Deteriorating of the error sources and the deviation of the quality characteristic (QC) of the product from the target value are ubiquitous in practice. Studying the relative contribution of the error sources to the QC deviation is helpful for improving the product performance effectively. In this study, we propose an error importance measure (EIM) method to quantify the relative contribution of error sources to the Taguchi quality loss that is caused by the QC deviation. The present worth of the expected Taguchi quality loss (ETQL) is used to characterize the deteriorating QC deviation. We use Taylor series expansion to decompose the time‐dependent ETQL and the present worth of ETQL into a series of fractions, representing the individual and the interaction contributions of the error sources. Based on the decomposition, the time‐dependent and the time‐independent EIM indices for one and a group of error sources are defined, respectively. The evaluation procedure for the EIM indices is provided and the properties are discussed. Finally, we provide a realistic application case to an aircraft wheel door mechanism to demonstrate the effectiveness of the proposed EIM method.
In this paper, we propose an error importance measure (EIM) method to quantify the relative contribution of error sources to the system output error. In order that the contribution of both variation and mean shift of error sources are taken into account, we use second-order moment to characterize the degree of system output deviation from ideal or target value. First, the second-order moment is decomposed into a series of terms through the Taylor series expansion, and the individual effects, the interaction effects, and the total effects for one or a group of error sources are defined accordingly. Second, we define the EIM indices as the value of total effect divided by second-order moment of output error. Third, three test models and an application case are introduced to demonstrate the effectiveness and engineering significance of the proposed EIM indices. The results show that the EIM indices can reflect both the impacts of variation and mean the shift in error sources.
To reduce the time of aircraft passenger evacuation in an unplanned emergency and improve passenger safety, this article proposed a dynamic estimation method of an aircraft emergency evacuation process; optimal performance statistics can be estimated efficiently. Then, the emergency guiding model is established based on the cellular automata theory. In this model, multiple factors are considered, such as seat pitch, exit width, and occupant behavior. A total of six categories (target exit choice, movement direction selection, movement speed calculation, behavior representation, crew operation, and exit modeling) and 24 evacuation regulations are included. Two kinds of civil aircraft with 90 seats and 149 seats were tested individually using the proposed model and a traditional model. The total evacuation time can be reduced by more than 5%, and optimal performance statistics can be reduced by more than 30%. The results indicate that with this model, more lives can be saved in the case of an emergency.
The gear door lock is one of the most important parts of the landing gear system of airplane. It has high production cost and high reliability. There are many factors influence its reliability and life, and these factors interact with each other. In this paper, a reliability test method based on small samples and multi factors is proposed for gear door lock, where the life is considered to be the reliability character. The work process of this method is composed of the prepare work, the executing of test and the after-treatment of test. A test system considering multi factors for gear door lock is then designed, which is composed of integrated environmental test chamber, and vibrator, and hydraulic system, and video system. The test system can simulate the combined influence of multi factors on the lock. A test cramp is designed also, which can apply the working load on the lock, and can fulfill the demand of vibrator. In the situation of single sample, a reliability assessment method is proposed. Finally, we explained how to use the reliability test method, and analyzed the reliability of the gear door lock.
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