Error/Uncertainty
What are two ways to calculate propagation of uncertainty in calculations?Max/Min CalculationsRelative Uncertainty EquationsHow do you calculate the uncertainty in your calculation of Young’s Modulus using the Euler Buckling equation,
Error/Uncertainty
Uncertaintyis an interval around a value such that any repetition will produce a new result that lies within that interval.Errorrefers to the disagreement between a measurement and the true or accepted value
Mechanical Material Properties Testing
Compression TestFailure by buckling or crushing (or shattering glass)Wood: Crush if L/d < 10, Buckle if L/d > 10
Modes of Buckling
Materials Lab and Uncertainty
ObjectivesReview materials lab objectives and analysisUnderstand uncertainty in materialslab
Experiment 1: Tensile Test
Objective 1:Show that the tensile force required to break a rod is of the formP = kR2(wherePis the force required to break the material in tension,kis a constant determined by the material,Ris the radius of the cylindrical specimen being tested).Objective 2:Determine the tensile strength (maximum stress in tension, ultimate tensile strength) of spaghettidirectly
Experiment 2: Bending Test
Objective 1:Determine Young’s Modulus for spaghetti using the bending equationObjective 2:Determine the tensile strength of spaghettiindirectly
Experiment 3: Buckling Test
Objective 1:To prove that the Euler buckling loadPfor a cylindrical specimen of material can be accurately expressed by the following equation:(wherePis the “critical” buckling load,Ais the cross-sectional area of the specimen tested,Eis Young’s Modulus for the material,kis a constant that depends on how the rod is held,Lis the length of the specimen, andRis the radius of the cylindrical specimen).Objective 2:To determine Young’s Modulus for spaghetti using the Euler Buckling equation
Report Format
12 pt Times New Roman or Calibri 11 pt1.5 spacingMini reports combined:AbstractIntroductionProcedure:Tension LabBending LabBuckling LabResults:Tension LabBending LabBuckling LabDiscussion:Tension labBending LabBuckling LabConclusion
Due Dates
3 mini-labsEach group member completes a section (3 group members, 3 sections) –due 5pm Sundayto coordinatorCombine sections into one lab reportE-mail to another group’s coordinator to proofreaddue 8pm MondayFinal group report, single Word orOpenOfficedocument,due 8am Tuesdayby e-mailCopymscott@bpi.eduon all of these e-mailed files – assignment grades for each group member.
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