CAJ | 학술논문

针对起落架缓冲支柱和轮胎的非线性特性,应用等效线性模型,提出一种预估刚性机体在弹性起落架上的固有频率计算方法.利用缓冲支柱和轮胎的刚度和阻尼试验数据,采用循环迭代方法计算了机体耦合振动的固有频率;分析了直升机重量、旋翼拉力、舰面运动状态、舰面风力等因素对机体模态固有频率的影响.对最不稳定的机体侧向二阶模态而言,最大设计重量和大升力状态时其固有频率最低,与最小重量、零升力状态相比其稳定转速余度减少约133 r/min;文中假设的舰面运动状态和舰面风力对机体模态的固有频率影响很小,而采用纵、横侧向独立的简化模型来预估机体模态固有频率具有足够的精度.
침대기락가완충지주화륜태적비선성특성,응용등효선성모형,제출일충예고강성궤체재탄성기락가상적고유빈솔계산방법.이용완충지주화륜태적강도화조니시험수거,채용순배질대방법계산료궤체우합진동적고유빈솔;분석료직승궤중량、선익랍력、함면운동상태、함면풍력등인소대궤체모태고유빈솔적영향.대최불은정적궤체측향이계모태이언,최대설계중량화대승력상태시기고유빈솔최저,여최소중량、령승력상태상비기은정전속여도감소약133 r/min;문중가설적함면운동상태화함면풍력대궤체모태적고유빈솔영향흔소,이채용종、횡측향독립적간화모형래예고궤체모태고유빈솔구유족구적정도.
Aiming at nonlinear properties of landing gear oleo shock absorber and tire, a calculation method was presented to predict the natural frequencies of rigid body fuselage free vibrations on elastic landing gears from equivalent linear model. Application of oleo shock absorber and tire equivalent stiffness and damping test data, an iterative procedure was utilized to solve the fuselage natural frequencies. The various effects such as helicopter gross weight, rotor lift, ship motion state and wind ship-borne to natural frequencies were analyzed. For the fuselage second lateral mode, which is the least stable fuselage mode, its natural frequency is the lowest for the case of maximum gross weight with high rotor lift. In such a case the stability margin of rotary revolution will be reduced about 133r/min compared to the case of minimum gross weight with zero rotor lift. All types of ship motion state and wind ship-borne hypotheses in this paper had hardly effects to fuselage natural frequencies. A simple decoupling model, independent in fuselage longitudinal-pitch and lateral-roll motions, showed enough precisions in natural frequency predictions.