Shimmy can reduce the service life of the nose landing gear, affect ride comfort, and even cause fuselage damage leading to aircraft crashes. Taking a light aircraft as the research object, the torsional freedom of la...Shimmy can reduce the service life of the nose landing gear, affect ride comfort, and even cause fuselage damage leading to aircraft crashes. Taking a light aircraft as the research object, the torsional freedom of landing gear around strut axis and lateral deformation of tire are considered. Since the landing gear shimmy is a nonlinear system, a nonlinear mechanical model of the front landing gear shimmy is established. Sobol index method is proposed to analyze the influence of structural parameters on the stability region of the nose landing gear, and Routh-Huritz criterion is used to verify the reliability of the analysis results of Sobol index method. We analyse the effect of torsional stiffness of strut, caster length, rated initial tire inflation pressure, rake angle, and vertical force on the stability region of theront landing gear. And the research shows that the optimization of the torsional stiffness of the strut and the caster length of the nose landing gear should be emphasized, and the influence of vertical force on the stability region of the nose landing gear should be paid attention to.展开更多
采用全概率方法建立非电传爆系统可靠度与传爆环节可靠度的不确定性传递模型,将应用广泛的Sobol全局灵敏度指标推广到非电传爆系统,并采用发展成熟的数值模拟法(Monte Carlo,MC)与单层数值模拟法(Single Monte Carlo,SMC)对指标进行求解...采用全概率方法建立非电传爆系统可靠度与传爆环节可靠度的不确定性传递模型,将应用广泛的Sobol全局灵敏度指标推广到非电传爆系统,并采用发展成熟的数值模拟法(Monte Carlo,MC)与单层数值模拟法(Single Monte Carlo,SMC)对指标进行求解,得到各传爆环节可靠度的重要性排序。根据所得重要性排序,即可有针对性地逐步提高重要传爆环节的可靠度以达到提高系统可靠度的目的。所提指标及方法应用到某非电传爆系统中,证实了其有效性及合理性。展开更多
A comprehensive mission sensitivity analysis index based on Sobol's index called global mission sensitivity( GMS) was proposed in this paper which focused on analyzing the mission sensitivity of components of phas...A comprehensive mission sensitivity analysis index based on Sobol's index called global mission sensitivity( GMS) was proposed in this paper which focused on analyzing the mission sensitivity of components of phased mission systems( PMS). The simulation strategy of GMS based on a Petri net and Monte Carlo method was presented which had broad applicability. Finally,the GMS and Birnbaum's sensitivity of components in a PMS example were compared. The GMS of component is demonstrated to be more adaptable to reflect the component mission sensitivity when the rated reliability parameters of components cannot be obtained, and components have state dependency or the system is subjected to common cause failure.展开更多
文摘Shimmy can reduce the service life of the nose landing gear, affect ride comfort, and even cause fuselage damage leading to aircraft crashes. Taking a light aircraft as the research object, the torsional freedom of landing gear around strut axis and lateral deformation of tire are considered. Since the landing gear shimmy is a nonlinear system, a nonlinear mechanical model of the front landing gear shimmy is established. Sobol index method is proposed to analyze the influence of structural parameters on the stability region of the nose landing gear, and Routh-Huritz criterion is used to verify the reliability of the analysis results of Sobol index method. We analyse the effect of torsional stiffness of strut, caster length, rated initial tire inflation pressure, rake angle, and vertical force on the stability region of theront landing gear. And the research shows that the optimization of the torsional stiffness of the strut and the caster length of the nose landing gear should be emphasized, and the influence of vertical force on the stability region of the nose landing gear should be paid attention to.
文摘采用全概率方法建立非电传爆系统可靠度与传爆环节可靠度的不确定性传递模型,将应用广泛的Sobol全局灵敏度指标推广到非电传爆系统,并采用发展成熟的数值模拟法(Monte Carlo,MC)与单层数值模拟法(Single Monte Carlo,SMC)对指标进行求解,得到各传爆环节可靠度的重要性排序。根据所得重要性排序,即可有针对性地逐步提高重要传爆环节的可靠度以达到提高系统可靠度的目的。所提指标及方法应用到某非电传爆系统中,证实了其有效性及合理性。
基金National Natural Science Foundation of China(No.71071159)
文摘A comprehensive mission sensitivity analysis index based on Sobol's index called global mission sensitivity( GMS) was proposed in this paper which focused on analyzing the mission sensitivity of components of phased mission systems( PMS). The simulation strategy of GMS based on a Petri net and Monte Carlo method was presented which had broad applicability. Finally,the GMS and Birnbaum's sensitivity of components in a PMS example were compared. The GMS of component is demonstrated to be more adaptable to reflect the component mission sensitivity when the rated reliability parameters of components cannot be obtained, and components have state dependency or the system is subjected to common cause failure.
