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ACCELERATING & ENABLING DESIGN EXCELLENCE
Importance & Application of
ETS I Series Shaker System
Prepared By Mel Tan
ETS Solutions Asia Pte Ltd
60 Kaki Bukit Place, Eunos Techpark, #08-14, Singapore 415979
Tel: +65 - 6340 1036 Fax: +65 - 6340 1037
sales@etssolution-asia.com www.etssolution-asia.com
Copyright © 2014 ETS Solutions. All rights reserved.
This document and translations of it may be copied and furnished to others, and derivative works that comment on
or otherwise explain it or assist in its implementation may be prepared, copied, published, and distributed, in whole
or in part, without restriction of any kind, provided that the above copyright notice and this section are included on all
such copies and derivative works. However, this document itself may not be modified in any way, including by
removing the copyright notice or references to ETS Solutions, without the permission of the copyright owners.
This document and the information contained herein is provided on an "AS IS" basis and ETS Solutions DISCLAIMS
ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY W ARRANTY THAT THE
USE OF THE INFORMATION HEREIN W ILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright © 2014 ETS Solutions. All rights reserved.
This document and translations of it may be copied and furnished to others, and derivative works that comment on or
otherwise explain it or assist in its implementation may be prepared, copied, published, and distributed, in whole or in
part, without restriction of any kind, provided that the above copyright notice and this section are included on all such
copies and derivative works. However, this document itself may not be modified in any way, including by removing
the copyright notice or references to ETS Solutions, except as needed for the purpose of developing any document
or deliverable produced by ETS Technical Team (in which case the rules applicable to copyrights, as set forth in the
ETS Policy, must be followed) or as required to translate it into languages other than English. The limited
permissions granted above are perpetual and will not be revoked by ETS Solutions or its successors or assigns.
This document and the information contained herein is provided on an "AS IS" basis and ETS Solutions DISCLAIMS
ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY W ARRANTY THAT THE
USE OF THE INFORMATION HEREIN W ILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
All brands, and product names, other than those owned by ETS Solutions, are used for identification purposes only
and may be trademarks that are the sole property of their respective owners.
Any comments relating to the material contained in this document may be submitted to:
ETS Solutions Asia Pte Ltd
60 Kaki Bukit Place, Eunos Techpark, #08-14, Singapore 415979
Tel: +65 – 6340 1036 Fax: +65 – 6340 1037
sales@etssolution-asia.com
www.etssolution-asia.com
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Table of Contents
Topic
Page No.
Acknowledgements.................................................................................................................................... 4
Introduction to “Vibration” & Need for Vibration Testing............................................................................ 5
Basics of Vibration Testing........................................................................................................................ 6
Benefits of Vibration Testing…………………………………………………………………………………… 6
Limitations of Existing Vibration Testing Systems…………………………………………………………… 7
Construction of Conventional Armature…..…………………………………………………………………… 8
ETS I series Vibration Testing System……………………………………………………………………….. 9
EAS-Y Ring Armature…………………………………………………………………………………………... 9
Construction of EAS-Y Ring Armature……………………………………………………………………….. 10
Construction of the Shaker System........................................................................................................... 11
ETS I 1045 Performance Results – Sine Sweep....................................................................................... 13
ETS I 1045 Performance Results – Random…......................................................................................... 13
ETS I 1045 Performance Results – Shock………..................................................................................... 14
Applications................................................................................................................................................ 14
Test Simulation Results for EIA/ECA-364-28E Standard Test V............................................................. 16
Test Simulation Results for GMW3172 Standard..................................................................................... 18
Test Simulation of IEC 61373 Standard…................................................................................................ 19
Partial Shaker References........................................................................................................................ 21
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Acknowledgements
We would like to thank the following individuals for their participation and contribution to the development
of this document:
Mel Tan
Mauro Berno
Rohit Bansal
M.T. Utama
Graham Carmichel
Richard Chen
Q.S. Zhang
G.H. Zhang
Z.X. Wang
Jenny Yue
ETS Solutions, Singapore
ETS Solutions, Singapore
ETS Solutions, Singapore
ETS Solutions, Singapore
ETS Solutions, USA
ETS Solutions, China
ETS Solutions, China
ETS Solutions, China
ETS Solutions, China
ETS Solutions, China
This joint document from ETS Solutions Pte Ltd. is written to help companies and technical community at
large to navigate the myriad of overlapping technical products in vibration testing industry, produced by
various organizations.
This document explains and positions the ETS I series shaker system in view of the modern day industry
requirements and existing competitive products in market. This document is intended to serve as a guide
to the reader to help differentiate and select specifications appropriate to their needs.
This document outlines where the works are similar and helps users of the technical products produced by
ETS Solutions to understand the strengths of each body of work and select the technical products most
appropriate for their needs, consistent with where they are today, and where they plan to head on their
journeys.
A secondary goal was to establish collaboration between the existing testing procedures and practices to
encourage consistency across the testing standards. It is anticipated that future products and solutions by
ETS Solutions Pte Ltd. will consider the relative positioning described here to reduce overlaps and gaps
between related standards and practices.
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Introduction to “Vibration” and Need for Vibration Testing
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The oscillations may be
periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.
There are three main reasons for which we require vibration testing:
- To ensure reliability, functionality and structural integrity.
You want the equipment to be reliable, to continue to function correctly and – to put it bluntly – you don’t want it to fall
apart.
Even equipment that is permanently fixed in one place needs to withstand vibration during its lifecycle. In fact, there are
four specific stages in the lifecycle of a product when it might have to withstand vibration:
Assembly:
Whilst the equipment is being manufactured, circuit boards and other components are often subject to shock and
vibration – for example when a PCB is being put into its housing and may be dropped on the assembly bench.
Packaged transportation:
When the equipment is being transported, must withstand vibration, shocks and drops. For some types of equipment
– e.g. telecoms systems – packaged transportation is the time when the equipment is subjected to the greatest
mechanical stresses.
Installation:
Equipment that must be installed needs to withstand manual handling
Service environment:
The environment in which the equipment must operate. The challenges can range from track vibrations and the shock
of shunting in rail applications, engine and gearbox induced vibration on road vehicles and aircraft, as well as the need
to survive handling and drops in the case of portable consumer electronics.
Consumers expect and demand products of high quality and reliability. To fulfill these requirements we must consider
vibration, since at some time in its life the product will be subjected to vibration. Poor mechanical design will result in
mechanical failure and customer dissatisfaction which will add cost and reduce credibility.
COST
Product Failure
CREDIBILITY
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Basics of Vibration Testing
The most common types of vibration testing services conducted by vibration test labs are Sinusoidal and Random.
Sine (one-frequency-at-a-time) tests are performed to survey the structural response of the device under test
(DUT).
A random (all frequencies at once) test is generally considered to more closely replicate a real world
environment, such as road inputs to a moving automobile.
Most vibration testing is conducted in a 'single DUT axis' at a time, even though most real-world vibration occurs
in various axes simultaneously. MIL-STD-810G, released in late 2008, Test Method 527, calls for multiple exciter
testing. The vibration test fixture which is used to attach the DUT to the shaker table must be designed for the
frequency range of the vibration test spectrum. Generally for smaller fixtures and lower frequency ranges, the
designer targets a fixture design which is free of resonances in the test frequency range. This becomes more
difficult as the DUT gets larger and as the test frequency increases, in these cases multi-point control strategies
can be employed to mitigate some of the resonances which may be present in the future.
Benefits of Vibration Testing
Some key benefits of vibration testing are:
•
Reduce product development time
•
Ensure new products are fit for purpose
•
Reduce in-plant rework due to QA rejection
•
Reduce damage in transit and subsequent rejection by the customer
•
Reduce marginal or non-performance rejection under W arranty
•
Reduce legal costs and damage claims due to incorrect operation of the product
•
Maintain a good reputation for the company and its products
•
Maintain profit margins
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Limitations of Existing Vibration Testing Systems
Most high force d i r e c t coupled a r m a t u r e utilize an armature construction design of electrical windings, epoxy
bonded joints, high amperage flexures (direct input power to the coil), and high pressure hoses to cool the windings
( cooling water in and out of the coil). Each of these components is subjected to the same vibration and/or shock
levels applied to the test specimen. Repeated high level operation c a n leads to fatigue failures, water leaks,
cracked epoxy joints, burned out windings, or voltage breakdown in the coil.
Typical shaker lower guidance is usually a configuration of rollers or shaft housing with small ball bearing composite
assembly. Such design is usually sufficient to handle low to medium force shaker where the test articles are usually
of moderate weight and size. The high force shaker (>70kN typically) vibration testing system is unable to handle
larger test article and mass. The CG of such test articles cannot be easily controlled which can result in high
overturning moment and causes great stress to the ball bearing assembly. At certain instances, failures can occur to
the extent of damaging the armature and the stator coil where the lower guidance breakdown. The
hydrostatic bearing that is incorporated in I series shaker system is designed to handle 9000Nm side loading. The
superb bearing design is capable to extend greater test capabilities and make the shaker system much more
reliable.
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Construction of a Conventional Armature
Below are real time snapshots of a Conventional Armature Structure:
As can be seen above, a traditional armature structure essentially contains coil windings that make the whole
assembly vulnerable to failures. This can be resolved by having a single piece design and removing the direct
contact of windings to the main armature structure.
The link below illustrates the mode that’ll be experienced by an armature under a real testing condition:
https://www.youtube.com/watch?v=Mhj3ttdW JOY&feature=youtu.be
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ETS “I” Series Vibration Testing System
The I Series is designed to meet military and international test standards including MIL, ASTM, IEC, ISO, BS
and JIS. The "I" Series also meets typical vibration test requirements of other medium to large sized electronic
assemblies, automotive parts, aviation and avionics parts. The Extreme Acceleration Shaker Y-Ring (EAS-Y
Ring) armature is a revolutionary design which will allow using a proportioned head expander to test multiple
specimens simultaneously yet achieving good vibration transmissibility ratio. Other test requirements including
transportation, vibration, simulation combined vibration-climatic test and seismic simulations for small size
components c a n easily be fulfilled by the ETS "I" Series.
FEATURES OF THE EAS-Y RING ARMATURE
The EAS-Y Ring armature is the latest advanced shaker design available from ETS Solutions. The unique solid
metallic armature simplifies the electrical interconnection and supply. The mechanical durability and reliability also
increase tremendously as compare with traditional armature coil winding designs. The two key fundamental designs
make the I Series shaker armature the most reliable and high performance shaker systems available.
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Construction of EAS-Y Ring Armature
The EAS-Y Ring armature is a simple two-piece metal structure. No electrical current leads or water cooling
connections are needed. There are no electrical windings. All points on the armature are at ground potential at all
times. There is no possibility of voltage breakdown. No electrical insulation is utilized anywhere in the armature
assembly because there is zero voltage potential between any two points on the ring, and between the ring and
ground.
Consider an armature consisting of two rigid members bolted together with high performance guidance system
that is task to deliver side load performances up to 180g sine and 100g random. The E A S -Y Ring is the most
ideal system to carry the extreme vibration test requirements available.
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Construction of EAS-Y Ring Armature
Figures above show the “I” series shaker system uses an EAS-Y Ring armature structure which is practically a single
piece design without windings directly wounded on the armature body.
A shaker is an electromechanical transducer that converts electrical current into mechanical force for vibration
testing. To accomplish this, the shaker uses the characteristics of current flow crossing a magnetic field.
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“I” series is designed to test payloads of up to 500kg. Design features meet the testing requirements of small
components to medium sized test specimens for the automotive, aviation, military, medical and electronic
manufacturing industries.
ETS Solutions MPA Series Power Amplifier applies specific current waveforms called Drive Signals through the
Armature to control its movement. In shaker design, the flux density and length of the armature coil is held constant.
These constants allow the Drive Signal’s current waveforms to directly control the movement of the armature coil.
Therefore, the Drive Signal waveforms are applied to the product through the armature movement.
Figure: Shaker Structure
Figure: Shaker Major Parts
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ETS I SERIES PERFORMANCE CURVE
Following are the Performance Test Result from an ETS Multi Excitation Testing System which consists of 3 x 50
kN single axis vibration shaker. There were three tasks which were performed: Sine Sweep, Random, and Shock.
1. Sine Sweep, 140G, 5 – 2000 Hz
2. Random, 120 Grms, 20 – 2000 Hz
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3. Shock, 75G, 11ms, Half Sine
ETS I Series shaker system is suitable for applications where it is required to:
1.
2.
3.
Perform Random Test above 50grms
Perform Sine Test above 70g peak
Perform the different mixed mode test (sine on random, random on random, sine and random on random)
The system is suitable to comply with the widely accepted MIL-STD-810 standard.
A Brief Introduction to MIL-STD-810 Standard:
MIL-STD-810, Environmental Engineering Considerations and Laboratory Tests is a United States Military Standard
that emphasizes tailoring the equipment's environmental design and test limits to the conditions that it will
experience throughout its service life, and establishing chamber test methods that replicate the effects of
environments on the equipment rather than imitating the environments themselves. The MIL-STD-810 test series
are approved for use by all departments and agencies of the United States Department of Defense (DoD). Although
prepared specifically for military applications, the standard is often used for commercial products as well.
Various types of tests that can be performed are as follows:
1.
Development Test:
Development testing is used to determine characteristics of materiel, to uncover design and construction
deficiencies, and to evaluate corrective actions. Begin as early as practical in the development, and continue as the
design matures. The ultimate purpose is to assure developed materiel is compatible with the environmental life
cycle, and that formal testing does not result in failure. The tests have a variety of specific objectives. Therefore,
allow considerable freedom in selecting test vibration levels, excitation, frequency ranges, and durations. Typical
programs might include modal analysis to verify analytical mode shapes and frequencies, and sine dwell, swept sine,
transient, or random excitation transient vibration to evaluate function, fatigue life, or wear life. The test types, levels,
and frequencies are selected to accomplish specific test objectives. Levels may be lower than life cycle
environments to avoid damage to a prototype, higher to verify structural integrity, or raised in steps to evaluate
performance variations and fragility.
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2. Qualification Test:
Qualification testing is conducted to determine compliance of a material with specific environmental
requirements. Such tests are commonly a contractual requirement and will include specific test specifications.
Qualification tests should be conducted using an excitation that has the same basic characteristics as the anticipated
service environment. For most items, this consists of a functional test and an endurance test (sometimes
combined). The functional test represents the worst case vibration (or envelope of worst case conditions) of the
environmental life cycle. The endurance test is a fatigue test representing an entire life cycle. Often, vibration can be
combined with other environmental stresses.
2.1. Functional Test:
Functional testing is conducted to verify that the material is functioning as required while exposed to worst case
operational vibration. Full function verification is performed at the beginning, middle and end of each test segment.
2.2. Endurance Test:
Endurance testing is conducted to reveal time-dependent failures. In many cases the test is accelerated in order to
produce the same damage as the entire duration of the required service life. Generally, it is not required to have an
item powered-up during the endurance phase of test. We define the test time at maximum service levels (functional
levels) that is equivalent to a vibration lifetime (levels vary throughout each mission). Use the equivalent time as the
functional test duration, thereby combining functional and endurance tests. There may be cases when this test
duration is too long to be compatible with program restraints. In these cases, use as long of a test duration as is
practical and use the fatigue relationship to define the test level. While this approach does not completely eliminate
nonlinearity questions, it does limit levels to more realistic maximums. Generally, the test item will not be in a
powered-up state during the endurance (“non-operating”) phase of testing; particularly in a situation in which the
test levels have been exaggerated beyond maximum measured values in order to significantly compress the test
duration.
3. Durability test:
Durability testing is a real-time (non-exaggerated) simulation of the environmental life cycle to a high degree of
accuracy. A durability analysis precedes the test and is used to determine which environmental factors (vibration,
temperature, altitude, humidity, etc.) must be included in the test to achieve realistic results. Although the test is
intended to be a real time simulation of the life cycle, it may be shortened by truncation if feasible. Truncation is the
elimination of time segments that are shown by the durability analysis to be benign with regard to materiel function
and life. Durability analyses should use fatigue and fracture data applicable to each material.
4. Reliability test:
Reliability testing is accomplished to obtain statistical definitions of materiel failure rates. These tests may be
development tests or qualification tests. The accuracy of the resulting data is improved by improving realism of the
environmental simulation. Test requirements are developed by engineers responsible for materiel reliability.
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5. Worthiness test:
When unqualified materiel is to be evaluated in the field, verification that the materiel will function satisfactorily is
normally required for safety and/or test efficiency reasons. This is accomplished by environmental worthiness
test. The worthiness test is identical to a qualification test except that it covers only the life cycle of the field
evaluation. Levels are usually typical operating levels unless safety is involved; then maximum operating levels are
necessary. Durations are either equivalent to a complete system/subsystem test, long enough to check materiel
function, or an arbitrary short time (5 or 10 minutes). For safety driven worthiness test, the test item is considered to
be consumed by the test (the test item may not be used in the field). An identical item of hardware is used in the
field evaluation. When safety is not an issue, an item may be subjected to a minimum time functional test and then
used in the field evaluation. When it is required to evaluate the cumulative environmental effects of vibration
and environments such as temperature, altitude, humidity, leakage, or EMI/EMC, a single test item should be
exposed to all environmental conditions. For air worthiness testing, a three step approach may be required. For
example, this could include conducting and initial laboratory vibration test, followed by experimental flight testing to
acquire the actual exposure levels, and ending with a qualification test based on the measured field data.
Test Simulation Results for EIA/ECA-364-28E Standard Test VI
This is a standard test procedure used to assess ability of electrical connector components to withstand specified
severities of vibration.
All these tests require sine/random vibration testing environment.
Below is a simulation model for one of these requirements. Random vibrations have been applied in this case.
As can be seen the max. Tolerable G RMS required is 48.09!
Hence the test setup should be able to able to provide testing environment up to 62.05 G RMS at which the test will
be aborted.
As can be seen the max. Tolerable G RMS required in this case is 48.09!
Hence the test setup should be able to provide testing environment up to 62.05 G RMS before which the test will be
aborted.
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As can be seen the max. Tolerable G RMS required in this case is 57.52!
Hence the test setup should be able to provide testing environment up to 76.41 G RMS before which the test will be
aborted.
I series shaker systems are designed to provide a testing environment up to 180G sine and 100G random vibrations,
hence is fit to be utilized as a testing equipment for verifying these standards. Further, the robust nature of I series
shaker makes it more reliable under such heavy applications.
Test Simulation Results for GMW3172 Standard
GMW3172 is also an important vibration standard widely used.
This standard applies to Electrical/Electronic (E/E) components for
passenger or commercial vehicles and trucks. The standard
describes the environmental and durability tests for E/E
components based on mounting location. This standard specifies
Environmental/
Durability
requirements
and
Analytical/
Development/Validation (A/D/V) activities for E/E components that
are used in a vehicle environment to ensure reliability over a life
time.
This test shall verify the component’s immunity to mechanical
shock events produced by minor collisions (less than 16 mile/h or
25.7 km/h or 7.14 m/s).
this table
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As seen above, the vibration testing requirements for this standard requires a peak of 100G to be applied for
duration of 11ms thus creating 120 impacts. This would require a shaker system to induce shocks at less than 7.14
m/s.
I series shaker system has 3 m/s or better making it ideal for velocity and acceleration applications!
Below is the Acceleration vs Time curve to determine velocity and displacement fluctuations during vibration testing:
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Test Simulation Results for IEC 61373 Standard
Another application that will need an advance system to fulfill the test requirement is IEC 61373. This standard
applies to components or equipment which is mounted in railway vehicle and subjected to vibrations and shock
owing to the nature of railway operational environment. There are 3 categories available in this standard:
1. Class 1 : Body Mounted
2. Class 2 : Bogie Mounted
3. Class 3 : Axle Mounted
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As can be noticed, to produce a peak altitude of 100 G it is
required for a shaker system to create displacement of
9.27mm pk-pk at a velocity of 3.523m/s peak.
To create such a vibrational effect it is required for the system to
be robust and with least no. of components and joints.
If performance characteristics of existing shaker systems are
anything to go by, there is a failure every six months!!!
I series shaker system resolves this problem by
having an Extreme Acceleration Shaker Y-Ring (EAS-Y Ring)
armature which gives it the robustness to generate high level
of vibrations.
The figure below illustrate the intensity of armature fluctuations
developed in I series shaker system at 100 G, to produce the
required vibrational environment.
Partial Shaker References
I 1045 Shaker References: ATE
Detroit, MI
ETL Dallas, TX PTS
Orlando,
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