TNO cOmbiNes experT kNOwledge wiTh specialisT faciliTies fOr shOck aNd vibraTiON TesTiNg

Shock and vibration

Shock expertiSeWith over 40 years of experience, TNO provides both experimental and theoretical shock expertise for a world-wide customer base. The shock facilities at the TNO Structural Dynamics lab have been developed to simulate the effect of a shock wave generated from a non-contact underwater explosion. However, our shock tables are extremely versatile and can be adjusted to provide shocks required in other industries, such as, aerospace, civil infrastructure, transportation and space sectors.

Moreover, bespoke experimental rigs can be built to simulate the extremes of shock; for example, shock pulses generated by pyrotechnic blasts.

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in red. again, the NaTO STaNaG criteria is satisfied. Finally, the measured results are shown as an acceleration time trace.

Each shock machine can be tuned to our customer’s individual requirement. a guideline of the maximum capabilities of each machine is given in the table above.

in the situation where the payload exceeds the capacity of our machines, the pulse duration required is shorter or longer, or the required acceleration differs from that stated above, we provide specific solutions. Please contact us for more information.

StandardS Our shock tables satisfy the b, c, D, NSS1 and NSS2 shock curves from standards br3021 and br8470. However, we regularly test to our client’s specific requirements. We can also simulate the bv043 shock levels. Tests are typically validated against the NaTO STaNaG 4141 and 4549 criteria.

PoSt-ProceSSingState-of-the-art instrumentation is used to measure the applied shocks. Through the use of in-house software, we provide results in terms of acceleration, velocity and displacement time traces. Moreover, according to the NaTO STaNaG requirements, we validate tests through the use of shock response spectra (SrS). Examples are given below.

br STaNDarDShown to the right, in the two top figures: this requirement is given in terms of a theoretical acceleration time trace; the br8470 b pulse is shown in blue. This requirement is compared to the measured test accelerations; shown in red. an SrS comparison between the requirement and the measured results is shown to satisfy the NaTO STaNaG validation criteria.

NaTO STaNDarDShown to the right, in the lower two figures: in blue, the customer’s individual requirement is given in terms of a ‘three-line’ SrS of maximum displacement (left diagonal), acceleration (right diagonal) and velocity (horizontal line). The SrS computed from the measured test acceleration is shown

Shock teSting facilitieSat TNO we have three specialised shock testing machines: a vertical light-weight machine (a); a medium-weight machine (b); and a heavy-weight horizontal machine (c).

a.

b.

c.

Photo: Thales

testing machine light-weight Medium-weight heavy-weightShock direction vertical vertical HorizontalTable dimensions (mm) ∅ 750 1500 × 1500 5000 × 3000Max. payload (kg) 500 5000 10000Max. displacement (mm) 70 70 70Max. velocity (m/s) 9 6 2Max. acceleration (m/s2) 100-5000 100-4000 10-500Pulse duration (ms) 3-20 4-20 5-20

BR standard

NATO standard

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droP teStS Drop test facilities are also available, including a rig with a drop masses from 1 to 9 tonnes. in combination with cantilevered beams, this can be used for generating large impact loads of mega-Newtons.

PyroShockWe provide drop test facilities which simulate the high accelerations ‘pyroshock’ pulses found in space applications. as an example, shown above is a measured result in terms of an acceleration SrS against a black requirement line.

Vibration teStingEquipment requiring validation against vibration may be tested on our large shaker facility. This shaker may also be used to generate low level shock pulses and used to perform bump tests.

a guideline of the maximum capabilities of our shaker are given above. Once more, expert use of instrumentation is used to obtain and post-process the test results. Some examples are shown above right where, from top to bottom, we show results from a random vibration sweep, a power spectral density plot, a generated shock pulse and the corresponding shock SrS.again, in the situation where the payload exceeds the capacity of our machines please contact us for specific solutions. For example, we perform controlled shaker tests on large masses of several tonnes using hydraulic actuators. Here, the frequency can range from 1-100 Hz with corresponding displacements from tens to tenths of a millimetre.

We also provide other facilities for expert testing in the field of shock, shake and vibrations and, as mentioned earlier, we like to push the limits of what is possible!

testing machine ShakerTest direction vertical HorizontalMax. payload (kg) 700 1500Excitation frequency (Hz) 1-2000Max. assembly surface (mm) 1250 × 1250Max. force (N) 55000 (sine), 53000 (random) 166000 (shock)Max. amplitude (random and shock) (mm) 34 peak-to-peakMax. shock velocity (m/s) 1.6

Photo: Thales

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cliMate teStingvibration testing can also be carried out in our climate chamber. This has base dimensions 1.4 m by 1.4 m, with height 2.5 m. The internal temperature can range from –40° c to +150° c, with a relative humidity level between 30% and 90%.

PuShing the liMitS vertical shock testing of an extremely large item: 5 m × 5 m with a mass over 5 tonnes!

full Shock Scale trialSin addition to our on-site work, we also carry out off-shore full-scale shock trials, where over 1000 measurement channels are available; see also cover page.

More Our expertise in instrumentation and post-processing may also include 2D and 3D optical strain measurements and/or high-speed camera footage of the tests. We also have expertise in the impact and vibration monitoring of off-shore pile-driving. Moreover, shock testing setups may be built for specific requirement; such as, the aforementioned high acceleration ‘pyroshock’ pulses found in space applications. We also offer a service for designing shock machines and hold both theoretical and practical shock courses. Our shock expertise has also contributed to the development of new standards.

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kirk Green, PhDStructural DynamicsProject ManagerT +31 88 866 31 89E kirk.green@tno.nl

Peter Paul van ’t veen, MScStructural Dynamicsresearch ManagerT +31 88 866 53 67E peter_paul.vantveen@tno.nl

Pieter boersma, MScMaritime & Offshorebusiness Line ManagerT +31 88 866 33 65E pieter.boersma@tno.nl

TNO.NL/MariTiME

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What tno can do for youat TNO – an independent research organisation – over 4,000 experts work daily to support thousands of customers worldwide in domains ranging from Defence and Public Safety to automotive, from iT to Human Factors. based on deep knowledge and expertise built up in decades of projects for Navies and offshore companies worldwide, TNO helps the maritime industry to develop and apply innovative products, use sustainable resources and optimise processes and production chains.