CN109783953A - A new method for calculating the landing dynamic load of aircraft - Google Patents
A new method for calculating the landing dynamic load of aircraft Download PDFInfo
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Abstract
The invention discloses a kind of calculation methods of type aircraft landing dynamic load, in order to study load response rule of pavement slab under the action of high tire pressure, big quality, short take-off and landing, according to the mechanical characteristic and the characteristics of motion of type aircraft, analyze undercarriage-wheel-road face coupling, and consider that airplane aerodynamic changes, it is established that the aircraft floor kinetic model of 5DOF.Differential equation group is solved by four step Runge-Kutta, studies the road area load variation issue with space at any time.Result of study shows: the road face dynamic load factor that type aircraft main landing gear generates can reach 1.4, and aircraft subsidence velocity is the principal element for influencing landing load.
Description
Technical field
The present invention relates to aeronautical technologies and airport engineering field, specifically, being related to a kind of type aircraft landing dynamic load
Calculation method.
Background technique
With the rapid development of China's aviation and Defence business, large quantities of type aircrafts such as J-20, Y-20, C919, An-
225, J-31 etc., into the people visual field.These type aircrafts often have the characteristics that big weight, high tire pressure, short take-off and landing.By
In the change of aircraft parameter drop characteristic with, great variety occurs more in the past for ground load characteristic.And the machine that China is existing
In the rigid pavement design specification of field, only with constant dynamic load factor KdTo reflect aircraft to the characteristic of road area load: at road face end
Portion when tire pressure q >=1.08MPa, takes Kd=1.25；When q < 1.08MPa, K is takend=1.20, the novel aircraft tire pressure in China is remote
Much larger than 1.25MPa.It is this to gain knowledge by elastic system theory and static(al), dynamic load is equivalent to dead load, then analyze
The method of face structural stress, aircraft weight is little, tire pressure is small, in the lower situation of subsidence velocity it is substantially reasonable but right
Type aircraft is still indicated obviously to lack scientific and applicability with static behavior.Currently, domestic and foreign scholars are dynamic to aircraft floor
Mechanics and road (road) face Structural Dynamics all achieve certain research achievement in respective field, but still there are many queries:
Such as the ground load measured data of type aircraft is extremely lacked, meets the aircraft and road plane system coupling machine of actual state
It manages still unclear.Therefore, research type aircraft load action rule and road face mechanical response, it is fast to be in response to national defence aviation industry
Fast development situation and airfield pavement design requirement Basic Problems urgently to be resolved.
Summary of the invention
For type aircraft landing to the load characteristic problem of airfield runway, in analysis type aircraft landing characteristics and aircraft
On the basis of each subsystem, aircraft floor dynamics mathematical model is established, considers that different landing conditions are got off the plane and road plane system
Coupling mechanism, the present invention propose a kind of calculation method of type aircraft landing dynamic load.
Its technical solution is as follows:
A kind of calculation method of type aircraft landing dynamic load, comprising the following steps:
Step 1, the sliding race stage force analysis of aircraft landing.
Step 2, the aircraft floor kinetic model for establishing 5DOF.
Step 3 establishes mechanical balance equation in each freedom degree direction.
Step 4 solves differential equation group by four step Runge-Kutta.
Further, the results showed that the road face dynamic load factor that type aircraft main landing gear generates can reach 1.4.
Further, aircraft main landing gear active force accounting can reach 98% or more, and nose-gear landing load is smaller.
Further, aircraft subsidence velocity is the principal element for influencing landing load, and landing quality is secondly, tire pressure and pitch angle
Road face dynamic load is influenced little.
The present invention provides a kind of calculation methods of aircraft dynamic load simplified, touched briefly on the essentials, and are convenient for engineering staff
Researching and designing meets engineering calculation requirement.
Detailed description of the invention
Fig. 1 is aircraft force analysis figure；
Fig. 2 is aircraft floor kinetic model；
Fig. 3 is body nodal point vertical displacement change curve；
Fig. 4 is aircraft pitch angle change curve；
Fig. 5 is coasting distance change curve；
Fig. 6 is nose-gear landing loads change curve；
Fig. 7 is main landing gear landing loads change curve；
Fig. 8 is main landing gear buffer function accounting curve；
Fig. 9 is the changing rule of main landing gear landing load under the influence of landing quality；
Figure 10 is the changing rule of main landing gear dynamic load factor under the influence of landing quality；
Figure 11 is the changing rule of main landing gear dynamic load factor under the influence of tire pressure；
Figure 12 is the changing rule of main landing gear dynamic load factor under the influence of subsidence velocity；
Figure 13 is the changing rule of main landing gear dynamic load factor under the influence of pitch angle；
Figure 14 is the changing rule of nose-gear dynamic load factor under the influence of pitch angle.
Specific embodiment
Technical solution of the present invention is described in more detail with reference to the accompanying drawings and detailed description.
During aircraft landing, aircraft gliding speed can be divided into both vertically as well as horizontally, the subsidence velocity of vertical direction,
Shock effect is generated to road face, forms dynamic load；Horizontal velocity makes wheel and road face generate relative motion, forms frictional force, rubs
Wipe the size that power size depends on coefficient of friction and vertical load.
Aircraft in alighting run, self gravity W, air drag D, lift L, face main landing gear vertical force
Fz1, frictional force Fx1, face nose-gear vertical force Fz2, frictional force Fx2Collective effect under, be decelerated to and normally slide speed
Degree, system of then flying off the runway, aircraft force analysis are as shown in Figure 1.
In sliding race on runway, ground faces to be transmitted on body when the active force of aircraft by undercarriage aircraft, therefore
Undercarriage has an important influence aircraft floor kinetic characteristics.Undercarriage is mainly by pillar, buffer, wheel system, support
Or the part such as extension and retraction system forms, major function is support and buffer function, to improve the stress feelings on aircraft vertical direction
Condition.When calculating, Landing Gear System is reduced to undercarriage buffer and wheel system.
The effect of buffer can be reduced to oil liquid damping action power and air spring force in undercarriage.Aero tyre
It can be divided into two parts effect, i.e. tire flexibility power and damping force, as shown in Figure 2.Aircraft by fuselage system, main landing gear system and
Nose-gear system composition.m0, m1, m2The respectively quality of airframe system, the quality of main landing gear system, nose-gear
The quality of system.J0For the rotary inertia of airframe system.s1, s2The respectively center of gravity of airplane is to nose-gear, main gear wheels
The distance of axis center.k1, k2, k3, k4Respectively main landing gear suspension coefficient of elasticity, main landing gear tire coefficient of elasticity are preceding
Undercarriage suspension coefficient of elasticity, nose-gear tire spring rate.c1, c2, c3, c4Respectively main landing gear suspension
Damped coefficient, main landing gear tire damped coefficient, nose-gear suspension damped coefficient, nose-gear tire damped coefficient.θ
For airframe pitch angle.z0, z1, z2Respectively airframe center of gravity, main landing gear suspension center of gravity and nose-gear hang center of gravity
The vertical displacement at place.
To airframe system m0, formula (1) is obtained by the Rigid Body in Rotation With differential equation:
In formula,For the angular speed of airframe system.For the angular acceleration of airframe system.For
The vertical velocity of airframe center of gravity, main landing gear suspension center of gravity and nose-gear suspension center of gravity.Fh1, Fa1It is risen based on respectively
Fall frame buffer damping action power and air spring force.Fh2, Fa2Respectively nose landing gear bumper damping action power and air bullet
Spring force.
There are the differential equation (2) on fuselage vertical direction:
In formula, x0For the horizontal displacement on vector,For the course speed of airframe center of gravity.Center of gravity is hung for airframe center of gravity, main landing gear and nose-gear hangs the vertical velocity of center of gravity
And the course acceleration of airframe center of gravity, g are acceleration of gravity, kLFor comprehensive lift coefficient, k is takenL=0.5CLρ S, wherein
Lift factor CL=2 π (θ-θ0), θ0For aerofoil profile zero-lift angle, ρ is atmospheric density, and S is wing area.
To main landing gear suspension m1Analysis, establishes differential equation of motion (3) in the vertical direction:
In formula, Fk1, Ff1The elastic force and damping action power of main landing gear tire respectively.
To nose-gear suspension m2Analysis, establishes differential equation of motion (4) in the vertical direction:
In formula, Fk2, Ff2The elastic force and damping action power of nose-gear tire respectively.
On the sliding race direction of aircraft landing, differential equation of motion (5) are integrally established to aircraft:
In conjunction with the empirical equation (6) of tire spring rate, (7)
k2=34.514+0.387p0+21.816p0z1 (6)
k4=34.514+0.387p0+21.816p0z2 (7)
In formula, p0For the initial tire pressure of aircraft.μ is between longitudinal sliding motion coefficient of friction, with straight skidding rate
Relationship Comparison is complicated, can be provided by empirical equation (8):
In formula, SgFor slip rate, is defined as:
VxFor aircraft taxi speed, VωFor tire linear velocity, r is tire radius, and δ is squeegee action amount, and ω is tyre revolution
Moving-wire speed.
Simultaneous (1)~(9) differential equation obtains five yuan of differential equation groups (10) of second order:
In formula, sign is sign function:
Then dynamic load of the tire to road face are as follows:
q1, q2For road face incentive action.
Initial Value Problems of One Order System of Ordinary Differential can be turned to by substitution of variable to the initial-value problem of differential equation of higher order
It is calculated.
If m=2,3,4 ..., there are m rank Initial Value Problems For Ordinary Differential Equations:
Enable y1=z, y2=z ' ..., ym=z(m-1), then above formula just turns to first-order ordinary differential equation system:
To the Solve problems of first order differential equation system, since quadravalence Runge-Kutta (imperial lattice-library tower) method being capable of basis
The required precision in each stage changes step-length, and programs and use and be all easier to, extensive in practical engineering application, therefore the present invention adopts
It is solved with the method.
The dynamic differential equation group of landing period is subjected to variable conversion, by five yuan of differential equations of second order in step 2
Group depression of order turns to following formula.It enables:
Take q1, q2It is 0, five yuan of differential equation group conversions of second order in step 1 are as follows:
By numerical value computing differential equation group, numerical solution is obtained, aircraft landing characteristic is as shown in Fig. 3-Fig. 8, each factor shadow
Sound gets off the plane dynamic load properties change curve as shown in Fig. 9-Figure 14.
The foregoing is only a preferred embodiment of the present invention, the scope of protection of the present invention is not limited to this, it is any ripe
Know those skilled in the art within the technical scope of the present disclosure, the letter for the technical solution that can be become apparent to
Altered or equivalence replacement are fallen within the protection scope of the present invention.
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Cited By (5)
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|---|---|---|---|---|
| CN110341980A (en) * | 2019-07-11 | 2019-10-18 | 中国人民解放军空军工程大学 | Analysis method of aircraft taking off and landing at plateau |
| CN112173158A (en) * | 2020-09-25 | 2021-01-05 | 中国直升机设计研究所 | Landing/ship-borne load calculation method for wheeled landing gear helicopter |
| CN112597641A (en) * | 2020-12-10 | 2021-04-02 | 上海宇航系统工程研究所 | Carrier landing stability optimization method |
| CN114386157A (en) * | 2020-10-16 | 2022-04-22 | 中航西飞民用飞机有限责任公司 | Damping design method for main landing gear buffer of airplane |
| CN116167249A (en) * | 2023-04-23 | 2023-05-26 | 民航机场规划设计研究总院有限公司 | Dynamic load calculation method, device and storage medium for aircraft asymmetrical landing |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110341980A (en) * | 2019-07-11 | 2019-10-18 | 中国人民解放军空军工程大学 | Analysis method of aircraft taking off and landing at plateau |
| CN110341980B (en) * | 2019-07-11 | 2022-11-01 | 中国人民解放军空军工程大学 | Airplane plateau take-off and landing load reduction use analysis method |
| CN112173158A (en) * | 2020-09-25 | 2021-01-05 | 中国直升机设计研究所 | Landing/ship-borne load calculation method for wheeled landing gear helicopter |
| CN114386157A (en) * | 2020-10-16 | 2022-04-22 | 中航西飞民用飞机有限责任公司 | Damping design method for main landing gear buffer of airplane |
| CN114386157B (en) * | 2020-10-16 | 2024-12-17 | 中航西飞民用飞机有限责任公司 | Damping design method for main landing gear buffer of airplane |
| CN112597641A (en) * | 2020-12-10 | 2021-04-02 | 上海宇航系统工程研究所 | Carrier landing stability optimization method |
| CN112597641B (en) * | 2020-12-10 | 2022-07-22 | 上海宇航系统工程研究所 | Carrier landing stability optimization method |
| CN116167249A (en) * | 2023-04-23 | 2023-05-26 | 民航机场规划设计研究总院有限公司 | Dynamic load calculation method, device and storage medium for aircraft asymmetrical landing |
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