MDI Vibration Analysis

1Vibration Analysis using ADAMSVibration Analysis using ADAMS General Introduction and General Introduction and

Application ExamplesApplication Examples

Gabriele Ferrarotti, Vikram Sohoni,Francesco Ambrogi

Mechanical Dynamics

ADAMS/Vibration: Your Solution for Frequency Domain Analysis

Key Vibration Issues FacingKey Vibration Issues FacingEngineers and DesignersEngineers and Designers

How comfortable is the ride, whether in anautomobile, airplane, railcar, or off roadmachinery?

Will excitations in one part of the system interactwith another part of the system?

When problems occur, how can they be isolated?

2ADAMS/Vibration: Your Solution for Frequency Domain Analysis

Industry efforts andIndustry efforts andmetricsmetrics

Good vibration characteristics are a purchasemotivator and improve customer satisfaction

Need a good way to measure a design Optimum NVH often conflicts with other attributes

such as durability or vehicle dynamic performance Need a way to balanced competing requirements

Significant efforts are spent to understand andquantify customer NVH requirements into objectiveterms and to define specific tests that relate tocustomer events

Current methods are expensive


Industry efforts andIndustry efforts andmetricsmetrics

NVH involves both objective and subjectivedevelopment

Part of the process can be quantified withanalytical tools

Suppliers must tune their systems/components(right the first time) to the prototype vehicle orelse they are responsible for NVH resolution

Need a way to study system Issues are often discovered late in the prototype

development process resulting in money and timeloss

Value in designing the right way


A way to study system level vibrations the sameway you can now study system level motionproblems

The NeedThe Need



much faster!


Solution:Solution:MDI Extends the Scope ofMDI Extends the Scope of

Virtual PrototypingVirtual Prototyping

Motion/

PerformanceSafety

Durability/

FatigueNoise/

Vibration


Take your system to different operating pointsto analyze the vibratory behavior (without having to create new models!)

Include effects of hydraulics, controls, and othersubsystems on the vibration characteristics

Analyze system modes including attachmentcharacteristics and other nonlinearcharacteristics

Three reasons to useThree reasons to useADAMS/VibrationADAMS/Vibration


Analyze the Vibratory Behavior inAnalyze the Vibratory Behavior inDifferent ConfigurationsDifferent Configurations

Satellite Example: System eigenvalues shift

according to Panel deployment angle Locking condition Contact condition Actual spring rates

This shift effects attitudecontrol margin, pointing jittermagnitude, and structuralloading conditions


Analyze the Vibratory Behavior inAnalyze the Vibratory Behavior inDifferent ConfigurationsDifferent Configurations

Railcar Example: System eigenvalues shift

according to Equivalent conicity Suspension stiffnesses Damper characteristics

This shift effects railcarstability and runningcomfort


Include Effects of Hydraulics andInclude Effects of Hydraulics andControls on System BehaviorControls on System Behavior

Hydraulics Example: Apply input vibration to control valve and see effect at

cylinder pressure and boom movement in frequencyresponse function plots and animations


Analyze System Modes includingAnalyze System Modes includingAttachment CharacteristicsAttachment Characteristics

Automotive Example: Engine mount

displacements due tocombustion forces independency of Engine mount

characteristics Engine mount position

Frequency domainanalysis helps designersto improve engine mountinstallations


ADAMS/Vibration 11.0ADAMS/Vibration 11.0CapabilitiesCapabilities

Frequency domain input forcing functions Frequency response function calculations Modal participation tables Forced vibration animation Forced vibration plotting Generate linear subsystems


How does it work:How does it work:Simplified/Unified ApproachSimplified/Unified Approach

Motion or VibrationSimulation ProcessInput Post-processing

Solution

Time or Frequency Domain

Inputs

Plots, Animation, Tables, other time and frequency data


ADAMS/VibrationADAMS/VibrationWalkthruWalkthru......

Step 1 Create input channels, output channels, and actuators

Actuatorassociated

with an inputchannel

Splinedefines

PSD



Step 2 Run Analysis

Define inputs/outputs to use

Define operating point,frequency range, and steps



Step 3 Post-Processing

SystemModes

FrequencyResponseFunctions

PowerSpectralDensity

ModalParticipationTables



Step 4 Graphic

Post-Processing

Normal ModeAnimation

ForcedVibrationAnimation


Functional Digital CarFunctional Digital CarIncluding VibrationIncluding Vibration

Full Vehicle

Chassis Engine Driveline Body

Suspension

Steering

Brakes

Tires

Valvetrain

Cranktrain

Chain/Belt

Acc. Drives

Transmission

Clutch

Differential

Axles/CV

Body-in-white

Frame

Seating

Restraints

Road

Driver

Test Rigs

Packaging Ride& Handling Durability Vibrations

NVHVibration

10


Full Aircraft

Undercarriage Engine Flight Controls Stores/Devices

Retraction

Steering

Brakes

Tires

Compressor

Gearbox

Vanes

Valves

Control Surface

Mechanism

Gearbox

APU

Separation

Latches

Pilot Eject

Arresting

Runway/Air Conditions

Pilot

Test Rigs

Functional Digital AircraftFunctional Digital AircraftIncluding VibrationIncluding Vibration


NVHVibration


Full Railway System

Bogie Body Accessories Permanent Way

Suspensions

Wheels / Contact

Dampers

Interference

Packaging

Passenger Safety

Brakes

Engine groups

Track beams

Ballasts

BridgesActive devices

Pantographs

Functional Digital TrainFunctional Digital TrainIncluding VibrationIncluding Vibration


NVHVibration

Test Rigs

11


What to make?DECISION

Integrated Simulation andTesting Environment

Will it work?DECISION

Will it last?

Are you sure?DECISION

DECISION

Virtual Virtual TestLabTestLabIncluding VibrationIncluding Vibration

Get with a virtual model the frequency domain results a testengineer would obtain with a physical model


ConclusionsConclusions Add-on product targeted

at existing ADAMS userswith existing ADAMSmodels

Allows the investigation ofsystem level vibrationsthe same way system levelmotions are studied

Quickly investigates theinfluence of parametervariation on the vibratorybehavior of the system

Documents

MDI Vibration Analysis