Major differences between HALT and ED

Major Differences between

Random Vibration Tables and

Electro-Dynamic Shakers

Overview

Overview

• Random Vibration (HALT)

Overview

• Random Vibration (HALT)

Highly Accelerated Life Test

Overview

• Random Vibration (HALT)

Highly Accelerated Life Test

The test article is subjected to all 6 possible axes of motion (X, Y, Z, Roll, Pitch, and Yaw) at the

same time. This is subject to the limits of Newtonian Physics, where an object can only move in one

direction at any instant.

Overview

• Random Vibration (HALT)

Highly Accelerated Life Test

The test article is subjected to all 6 possible axes of motion (X, Y, Z, Roll, Pitch, and Yaw) at the

same time. This is subject to the limits of Newtonian Physics, where an object can only move in one

direction at any instant.

Why? The Goal of HALT testing is to quickly find failures in a design. The

cause of the failure is then determined and the design is strengthened

and testing continues until failures occur at levels of stress higher than a

product sees in usual service.

Overview

• Random Vibration (HALT)

Highly Accelerated Life Test

The test article is subjected to all 6 possible axes of motion (X, Y, Z, Roll, Pitch, and Yaw) at the

same time. This is subject to the limits of Newtonian Physics, where an object can only move in one

direction at any instant.

Why? The Goal of HALT testing is to quickly find failures in a design. The

cause of the failure is then determined and the design is strengthened

and testing continues until failures occur at levels of stress higher than a

product sees in usual service.

When? Usually during product

development, but can also

be done later to improve the

design.

Overview

Overview

• Electro-Dynamic (ED)

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Limited to ONE axis of motion,

unless multiple tests are used

to move an object in 2 or 3

axes.

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Limited to ONE axis of motion,

unless multiple tests are used

to move an object in 2 or 3

axes.

Other Key

Differences

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Limited to ONE axis of motion,

unless multiple tests are used

to move an object in 2 or 3

axes.

Other Key

Differences Frequency

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Limited to ONE axis of motion,

unless multiple tests are used

to move an object in 2 or 3

axes.

Other Key

Differences Peak Frequency

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Limited to ONE axis of motion,

unless multiple tests are used

to move an object in 2 or 3

axes.

Other Key

Differences Peak Frequency Motion

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Limited to ONE axis of motion,

unless multiple tests are used

to move an object in 2 or 3

axes.

Other Key

Differences Peak Frequency Motion Fixturing

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Limited to ONE axis of motion,

unless multiple tests are used

to move an object in 2 or 3

axes.

Other Key

Differences Peak Frequency Motion Fixturing Displacement

Overview

• Electro-Dynamic (ED)

May be used for the same purpose as HALT

Major Difference?

Limited to ONE axis of motion,

unless multiple tests are used

to move an object in 2 or 3

axes.

Other Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT Wide band FIXED

frequency response to create

the PSD energy.

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT Wide band FIXED

frequency response to create

the PSD energy.

Approximately 20HZ to 12kHz with fairly flat average power.

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT Wide band FIXED

frequency response to create the PSD

energy.

Approximately 20HZ to 12kHz with fairly flat average power.

ED PSD is programmed into the controller to achieve a given

PSD curve.

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT

Wide band FIXED frequency response to create the PSD

energy.

Approximately 20HZ to 12kHz with fairly flat average power.

ED

PSD is programmed into the controller to achieve a given

PSD curve.

Typically the energy is concentrated in a given area of interest for the test, and is

usually based on empirical measurements of the

environment that the unit under test will need to endure

during its lifecycle.

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT The peak for any

individual random shock impulse is typically 10X the average providing

more headroom for any individual shock pulse.

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT The peak for any

individual random shock impulse is typically 10X the average providing

more headroom for any individual shock pulse.

This is due to the shock hammers under the table

that produce shock waves.

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT The peak for any

individual random shock impulse is typically 10X the average providing

more headroom for any individual shock pulse.

This is due to the shock hammers under the table

that produce shock waves.

ED Due to the differences in the way the table works it is unable to achieve large instantaneous

shock pulses.

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT 6 degrees of

freedom motion, X, Y, Z, Pitch, Roll and Yaw

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT 6 degrees of

freedom motion, X, Y, Z, Pitch, Roll and Yaw

ED

Single axis at a time only.

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT 6 degrees of

freedom motion, X, Y, Z, Pitch, Roll and

Yaw

ED

Single axis at a time only.

One must shift the orientation of the part on axis at a time X, Y and Z

only.

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT

Fixtures are much lighter

than ED shaker fixtures.

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT

Fixtures are much lighter than ED shaker fixtures.

ED

Sometimes massive to accommodate a heavier load with

more displacement.

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT

Displacement is on the order of millimeters, and not controllable.

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT

Displacement is on the order of millimeters, and not controllable.

ED

Can move more than one inch,

typically about ½ cm.

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT Discovery test to rapidly find weaknesses using

accelerated stress conditions.

Find a weakness… Improve the weakness

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT Discovery test to rapidly find weaknesses using

accelerated stress conditions.

Find a weakness… Improve the weakness

There are many books and consultants available

on the subject of test design.

ED

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT Discovery test to rapidly find weaknesses using

accelerated stress conditions.

Find a weakness… Improve the weakness

There are many books and consultants available

on the subject of test design.

ED

There are standards and MIL Specs written around

this type of testing.

Key

Differences Peak Frequency Motion Fixturing Displacement Test

Design

HALT Discovery test to rapidly find weaknesses using

accelerated stress conditions.

Find a weakness… Improve the weakness

There are many books and consultants available

on the subject of test design.

ED

There are standards and MIL Specs written around

this type of testing.

The test engineer may often have the specs or standards imposed by a

customer

Additional Differences

HALT ED

Additional Differences

HALT ED

Additional Differences

HALT ED

Can achieve a more severe

test.

Can use larger parts such as

motor housings or castings.

Additional Differences

HALT ED

Conclusion

• Neither HALT or ED shakers are necessarily

better than the other. It all depends on the

specific product and test being run.

Conclusion

• Neither HALT or ED shakers are necessarily

better than the other. It all depends on the

specific product and test being run.

• In some cases, the test results from an ED

Shaker table can be correlated to a HALT

chamber table by running HALT discovery

testing after finding destruct points with an

ED Shaker, but it depends on the type of

part being tested.

For more information,

please contact

Cincinnati Sub-Zero or visit

www.cszindustrial.com