Fundamentals of Low Intensity Shock Calibration

Low intensity shock metrology for safety related applications Fundamentals of Low Intensity Shock Calibration Speaker : Yu-Chung Huang Date : 2014.08.20 Center for Measurement Standards/ Industrial Technology Research Institute Bldg. 16, 321 Kuang Fu Rd, Sec. 2 Hsinchu, Taiwan 1

Outline 1. Shock for Industry Application. 2. ISO Standard for Calibration of Vibration and Shock Transducers. 3. Study for ISO 16063-22. 4. Comparison Shock Calibration System in CMS. 5. Study for ISO 16063-13. 6. Primary Low Shock Calibration System in CMS. 7. References. 2

Shock for Industry Application Car colliding human 600 m/s 2 chest safety : Automobile collision Shock testing machine Electric equipment shock test 4

Example : Lens Shock Test TEST SPECIFICATION: Wave Form :Half sine wave Acceleration :50 g Duration Time :20 ms No. of Shock :Each axis 3 times Shock Direction :X,Y,Z axis X axis Y axis Z axis 5

Example : Vehicle Video Recorder TEST SPECIFICATION: Wave Form :Half sine wave Acceleration :50 g Duration Time :26 ms No. of Shock :Each axis 5 times Shock Direction :Y axis 6

Example : LCD Monitor TEST SPECIFICATION: (operation ) Wave Form :Half sine wave Acceleration :50 g Velocity Change :11 ms No. of Shock :Each axis 3 times Shock Direction :±X, ±Y, ±Z axis 7

Example : Battery SHOCK TEST SPECIFICATION: Wave Form :Half sine wave Acceleration :5,000 g Duration :0.3 ms Test Axis :±X, ±Y, ±Z axis No. of Shock :Each axis 3 times Total Test Time :18 times 8

Example : Car Monitor TEST SPECIFICATION: Wave Form :Square wave Acceleration :65 g Velocity Change :4.78 m/sec No. of Shock :Each axis 1 time Shock Direction :±X, ±Y, ±Z axis 9

Example : Speaker Box TEST SPECIFICATION: Wave Form :Square wave Acceleration :40 g Duration Time :8.2 ms Test Axis :±X, ±Y, ±Z axis No. of Shock :Each axis 3 times 10

Example : PC Panel TEST SPECIFICATION: (1) Wave Form :Sawtooth wave (Operating) Acceleration :40 g Duration Time :11 ms No. of Shock :Each axis 3 times Shock Direction :±X, ±Y, ±Z axis (2) Wave Form :Sawtooth wave (Non-Operating) Acceleration :75 g Duration Time :11 ms No. of Shock :Each axis 3 times Shock Direction :±X, ±Y, ±Z axis 11

ISO Standard for Calibration of Vibration and Shock Transducers Methods for the calibration of vibration and shock transducers ISO 16063-1 Basic Concepts Primary Method Comparison Method Environment Calibration Other Method ISO 16063-11 Primary vibration ISO 16063-12 Reciprocity method ISO 16063-13 Primary shock ISO 16063-15 Primary angular vibration ISO 16063-21 Comparison vibration ISO 16063-22 Comparison shock ISO 16063-23 Comparison angular vibration ISO 16063-31 Transverse vibration sensitivity ISO 16063-32 Resonance test ISO 16063-41 Calibration of laser vibrometers ISO 16063-42 Calibration of seismometer 13

ISO 16063-22 Shock calibration by comparison to a reference transducer 2005(E) 15

Study for ISO Standard 16063-22 Shock Signal Generation by Hammer-Anvil Motion events by two elastic solid bodies bumping. Different velocity V 1 -V 2 Spring represents the elasticity of contact surfaces. Acceleration, Velocity, Displacement - time waveform Refer SPEKTRA 16

Study for ISO Standard 16063-22 Shock Signal Generation by Hopkinson Bar Propagation and reflection characteristics of a mechanical wave in a slender bar. Slender bar : length / diameter >80 CMS Refer SPEKTRA Acceleration, Velocity - time waveform 17

Study for ISO Standard 16063-22 Pendulum Shock Calibrator Shock peak magnitude of 100 m/s 2 to 1500 m/s 2 with pulse durations of 3 ms to 8 ms are created with pendulum. 18

Study for ISO Standard 16063-22 Drop Shock Calibrator mounting of transducers, anvil, and test mass Shock peak magnitude of 100 m/s 2 to 100 km/s 2 with pulse durations of 0.1 ms to 10 ms are created with dropball. 19

Study for ISO Standard 16063-22 Pneumatically Operated Piston Shock Calibrator Shock peak magnitude of 200 m/s 2 to 100 km/s 2 with pulse durations of 0.1 ms to 3 ms are created with Pneumatically. Shock pulse in general are determined by velocity of projectile, the mass of the target and deformation of material between them. 20

Study for ISO Standard 16063-22 Others Oscilloscope : minimum frequency range from d.c. to 1 MHz Waveform recorder with computer interface: resolution >12 bit room temperature : (23±3) relative humidity:75 % maximum. Calculation of shock sensitivity for anvil shock calibrators Selection of maximum value as peak-value 21

Study for ISO Standard 16063-22 Uncertainty reference conditions for secondary shock calibration 22

Comparison Shock Calibration System in CMS from 1990 to 2008 GPIB Computer Scope Steel ball S u =(V u /V r ) S r mv ( m/ s S u : Sensitivity of DUT S r : Sensitivity of Std. shock accelerometer V u : Voltage of DUT V r : Voltage of Std. shock accelerometer 2 ) Charge amplifier ENDEVCO 2965C Standard accelerometer Calibrated accelerometer Reference accelerometer traces to PTB. Expanded Uncertainties 2.5 % with acceleration range from 1000 m/s 2 to 10000 m/s 2. Comparison Shock System 24

Comparison Shock Calibration System in CMS from 2008 to 2014 Reference accelerometer traces to PTB and NML. Expanded Uncertainties 2.1 % with acceleration range from 1000 m/s 2 to 10000 m/s 2. 25

Comparison Shock Calibration System in CMS 2015~ Extend to lower intensity for industry need 26

ISO 16063-13 Primary shock calibration using laser interferometry 2001 28

Study for ISO Standard 16063-13 Signal processing scheme for determining shock sensitivity 2 st () Shock exciter s( t ), v( t ), a ( t ) 1 a() t u ( t ) cos ( t ) p 1 H om odyne: Interferometery u ( t ) r sin( ( t ) ) q 2 Accelerometer H eterodyne: u ( t) u cos( t ( t)) h m h A/D 3 A/D Amplitude: u m Spectrum: U ( f ) U exp j U Modulation 1 ( n) 4 s( n) a Amplitude: Spectrum: m A( f ) A exp j A Shock sensitivity: S Complex sensitivity: S sh u a U m m exp j( ) a U A A 4 29

Study for ISO Standard 16063-13 1. Shock Exciter Hammer Impact Anvil Excitation 200 180 160 140 Rigid Body Motion 120 100 80 60 40 20 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 x 10-3 4 x 104 Hopkinson Bar Excitation 3 2 Wave Propagation 1 0-1 -2-3 -4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x 10-3 Shock signal 30

Study for ISO Standard 16063-13 Displacement, Velocity and Acceleration Curves for Excitation Hammer Impact Anvil Excitation T sin sec sec sec Half-sine squared acceleration shape Velocity Displacement 31

Study for ISO Standard 16063-13 2. Interferometer-- Michelson Interferometer Michelson Interferometer Homodyne One channel output 32

Study for ISO Standard 16063-13 2. Interferometer-- Michelson Interferometer input output Method Vibration Calibration Fringe-Counting Method Shock Calibration Time Sequence Method No phase calibration information 33

Study for ISO Standard 16063-13 2. Interferometer-- Modified Michelson Interferometer Modified Michelson Interferometer Homodyne Orthogonal signal output 34

Study for ISO Standard 16063-13 2. Interferometer-- Modified Michelson Interferometer input output Method Vibration Calibration u1 and u2 phase difference 90 Sine approximation Method Shock Calibration Phase Method Phase calibration information 35

Study for ISO Standard 16063-13 2. Interferometer Quadrature Signals Typical Quadrature Signals for Shock Excitation u1 cos ( t) p u2 r sin[ ( t) ] q u1 u2 sec sec 36

Study for ISO Standard 16063-13 3. Signal Data Processing u 2 u 1 u1( t) ( t) atan[ ( n ) ] u2( t ( t ) ) n S( t) ( t) 4 Quadrature signals a series of modulation phase values a series of displacement values 37

Study for ISO Standard 16063-13 3. Signal Data Processing Signal waveform produced by Shock system of CMS Displacement u1 u2 Velocity Acceleration Accelerometer output voltage Phase 38

Study for ISO Standard 16063-13 4. Calibration Result u max Shock Sensitivity a max S sh u a max max 39

Shock Calibration System in CMS System Structure Shock machine 9 0 90 11 12 Recorder 1 2 10 3 4 5 6 7 8 Interferometer Optical table Shock machine 1. Controller 2. Programmable DC supply 3. High speed electromagnetic hammer 4. Airborne hammer 5.Trigger unit 6. PU rubber 7. Airborne anvil 8. Accelerometer 9. Charge amplifier Interferometer 10. Laser 11. Ligh detectors Recorder 12.Digital scope: NI 5124-50 MHz 12 bit (Quadrature Interferometer signal) NI 5922-10 MHz 16 bit (Accelerometer output Voltage) 41

Shock Calibration System in CMS Calibration System Photo Recorder & Display Interferometer Shock machine Acceleration: 200 m/s 2 to 10000 m/s 2 Pulse duration : < 3 ms 42

Shock Calibration System in CMS Laser Interferometer (Modified Michelson interferometer + Mach-Zehnder interferometer) u 1 u 2 u 1 u 2 Quadrature signals 43

Shock Calibration System in CMS Shock Machine High speed electromagnetic hammer Airborne hammer : velocity up to 2.6 m/s Trigger device Airborne anvil Accelerometer Electromagnetic controller Vmax DC source supply Optical table Different hardness PU rubber Shore hardness 95/85/75/65/55 Porous Air Bushing : Allow Airborne anvil and hammer frictionless linear and rotary motion and radial air gap 4 µm. Cylindrical Anvil, Hammer length 200 mm, diameter 25 mm material : steel or aluminum. 44

Shock Calibration System in CMS Transverse Motion Ratio of peak acceleration between z- axis and x-,y- axis. Maximum transverse motion is about 4 % Y-axis X-axis Z-axis Triaxial accelerometer ENDEVCO 2270 and charge amplifier ENDEVCO 133, which accelerometer provides the excellent vibration characteristics: such as maximum transverse sensitivity 0.3 %. 45

Shock Calibration System in CMS Relative Motion Back-to back reference standard accelerometer is calibrated Accelerometer Reference Surface and the Spot Sensed by Interferometer 46

Shock Calibration System in CMS Different Rubber Black PU rubber shock time : 0.5 ms to 0.8 ms shock acceleration: 1160 m/s 2 to 5980 m/s 2 Two-layer red PU rubber shock time: 3 ms to 4 ms, shock acceleration: 130 m/s 2 to 950 m/s 2 47

Rubber V.S. Duration-Pilot Study Comparison Different Rubber 48

Shock Calibration System in CMS Calibration Procedure Turn on system and warm up 30 min. Room Temp.:(23.0 3.0) Relative Humidty:(50 20) % Ambient conditions check Mounting sensor and PU rubber Adjust interferometer signal Setting shock acceleration and input voltage Shock acceleration (m/s 2 ) Input Voltage (V) 200 17.4 1000 52.6 2000 44.8 3000 60.8 4000 78.2 5000 100 Conduct 10 times calibration 49

Shock Calibration System in CMS Software Function 50

Shock Calibration System in CMS Ten Times Measurement 51

Shock Calibration System in CMS Expression of Uncertainty of measurement in Calibration 52

References Hong-Bo Hu, Yu-Chung Huang, Jiun-Kai Chen, Guest Reserach Report on Primary Calibration for Shock Acceleration in NML, 2011 ISO 16063-13, Methods for the calibration of vibration and shock transducers-part 13: Primary shock calibration using laser interferometry, 2001. Yu-Chung Huang, Measurement system validation procedure for shock accelerometer- phase operational method, ITRI, 2009. Yu-Chung Huang, Jiun-Kai Chen, Hsin-Chia Ho, Chung-Sheng Tu, Chao- Jung Chen, The Set Up of Primary Calibration System for Shock Acceleration in NML,IMEKO 20010 TC3, TC5 and TC22 International Conference, pp. 265-268, 2011. Hideaki Nozato, Takashi Usuda, Akihiro Oota, Tamio Ishigami and Katsuhisa Kudo, Development of Shock Acceleration Calibration Machine in NMIJ, IMEKO 20th TC3, 3rd TC16 and 1st TC22 International Conference, pp. 215-223, 2007. 54

Thanks for your attention 55