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MSC Software Confidential MSC Software Confidential

Multibody dynamics simulation of an integrated

landing gear system using MSC.ADAMS

Presented By: Joey Jin

May 10, 2013

MSC Software Confidential

• MAG is the landing gear supplier to several major fixed and

rotary wing OEMs, including Bell Helicopter Textron, Eurocopter,

Agusta-Westland, Diamond Aircraft, Eclipse Aerospace, Piper

Aircraft, Turkish Aerospace Industries and the Korean Aerospace

Industry.

• Engineering capabilities include design, performance, stress and

fatigue life assessments as well as reliability analyses.

Mecaer Aviation Group (MAG)

2


Requirement of Redesign Nose

Landing Gear

3


Nose Landing Gear

4

This NLG is a semi-levered

suspension type shock strut

incorporating a single wheel/tire

installed on a wheel axle between

the two arms of a double-sided

wheel fork. This gear is a semi-

levered suspension type with the

wheel trailed backwards and free

to swivel over 360o. The shock

absorber is an oleo-pneumatic

type, with a separator piston

between oil and nitrogen chamber.

Upper Drag Brace

Lower Drag Brace

Over-center Spring

Cartridge

Turning Support

Piston

Main Fitting

Toque Link

Trailing Arm

NLG Component

Bell Crank


Bell Crank and Actuator

5

Actuator An electrically actuator

is equipped to perform

retraction/extension of landing

gear

Bell Crank The interface load on

the Bell Crank during the

retraction/extension cycles

needs to be monitored for

fatigue analysis

Bell Crank and Actuator

Bell

Crank

Actuator

Piston

0

2

4

6

8

0 5 10

Str

oke (

inc

h)

Time (s)

Actuator Stroke vs. Time


Retraction/Extension in ADAMS

6


Nose Landing Gear

7

A Rigid Body Model was built in

MSC.ADAMS to simulate the

Retraction/Extension of NLG.

The geometry was directly

imported from CAD software.

NLG ADAMS Model (Rigid)


Nose Landing Gear

8

1st Scenario:


Upper Stopper stops the NLG at fully

retraction position, modelled by

contact between Upper Stopper and

Upper Drag Brace

Stopper acts between the Upper Drag

Brace and Lower Drag Brace. Action

at the fully extension position. It is

modelled by the contact.

Upper

Stopper

Stopper


Nose Landing Gear

9


Over Centre Spring

Friction Consider

Contact


Nose Landing Gear

10

A Flex Body Model was built in

MSC.ADAMS to simulate the

Retraction/Extension of NLG.

Main Fitting, Upper Drag Brace

and Lower Drag Brace are

switched to flexible bodies.

2nd Scenario:

NLG ADAMS Model (Flex Body)

Flexible


Nose Landing Gear

11

Main Fitting, Upper Drag Brace

and Lower Drag Brace are

switched to flexible bodies.

Stiffness Matrices for the NLG at

the Fuselage/Main Fitting

attachments and Actuator

attachment are introduced into

ADAMS simulation.

3rd Scenario:

NLG ADAMS Model (Flex Body

and Flex Attachments)

Flexible

Attachment


Retraction/Extension Animation

12


Baseline: Simulation vs. Test (Rigid Bodies)

13

-1000.000

-800.000

-600.000

-400.000

-200.000

0.000

200.000

400.000

600.000

800.000

0.000 2.000 4.000 6.000 8.000 10.000 12.000

Lo

ad

(lb

f)

Time (s)

Actuator Load Spring: Stiffness=19 lbf/inch, Preload=44 lbf

Test Data

Simulation Data2e

3e

4e

5e

6e 6r

5r

4r

3r

2r

1r

1e


Redesign: Simulation vs. Test (Rigid Bodies)

14

-600

-500

-400

-300

-200

-100

0

100

200

300

400

500

0 1 2 3 4 5 6 7 8 9 10 11 12

Actu

ato

r F

orc

e (

lbf)

Time (s)

Stiffness=23 lbf/inch, Preload=27 lbf

Test

Rigid


Baseline Model (All Scenarios)

15


Redesign Model (All Scenarios)

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Bellcrank FEA Results FEM Based Fatigue Life Assessments

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Bellcrank Finite Element Model

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Bellcrank: 10-node tetrahedral

elements with aluminium

properties

Pin: 8-node hexahedral

elements with steel properties

Bushing: neglected and glued

contact used between the

interface pin & bellcrank

Link & Actuator: interface loads

are applied to FEM through

RBE2 MPCs (baseline model)

Characteristics


FEM Results

19

Max. Tension & Max. Compression

Actuator Loads are taken from

Extension & Retraction curves

obtained by MSC.ADAMS

simulations.

von Mises Stress Max. Tension

Max. Compression


FEM Results (Displacement Distribution)

20

Point 1r Point 2r Point 3r Point 4r Point 5r Point 6r

Point 1e Point 2e Point 3e Point 4e Point 5e Point 6e


von Mises Stress Distribution

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Max. Principal Stress Distribution

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• With MSC.ADAMS, virtual prototypes of a complete landing gear

system can be built efficiently (reducing engineering time, cost

and risk);

• MSC.ADAMS models for retraction and extension cycles can be

used to improve design and to investigate quickly new ideas with

ease;

• Simulation results demonstrated good agreements with the test

data for both scenarios (baseline & redesign);

• In general, both (rigid & flex) simulations predict conservative

loads for extension and retraction cycles.

Conclusion

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