shock and vibration tests on smartscan …...• electromagnetic shaker: lds v650 with pa1000/l...

Smart Fibres Ltd · 3 Brants Bridge · Bracknell · RG12 9BG · United Kingdom

Email: [email protected] · Web: www.smartfibres.com

Tel: +44 1344 484111 · Fax: +44 1344 486759

Directors: C Staveley · A Melrose · Registered in England: 3563533 · VAT Registration No: GB723426060

Registered Office: 141 Dedworth Road · Windsor · Berkshire · SL4 5BB · United Kingdom

SENSE THE FUTURE

Certificate No: LRQ 4003532

Shock and Vibration Tests on SmartScan Interrogators to ISO 13628-6:

Document Ref: 7-049-3046A

Document Date: 28/7/2012

Prepared by: CD, LH

Approved by: CD

This information herein is the property of Smart Fibres Ltd and is to be held strictly in confidence by the recipient. No copy is to be made without the written permission of Smart Fibres Ltd. Disclosures of any of the information herein is to be made only to such persons who need such information during the course of their engagement or employment at Smart Fibres Ltd or under the written authority of Smart Fibres Ltd. Any patent applications, patents and/or design applications, registered designs or copyrights arising from or contained in the information herein, shall be considered the property of Smart Fibres Ltd and as such are subject to the aforementioned obligation of confidence on the recipient.

28/7/2012 7-049-3046A

1 Introduction.................................................................................................................. 3

1.1 Details of the Standard ......................................................................................... 3

2 Method......................................................................................................................... 3

2.1 Equipment Used: .................................................................................................. 4

3 Results......................................................................................................................... 5

3.1 Vibration Tests...................................................................................................... 5

3.2 Shock Tests.......................................................................................................... 7

4 Summary ..................................................................................................................... 9

Document Revision History:

Issue Issue Date Change A 28th July 2012 New document

28/7/2012 7-049-3046A

1 INTRODUCTION Subsea Production Control equipment for the oil and gas industry must conform to EN ISO 13628-6. This includes

subsea equipment modules (SEMs) such as a SmartScan or SmartScope interrogator packaged in a pressure vessel.

Part of the qualification test programme for this standard is shock and vibration testing, to ensure that the equipment

is robust enough to stand up to the environment it will see during transportation, handling, installation and operation.

Qualification tests may be performed on examples of the component to demonstrate its suitability for the

environment. Additionally, Environmental Stress Screening (ESS) tests may be applied to each example of the

component to weed out faulty or weak devices.

1.1 DETAILS OF THE STANDARD

There are two standard qualification tests for electronic equipment. Printed circuit boards (PCBs) and sub-assemblies

shall be qualified to standard Q1. Modules consisting of a number of PCBs assembled into a rack-type frame shall be

qualified to standard Q2. Individual circuit boards in the assembly do not require testing to Q1 if the whole module is

qualified according to Q2. The Equipment Under Test (EUT) must be monitored during all ESS (random vibration

testing). Monitoring during swept sine and shock testing is not required but may be preferred.

The specifications for Q1 and Q2 are as follows:

Q1:

Vibration: 5 to 25 Hz, +/- 2 mm displacement, then 25 to 1000 Hz 5 g acceleration.

Shock: 30g, 11 ms half sine.

Q2:

Vibration: 5 to 25 Hz, +/- 2 mm displacement, then 25 to 150 Hz 5 g acceleration.

Shock: 10g, 11 ms half sine.

The maximum vibration sweep rate is to be one octave per minute. It must be low enough to allow any resonance to

build up to maximum amplitude. A double sweep shall be performed from minimum to maximum frequency and

back again. There must be no resonance having a mechanical amplification factor of greater than 10.

The full test programme consists of vibration testing along three mutually perpendicular axes and four shocks in each

of six directions in the same axes.

No significant damage shall have occurred after shock and vibration tests and the EUT must pass a test of 100%

functionality.

2 METHOD

Remove the rubber feet from the bottom of the SmartScan and undo the four tamper-proof screws holding the two

halves of the enclosure together. Mount the SmartScan to the test bracket (7049-1053 A) with countersunk M3

screws passing through the bracket and into the four holes in the bottom of the SmartScan. Use vibration-resistant

threadlock if possible and do the screws up firmly. Now mount the bracket to the top plate of the shaker with M6

socket screws. Fit the feedback accelerometer into one of the tapped holes provided in the bracket.

Power the SmartScan and connect the Ethernet Lead. Connect test FBGs to all 4 output channels. You may choose to

use a drop of threadlock on the FC/APC connectors but take care not to contaminate the mating optical surfaces. The

test FBGs must remain stable throughout the test period. Suitable artefacts are athermal FBGs or any standard FBG,

kept at a constant temperature (ideally less that 1 °C change during the test).

28/7/2012 7-049-3046A

Available athermal FBG wavelengths are 1535, 1550 and 1565 nm.

The test is to be carried out to Q2 as described above. Build up to the specified vibration level in steps of 1, 2.5, 4 and

5 g peak acceleration for example. Record FBG data at 1 kHz or more for the whole of each sweep. Take spectra at

the beginning and end of each sweep to look for changes in light output, bearing in mind that any change may be due

to movement at the front panel connector rather than a fault in the EUT. Pay attention to any signs of mechanical

resonance and make notes accordingly.

An accelerometer may be fixed to the interrogator casing to record any resonances of the box and perhaps give an

indication of any resonances of internal components.

Repeat the above steps to do tests in the other axes by using the test brackets: 7049-1051, 7049-1052, 7049-1053,

7049-1054. The SmartScan and the test bracket need to be assembled according to assembly drawing 7049-2019.

Figure 1 to 3 below shows the SmartScan, mounted to the shaker and test bracket in 3 axes. Note there are always

two accelerometers – one control accelerometer and one response accelerometer mounted close to the tested

instrument. Note further that the optical and Ethernet connectors are not special vibration-resistant types.

Figure 1. SmartScan on the shaker in axis 1. Figure 2. Smartscan on the shaker in axis 2 Figure 3. Smartscan on the shaker in axis 3

2.1 EQUIPMENT USED:

• Electromagnetic Shaker: LDS V650 with PA1000/L amplifier and FPS 10L field power supply.

• LDS COMETUSB Shaker Controller, PC running LDS Value software

• FBGs in athermal packaging, apodised, 100% reflectivity, half-width <0.25 nm

• Accelerometer 1 DeltaTron 4514-001 (calibrated 29/03/2012)

• Accelerometer 2 DeltaTron 4517-002 (calibrated 21/02/2012)

28/7/2012 7-049-3046A

3 RESULTS

3.1 VIBRATION TESTS

Figures 4, 6 and 8 below are plots of the amplitude of the control and response accelerometer signals vs vibration

frequency. Note that the control signals followed the ISO 13628-6 Q2 test specification very closely. Some deviation

in the response accelerometer signals were noticed at higher frequencies but the amplitudes of the change was well

below the 10x threshold prescribed by the standard.

The outputs of the SmartScan are shown in Figures 5,7 and 9. The test FBGs were scanned at 1250 Hz and the data

averaged down to 10 Hz to provide a low-noise signal. This makes it easier to see any underlying fluctuations in the

interrogator output. The total deviations of measured FBG wavelength from the beginning to the end of the tests

were 0.5 pm. This is less than the unaveraged resolution of the instrument (0.8 pm) and well below the operating

stability specification of +/- 5 pm.

input1(f)

input2(f)

150.005.00 10.00 100.00

8.9125

0.1122

1.0000

Frequency (Hz)

gn

Figure 4. Axis 1, accelerometer frequency response plots. Input 2 is the control accelerometer; input 1 is the response accelerometer.

Figure 5. Axis 1 frequency response of athermal test FBGs.

28/7/2012 7-049-3046A

input1(f)

input2(f)

150.005.00 10.00 100.00

8.9125

0.1122

1.0000

Frequency (Hz)

gn


-1.5

-1

-0.5

0

0.5

1

1.5

0 25 50 75 100 125 150

Frequency [Hz]

Ath

erm

al F

BG

Sh

ift

[pm

]

ch1ch2ch3ch4


input1(f)

input2(f)

150.005.00 10.00 100.00

8.9125

0.1122

1.0000

Frequency (Hz)

gn


28/7/2012 7-049-3046A

-1.5

-1

-0.5

0

0.5

1

1.5

0 25 50 75 100 125 150

Frequency [Hz]

Ath

erm

al F

BG

Sh

ift

[pm

]

ch1ch2ch3ch4


3.2 SHOCK TESTS

Figures 10, 12 and 14 below are plots of the amplitude of the control and response accelerometer signals vs time. The

figures represent one shock pulse that has been repeated four times within 20 seconds. Note that the control signals

followed the ISO 13628-6 Q2 test specification very closely. The control signal (shock pulse) has been slowly built up

to a maximum level of 100% by performing shocks at 25%, 50% and 75%. The data was logged continuously during all

the steps. Some deviations in the response accelerometer signals were noticed due to the system dynamics. The

deviations were below those required by ISO 13628-6 levels.

The outputs of the SmartScan are shown in Figures 11,13 and 15. The test FBGs were scanned at 1250 Hz and the

data averaged down to 25 Hz to provide a low-noise signal. This makes it easier to see any underlying fluctuations in

the interrogator output. There is a linear shift on tested athermal FBGs due to the ambient temperature change. The

total deviations of measured FBG wavelength from the beginning to the end of the tests were 0.5 pm. This is less

than the unaveraged resolution of the instrument (0.8 pm) and well below the operating stability specification of +/- 5

pm. There is a linear shift on tested athermal FBGs due to the ambient temperature change.

Figure 10. Axis 1, accelerometer frequency response plots. Input 2 is the control accelerometer; input 1 is the response accelerometer

input2(t)

input1(t)

0.04-0.03 -0.02 -0.01 0 0.01 0.02 0.03

15.0000

-6.5000-6.0000

-4.5000

-3.0000

-1.5000

0

1.5000

3.0000

4.5000

6.0000

7.5000

9.0000

10.5000

12.0000

13.5000

Time (Seconds)

gn

input2(t)

input1(t)

0.04-0.03 -0.02 -0.01 0 0.01 0.02 0.03

6.4000

-15.0000

-13.5000

-12.0000

-10.5000

-9.0000

-7.5000

-6.0000

-4.5000

-3.0000

-1.5000

0

1.5000

3.0000

4.5000

Time (Seconds)

gn

28/7/2012 7-049-3046A

-1

-0.5

0

0.5

1

1.5

2

0 20 40 60 80 100 120

time [s]

Ath

erm

al F

BG

Sh

ift

[pm

]

ch1

ch2

ch3

ch4

4x Shocks at 100% level (positive)

4x Shocks at 100% level (negative)

Figure 11. Axis 1 athermal test FBGs response.


-1

-0.5

0

0.5

1

1.5

2

0 20 40 60 80 100 120

time [s]

Ath

erm

al F

BG

Sh

ift

[pm

]

ch1

ch2

ch3

ch4




input2(t)

input1(t)

0.04-0.03 -0.02 -0.01 0 0.01 0.02 0.03

14.0000

-3.9000

-3.0000

-1.5000

0

1.5000

3.0000

4.5000

6.0000

7.5000

9.0000

10.5000

12.0000

Time (Seconds)

gn

input2(t)

input1(t)

0.04-0.03 -0.02 -0.01 0 0.01 0.02 0.03

3.9000

-14.0000-13.5000

-12.0000

-10.5000

-9.0000

-7.5000

-6.0000

-4.5000

-3.0000

-1.5000

0

1.5000

3.0000

Time (Seconds)

gn

28/7/2012 7-049-3046A


-1.5

-1

-0.5

0

0.5

1

1.5

0 20 40 60 80 100 120

time [s]

Ath

erm

al F

BG

Sh

ift

[pm

]

ch1

ch2

ch3

ch4




4 SUMMARY

• The SmartScan interrogator passed a shock and vibration tests performed according to the ISO 13628-6

standard.

• A small amount of mechanical amplification was recorded by a response accelerometer mounted on the

SmartScan enclosure during vibration test. Further work will be performed to discover the source of this

effect.

input2(t)

input1(t)

0.04-0.03 -0.02 -0.01 0 0.01 0.02 0.03

14.0000

-4.9000-4.5000

-3.0000

-1.5000

0

1.5000

3.0000

4.5000

6.0000

7.5000

9.0000

10.5000

12.0000

Time (Seconds)

gn

input2(t)

input1(t)

0.04-0.03 -0.02 -0.01 0 0.01 0.02 0.03

4.9000

-14.0000-13.5000

-12.0000

-10.5000

-9.0000

-7.5000

-6.0000

-4.5000

-3.0000

-1.5000

0

1.5000

3.0000

Time (Seconds)

gn

shock and vibration tests on smartscan …...• electromagnetic shaker: lds v650 with pa1000/l...

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