Week 6 – MSE508/L

1. Week 6 – MSE508/L Costea, Ph.D. Computer Aided Engineering (CAE)

2. Computer Aided Engineering • CAE design stages • CAE production engineering stages CAE fits into the design process at: • Synthesis level – DFMA • Analysis level • Evaluation level CAE provides productivity tools to aid the production engineering as well.

3. CAE • Definition: The analysis and evaluation of engineering design using computer-based techniques to calculate product operational, functional, and manufacturing parameters too complex for classical methods • CAE is part of the design process in Synthesis, Analysis, and Evaluation level. • CAE also includes: • Group Technology (GT) • Computer-Aided Process Planning (CAPP) • Computer-Aided Manufacturing (CAM)

4. Synthesis Stage • Synthesis Stage: Enriches the product by adding basic geometric detail and reshapes the product by applying DFMA. • Design for Manufacturing Assembly (DFMA). Any procedure or design process that considers the production factors from the beginning of the product design. • DFMA aims to: • Answer the question: Is the design optimum for manufacturing and assembly? • Analyze the manufacture and the assembly of the finished product to result in lower product cost

5. Synthesis Stage • DFMA is manual or computer-based: • Manual: Provides a step-by-step procedure to query the designer about part function, material limitations, and part access during assembly • Computer: The designer enters the specifications for the part design and the software provides a quantitative analysis of the alternative designs.

6. Analysis Stage • Analysis Stage: Testing the product with two main categories, Finite-Element Analysis (FEA), and Mass Property Analysis (MPA) • FEA: A numerical program technique for analyzing and studying the functional performance of a structure or circuit by dividing the object into a number of small building blocks, called finite elements. • Mass Property Analysis: Calculates and returns numerical values that describe properties of the drawing geometry selected

7. Analysis Stage • FEA Includes: • Static Analysis: Deflections, strains, and stresses in structures • Transient Dynamic Analysis: Deflections and stress under load • Natural Frequency Analysis: Stresses during resonant frequency which can be destructive • Heat Transfer Analysis: Temperature distribution, steady state, and transient heat transfer in a structure • Motion Analysis (Kinematics): Computes geometric properties to determine needs of a required motion • Fluid Analysis: Flow, diffusion, dispersion, and consolidation characteristics of a fluid under varying controlled conditions

8. Analysis Stage • Mass Property Analysis includes: • Mass • Bounding box • Centroid • Moments of inertia • Products of inertia • Radii of gyration • Principal moments with X-Y-Z directions about centroid

9. Evaluation Stage • Evaluation Stage: Examination of data to determine the degree of match between the actual design and the initial design goals and specifications • Evaluation Stage includes: • Prototyping • RP, SLA, SGC, SLS, 3DP, FDM, LOM • Various software programs For acronyms see next slide…

10. RP- ACRONYMS • Laminated Object Manufacturing (LOM) pp. 563 – 564 text Chang • Fused Deposition Modeling (FDM) • Selective Laser Sintering (SLS) • Sterolithography (SLA) • Solid Ground Curing http://www.efunda.com/processes/rapid_prototyping/sgc.cfm ( good, but you must pay after a brief use of efunda a subscription fee)

11. http://www.societyofrobots.com/mechanics_FEA.shtml FEA Tutorial – emphasis on robots but very good • http://www.andrew.cmu.edu/user/sowen/softsurv.html A Survey of Unstructured Mesh Generation Technology

12. http://en.wikipedia.org/wiki/Finite_Element_Analysis

13. CAE Software • ANSYS (in AutoCAD) http://www.ansys.com/solutions/meshing.asp • COSMOS (in SolidWorks) • CATIA http://www.journeyed.com/itemDetail.asp?itmNo=74464939N • MSC Nastran Patram Adams http://www.mscsoftware.com/products/mdpatran.cfm?Q=457&Z=430 • Others • http://www.esi-group.com/products/Fluid-Dynamics

14. Group Technology • Group Technology: A manufacturing philosophy that justifies small and medium-size batch production by capitalizing on design and/or manufacturing similarities among component parts • GT is the beginning stage of Computer-Aided Process Planning • (Will expand upon this later)

15. Computer-Aided Process Planning (CAPP) • CAPP: A system designed to improve the process planning in the integrated environment • CAPP includes two techniques: • Variant: Uses a library of manually prepared process plans in a database and a retrieval system to match components on new parts to existing process plans of similar components • Generative: Creates plans for new components without referring to existing plans or with the assistance of a human planner

16. Computer-Aided Process Planning (CAPP) • Variant (Figure 5-24, 5-25): • A new production component is given a family code • The part is passed to a part-family search to determine the family code • The standard plan for that family is retrieved • A human adjuster makes the needed changes to the plan • Advantage: A reduction in process planning time by almost 50%

17. Computer-Aided Process Planning (CAPP) • Generative (Figure 5-26): • Convert the design specifications into a format compatible with CAPP software which typically include: • Code • Descriptive Language • CAD • The decision logic portion of CAPP creates an operational plan based on the following: • Production machine capability • Tooling • Fixtures • Time standards • Design specifications

18. Computer-Aided Process Planning (CAPP) • Generative advantages: • Process plans are created rapidly and consistently • New plans are created as fast as those plans similar to existing components • Serves as an interface from the designer to the shop floor (Figure 5-27) Source: Computer Integrated Manufacturing, 2nd Edition, James A. Rehg, and Henry W. Kraebber, Prentice-Hall 2001, pp. 138-171