An optimized model is established to improve the accuracy and efficiency of lifetime estimation for LED-based light bars. A Weibull function is used to fit test data of remaining luminance under two groups of accelerated stresses, and a method for determining the optimal test time is put forward. The results show that the optimized model for lifetime prediction best reflects the characteristic of luminance degradation. Furthermore, the error of the accelerated lifetime first decreases and then increases, finally decreasing again, which confirms that the method for determining the optimal test time is feasible given the level of accuracy required.

为了准确预测航空陀螺电机寿命,利用对数正态分布函数来描述其寿命分布,采用最小二乘法(LSM)估计了对数均值、对数标准差及加速参数,对陀螺电机寿命是否服从对数正态分布进行了K-S检验,并利用自行开发的寿命预测软件计算出平均寿命和中位寿命.结果表明,航空陀螺电机寿命满足对数正态分布,其寿命特征和温度应力的关系符合阿伦尼斯方程,预测出的陀螺电机寿命精度较高,利用精确计算的加速参数可实现在短时间(10 h)内估算其寿命,为航空陀螺电机设计提供技术参考.

In order to accurately obtain the life information of LED lamps in a short time,three-parameter Weibull function was applied to describing the life distribution based on three groups of constant-stress accelerated life test data.The processing and analysis on test data was achieved by Bilinear Re-gression Method (BRM),and the self-developed life prediction software was employed to precisely calculate the life of LED lamps under normal working stress.The numerical results show that the LED lamps life submits to three-parameter Weibull distribution,and the accelerated model meets the Arrhenius equation.The LED lamps’life predicted precisely can provide technical references for engi-neering technicians with regard to the product’s reliability design.

Aiming at improving vibration performance of 1.5 MW wind turbine blades, the theoretical model and the calculation process of vibration problems under geometric nonlinearity and unidirectional fluid-structure interaction (UFSI) were presented. The dynamic stability analysis on a 1.5 MW wind turbine blade was carried out. Both the maximum brandish displacement and the maximum Mises stress increase nonlinearly with the increase of wind speed. The influences of turbulent effect, wind shear effect and their joint effect on displacement and stress increase sequentially. Furthermore, the stability critical curves are calculated and analyzed. As a result, the stability region is established where the wind turbine blade can run safely.