mechanism, and it is appliedin an Accelerated Life Test (ALT) and an Accelerated Reliability Growth Test (ARGT). The conditionsof the common failure mechanism are obtained. The essential relationship between the conditions andthe Accelerated Factor (A_f) is proposed by using the energy model.
文摘高温可靠性测试如高温栅偏(High Temperature Gate Bias,HTGB)、高温反偏(High Temperature Reverse Bias,HTRB)、高温高湿反偏(High Humidity High Temperature Reverse Bias,H3TRB)是器件出厂和寿命评估必备的测试。然而,不同标准的测试条件不尽相同,其对应的内在机理也不明确。为讨论测试条件的确定原则,首先从单个和耦合的温度、电场、湿度加速老化模型出发,论述了相关测试标准所用模型,分析了其应用范围和使用原则。进一步地,总结了现有各类标准下的测试条件,计算了电动汽车模块正常运行30年所需HTGB、HTRB、H3TRB加速老化时间分别为832 h、866 h、1038 h,测试的样本数均为70,并指出测试时间、样本数需根据实际工况决定。最后,基于以上分析,提出了一种加速老化时间、样本数可调的高温可靠性测试流程。
基金the National Key R&D Program of China(No.2017YFB0902705)
文摘Based on Wiener process model, a new approach for reliability evaluation of cross-linked polyethylene(XLPE) is proposed to improve the lifetime evaluation reliability of XLPE under multi-stressing conditions and study the failure probability distribution. In this paper, two accelerated aging tests are carried out under combined thermal and vibration conditions. The volume resistance degradation data of XLPE samples are tested with a24 h interval under the accelerated stressing conditions at(130℃, 12 m/s^2) and(150℃, 8.5 m/s^2), respectively.Nonlinear degradation data obtained from the experiment are transformed to linear intermediate-variable values using time scaling function, and then linearized degradation data are calculated and evaluated on the basis of linear Wiener process model. Considering traditional Arrhenius equation and inverse power criterion, parameters of the linear Wiener model are estimated according to the maximum likelihood function. The relationship curves on probability density and reliability are given, and the lifetime distribution of XLPE under different stressing conditions is also obtained for evaluating the reliability of XLPE insulation. Finally, the life expectancy of XLPE is 17.9 a under an allowance temperature of 90℃ and an actual vibration acceleration of 0.5 m/s^2. The approach and results in this paper may be used for reliability assessment of high-voltage multiple samples or apparatuses.
