Professional Development Short Course On:

                  Applied Measurements Engineering


                          ...
Applied Measurement Engineering
                       How to Design Effective Computer-driven Measurement Systems
       ...
www.ATIcourses.com

Boost Your Skills                                             349 Berkshire Drive
                    ...
Applied Measurements Engineering




  You get judged by English Common Law.
  You are innocent until proven guilty.

  Yo...
Applied Measurements Engineering

                  PROFESSIONAL CONTEXT FOR
                  MEASUREMENTS ENGINEERING
Co...
Applied Measurements Engineering

                                       A POPULAR VIEW OF THE
                           ...
Applied Measurements Engineering

                A MORE EFFECTIVE VIEW OF THE
                   MEASUREMENTS UNIVERSE

 ...
Applied Measurements Engineering

           WHAT MEASUREMENT SYSTEMS ARE
                 WE TALKING ABOUT?
       Measur...
Applied Measurements Engineering


INSTRUMENTATION . . . OR . . . MEASUREMENTS?


• Instrumentation
   – The arrangement o...
Applied Measurements Engineering

 INSTRUMENTATION . . . OR . . . MEASUREMENTS?

• Measurements
   – The application of sc...
Applied Measurements Engineering


   DATA ACCURACY . . . OR. . .DATA VALIDITY?

• Accuracy
   – System output reflects th...
Applied Measurements Engineering

ACCURACY - CENTRIC VIEW CAN LEAD TO
 ASSUMED UNCERTAINTIES LIKE THESE




              ...
Applied Measurements Engineering
 ACCURACY - CENTRIC VIEW CAN LEAD TO
       PROBLEMS LIKE THESE
  The Valid Reality….    ...
Applied Measurements Engineering

      ACCURACY - CENTRIC VIEW CAN LEAD TO
   PROBLEMS IN A FREQUENCY RICH ENVIRONMENT

A...
Applied Measurements Engineering

A SYSTEMS VIEW OF MEASUREMENTS UNCERTAINTY

  1. Undisturbed value:              Value o...
Applied Measurements Engineering

            TYPICAL EXAMPLE FROM
               THE LITERATURE

1. Undisturbed Value

2....
Applied Measurements Engineering
                                                    TRANSIENT SURFACE TEMPERATURES IN A S...
Applied Measurements Engineering


   DATA ACCURACY . . . OR . . . DATA VALIDITY?
• Validity
    – System output faithfull...
Applied Measurements Engineering


          ENERGY AND INFORMATION FLOW IN
              MEASUREMENT SYSTEMS



         ...
Applied Measurements Engineering

      THE ENERGY RELATED CHALLENGE OF
         MEASUREMENTS ENGINEERING
• It is inevitab...
Applied Measurements Engineering

MEASUREMENT SYSTEM RESPONSE SYNDROMES
             -- AN EXAMPLE
      Syndrome, n.: a s...
Applied Measurements Engineering

MEASUREMENT SYSTEM RESPONSE SYNDROMES
             -- AN EXAMPLE

•   Moisture: The gas ...
Applied Measurements Engineering

MEASUREMENT SYSTEM RESPONSE SYNDROMES
 Measurement system component responses to
 their ...
Applied Measurements Engineering

            MEASUREMENT SYSTEM RESPONSE
                  SYNDROME MODEL
               ...
Applied Measurements Engineering

 MEASUREMENT SYSTEM RESPONSE SYNDROME
          -- VALID STRAIN DATA
                   ...
Applied Measurements Engineering

                  CONSTANTAN STRAIN GAGE MOUNTED
                ON KEVLAR COMPOSITE CAN...
Applied Measurements Engineering

     MEASUREMENT SYSTEM RESPONSE SYNDROMES
  - THERMAL ZERO SHIFT DUE TO THERMOCOUPLE EM...
Applied Measurements Engineering
MEASUREMENT SYSTEM RESPONSE SYNDROME -
   - TEMPERATURE INDUCED GAGE FACTOR
             ...
Applied Measurements Engineering

            CONSTANTAN GAGE INSTALLED ON ALUMINUM
              CANTILEVER BEAM SUBJECT ...
Applied Measurements Engineering

MEASUREMENT SYSTEM RESPONSE SYNDROME -
     - “PIEZOELECTRIC” STRAIN GAGE
              ...
Applied Measurements Engineering




                                        SHOCK OUT PUT FROM "PIEZOELECT RIC" ST RAIN G...
Applied Measurements Engineering

         FOUR BASIC DESIGN APPROACHES

 • Use any old components, hook them up to
   som...
Applied Measurements Engineering

         FOUR BASIC DESIGN APPROACHES


• Design a measurement system to operate in the
...
You have enjoyed ATI's preview of
         Applied Measurements Engineering



    Please post your comments and questions...
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ATI Courses Professional Development Short Course Applied Measurement Engineering Sampler

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How do you know your test measurements are valid? Since NIST traceability actually guarantees little about your test data, how do you know? Could you prove validity to your customer? What is the right measurements solution for your testing requirements? Is it really as simple as the vendors say? What is your real cost of invalid, ambiguous data causing retest or, worst of all, hardware redesign?
This course is for engineers, scientists, and managers who must use systems to understand experimental test measurements on a daily basis. Learn how to design, buy and operate effective automated measurement systems providing demonstrably valid test data, the first time.

Fundamental & underlying engineering principles governing the design and operation of effective automated systems are demonstrated experimentally.

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ATI Courses Professional Development Short Course Applied Measurement Engineering Sampler

  1. 1. Professional Development Short Course On: Applied Measurements Engineering Instructor: Charles P. Wright ATI Course Schedule: http://www.ATIcourses.com/schedule.htm ATI's Applied Measurements Engineering: http://www.aticourses.com/applied_measurement_engineering.htm
  2. 2. Applied Measurement Engineering How to Design Effective Computer-driven Measurement Systems Summary How do you know your test measurements are valid? November 17-19, 2008 Since NIST traceability actually guarantees little about your test data, how do you know? Could you prove Laurel, Maryland validity to your customer? What is the right measurements solution for your testing requirements? Is it $1590 8:30am - 4:00pm really as simple as the vendors say? What is your real cost "Register 3 or More & Receive $10000 each of invalid, ambiguous data causing retest or, worst of all, Off The Course Tuition." hardware redesign? This course is for engineers, scientists, and managers who must use systems to understand experimental test measurements on a daily basis. Learn how to design, buy and operate effective automated measurement systems Course Outline providing demonstrably valid test data, the first time. 1. Basic Measurement Concepts. Fourteen real measurement horror stories and Fundamental & underlying engineering principles why they happened. Measurements or instrumentation? Data validity or data governing the design and operation of effective accuracy? Why you want less than 1/16th of the information from your system. automated systems are demonstrated experimentally. 2. Measurement System Transfer Functions and Linearity. Frequency and The result? Skilled people running more effective testing programs generating unambiguous data, lowered phase responses -- more complicated than most think. First, second and higher design verification risk and cost, and delighted customers. order systems. Single degree-of-freedom systems and damping. Output/input Attendees receive a workbook and the instructor's book, linearity. Applied Measurements Engineering. 3. Frequency Content or Wave Shape Reproduction? Rules for the reproduction of frequency content. Rules for the reproduction of wave shape. What You Will Learn What price do you pay when you violate the rules? How can you recover? • How to guarantee your data. 4. Non-Self Generating Transducers. Load cells, strain gages, resistance • How to set the crucial system transfer functions to assure temperature transducers, piezoresistive and servo transducers, etc. The basic valid data. transducer model. Proper techniques for system set-up and operation. • How to follow the rules for waveshape and spectral 5. Wheatstone Bridge. The bridge as a computer. Bridge equations. Valid shunt reproduction of data. calibration techniques and calculation. The three wire circuit. Up to ten wire • The twelve things you have to control before you can circuits! sample properly. 6. Self Generating Transducers. Piezoelectric transducers. "Charge" amplifiers • How to absolutely eliminate deadly aliasing. and why they work. Thermoelectricity and thermocouples. The gradient • How to identify and prevent 40% errors in 0.1% ENGINEERING systems! approach to thermocouple temperature measurements. • Foolproof automated methods for noise level 7. The General Transducer Model and Noise. How all transducers and identification and control. components really work. Bulletproof noise level hunting and documentation • How to operate successfully in the PC-based data procedures. Differential systems and common mode performance. acquisition system market. Noise/Identification/Reduction Methods. 8. Information Conversion. Carrier systems and why they work. Sinusoidal Instructor excitation. Pulse train excitation--zero based and zero centered. Real examples. Charles P. Wright (Chuck), founder of TRW Space 9. Frequency Analysis. Fourier spectra. Power or auto spectral density. Octave and Technology Division's Measurements Engineering and one-third octave analyses. Shock response spectra--what do they really tell Department, has three decades of direct experience in the you? design and operation of advanced multichannel, computer- driven measurement systems. He developed the 10. Sampled Measurement Systems. The twelve things you must know before knowledge-based measurement system concept as the you sample. Nonsimultaneous or simultaneous sample and hold? Aliasing and highest expression of systems design and operational undersampling errors and how to prevent them. What antialiasing filters should performance. He has published 60+ technical papers on you use and why? measurement system design, operation, and test process 11. Data Validation Methodologies. How do you know your data is valid? How improvement. As a contributing editor of Personal Engineering and Instrumentation News, he has written to use your software to answer the question. 40+ bimonthly expert columns on Data 12. Knowledge-Based System Design Principles. The highest level of system Acquisition since 1991. His book Applied design. Operating effective measurement systems. World-class examples from Measurements Engineering -- How to the spacecraft dynamics, thermal, and quasi-static structural test worlds. Design Effective Mechanical Measurement Systems was published in 1995 by Prentice 13. The Subject of Software. Commercial software. Commercial vs. in-house Hall. Education: BSME/MS Measurements developed software. Where's the risk? Engineering, Arizona State University; MS 14. The Crucial Stuff They Didn't Teach You in College. The subjects of craft, Management, University of Southern skill, responsibility, and professionalism as they relate to test measurements. California. 42 – Vol. 93 Register online at www.ATIcourses.com or call ATI at 888.501.2100 or 410.956.8805
  3. 3. www.ATIcourses.com Boost Your Skills 349 Berkshire Drive Riva, Maryland 21140 with On-Site Courses Telephone 1-888-501-2100 / (410) 965-8805 Tailored to Your Needs Fax (410) 956-5785 Email: ATI@ATIcourses.com The Applied Technology Institute specializes in training programs for technical professionals. Our courses keep you current in the state-of-the-art technology that is essential to keep your company on the cutting edge in today’s highly competitive marketplace. Since 1984, ATI has earned the trust of training departments nationwide, and has presented on-site training at the major Navy, Air Force and NASA centers, and for a large number of contractors. Our training increases effectiveness and productivity. Learn from the proven best. For a Free On-Site Quote Visit Us At: http://www.ATIcourses.com/free_onsite_quote.asp For Our Current Public Course Schedule Go To: http://www.ATIcourses.com/schedule.htm
  4. 4. Applied Measurements Engineering You get judged by English Common Law. You are innocent until proven guilty. Your measurement systems must be judged by Napoleonic Law. They are guilty until proven innocent. Prof. Peter Stein Can you provide the proof? 2
  5. 5. Applied Measurements Engineering PROFESSIONAL CONTEXT FOR MEASUREMENTS ENGINEERING Context, n: the interrelated conditions in which something exists or occurs TEST ENVIRONMENT & NOISE LEVEL CONTROL/DOCUMENTATION MECHANICAL ENERGY AND TRANSDUCERS SIGNAL SIGNAL ANALOG DATA ENGINEERING INFORMATION CONDI- SHAPING ACQUISITION KNOWLEDGE FLOW TIONING BASE TEST PHENOMENON DIGITAL DATA ACQUISITION ANALOG SIGNAL HANDLING AND TRANSMISSION THE CUSTOMER DIGITAL SIGNAL HANDLING, ANALYSIS AND DISPLAY VALIDITY CHECKING METHODS SOFTWARE DEVELOPMENT AND CONTROL 3
  6. 6. Applied Measurements Engineering A POPULAR VIEW OF THE MEASUREMENTS UNIVERSE A Billion Samples Per Second! On Beyond Windows! Cryogenically cooled! VME! Pentium XXV Class! PCI! Hyper this and hyper that! Modular! Belchfire Gimmicks! GAZILLION Hoo Haa! 50 Mips! PLUG AND PLAY!! BYTE LASER GIGABYTES/SECOND! DISC SUPERFAST NETWORKS! STELLAR CLASS ANNOYING SUPERSPEEDY FUSION POWERED COMPLETE TEST TRANSDUCER, ENVIRONMENT CABLE & SIGNAL CONDITIONING NETWORKS DOHICKEYS COMPUTER!! WORLD’S A Really Fast Front End! 80 Mflops! MOST Quadruple Precision! VXI! Expandable! INCREDIBLE Optimized Compilers! Cute ICONS! Sigma-Delta A/Ds We have buses for you! TERMINALS! Universal Signal Conditioning Pods! Hook Up Anything! WARP DRIVE LASER PRINTER/PLOTTER 5000 x 5000 pixels! 10,000 colors in palette! Mice!! Trackballs!! Virtual Reality!! 4
  7. 7. Applied Measurements Engineering A MORE EFFECTIVE VIEW OF THE MEASUREMENTS UNIVERSE TEST ENVIRONMENT NOISE LEVELS DIGITAL COMPONENTS & SOFTWARE (maybe) INFO TEST TEST TRANS- DATA CUSTOMER’S SIGNAL SIGNAL SIGNAL CUSTOMER’S AND DUCERS & SIGNAL PHENOMENON CONDI- CONVER- PROCES- NEEDS CUSTOMER’S CABLING SHAPING TIONING SION SING NEEDS SYSTEM ENERGY SOME INSTRUMENTATION ORGANIZATIONS MOST INSTRUMENTATION ORGANIZATIONS PROFESSIONAL MEASUREMENTS ORGANIZATIONS SYSTEMS LEVEL MEASUREMENTS THINKING 5
  8. 8. Applied Measurements Engineering WHAT MEASUREMENT SYSTEMS ARE WE TALKING ABOUT? Measurements for Measurements for Measurement for DESIGN CALIBRATION CONTROL What would the input be What are the characteristics What is the output of if the measuring system of this system under specific the controlled phenomenon were not there? boundary conditions? or process? Phenomenon Source Observation Input Output MEASUREMENT Stimulus Response SYSTEM Excitation Overt, Observable Forcing Function Behavior Service Conditions INTERPRETATION: How much is too much? How much is too little? Decisions Adjustments Feedback for Control 6
  9. 9. Applied Measurements Engineering INSTRUMENTATION . . . OR . . . MEASUREMENTS? • Instrumentation – The arrangement of preselected individual links of a measuring chain into an operating unit – Emphasis is on the individual links and their accuracy – Boundary conditions are generally not emphasized nor controlled – Asks the question “What did the meter read?” 7
  10. 10. Applied Measurements Engineering INSTRUMENTATION . . . OR . . . MEASUREMENTS? • Measurements – The application of scientific and engineering principles to the design and use of measuring systems – Emphasis is on the entire system and on the validity of the data – Validity implies the system output faithfully represents the phenomenon under investigation as if the measuring system were not there – Boundary conditions are both understood and controlled – Asks the question “What would the system have read if it had not been there exchanging energy with the process?” 8
  11. 11. Applied Measurements Engineering DATA ACCURACY . . . OR. . .DATA VALIDITY? • Accuracy – System output reflects the achieved value within the transducer -- accurately answers the question “What did the meter read?” – Changes in process caused by the measurement system are neither controlled nor accounted for, and may be appreciable (uncorrected error). – Boundary conditions at the transducer/process boundary interface are not necessarily accounted for or controlled. – Requires little knowledge of the process under investigation. – 10 engineers will give you 15 definitions -- all different. 9
  12. 12. Applied Measurements Engineering ACCURACY - CENTRIC VIEW CAN LEAD TO ASSUMED UNCERTAINTIES LIKE THESE Do you believe these numbers? Do you believe these numbers? What’s missing with this view? What’s missing with this view? Courtesy of a certain periodical’s website tutorial on error analysis 10
  13. 13. Applied Measurements Engineering ACCURACY - CENTRIC VIEW CAN LEAD TO PROBLEMS LIKE THESE The Valid Reality…. Accurate but Invalid…. 5.6% low Hologram of the backside of 1% low a 7” dia, 800 gm symmetrical turbine disk The addition of aasingle 88gm The addition of single gm accelerometer on the front side accelerometer on the front side splits the mode into two new modes splits the mode into two new modes @ 5562 and 5830 Hz and changes the @ 5562 and 5830 Hz and changes the mode shape. These are accurately mode shape. These are accurately measured and totally invalid modes. measured and totally invalid modes. 11 Courtesy of Sandia National Laboratories, Albuquerque, New Mexico
  14. 14. Applied Measurements Engineering ACCURACY - CENTRIC VIEW CAN LEAD TO PROBLEMS IN A FREQUENCY RICH ENVIRONMENT Accelerometer calibration from an aerospace contractor, 25 to 5000Hz shows amplitude variations of over 4%. +2% Phase implications? Phase implications? - 2% Magnitude & phase Magnitude & phase corrections made? corrections made? Reflected in uncertainty Reflected in uncertainty analysis? analysis? 12
  15. 15. Applied Measurements Engineering A SYSTEMS VIEW OF MEASUREMENTS UNCERTAINTY 1. Undisturbed value: Value of the measureand if the system were not there to measure it. 2. Available value: Value with the system in place. 3. Achieved value: Value of the measureand achieved within the transducer. 4. Observed value: Value returned from the transducer using calibration relationships. 5. Corrected value: Value after all recognized errors have been applied. Courtesy of Dr.Robert Moffatt, Almost all uncertainty analyses exist Moffatt Thermosciences, Menlo Park, CA only in this box. 13
  16. 16. Applied Measurements Engineering TYPICAL EXAMPLE FROM THE LITERATURE 1. Undisturbed Value 2. Available Value 3. Achieved Value 4. Observed Value ERRORS NOTED IN A REPUTABLE THERMOCOUPLE SIGNAL CONDITIONING 5. Corrected Value MANUFACTURER’S WEB SITE Thermocouple wire-based error Cold junction compensation error A/D resolution and accuracy error Linearization error 14
  17. 17. Applied Measurements Engineering TRANSIENT SURFACE TEMPERATURES IN A SOLID ROCKET NOZZLE WITH ASBESTOS PHENOLIC THROAT -- MEASURED BY VARIOUS FLUSH MOUNTED PT-PT 10% RHO THERMOCOUPLES 3500 DATA FROM "THERMAL PROPERTIES OF THERMOCOUPLES,' THERMOCOUPLE JUNCTION TEMPERATURE ( F) BY J. NANIGIAN, NANMAC CORP. o 3000 ASBESTOS PHENOLIC THERMOWELL 2500 STAINLESS STEEL MOLYBDENUM THERMOWELL THERMOWELL WITH RDP150 INSERTS 2000 1500 MOLYDENUM VARIABLE 2500F Error! THERMOWELL THERMOWELL MATERIALS 1000 throat 500 ASBESTOS PHENOLIC NOZZLE 0 0 2 4 6 8 10 12 14 16 18 20 TIME AFTER IGNITION IN SECONDS 15
  18. 18. Applied Measurements Engineering DATA ACCURACY . . . OR . . . DATA VALIDITY? • Validity – System output faithfully represents the measured parameter as if the system were not there. – Validity includes accuracy and is, therefore, a higher level quality. – Measurement caused process changes controlled by design and negligible in an engineering sense. – Boundary conditions at all interfaces are controlled by design. – Requires knowledge of the process under investigation (solid mechanics, kinematics, dynamics, heat transfer, fluid mechanics, thermodynamics, materials, manufacturing, etc..). • How can you know whether than answer makes sense without understanding the phenomenon? 16
  19. 19. Applied Measurements Engineering ENERGY AND INFORMATION FLOW IN MEASUREMENT SYSTEMS TRANSFER OF TRANSFER OF MEASUREMENT = INFORMATION ABOUT + ENERGY WITH A A STATE OR PROCESS STATE OR PROCESS (The Data) (Applied Physics) THE ANSWER! THE PROBLEM! 17
  20. 20. Applied Measurements Engineering THE ENERGY RELATED CHALLENGE OF MEASUREMENTS ENGINEERING • It is inevitable that you are going to transfer energy with the process any time you make a measurement -- you will change the process. • Your job is to (1) allow the valid transfer of information from the process, while (2) minimizing the energy transfer with the process so it is insignificant in an engineering sense. You do this (or not!) with your design. • This crucial point is not well understood in the test community and major and bizarre uncorrected errors occur because of it every day. • Be aware. 18
  21. 21. Applied Measurements Engineering MEASUREMENT SYSTEM RESPONSE SYNDROMES -- AN EXAMPLE Syndrome, n.: a set of concurrent things that usually form an identifiable pattern • Strain: A turbine case is deflecting too much in operation. You want to measure this strain (desired environment). • Temperature: You are working on a hot turbine case. • Pressure: Strain gages and lead wires are inside the case subject to high dynamic pressure variations. • Motion: Turbine is vibrating like mad -- That’s why we’re running the test! • Radiation: The turbine sits next to a reactor. • Corrosion: The gas is corrosive. 19
  22. 22. Applied Measurements Engineering MEASUREMENT SYSTEM RESPONSE SYNDROMES -- AN EXAMPLE • Moisture: The gas is high pressure wet steam. • Electromagnetic fields: There’s a generator 3 feet away, and a superconducting magnet 18 inches away. • Time: By definition, time always passes during a test. • Etc.: You don’t even want to know about these! 20
  23. 23. Applied Measurements Engineering MEASUREMENT SYSTEM RESPONSE SYNDROMES Measurement system component responses to their environments are characterized by four levels of evidence…. • #1: Respond to both the desired and undesired portions of the environment simultaneously. What’s worse. . . . • #2: Respond with self generating and nonself generating mechanisms simultaneously. What’s worse. . . . . • #3: Evidence of these responses can be both temporary and permanent. What’s worse. . . . • #4: Any response can affect both amplitude (zero) and gain. 21
  24. 24. Applied Measurements Engineering MEASUREMENT SYSTEM RESPONSE SYNDROME MODEL DESIRED UNDESIRED #1 1. Environment (STRAIN) (TEMPERATURE) 2. Response Type NSG SG NSG SG 3. Response Evidence T P T P T P T P 4. Response Effect A M A M A M A M A M A M A M A M NSG = nonself generating SG = self generating T = temporary P = permanent A = additive (affects level, zero) M = multiplicative (affects gain) 22
  25. 25. Applied Measurements Engineering MEASUREMENT SYSTEM RESPONSE SYNDROME -- VALID STRAIN DATA VALID STRAIN DATA DESIRED UNDESIRED #1 1. Environment (STRAIN) (TEMPERATURE) 2. Response Type NSG SG NSG SG 3. Response Evidence T P T P T P T P 4. Response Effect A M A M A M A M A M A M A M A M NSG = nonself generating SG = self generating T = temporary P = permanent A = additive (affects level, zero) M = multiplicative (affects gain) 23
  26. 26. Applied Measurements Engineering CONSTANTAN STRAIN GAGE MOUNTED ON KEVLAR COMPOSITE CANTILEVER BEAM If you were reading strain… 5” long 2Vdc excitation for composite, 1” wide GF = 2 for the gage, you would 1/16th” thick read an equivalent 100µε with zero mechanical strain! Nonself generating Constantan gage Self generated noise level .. 16 awg copper leads 0.100 mVdc 5oF thermal gradient Digital Multimeter reading dc voltage 24
  27. 27. Applied Measurements Engineering MEASUREMENT SYSTEM RESPONSE SYNDROMES - THERMAL ZERO SHIFT DUE TO THERMOCOUPLE EMFS DESIRED UNDESIRED #1 1. Environment (STRAIN) (TEMPERATURE) 2. Response Type NSG SG NSG SG 3. Response Evidence T P T P T P T P 4. Response Effect A M A M A M A M A M A M A M A M NSG = nonself generating SG = self generating T = temporary P = permanent A = additive (affects level, zero) M = multiplicative (affects gain) 25
  28. 28. Applied Measurements Engineering MEASUREMENT SYSTEM RESPONSE SYNDROME - - TEMPERATURE INDUCED GAGE FACTOR CHANGE NOISE LEVEL - TEMPERATURE INDUCED GAGE FACTOR CHANGE DESIRED UNDESIRED #1 1. Environment (STRAIN) (TEMPERATURE) 2. Response Type NSG SG NSG SG T P T P T P T P 3. Response Evidence A M A M A M A M A M A M A M A M 4. Response Effect NSG = nonself generating SG = self generating T = temporary P = permanent A = additive (affects level) M = multiplicative (affects gain) 26
  29. 29. Applied Measurements Engineering CONSTANTAN GAGE INSTALLED ON ALUMINUM CANTILEVER BEAM SUBJECT TO SHOCK WHACK WITH HAMMER Self generated noise level .5”x.5”X 6” LONG Nonself generating ALUMINUM BEAM Constantan strain gage 16 awg copper wire + Vertical oscilloscope amplifier, differential - input, 50 µV/cm, 1MHz BW 27
  30. 30. Applied Measurements Engineering MEASUREMENT SYSTEM RESPONSE SYNDROME - - “PIEZOELECTRIC” STRAIN GAGE NOISE LEVEL - THE “PIEZOELECTRIC” STRAIN GAGE DESIRED UNDESIRED #1 1. Environment (DYNAMIC STRAIN) (MOTION) 2. Response Type NSG SG NSG SG 3. Response Evidence T P T P T P T P 4. Response Effect A M A M A M A M A M A M A M A M NSG = nonself generating SG = self generating T = temporary P = permanent A = additive (affects level, zero) M = multiplicative (affects gain) 28
  31. 31. Applied Measurements Engineering SHOCK OUT PUT FROM "PIEZOELECT RIC" ST RAIN GAGE (SELF GENERAT ING RESPONSE FOR ZERO EXCIT AT ION) 200 (NOISE 150 100 50 APPARENT MICROSTRAIN LEVEL) 0 -50 -100 -150 -200 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 T IME (SECONDS) 29
  32. 32. Applied Measurements Engineering FOUR BASIC DESIGN APPROACHES • Use any old components, hook them up to something and take readings. • Use a system calibrated over the entire environmental range – Measure the parameter of interest AND the entire environment – Compute corrections based on physics • Use a calibrated system, but modify the test environment so it duplicates the calibration environment 30
  33. 33. Applied Measurements Engineering FOUR BASIC DESIGN APPROACHES • Design a measurement system to operate in the entire test environment and give acceptable experimental errors without correction Only this last approach falls into the design category: VALID DATA, ON PURPOSE, THE FIRST TIME. This is based on the Unified Approach to the Engineering of Measurement Systems 31
  34. 34. You have enjoyed ATI's preview of Applied Measurements Engineering Please post your comments and questions to our blog: http://www.aticourses.com/wordpress-2.7/weblog1/ Sign-up for ATI's monthly Course Schedule Updates : http://www.aticourses.com/email_signup_page.html

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