Design Phase Presentation
Download
Report
Transcript Design Phase Presentation
DESIGN PHASE
What kind of analysis you
need to do?
MIME Senior Design Projects - Spring 2013
Overview
Design/Analysis Requirements
Common Design Issues
Welds
Fatigue
Safety
Quality
Design Requirements
What type of analyses do I need?
Technical Analysis
Description
Examples
1
Static Analysis
Calculate forces and moments for stationary
Lifts, supports, structures, connections.
components.
2
Dynamic Analysis
Calculate s, v, a of moving components and All moving components such as gears,
the forces and torques needed.
mechanisms, pulleys,
3
Power Analysis
Calculate the power needed to run the
machine.
Use the force and dynamic
4
Stress Analysis inclg FEA
Calculate stresses and compare with
strengths to see if failure would occur.
Components under high forces, moments or
torques such as support members.
5
Thermal Analysis
Calculate temperature, temp changes,
pressures, and possibly heat transfer.
Components including fluids where heat and
temperature are involved.
6
Fluid Flow Analysis
Calculate flow rate, speed, quantity,
pressure, and possibly temperature.
Determine pump sizes, pipe diameters, flow
measurement when you have fluids.
7
Process Analysis
8
Vibration Analysis
9
Cost Analysis
Improve business activities in order to
reduce overall costs, provide more efficient Lean manufacturing, six sigma and total quality
use of resources, and to better support and management.
add value for customers.
Determine vibration frequency, and if
vibration will be a problem.
Anything moving with a certain frequency. Also
some electrical components.
Determine the costs in the short run and
long run, as well as ROI.
Determine if it is more cost effective to produce
or to outsource a component.
Design Requirements
Measure twice, cut once
Make
sure you do adequate calculations and analysis
Tendency to build first, design later
Works
if you’re right the first time
Costs material, effort, and time if you’re wrong
Anticipate use
Anticipate misuse!
Design/Analysis
FREE BODY DIAGRAM
FEA
Approximate Design/Calculations
Is
it a beam or a plate?
Design/Analysis - FEA
Quality of input determines quality of output
“Magic” Black Box
Factors
Solid
model quality
Correct boundary conditions
Load accuracy
Proper material selection
Mesh quality
Correct Failure Criteria
Design/Analysis - FEA
Solid Model Quality
Balance
simplicity/accuracy
Use
your intuition to include features that will increase
stresses
Exclude trivial features
Correct Boundary Conditions
Make
sure your restraints accurately represent real
conditions
Check
degrees of freedom
Check fastener/mating conditions in assemblies
Design/Analysis - FEA
Load Accuracy
What
type of loading? point load? distributed load?
Am I missing loads? thermal? centripedal?
What is the magnitude? 10lbs? 500lbs? 1,000,000lbs?
Rationalize
with intuition
Determine with testing
Material Selection
Did
I select the correct material?
Are my properties in the correct units?
FEA – What to expect?
http://machinedesign.com/article/fe-update-expecting-too-much-from-fea-0710
Design/Analysis - FEA
Mesh Quality
Make
sure it is fine enough to
accurately depict features
Affects processing time
Design/Analysis - FEA
Correct Failure Criteria
Stress
based: yielding or fracture?
Excessive displacement
Loss of function
Corrosion
Thermal degradation
Fatigue
Remember that ductile and brittle materials
fail differently and have different failure
criteria!
Design/Analysis
When in doubt, do some hand calculations
Mathcad
and Matlab are very useful
Shigley is very useful
DANotes is a good resource as well:
http://www.mech.uwa.edu.au/DANotes/
Your
basic calculations and FEA should support each
other
If
they don’t, you should know why
Welds
Strength of welds
Location-
sharp corners?
Loading- stress state of weld?
Size
Quality of weld!
Fatigue
Fatigue
Are their cyclic loads?
Do fatigue analysis
S/n approach used in Shigley
Safety
Pinch points?
Sanitation?
Exposed wiring?
Warnings?
Quality
Deliverables should function well
Make sure products are durable
Double-check safety
References
References:
What
Kind of Analysis do you Need for your Project?,
Dr. Kramer, MIME Dept.
Photo Credits:
http://www.msha.gov/Accident_Prevention/Tips/im
ages/HandTools-Jacks.jpg
http://machinedesign.com/article/fe-updateexpecting-too-much-from-fea-0710