02 lms test introduction

Chiel Verhoeven

LMS Test introduction

2 copyright LMS International - 2012

Content

2 LMS Test systems

1 Company introduction

3 Sound engineering

4 Structural dynamics

5 Rotating machinery

6 Durability testing and analysis

2 Hardware - LMS Scadas

1 What is testing - DSP

3 Software - LMS Test.Lab

Agenda

The measurement chain

accelerations

rpm

Strains

forces

Pressures

Sensor Scadas PC


Sensors

rpm

forces

Pressures

Sensor Scadas PC

accelerations

Strains

Time t

Amplitude

[V]

“A sensor is a device that measures a measurable

attribute and converts it into a signal which can be

read by an observer or by an instrument.”

(Wikipedia)


Signal conditioning and data acquisition system (Scadas)

Sensor Scadas PC


Signal conditioning and data acquisition system (Scadas)

Acquisition

Software

Analysis

Software

Data Storage

Sensor

supply

ADCSignal

Conditioning Gain

Signal

Generator

Alias

Protection

DSPSensor

(S)

Analog Domain Digital Domain

Sensor Scadas PC


Measurement PC

PC with dedicated software

Communication with Scadas

Processing and storage of the channels

Analysis with measured data

Consolidate data for simulation input

Sensor Scadas PC

Analog to digital conversion

Quantification - Discretization

Sensor Scadas PC

Amplitude is divided in

discrete levels (bits)

16 bit – 65536

24 bit – 16777216

Level of the signal is measured with an interval (sampling frequency)


Issues with Digital signal processing

Aliasing

Leakage




Aliasing

fs = fsine

Observed frequency

= fs – fsine = 0 Hz

fs = 2 * fsine

Observed frequency

= fsine

Some examples:



Aliasing

∆t = 1/fs

General: fS < 2 * fsine fS - fsine



Anti-aliasing filter

Alias-free

Frequency

Log

Amplitude

80%

fBW

fs/2 fs

A

fs- fBW

3 dB roll off point

@ 80% of bandwidth



Leakage

Smaller amplitude

& smearing of

spectral contentHz

5 V Sine Wave - 3 Hz 5 V Sine Wave - 2.5 Hz

1 2 3 4 5 6

5V

Hz

1 2 3 4 5 6

?∆∆∆∆f = 1Hz

When your signal does not correspond to a spectral line

Why?

non-periodicity in observation window


Periodic Signals

T T = N ∆t


T T = N ∆t

!

Non Periodic Signals


Windows: Minimize Leakage

x

=

Window function

0

1

Original signal

Windowed signal




Agenda


LMS SCADAS

Measurement system for lab and field testing

Rugged

No moving components inside

MIL-STD810F shock and vibration tested

Flexibility

From 4 to 72 channels per frame

Master/slave extendable

Built-in battery

High performance

1 Gbit LAN connection

Sampling up to 204.8 kHz

Guaranteed anti-aliased data

Connectivity

Multi-functional input modules

GPS, CAN

V, ICP, Strain gauges, digital audio, thermocouples

Scadas Lab

LMS SCADAS frames

Scadas Lab platform

19” rack mounting

From 8 to 2000+ channels

160 Channels per frame

Master-slave connection with Scadas mobile

Up to 204.2 kHz sampling rate per channel

24-bit DSP technology

150dB spurious free dynamic range

14 MSamples throughput rate using high-speed Ethernet connection

N&V & Recorder

Lab, In-field & unattended

Scadas Recorder

Durability

Lab, In-field & unattended

Scadas Durability Recorder

LMS SCADAS frames

Scadas mobile platform

Classical N&V

Laboratory, in-field

Scadas Mobile

Tuned for classical NVH applications:

• PC-based measurements

• Built-in battery

• 1Gbit LAN

• Sampling at 204.8kHz

• V – ICP – Strain – Temperature

SCM plus:

• Recording on CF card

• PDA control

• Parallel storage

IP54 version of SCR

LMS Scadas modules

Accommodating a wide variety of NVH transducers

V8E: Voltage and ICP

VD8E: Voltage, ICP, differential inputs

VM8E: Voltage, ICP and microphone

VS8E: Voltage, ICP and digital audio

VC8E: Voltage, ICP and charge

VB8E: Voltage, ICP and bridge

DB8: Voltage and bridge

T8: Thermocouple

RV4: Torsional vibration inputs

• Accelerometers: piezoelectric, ICP or capacitive

• Force and pressure sensors: piezoelectric or strain gauges

• Microphones and SI probes: conventional or ICP

• Strain gauges: conventional 120Ω/350Ω or semiconductor

• Tacho sensors: inductive, capacitive, CAN or optical

• Temperature sensors: type E, J, K, N, R, S and T thermocouple




Agenda

Test types - Applications

Analysers

Applications

Troubleshooting

Field measurements

Examples

Sound level meter

FFT Analyser

Time recorder

Engineering tools

Applications

Acoustic analysis

Structural dynamics

In-depth analysis

Examples

LMS Test.Lab

LMS TecWare


0 200 400 600 800 1000

Frequency [Hz]

-80

-60

-40

-20

dB/1 [g]

D1: Run-up 2 M17: 5:Exhaust:2:+Z : FFT(M4) [g] Exhaust:2 +Z 0 [s]

Test types

LMS solutions

Analysers and time recording

Quick and easy setup

Powerful online processing

Single sheet user interface

Engineering tools

Advanced analysis options

Workflow guidance

Multiple disciplines



LMS Test.Xpress

LMS Test.Xpress

Recorder

Octave AnalyzerFFT Analyzer

Order Analyzer

StructuralRotating Machinery AcousticsEnvironmental &

Durability

Reporting

Data Sharing

Data access

LMS Test.Lab

Rotating machinery testing

What is my critical operational condition?

Operational instrumentation

Engine run-up

Colormap plotting

Tracking on rpm or time

Acquire throughput data

How does my structure respond?

Operational deflection shapes

Sound quality metrics

Audio replay and filtering

Sound diagnosis

Order tracking

Angle domain processing

Torsional vibration analysis

Which effects are engine related?

Acoustic testing

Does it sound right?Why is it annoying?

Sound Quality

replay/filter, psycho-acoustic metrics, objective & subjective evaluations

Do I meet quality objectives?

Acoustic Analyzer

SLM, Leq, Octave, Loudness, AI,..

Do I meet standards?

Sound Power & Pass-by Noise

Pressure & intensity basedIn-room, in-vehicle, near track

Material & Component Testingabsorption, transmission loss

in-tube, in-situ, in-room

What material should I use to reduce the levels?

What is the root cause?Source? Path?

Vibro-Acoustic Engineering

Transfer path AnalysisAcoustic Source QuantificationVibro-acoustic modal analysis

Where is the sound coming from?

Sound Source Localization

intensity – beam formingholography – focalization

dBA (Pa)

40

100

81

89

Structural testing

How can I excite my structure?

Hammer impact testing

Shaker testing

MIMO

Special cases?

Operational modal analysis

Operational deflection shapes

Time MDOF Approach

LMS Polymax

Automatic modal parameter selection

What are the natural frequencies?

Environmental testing

Will my structure survive

Vibration qualification

Closed loop control

Shock, Sine, Random

Combined modes and automation

MIL-STD, GAM-EG13R

Special cases?

Ground vibration testing

Climatic chamber

Mission Synthesis

Customer usage profile

Avoid under/over testing

Generate a universal test schedule

How realistic is the test schedule?

Chiel Verhoeven

Thank you

02 lms test introduction

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