Vibration and Shock in National Institute of Metrology Chenguang CAI Vibration and Gravity Lab E-mail: caichenguang@nim.ac.cn www.nim.ac.cn

Outline 1、Resume 2、Location of NIM 3、Staff of Vibration and Shock Lab in NIM 4、Working tasks 5、Measurement Standards 6、Research under doing 7、Research plan in next five years

Resume 2009.09 - Present National Institute of Metrology. Vibration and Shock calibration 2007.09 - 2009.08 Post doctor at Nokia Research Center. Research activities: User interaction sensing Resistive multi touch screen Dual-mode loudspeaker Multi-directivity sound device 3D display by controlling grating 2001.09 - 2007.07 PhD in Precision Instrumentation and Mechanics, Beijing University of Aeronautics and Astronautics. Research topic: close-loop controlling of resonant sensor 1997.09 - 2001.07 B.Sc. in Automatic Control, Beijing University of Aeronautics and Astronautics. The sound is modulated by a ultra sonic signal, High frequency signal attenuates quicker than low frequency signal.

NIM —— Locations of Two Campus 40 km

NIM —— Gates of Two Campus There are 13 tombs of emperors of Ming dynasties.

NIM —— Hepingli Campus

NIM —— Changping Campus

New Lab for Vibration and Shock 13m*5.5m*3m >500 ton

Staff of Vibration and Shock Lab Mechanics and Acoustics Division Vibration and Gravity Lab Acoustic Lab Mass Lab Force and Torque Lab Volume and Density Lab Hardness Lab

Staff of Vibration and Shock Lab Mechanics and Acoustics Division Vibration and Gravity Lab Head of the Lab Dr. CAI Chenguang Dr. LIU Zhihua Mr. ZUO Aibing Mr. LIU Aidong Mr. YANG Lifeng Mr. Hu Hongbo Mr. XIA Yan Mr. LI Jingshen Vibration and Shock 8 employees retire comparison Gravity 6 employees Speed Dr. SUN Qiao 4 employees CCAUV Delegate

Working tasks Research —— projects and budget from government Realization and dissemination of motion units Measuring methods and devices of motion units Service —— more than 2000 certificates Calibration of transducers, measuring chains and instruments Calibration/testing of vibration and shock generators Measurement of environmental vibration International Cooperation BIPM CCAUV APMP TCAUV ISO TC108

Ultra-low frequency vibration standard (1 m stroke) Vibration Measurement Standard Homodyne Heterodyne Interferometer Ultra-low frequency vibration standard (1 m stroke)

Low frequency vibration standard (vertical and horizontal) Vibration Measurement Standard Fundamental research and hearing aid assessment. Low frequency vibration standard (vertical and horizontal)

Middle frequency vibration standard (SE-09 is used now) Vibration Measurement Standard Fundamental research and hearing aid assessment. Middle frequency vibration standard (SE-09 is used now)

High frequency vibration standard (piezoelectric stack) Vibration Measurement Standard Fundamental research and hearing aid assessment. High frequency vibration standard (piezoelectric stack)

CS 18 primary vibration calibration system (2911 and APS 113) Vibration Measurement Standard Trade Economy CS 18 primary vibration calibration system (2911 and APS 113)

Low shock standard (electro-magnetic exciter) Shock Measurement Standard Fundamental research and hearing aid assessment. Low shock standard (electro-magnetic exciter)

Shock Measurement Standard Diameter High shock standard (Hopkins bar excited by air gun and piezoelectric stack)

Low Frequency and Middle Frequency (diffraction grating ) Angular Vibration Measurement Standard Low Frequency and Middle Frequency (diffraction grating )

Air bearing 3 axial shaker 3 Component Vibration Measure Standard Technician Air bearing 3 axial shaker

Frequency response by shock excitation Pulse width

In-situ calibration The key problem for in-situ calibration of vibration transducer is: Vibration Source! Solution for calibration purpose vibration source: Inverse piezoelectricity for accelerometers with exciting piezoelectric component; Lorentz force for transducers with calibration coil. The key problem for in-situ calibration of vibration transducer is: Vibration Source! The transducers cannot be detached from the local spot. How to excite them for calibration purposes? Solution for calibration purpose vibration source: For piezoelectric accelerometers, inverse piezoelectricity can be excited by an electric signal to produce inside seismic mass vibration. For magnetoelectric velocity transducers, Lorentz force can be excited by an electric signal to produce inside seismic mass vibration.

Operation Principle for coil type For vibration transducers with built-in calibration coil, in-situ calibration method had been researched, and an ISO standard (16063-45) is in process. The coil is excited by an electric signal to produce electromagnetic force to simulate inertia force to vibrate the pendulum.

Calibration Procedure for coil type E: Output electric signal Ue: Exciting electric signal Sv: Sensitivity S: Electric sensitivity c: Coefficient of calibration coil X: Vibration measured In Lab In Situ Calibrated by vibration standard Calibrated by electric signal Calculated Calibrated by electric signal Calculated

In-situ calibration for coil type The electric sensitivity “S” can be calibrated only by electric signals, it is possible and easy to calibrate in-situ. Based on S = c Sv, the performance of transducer can be reflected by “S”, it can be used to evaluate the validity and reliability of the transducer, and it is traceable to a vibration standard by “c”. In practice, manufactures only calibrate “c” in reference point (in static state) using gravity, and “c” is regarded as a constant. It causes big error in high frequency range.

Experiments of coil type X Y Z The key problem for in-situ calibration of vibration transducer is: Vibration Source! The transducers cannot be detached from the local spot. How to excite them for calibration purposes? Solution for calibration purpose vibration source: For piezoelectric accelerometers, inverse piezoelectricity can be excited by a electric signal to produce inside seismic mass vibration. For magnetoelectric velocity transducers, Lorentz force can be excited by a electric signal to produce inside seismic mass vibration. A triaxial transducer with built-in calibration coils was respectively calibrated by NIM low frequency primary vibration standard and calibration coils.

Experiments of accelerometers In Lab In Lab

Seismometer —— a kind of natural standard USGS NHNM 1×10-6 g USGS NHNM 1×10-8 g Intrinsic microseism frequency：3.2 Hz Magnitude: 0.05 μm/s Purpose: evaluation of vibration transducer resolution and noise.

Low Frequency Calibration Using Machine Vision Requirements： 1）Wind power generation monitoring 2）Power transmission line monitoring 3）Machine Vision monitoring method Problems: 1）How to reproduce the big vibration? 2）Laser vibrometer is not suitable for. 3）How to calibrate the cameras? Idea：A new trace methold 1）Virtual motion produced by a display. 2）Camera is calibrated by virtual motion. 3）Camera can be a transfer standard. 4）Rotary table is a choice for 1 g low frequency calibration.

Research plan in next five years National Quality Infrastructure (NQI) 1. Machine Vision based low frequency vibration calibration 2. 1 g low frequency vibration calibration by using rotary table 3. Angular rate and rectilinear acceleration calibration by a rotary table (centrifuge) Other Shock 1. Response of accelerometers by step excitation Vibration 1. Angular vibration calibration 2. Multi component vibration calibration 3. Impedance head calibration The concept was published in last APMP meeting in Beijing by the director of NIM. Jörn Stenger of PTB gave a presentation “Metrology and Industrie 4.0” . AQSIQ （General Administration of Quality Supervision, Inspection and Quarantine） APMP（Asia Pacific Metrology Programme）

Acoustic lab Noise measurement for standard power source, automobile, some electrical appliance.

Acoustic lab Fundamental research and hearing aid assessment.

Welcome to visit NIM! Phone: +86 10 64524622, Mobile: +86 13511028631 Don't hesitate, please contact me. Phone: +86 10 64524622, Mobile: +86 13511028631 E-mail: caichenguang@nim.ac.cn