Computer Aided Engineering

1. Computer Aided Engineering

2. 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)

3. 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

4. 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).

5. 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.

6. 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

7. 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:

8. 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

9. 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

10. 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

11. 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

12. What is the significance of • DFMA • FEA • Mass property analysis • to Automation Design?

13. Computer-aided Engineering Evaluation • Evaluation – to determine whether there is a match between the actual design and initial design goals. • Changes can be made based on evaluation • Most commonly used is PROTOTYPING

14. Prototyping techniques • Physical prototypes • Rapid prototyping • Stereolithography • Fused deposition modeling • LOM • Virtual prototyping

15. Computer-aided manufacturing

16. Computer-aided manufacturing • Effective use of computer technology in the planning, management and control of production for the enterprise • Wide range of automation technologies • Started with NC • CNC • Process modeling and simulation • Maintenance automation • Production cost analysis

17. 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

18. 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 STL format • Main format for rapid prototyping

19. PDES inc – working on the implementation of ISO 10303 STEP • STEP – standard for exchange of product model data • Web-based technologies • Modular applications for product data • Increasing interoperability among CAD/PDM, PDM/PDM, and ECAD/MCAD systems

20. Networking • Enterprise network – non-public communications system that allows for data exchange and connect different devices • Can be a few feet to thousands of miles • Production data is essential for control • Electronic communications important for data acquisition • Real time data acquisition the key to effective plant control

21. Levels of Plant floor communications

22. Levels - cont • Device - field devices e.g. sensors, valves • traditionally - devices communicate with PLC’s and have no ability to communicate with each other • current trend - addition of communication chips to field devices and allowing them to communicate through communications bus • Machine - equipment that produce or handle product • have their own controllers • PLC can be considered as a machine • machines can also be made to communicate with each other

23. Levels • Cell - a collection of machines use say for one group of products • Cell controller enables machines in a cell to communicate with each other

24. Networks Broken down into • Topology • Ring or Bus • Media or cable type • Twisted pair • Coaxial • Wireless (RF) • Fiber optics • access method or protocol • Master-slave • Serial • Ethernet • Ethernet IP

25. Internet IP addressing • Network devices include: • PCs, printers, sensors, PLCs, etc. • These are NODES • IP address identifies the node • TCP/IP – information (data) movement • TCP – data between applications • IP – data between host computers • IP address is 32 bit numeric written in four segments separated by periods • E.g 131.256.24.82

26. Network elements • Router – to forward data – interconnection between networks • Gateway – a type of router that allows entry to a network • Bridge – connects to LANs • Switch – filter and forward data between segments of LANs • Hub – connection point for nodes (usually multiple points

27. Data conversion • Role of IGES • PDM central to design and production data • Data conversion from one software or form to another is very critical • Example – page 209.