SENSE THE FUTURE Shock and Vibration Tests on SmartScan Interrogators to ISO 3628-6: Document Ref: 7-49-346A Document Date: 28/7/22 Prepared by: Approved by: CD, LH 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 desi applications, registered desis 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. Smart Fibres Ltd 3 Brants Bridge Bracknell RG2 9BG United Kingdom Email: info@smartfibres.com Web: www.smartfibres.com Tel: +44 344 484 Fax: +44 344 486759 Certificate No: LRQ 43532 Directors: C Staveley A Melrose Registered in England: 3563533 VAT Registration No: GB7234266 Registered Office: 4 Dedworth Road Windsor Berkshire SL4 5BB United Kingdom
Introduction... 3. Details of the Standard... 3 2 Method... 3 2. Equipment Used:... 4 3 Results... 5 3. Vibration Tests... 5 3.2 Shock Tests... 7 4 Summary... 9 Document Revision History: Issue Issue Date Change A 28 th July 22 New document Page 2 28/7/22 7-49-346A
INTRODUCTION Subsea Production Control equipment for the oil and gas industry must conform to EN ISO 3628-6. 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.. 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 Q. 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 Q 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 Q and Q2 are as follows: Q: Vibration: Shock: Q2: Vibration: Shock: 5 to 25 Hz, +/- 2 mm displacement, then 25 to Hz 5 g acceleration. 3g, ms half sine. 5 to 25 Hz, +/- 2 mm displacement, then 25 to 5 Hz 5 g acceleration. g, 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. 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 siificant damage shall have occurred after shock and vibration tests and the EUT must pass a test of % 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 (749-53 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 C change during the test). Page 3 28/7/22 7-49-346A
Available athermal FBG wavelengths are 535, 55 and 565 nm. The test is to be carried out to Q2 as described above. Build up to the specified vibration in steps of, 2.5, 4 and 5 g peak acceleration for example. Record FBG data at 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 sis 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: 749-5, 749-52, 749-53, 749-54. The SmartScan and the test bracket need to be assembled according to assembly drawing 749-29. Figure 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. SmartScan on the shaker in axis. Figure 2. Smartscan on the shaker in axis 2 Figure 3. Smartscan on the shaker in axis 3 2. EQUIPMENT USED: Electromaetic Shaker: LDS V65 with PA/L amplifier and FPS L field power supply. LDS COMETUSB Shaker Controller, PC running LDS Value software FBGs in athermal packaging, apodised, % reflectivity, half-width <.25 nm Accelerometer DeltaTron 454- (calibrated 29/3/22) Accelerometer 2 DeltaTron 457-2 (calibrated 2/2/22) Page 4 28/7/22 7-49-346A
3 RESULTS 3. VIBRATION TESTS Figures 4, 6 and 8 below are plots of the amplitude of the control and response accelerometer sials vs vibration frequency. Note that the control sials followed the ISO 3628-6 Q2 test specification very closely. Some deviation in the response accelerometer sials were noticed at higher frequencies but the amplitudes of the change was well below the x threshold prescribed by the standard. The outputs of the SmartScan are shown in Figures 5,7 and 9. The test FBGs were scanned at 25 Hz and the data averaged down to Hz to provide a low-noise sial. 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.5 pm. This is less than the unaveraged resolution of the instrument (.8 pm) and well below the operating stability specification of +/- 5 pm. 8.925 input(f) input2(f)..22 5... 5. Frequency (Hz) Figure 4. Axis, accelerometer frequency response plots. Input 2 is the control accelerometer; input is the response accelerometer. Figure 5. Axis frequency response of athermal test FBGs. Page 5 28/7/22 7-49-346A
8.925 input(f) input2(f)..22 5... 5. Frequency (Hz) Figure 6. Axis 2, accelerometer frequency response plots. Input is the control accelerometer; input 2 is the response accelerometer. Athermal FBG Shift [pm].5 -.5 - ch - 25 5 75 25 5 Frequency [Hz] Figure 7. Axis 2 frequency response of athermal test FBGs. 8.925 input(f) input2(f)..22 5... 5. Frequency (Hz) Figure 8. Axis 3, accelerometer frequency response plots. Input is the control accelerometer; input 2 is the response accelerometer. Page 6 28/7/22 7-49-346A
Athermal FBG Shift [pm].5 -.5 - ch - 25 5 75 25 5 Frequency [Hz] Figure 9. Axis 3 frequency response of athermal test FBGs. 3.2 SHOCK TESTS Figures, 2 and 4 below are plots of the amplitude of the control and response accelerometer sials vs time. The figures represent one shock pulse that has been repeated four times within 2 seconds. Note that the control sials followed the ISO 3628-6 Q2 test specification very closely. The control sial (shock pulse) has been slowly built up to a maximum of % by performing shocks at 25%, 5% and 75%. The data was logged continuously during all the steps. Some deviations in the response accelerometer sials were noticed due to the system dynamics. The deviations were below those required by ISO 3628-6 s. The outputs of the SmartScan are shown in Figures,3 and 5. The test FBGs were scanned at 25 Hz and the data averaged down to 25 Hz to provide a low-noise sial. 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.5 pm. This is less than the unaveraged resolution of the instrument (.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. 5. 6.4 3.5 2. 9. 7.5 6. 4.5 3. - -3. -4.5-6. -6.5 -.3 -.2 -...2.3.4 4.5 3. - -3. -4.5-6. -7.5-9. - -2. -3.5-5. -.3 -.2 -...2.3 Figure. Axis, accelerometer frequency response plots. Input 2 is the control accelerometer; input is the response accelerometer.4 Page 7 28/7/22 7-49-346A
Athermal FBG Shift [pm] 2.5 -.5 at % (positive) at % (negative) ch - 2 4 6 8 2 time [s] Figure. Axis athermal test FBGs response. 4. 2. 9. 7.5 6. 4.5 3. - -3. -3.9 -.3 -.2 -...2.3.4 3.9 3. - -3. -4.5-6. -7.5-9. - -2. -3.5-4. -.3 -.2 -...2.3 Figure 2. Axis 2, accelerometer frequency response plots. Input 2 is the control accelerometer; input is the response accelerometer.4 Athermal FBG Shift [pm] 2.5 -.5 at % (positive) at % (negative) ch - 2 4 6 8 2 time [s] Figure 3. Axis 2 athermal test FBGs response. Page 8 28/7/22 7-49-346A
4. 4.9 2. 3. 9. 7.5-6. -3. 4.5-4.5 3. -6. -7.5-9. - - -3. -2. -4.5-4.9 -.3 -.2 -...2.3.4-3.5-4. -.3 -.2 -...2.3 Figure 4. Axis 3, accelerometer frequency response plots. Input 2 is the control accelerometer; input is the response accelerometer.4 Athermal FBG Shift [pm].5 -.5 - at % (positive) at % (negative) ch - 2 4 6 8 2 time [s] Figure 5. Axis 3 athermal test FBGs response. 4 SUMMARY The SmartScan interrogator passed a shock and vibration tests performed according to the ISO 3628-6 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. Page 9 28/7/22 7-49-346A