25'107 Intro' to Engineering Session 15: Engineering Analysis

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25.107 Intro. to EngineeringSession 15
Engineering Analysis

• David O. Kazmer, P.E., Ph.D.

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Module ThreeEngineering Analysis

• Dates/Topics
• 10/26 Engineering Analysis
• 10/31 Units Conversion
• 11/2 Units Conversion (quiz)
• 11/7 Engineering Economics
• 11/9 Engineering Economics
• 11/14 Engineering Economics
• 11/16 Engineering Economics

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Agenda

• Introduction to Analysis
• Analysis in Engineering Education
• Purpose of Analysis
• Analytical Problem Solving
• Engineering Analysis Example
• Computer Aided Engineering (CAE)

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Engineering Is Analysis Based
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What Is the Purposeof Analysis?

• Provide a model of reality
• Develop causal relationships between decisions
  and outcomes
• Investigate alternatives without fully
  implementing physical systems
• The alternative?
• Lots lots of design-build-test
• Analytical thinking differentiates the engineer
  from the technician!

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When HowIs Analysis Used?
Failure Analysis WhyDidnt It Work?
Feasibility Analysis What Is Possible?
DefineProblem
GatherInfo
Test ImproveSolution
Concept Analysis HowMight It Work?
Detailed Analysis How Will It Work?
GenerateSolutions
Select DevelopSolution
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Agenda

• Introduction to Analysis
• Analysis in Engineering Education
• Purpose of Analysis
• Analytical Problem Solving
• Engineering Analysis Example
• Computer Aided Engineering (CAE)

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Analysis ExampleDraft of the Knock Nevis

• Specification
• Weight 465,000 tons4.1x109 N
• Length 458 m
• Width 69 m
• Draft ?

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Agenda

• Introduction to Analysis
• Analysis in Engineering Education
• Purpose of Analysis
• Analytical Problem Solving
• Engineering Analysis Example
• Computer Aided Engineering (CAE)

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Engineers Typically Use Special Analysis Packages

• Computer Aided Engineering Software
• Design AutoCAD, Pro/E, SolidWorks,
• Electrical Spice, E/Workbench,
• Structural/vibrations Abaqus, Adina, Marc,
• Fluids FIDAP, Fluent,
• Manufacturing Moldflow, ProcSim,
• Thermal Ansys, Cosmos
• Typical analysis costs 20,000/yr

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Scooter Body Design

• Design Decisions
• Shape
• Material
• Thickness
• Performance
• Strength?
• Weight?
• Cost?

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Modeling Steps
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Initial Body Design
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Cross Sections of Body
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Finite Element Mesh

• Finite elements decompose complex shapes into
  many features

Mesh
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Load and Boundary Conditions
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Results
Displacement
Stress
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Stress Results for Initial Design Thickness2.5
mm
Max stress 23840 Allowed stress5000
The stress of RED area is far above the allowed
stress!!
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RedesignThickness5 mm
Max stress8727 psi Allowed stress5000
The stress of RED area is still above the allowed
stress!
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Redesign Add Bosses
Boss
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Final Design Results
Max stress 4696 Allowed stress 5000
The MAX stress is below the allowed stress.
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Important Notes

• Trained monkeys can run sophisticated computer
  analyses
• Why should you be paid more to do it?
• Computers dont make decisions
• People do! (this means you!!)
• Your primary roles as engineers are
• Define problems
• Collect information
• Make creative solutions