CN104596697A - Undercarriage wheel brake kinetic moment measuring method - Google Patents

Abstract

An undercarriage wheel brake kinetic moment measuring method measures a brake kinetic moment in a loading state or an undercarriage wheel in a braking test of a large inertia dynamic test bed, solves the problems that a dynamic braking moment of a brake device cannot be directly measured as a torque/force sensor cannot be mounted on an undercarriage and the dynamic test brake moment of the undercarriage is measured, meets kinetic moment measuring requirements of a brake test of undercarriages with different structural sizes and is used for measuring the brake moment of a plane brake device in the loading state. The undercarriage can serve as an onboard device of a plane and has a huge use value. The measuring method has the advantages that the measuring method is simple in structure, convenient to mount, fine in universality and safety, can be widely used for undercarriage brake tests of various military aircrafts and civil aircrafts and other wheel power tests of an automobile and the like, and has important social significance and application prospects, and time and labor are saved.

Description

There is the wheel braking kinetic moment measuring method of undercarriage

Technical field

The invention belongs to aircraft brake experimental technique, be specifically related to a kind of method measured for the brake torque in airplane wheel installation state and other band undercarriage braking effort tests.

Background technology

Brake torque, also known as braking moment, the moment of the prevention wheel rolling produced by brake gear when being wheel braking is contrary with in conjunction with moment direction.It is one of key parameter of brake machine wheel design, be not only the foundation determining brake device structure parameter, and directly affect the structural strength of undercarriage, tire, wheel hub, be also calculate the sliding major parameter running performance, decelerability, ground run distance, sliding race time, absorption energy etc. of aircraft.Quiet brake torque and dynamic brake torque two kinds can be divided into by the motion state of wheel in using.Quiet brake torque: without the brake torque that brake gear during relative motion provides between wheel and ground.Dynamic brake torque: the brake torque that during sliding race, wheel brake provides.

Along with the development of aircraft, take off and increase gradually with land hourly velocity and weight, in taking-off and landing process, security issues become increasingly urgent, requires also more and more higher to the performance and reliability of brake system, and the ability on airport is maked a return voyage, continues fight capability and adapted to the safety that it is related to aircraft.Therefore, can it be ensure the sliding race of aircraft, one of safe important motivity pilot project of landing that wheel braking is tested, its objective is the requirement that wheel brake system will be examined to meet aircraft braking distance under different loads, guarantee that aircraft is sliding and run and landing safety.

The domestic brake torque for aircraft brake system is measured at present is all carry out on large-scale brake inertial test table before dispatching from the factory, and feasible measuring method for the brake gear be arranged on undercarriage, once becoming technological difficulties of undercarriage wheel braking test.

Chinese patent 201310652766 five-degree-of-freedom follow-up brake moment measurement device has spoken approvingly of a kind of brake torque measurement mechanism for testing with undercarriage wheel braking, its principle directly measures brake torque for utilizing torque sensor, its torque sensor one end is coaxially connected with brake gear by terminal pad, the other end connects load expansion link, and load expansion link is fixing with on test-bed by hold-down support.This device cannot realize the measurement of brake torque by analysis.Described in this patent, terminal pad and brake gear are installed together, and but do not speak approvingly of terminal pad and specifically with what part of brake gear are connected.The brake flange of brake gear divides Moving plate and two kinds, quiet dish, and Moving plate rotates with wheel, as terminal pad is connected with the Moving plate of brake gear, then makes wheel non-rotatable; Quiet dish and wheel shaft geo-stationary, if terminal pad is connected with the quiet dish of brake gear, and quiet dish fixes with the wheel shaft running through wheel, wheel shaft is connected with the opposite side undercarriage of wheel, a load mechanism of undercarriage inherently wheel, power suffered by bearing rod therewith described in device is power instead of reacting force in the same way, and the brake torque that the torque sensor therefore installed is measured is the moment of components of actual brake moment relative to bearing rod.

In addition, the braking principle due to aircraft relies on the friction of brake gear to absorb the kinetic energy of aircraft, and therefore brake flange forms high temperature heat reservoir, and as measured signal near heat reservoir, the signal temperature drift that high temperature causes is the technological difficulties that must solve.

Therefore, the wheel braking torgue measurement for band undercarriage is still technological difficulties of wheel braking test.

Summary of the invention

For overcoming the deficiency can not carrying out wheel braking torgue measurement to the wheel of band undercarriage existed in prior art, the present invention proposes a kind of wheel braking kinetic moment measuring method having undercarriage.

Detailed process of the present invention is as follows:

Step 1: force analysis.

When aircraft brake slides, airplane wheel wheel shaft is mainly stressed to be comprised: the brake torque that brake gear provides, the bending stress produced by Aircraft Load vertically downward, and when aircraft affects by crosswind, draws/pressure by the wind-induced axis in this side.Be applied in each stress on wheel shaft, the deformation that the strain had the greatest impact to accuracy of measurement causes for the bending stress of wheel shaft vertical direction, be mainly the applying of Aircraft Load, or cause because of ground out-of-flatness jolt and produce.The maximum position of the strain caused by bending stress is the upper and lower surface of wheel shaft, compressive strain is maximum at the upper surface of wheel shaft, stretching strain is that wheel shaft lower surface is maximum, linearly reduce from 0 ~ 90 ° according to wheel shaft surface circular arc radial line and vertical direction angle, therefore affect the two sides that minimum position is axle axis horizontal direction.

Step 2: determine strain gauge adhesion position and mode.When determining the paste position of foil gauge, needing to consider the temperature compensation mode of foil gauge, eliminating Aircraft Load and be applied to bending strain on wheel wheel shaft, and the sensitivity of measuring and accuracy.For this reason, determine that strain gauge adhesion position and mode are:

Described is the wheel shaft surface of strain gauge adhesion position between undercarriage leg and wheel hub, and makes the first foil gauge R ₁the center line of length direction and the second foil gauge R ₂angle between the center line of length direction and the axis of described wheel wheel shaft is respectively ± and 45 °, by described first foil gauge R ₁with the second foil gauge R ₂respectively must the strain stress at this place ₁and ε ₂, according to generalized Hooke law, obtain principle stress σ _i:

${\mathrm{\σ}}_i=\frac{E{\mathrm{\ϵ}}_i}{1+\mathrm{\μ}}---\left(1\right)$

In formula (1): ε i is strain value, E is Young modulus, and μ is the Poisson ratio of measured piece.

Described principle stress σ _icomprise tensile stress sigma ₁with compressive stress-σ ₂, and described tensile stress sigma ₁with compressive stress-σ ₂two, direction mutually vertical.

And | σ ₁|=|-σ ₂| (2)

Principle stress value equals maximum shear

|σ _i|＝τ _max(3)

The maximum shear produced by moment of torsion is

${\mathrm{\τ}}_{\max }=\left|{\mathrm{\σ}}_i\right|=\left|\frac{E{\mathrm{\ϵ}}_i}{1+\mathrm{\μ}}\right|---\left(4\right)$

At the first foil gauge R with stickup ₁with the second foil gauge R ₂the plane of symmetry on paste the 3rd foil gauge R ₃with the 4th foil gauge R ₄.The first described foil gauge R ₁with the 4th foil gauge R ₄symmetry, the second foil gauge R ₂with the 3rd foil gauge R ₃symmetrical.

Two groups are divided, the first foil gauge R by four foil gauges ₁with the second foil gauge R ₂one group, the 3rd foil gauge R ₃with the 4th foil gauge R ₄one group, often organize strain gauge adhesion direction mutually vertical, and be 45 ° with axis angle, be symmetrically respectively pasted on the minimum wheel shaft both sides of the deformation that caused by bending stress, specifically crossing with wheel shaft periphery in axis horizontal face straight line surfaces place.

5th step: paste foil gauge.The strain gauge adhesion position determined according to step 2 and mode, according to a conventional method by the first foil gauge R ₁, the second foil gauge R ₂, the 3rd foil gauge R ₃with the 4th foil gauge R ₄be pasted onto wheel shaft surface.

Step 3: connect each foil gauge.By the first foil gauge R ₁, the second foil gauge R ₂, the 3rd foil gauge R ₃with the 4th foil gauge R ₄by the series connection of full-bridge circuit connection, and access data acquisition system according to a conventional method.

Step 4: wheels-locked testing.Test according to gear test specification, carry out data signal acquisition simultaneously and store.

Step 5: Measurement and Data Processing.

The first step: filtering.

Second step: the strain data of wheel shaft is converted to brake torque.Realize described axial strain of taking turns by formula (6) and be converted to brake torque:

Wheel wheel shaft moment of torsion

In formula, Torsion Section coefficient d is wheel shaft diameter;

By foil gauge full-bridge circuit connection, obtain full-bridge circuit output voltage u by formula (7) ₀

$u_o=\frac{E}{4}k{\mathrm{\ϵ}}_i=\frac{E}{4}k[{\mathrm{\ϵ}}_1-(-{\mathrm{\ϵ}}_2)+{\mathrm{\ϵ}}_3-(-{\mathrm{\ϵ}}_4)]---\left(7\right)$

ε in formula _ifor the strain value read surveyed by strainmeter, ε ₁be the first foil gauge R ₁strain value, ε ₂be the second foil gauge R ₂strain value, ε ₃be the 3rd foil gauge R ₃strain value, ε ₄be the 4th foil gauge R ₄strain value.

Obtained by formula (7)

Brake torque is drawn by formula (6,7)

$M=M_k=\left|\frac{E{\mathrm{\ϵ}}_i}{1+\mathrm{\μ}}\right|\·\frac{\mathrm{\π}{D}^3}{64}---\left(8\right)$

Brake torque curve is obtained by formula (8).So far, the wheel braking kinetic moment completing undercarriage is measured.

Aircraft under static state, wheel wheel shaft the stressed radial force be vertically downward applied to for Aircraft Load on wheel shaft, stress is bending stress.When aircraft brakes in sliding, wheel wheel shaft is except the bending stress applied by Aircraft Load, and also bearing the torsion that brake gear applies, is shear stress.The torsional moment that the brake gear that this place is stated produces wheel wheel shaft, is brake torque.

For bending stress, adopt axisymmetric strain gauge adhesion method, offset the bending stress superposed because of the applying of Aircraft Load.

Under torsional interaction, the arbitrary unit area in rotating shaft surface is in pure shear stress ζ state, and it is equivalent to become with axis ± the principle stress σ of 45 ° of deflections ₁and σ _2,wherein σ ₁direction is stretching strain ε _1,ε _3,σ ₂direction is compressive strain ε ₂, ε ₄, therefore along becoming ± 45 ° of directions stickup foil gauges with axis, can strain be measured.

Averaged by the two panels foil gauge of symmetrical mounting method, the bending stress effect caused by tyre load straight up can be offset, thus obtain the strain under the pure shear stress suffered by rotating shaft surface.

Shear stress size can be calculated by strainometer according to the knowledge of the mechanics of materials again, thus calculate brake torsional moment.Or obtain brake torque by the method for demarcating.

The measurement mechanism of airplane wheel axle braking effort square of the present invention, for under being in installation state, or wheel in the wheels-locked testing of large-scale inertia momentum test platform band undercarriage, the braking effort square that carried out is measured, and solves due to cannot mounting torque/force snesor and cannot carry out to the dynamic brake moment of brake gear the problem directly measured on undercarriage.

The present invention's kinetic moment that simple structure meets the wheels-locked testing of different structure size undercarriage measures requirement, solve the difficult problem that undercarriage dynamic test brake torque is measured, and the measurement of brake torque when being creatively in installation state for aircraft brake system, the airborne equipment that can be used as aircraft uses, and has huge use value.The present invention has the advantages such as structure simply, easy for installation, laborsaving saves time, versatility is good, security is good, other wheel dynamic tests tests such as various military secret, the wheels-locked testing of civil aircraft undercarriage and automobile can be widely used in, there is important social effect and application prospect.

Because the present invention uses, the present situation that the measurement changing current brake torque is only measured when wheel is done experiment on inertial test table, work condition state data when using brake gear is actual can be obtained, provide brake gear intensity and life appraisal accurately, the brake gear better for research performance provides test basis.

Accompanying drawing explanation

Fig. 1 is structural representation of the present invention.

Fig. 2 is the connection diagram of foil gauge.

Fig. 3 is paste position schematic diagram.

Fig. 4 is the stressed schematic diagram of wheel shaft, and wherein, 4a is wheel shaft positive side unit area force diagram, and 4b is wheel shaft dorsal surface unit area force diagram.

Fig. 5 is process flow diagram of the present invention.In figure:

1. wheel; 2. wheel hub and brake gear; 3. wheel shaft; 4. undercarriage leg; 5. foil gauge; 6. data acquisition system (DAS).

Embodiment

The present embodiment is the brake torque measurement that aircraft carries out wheels-locked testing after runway slides.

Described foil gauge 5 has 4, is respectively the first foil gauge R ₁, the second foil gauge R ₂, the 3rd foil gauge R ₃with the 4th foil gauge R ₄.Data acquisition system (DAS) 6 is conventional strain acquisition system.Wherein, four foil gauges are divided into two groups, the first foil gauge R ₁with the second foil gauge R ₂one group, the 3rd foil gauge R ₃with the 4th foil gauge R ₄one group; Two groups of foil gauge symmetries are pasted onto the wheel shaft surface between wheel hub and undercarriage leg 4, and are on the surface level residing for axle axis.Angle between the center line of two foil gauge length directions in described often group is 90 degree, and the center line of described two foil gauge length directions and axis angle are 45 °.

Connected by full bridge circuit between described four foil gauges, and each output terminal in this bridge circuit respectively with each orifice of data acquisition system (DAS) 6.Connected by full bridge circuit between described each foil gauge, temperature compensation each other, answer brake gear to absorb aircraft kinetic energy and the impact of temperature variation that produces to eliminate.

In the present embodiment, when aircraft brake slides, produce brake torque by brake gear, consume aircraft kinetic energy with this.During brake, wheel 1 produces brake torque at wheel hub and brake gear 2 place, and the right cylinder shown as on wheel shaft 3 produces the strain brought by torsional moment, and the present embodiment utilizes the strain on four foil gauge 5 wheel axle 3 surfaces, with indirect inspection brake torque.

Detailed process of the present invention is as follows:

Step 1: force analysis.

When aircraft brake slides, the stressing conditions of airplane wheel wheel shaft 3 is very complicated, wheel wheel shaft 3 is mainly stressed to be comprised: the brake torque that brake gear provides, the bending stress produced by Aircraft Load vertically downward, and when aircraft affects by crosswind, draws/pressure by the wind-induced axis in this side.Be applied in each stress on wheel shaft, the deformation that the strain had the greatest impact to accuracy of measurement causes for the bending stress of wheel shaft vertical direction, be mainly the applying of Aircraft Load, or cause because of ground out-of-flatness jolt and produce.The maximum position of the strain caused by bending stress is the upper and lower surface of wheel shaft, compressive strain is maximum at the upper surface of wheel shaft, stretching strain is that wheel shaft lower surface is maximum, linearly reduce from 0 ~ 90 ° according to wheel shaft surface circular arc radial line and vertical direction angle, therefore affect the two sides that minimum position is axle axis horizontal direction.

Step 2: determine strain gauge adhesion position and mode.When determining the paste position of foil gauge, needing to consider the temperature compensation mode of foil gauge, eliminating Aircraft Load and be applied to bending strain on wheel wheel shaft, and the sensitivity of measuring and accuracy.

The first step: determine strain gauge adhesion region.The wheel shaft surface chosen on wheel wheel shaft between undercarriage leg and wheel hub is strain gauge adhesion region.

Second step: determine strain gauge adhesion angle: known by the mechanics of materials, for the moment of torsion that wheel wheel shaft produces, become with axle axis ± direction of 45 ° is principal direction of stress.Becoming with the axis of described wheel wheel shaft ± direction of 45 ° on paste the first foil gauge R ₁with the second foil gauge R ₂, by described first foil gauge R ₁with the second foil gauge R ₂respectively must the strain stress at this place ₁and ε ₂, according to generalized Hooke law, obtain principle stress σ _i:

${\mathrm{\σ}}_i=\frac{E{\mathrm{\ϵ}}_i}{1+\mathrm{\μ}}---\left(1\right)$

In formula (1): ε _ifor strain value, E is Young modulus, and μ is the Poisson ratio of measured piece.

Described principle stress σ _icomprise tensile stress sigma ₁with compressive stress-σ ₂, and described tensile stress sigma ₁with compressive stress-σ ₂two, direction mutually vertical.

And | σ ₁|=|-σ ₂| (2)

Principle stress value equals maximum shear

|σ _i|＝τ _max(3)

The maximum shear produced by moment of torsion is

${\mathrm{\τ}}_{\max }=\left|{\mathrm{\σ}}_i\right|=\left|\frac{E{\mathrm{\ϵ}}_i}{1+\mathrm{\μ}}\right|---\left(4\right)$

Second step: the temperature compensation mode determining foil gauge.Determinand has the thermal expansivity of oneself, so can elongate or shorten along with the change of temperature.Wheel is when braking, and brake gear absorbs aircraft kinetic transformation and becomes heat energy, and wheel shaft temperature can rise thereupon.With the first foil gauge R ₁the second foil gauge R is pasted in vertical direction ₂.First foil gauge R ₁with the second foil gauge R ₂be in same temperature environment, the stroke caused by temperature is identical, and the strain facies namely caused by temperature is same, so the output voltage caused by temperature is zero, therefore two panels foil gauge temperature compensates each other, and can offset the impact of tension/compressive stress.

3rd step: determine the removing method of bending strain and the raising method of measurement sensistivity.At the first foil gauge R with stickup ₁with the second foil gauge R ₂the plane of symmetry on paste the 3rd foil gauge R ₃with the 4th foil gauge R ₄.The first described foil gauge R ₁with the 4th foil gauge R ₄symmetry, the second foil gauge R ₂with the 3rd foil gauge R ₃symmetrical.For the strain that bending stress produces on wheel shaft, at the first foil gauge R ₁with the 4th foil gauge R ₄the strain that place produces is stretching strain △ R ₁with △ R ₄, the second foil gauge R ₂with the 3rd foil gauge R ₃place is compressive strain-△ R ₂with-△ R ₃, the strain value that the two groups of foil gauges pasted in symmetry under same bending stress produce is equal:

|△R ₁|＝|-△R ₂|＝|-△R ₃|＝|△R ₄| (5)

Therefore, symmetrical method of attaching eliminates the bending stress impact applied on wheel shaft by Aircraft Load and the bending stress impact caused because of reasons such as ground out-of-flatnesses, and makes bridge output voltage add one times, improves measurement sensistivity.

4th step: improve accuracy of measurement.From the force analysis of step 1, be applied in each stress on wheel shaft, the deformation that the strain had the greatest impact to accuracy of measurement causes for the bending stress of wheel shaft vertical direction, divide two groups by four foil gauges, R ₁with R ₂one group, R ₃with R ₄one group, often organize strain gauge adhesion direction mutually vertical, and be 45 ° with axis angle, be symmetrically respectively pasted on the minimum wheel shaft both sides of the deformation that caused by bending stress, specifically crossing with wheel shaft periphery in axis horizontal face straight line surfaces place.

5th step: paste foil gauge.According to a conventional method the pre-treatment of stickup foil gauge is carried out to wheel shaft surface and by above requirement, by foil gauge R ₁, foil gauge R ₂, foil gauge R ₃with foil gauge R ₄be pasted onto wheel shaft surface.

Step 3: by foil gauge R ₁, foil gauge R ₂, foil gauge R ₃with foil gauge R ₄by the series connection of full-bridge circuit connection, and access data acquisition system 6 according to a conventional method.

Step 4: wheels-locked testing.Test according to gear test specification, carry out data signal acquisition simultaneously and store.

Step 5: Measurement and Data Processing.

The first step: filtering.Measured strain data is carried out filtering according to a conventional method, removes the burr because vibration etc. causes.

Second step: the strain data of wheel shaft is converted to brake torque.Realize described axial strain of taking turns by formula (6) and be converted to brake torque:

Wheel wheel shaft moment of torsion

In formula, Torsion Section coefficient d is wheel shaft diameter;

By foil gauge full-bridge circuit connection, obtain full-bridge circuit output voltage u by formula (7) ₀

$u_o=\frac{E}{4}k{\mathrm{\ϵ}}_i=\frac{E}{4}k[{\mathrm{\ϵ}}_1-(-{\mathrm{\ϵ}}_2)+{\mathrm{\ϵ}}_3-(-{\mathrm{\ϵ}}_4)]---\left(7\right)$

ε in formula _ifor the strain value read surveyed by strainmeter, ε ₁for foil gauge R ₁strain value, ε ₂for foil gauge R ₂strain value, ε ₃for foil gauge R ₃strain value, ε ₄for foil gauge R ₄strain value.

From formula (7)

Brake torque is drawn by formula (6,7)

$M=M_k=\left|\frac{E{\mathrm{\ϵ}}_i}{1+\mathrm{\μ}}\right|\·\frac{\mathrm{\π}{D}^3}{64}---\left(8\right)$

The brake torque curve drawn by formula (8), is the present invention's final gained brake torque data and curves.So far, the wheel braking kinetic moment completing undercarriage is measured.

Claims (1)

1. have a wheel braking kinetic moment measuring method for undercarriage, it is characterized in that, detailed process is as follows:

Step 1: force analysis;

When aircraft brake slides, airplane wheel wheel shaft is mainly stressed to be comprised: the brake torque that brake gear provides, the bending stress produced by Aircraft Load vertically downward, and when aircraft affects by crosswind, draws/pressure by the wind-induced axis in this side; Be applied in each stress on wheel shaft, the deformation that the strain had the greatest impact to accuracy of measurement causes for the bending stress of wheel shaft vertical direction, be mainly the applying of Aircraft Load, or cause because of ground out-of-flatness jolt and produce; The maximum position of the strain caused by bending stress is the upper and lower surface of wheel shaft, compressive strain is maximum at the upper surface of wheel shaft, stretching strain is that wheel shaft lower surface is maximum, linearly reduce from 0 ~ 90 ° according to wheel shaft surface circular arc radial line and vertical direction angle, therefore affect the two sides that minimum position is axle axis horizontal direction;

Step 2: determine strain gauge adhesion position and mode; When determining the paste position of foil gauge, needing to consider the temperature compensation mode of foil gauge, eliminating Aircraft Load and be applied to bending strain on wheel wheel shaft, and the sensitivity of measuring and accuracy; For this reason, determine that strain gauge adhesion position and mode are:

Described is the wheel shaft surface of strain gauge adhesion position between undercarriage leg and wheel hub, and makes the first foil gauge R ₁the center line of length direction and the second foil gauge R ₂angle between the center line of length direction and the axis of described wheel wheel shaft is respectively ± and 45 °, by described first foil gauge R ₁with the second foil gauge R ₂respectively must the strain stress at this place ₁and ε ₂, according to generalized Hooke law, obtain principle stress σ _i:

${\mathrm{\σ}}_i=\frac{{\mathrm{E\ϵ}}_i}{1+\mathrm{\μ}}---\left(1\right)$

In formula (1): ε i is strain value, E is Young modulus, and μ is the Poisson ratio of measured piece;

Described principle stress σ _icomprise tensile stress sigma ₁with compressive stress-σ ₂, and described tensile stress sigma ₁with compressive stress-σ ₂two, direction mutually vertical;

And | σ ₁|=|-σ ₂| (2)

Principle stress value equals maximum shear

|σ _i|＝τ _max(3)

The maximum shear produced by moment of torsion is

${\mathrm{\τ}}_{\max }=\left|{\mathrm{\σ}}_i\right|=\left|\frac{{\mathrm{E\ϵ}}_i}{1+\mathrm{\μ}}\right|---\left(4\right)$

At the first foil gauge R with stickup ₁with the second foil gauge R ₂the plane of symmetry on paste the 3rd foil gauge R ₃with the 4th foil gauge R ₄; The first described foil gauge R ₁with the 4th foil gauge R ₄symmetry, the second foil gauge R ₂with the 3rd foil gauge R ₃symmetrical;

Two groups are divided, the first foil gauge R by four foil gauges ₁with the second foil gauge R ₂one group, the 3rd foil gauge R ₃with the 4th foil gauge R ₄one group, often organize strain gauge adhesion direction mutually vertical, and be 45 ° with axis angle, be symmetrically respectively pasted on the minimum wheel shaft both sides of the deformation that caused by bending stress, specifically crossing with wheel shaft periphery in axis horizontal face straight line surfaces place;

5th step: paste foil gauge; The strain gauge adhesion position determined according to step 2 and mode, according to a conventional method by the first foil gauge R ₁, the second foil gauge R ₂, the 3rd foil gauge R ₃with the 4th foil gauge R ₄be pasted onto wheel shaft surface;

Step 3: connect each foil gauge; By the first foil gauge R ₁, the second foil gauge R ₂, the 3rd foil gauge R ₃with the 4th foil gauge R ₄by the series connection of full-bridge circuit connection, and access data acquisition system according to a conventional method;

Step 4: wheels-locked testing; Test according to gear test specification, carry out data signal acquisition simultaneously and store;

Step 5: Measurement and Data Processing;

The first step: filtering;

Second step: the strain data of wheel shaft is converted to brake torque; Realize described axial strain of taking turns by formula (6) and be converted to brake torque:

Wheel wheel shaft moment of torsion

In formula, Torsion Section coefficient d is wheel shaft diameter;

By foil gauge full-bridge circuit connection, obtain full-bridge circuit output voltage u by formula (7) ₀

$u_o=\frac{E}{4}k{\mathrm{\ϵ}}_i=\frac{E}{4}k[{\mathrm{\ϵ}}_1-\left({-\mathrm{\ϵ}}_2\right)+{\mathrm{\ϵ}}_3-\left({-\mathrm{\ϵ}}_4\right)]---\left(7\right)$

ε in formula _ifor the strain value read surveyed by strainmeter, ε ₁be the first foil gauge R ₁strain value, ε ₂be the second foil gauge R ₂strain value, ε ₃be the 3rd foil gauge R ₃strain value, ε ₄be the 4th foil gauge R ₄strain value;

Obtained by formula (7)

Brake torque is drawn by formula (6,7)

$M=M_k=\left|\frac{{\mathrm{E\ϵ}}_i}{1+\mathrm{\μ}}\right|\·\frac{{\mathrm{\πD}}^3}{64}---\left(8\right)$

Brake torque curve is obtained by formula (8); So far, the wheel braking kinetic moment completing undercarriage is measured.