ME 302 MECHANICAL MEASUREMENT

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ME 302 MECHANICAL MEASUREMENT

• Second Semester 1429
• Dr. A. SHIBL

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ME 302 Individual Project

• Select any mechanical variable or parameters of
  interest to you to measure.
• Determine two methods for its measurements.
• Estimate the expected measurement accuracy method
  using uncertainty analysis
• Perform the measurement by yourself (with
  replications)
• Write project report as per hand-out.
• Prepare 5-7 slides on PowerPoint for Seminar
• Select project before 23/2/1429 Seminar ASAP
  

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ME 302 LABORATORY PROCEDURE

• Required Lab. Notebook to be signed by TA.
• Read over the experiment before lab.
• Title of Exp., Date, Lab., Students Names (
  max. 3 )
• Objectivedata analysis, planning of
  exp.,uncertainty.
• Sketch apparatus, test rig, instrumentation.
• Describe the procedure, dims. analysis,
  calibration...
• Record exp. data with replications and
  observations.
• Discuss results and analyze data and
  uncertainty.
• Lab. Report max. 5 pages without figures and
  tables. Attach a
  copy of your lab. notebook pages.
• Lab. Report Grading depends on Objective,
  instrument and sensor used, clarity, dims.
  analysis, error analysis, results and discussion.

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Effective Communication

• Technical Writing Lab. Report, proposal,
  Progress Report, Technical Paper.
• AbstractIntroductionTheoryExp. program
• Results and Discussions Conclusions.
• Oral Presentation Seminar using P.Point
• Sequence and No of slides 1min./slide
• Use figures and graphs -- Avoid tables.

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ME 302 PRESENTATION

• Sequence Introduction Experiment Theory
  Results Summary / Conclusions.
• Number of Slides Length of talk Emphasis.
• Materials Information Figures Graphs Avoid
  Tables
• Preparation Clarity One idea per slide.
• Practice One minute for each slide (5-7 slides)
  
• Presentation Use pointer Talk steadily
  Figure titles Axes labels.
• Start with axes then
  describe each curve Viewgraphs fit
  screen

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Objectives of Mechanical Measurements

• Measurement of physical variables Force vector
  (N), Velocity vector (m/sec.), T(oC), P (Pascal),
  Frequency (Hzcycle/sec)..
• Measurement of Mechanical Parameters Re?vd/µ,
  Mach No. v/c, PD0.5 ? V2
• Accurate and Reliable Measurements Real value
  vs Measured value

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Application of Mech. Measurements

• Monitoring and operation of process.
• Control of a process (accurate control fn
  measurement acc.)
• Experimentation
• - Testing and performance
  operation
• - Verification of properties or
  theory
• - Information needed for
  analysis
• e.g. Checking or evaluation of
• Oil viscosity variation with temp.
• Pump performance curve
• piping head loss
• Lift and drag of new airfoil
  shape.etc.

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Calibration using Primary or/and Secondary
Standards

• Known input signal and find the output.
• - To establish the correct output scale.
• - To find instrument reliability.
• - To eliminate bias error (systematic error)
• For linear relation o/p ? I/p needs single point
  calibration.
• For non-linear relation needs multi-point
  calibrations.
• Static calibration vs Dynamic calibration

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Primary Standards For Comparison and Calibration

• SI System Meter Kg -- Sec. Kelvin volt -
  Mole Ampere Radian
• LENGTH (meter) Distance traveled by light in
  vacuum during 1/299792458 of a sec.
• MASS (Kg.) International prototype (alloy of
  platinum and iridium) kept near Paris.
• TIME (Sec.) Duration of 9192631770 periods of
  the radiation emitted between two excitation
  levels of Cesium-133
• TEMPERATURE (Kelvin) K oC 273

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Dimensional Analysis

• Data presented in dimensionless form.
• Reducing No of experimental variables.
• No of variables - No of dims. No of p groups
• Use pi method or by inspection
• Basic dimensions M L T ?(kg,m,sec,ok)
• Saving(time)(10 tests vs- 104 tests for F fn
  (L,V,?, µ ))
• Force coef. F/?v2L2 fn (Reynolds number ?vL/µ)
• Helping in exp. Planning, insight, and
  similitude.

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Uncertainty of Measurements

• Measurement error Measured result - True value
• The true value of a measurand is Unknown ( Error
  is unknown )
• The potential value of error can be estimated
  (uncertainty)
• Two types of error
• - Systematic errors (bias) and Random errors
• ( Statistics to estimate random errors)

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SOURCE OF ERRORS
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BIAS AND RANDOM ERRORS
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Measurement errors
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Bias and Random Errors