基于能量法的起落架落震试验评定准则

Criteria for evaluation of landing gear drop test based on energy method

为通过理论分析建立一套用于起落架落震试验评定的基本准则,提出了一种使用起落架缓冲系统设计要求或其等效形式进行落震试验评定的方法,并从能量分析的角度给出了适用于陆基飞机起落架落震试验评定的统一设计要求。对于在落震试验中无法直接验证的耗能设计要求,通过能量等效的方法,研究了不同落震试验方法中的等效形式。对于仿升法落震试验,提出了利用反行程阻尼系数进行耗能评定,并建立了反行程阻尼系数与缓冲系统消耗能量之间的函数关系。在此基础之上,结合正反行程时间的限制条件,给出了耗能极值问题的计算方法。对于减缩质量法落震试验,建立了缓冲系统耗能系数和机轮不跳离地面之间的联系,研究了随过载增大实现机轮不跳离地面的可行性。最后,研究了两种落震试验方法的能力范围,并给出减缩质量法和仿升法等效的条件。

In order to establish a set of basic criterias for the evaluation of landing gear drop test by theoretical analysis,an approach using the requirements of the landing gear design or its equivalent forms is proposed to evaluate landing gear drop tests,and a set of all design requirements that fit the landing gear drop test of land-based aircrafts is given based on energy analysis.For the energy-dissipated design that cannot be verified directly,equivalent forms of energy dissipation requirements under different drop test conditions are developed by energy equivalent method.For the simulated air-borne impacts,the anti-stroke damping coefficient is defined to evaluate the capability of dissipating energy,and an equation for the relationship between the coefficient and the dissipated energy is established.Considering the limited time in the process of compression and rebound,the maximum value of the dissipated energy can be obtained with this equation.For the reduced-mass method,the relationship between energy dissipation and wheel motion is established,and the feasibility to avoid the jumpoff of the wheels is studied.The capabilities of the two methods for the drop test are compared,and the equivalent conditions of the two methods are given.