Design Automation and CAE

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Design Automation and CAE
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• CAE - analysis, evaluation of engineering design
  data using computer-based techniques to calculate
  product OPERATIONAL, FUNCTIONAL, MANUFACTURING
  PARAMETERS
• design process - CAD, DFMA
• production engineering - GT, CAPP, CAM (NC, CNC)

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• CAD Data Exchange
• Translation software that transfers data from one
  software to another
• Translators also transfer data from CAD to CAM
  software
• DXF Format
• Drawing Exchange File (Drawing transfer file)
• allows CAD data to be written in ASCII file that
  contains information about the design. Can be
  read by other CAD software or CAM to generate NC
  codes

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• IGES - Initial Graphics Exchange Standard
• Initially developed by NIST and adopted later as
  ANSI and ISO standards
• IGES contains data on geometric entities and
  parameters associated with the entities
• PDES - Product Description Exchange Standard
• has been broadened to stand for Product
  Description Exchange for STEP
• PDES - US effort and STEP - European effort
  together now becoming an ISO standard
• defines product data from design to production
  including Solid modeling (CSG, B-Rep, e.t.c),
  process plans, pre-processors for FEA, e.t.c.

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Design for Manufacturing and Assembly
Design for Manufacturing and Assembly (DFMA) is
any procedure or design process that considers
the production factors from the beginning of the
product design - Design an activity from
conceptualization to evaluation must focus on
generating designs that meet market
specifications and can be manufactured
cost-effectively
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• DFMA started with two separate thrusts
• producibility engineering - produce simpler parts
  that are easily manufactured
• design for assembly - reduce number of parts by
  eliminating or combining them
• DFMA - a holistic approach to design analysis
  since both manufacture and assembly are
  considered simultaneously.
• Result - reduced total product costs (NB - 70 of
  product cost are design oriented 80 of quality
  problems are because of poor design).

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• DFMA Process-
• step-by-step procedure to query the designer
  about part function, material limitations, part
  access during assembly.
• Software calculates assembly time, product cost
  and benchmark theoretical min. no. of parts.
• The manufacturing component of the software will
  access various material options (e.g. steel vs
  plastic) or manufacturing processes (e.g.
  machining vs die-casting) for most cost-effective
  production.

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• DFMA Evaluation
• Apply design guidelines
• Assembly method scoring chart
• Both these are easily built into the software.
• In the DFMA software systems, designer will enter
  specifications and the software will provide a
  quantitative analysis for the alternative designs
• Discuss Ex. 5-1 and 5-2
• Group activity - see handout.

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Computer-Aided Engineering

• CAE provides a wide variety of software for
  engineering analysis of designs
• In many modern applications, CAE data is obtained
  from CAD drawings
• Systems are linked through CAE so that different
  applications can share information in the
  database e.g. FEA, NC
• For design automation, several areas of CAE are
  used

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• Finite Element Analysis
• numerical technique for analyzing and studying
  functional performance of a structure or circuit
• structure is divided into a number of small
  ELEMENTS
• analysis of the structure by applying some
  numerical techniques
• post-processing and interpretation of results
• Common applications - statics, transient
  dynamics, modal, thermal, fluids,
  electromagnetics, motion

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• Static analysis - stresses, strains and
  deflections under static loads
• Transient dynamic analysis - stresses and
  deformations, natural frequencies and frequency
  response under dynamic loads
• Modal Analysis - natural frequencies, mode
  shapes for free vibrations
• Thermal analysis - temperatures and heat transfer
• Electromagnetic analysis - behavior under
  electromagnetic fields
• Motion analysis - kinematics (displacement,
  velocity and acceleration)
• Fluid analysis - flow, diffusion, dispersion, CFD

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• Mass property analysis
• a CAE function of CAD that returns numerical
  values which describe the properties of the
  geometry selected.
• 2-D areas, centroids
• 3-D volume, mass, surface area, centroids,
  moments of inertia
• Mass property is usually in-built in the CAD
  software - reduces time and effort by designer to
  calculate these entities

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• Interference Checking
• checks 2-D models for interferences between
  components e.g. in mechanical assemblies
• Tolerance analysis
• checks for tolerances and how they affect
  manufacture, assembly and overall dimension
• Kinematics and dynamics analysis
• analysis of motions esp. of mechanical linkages
• Discrete Event Simulation
• model complex operations such as those in a
  manufacturing cell

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• Conclusions
• What is the significance of
• DFMA
• FEA
• Mass property analysis
• to Automation Design?
• PP 150 - 154 List CAE software for other
  functions
• To be covered later RR, GT, CAPP, CAM/NC-CNC,
  Communications