EGS India Product Design Newsletter - February 2008 Edition

EGS India Newsletter February 2008
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EGS India Newsletter October 2007
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Volume 1 Issue III
Design Services FEA Services
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SolidWorks CAD
Cosmos FEA
Training

February 2008

Design Engineering Out-sourcing is gaining momentum in India.  Ranging from concept validation to value-addition-value-engineering (VAVE) to new product development, Engineering Design Consulting is opening up new vistas of opportunities for our Engineering Community.

Instead of focussing on knowledge of CAD tools, the prime need of the hour is to develop capabilities  in areas of designs involving Fit, Form and Function.  Applications of Finite Element Analysis, Kinematic Analysis, Synthesis of Mechanisms, Geometric Dimensioning & Tolerancing have been brought into focus for rapid product engineering with a view to reduce the time to market for new products while increasing reliability.

More than the knowledge of CAD/ CAE toolsets, it is imperative that the basis for Design needs to be addressed with emphasis on establishing a design process with clear enumeration of design objectives, constraints, feasibility checks, Failure Modes among other parameters for successful and reliable product design and development.

Yours sincerely
Editor

What is Inside?
Finite Element Thought For The Day
Geometric Dimensioning & Tolerancing
Simple Steps in FEA to validate Designs?
Did You Know?
Transition from AutoCAD to SolidWorks
INTEC 2008 Engineering Fair

"Imagination is more important than Knowledge "

- Albert Einstein

Finite Element Thought For The Day www.egsindia.com
Finite Element Analysis Results need to be evaluated in light of errors that are a part of the analytical process.  Errors due to Discretization (breaking a hole in a plate in terms of finite edges for example), Integration (computing the area under a curver to cite an instance), Floating Point (computational), Truncation (significant digits during solution) and Shape Function Choice ( assumed displacement field) are intrinsic to any FE code.  However, these can be minimized or eliminated by proper choice of elements, integration methods, modelling strategies ( to reduce computational oscillations), checking convergence and distribution of constraints and applied loads.  Without an eye for the detail, even a trivial engineering simulation can lead to erroneous results and interpretations that a design engineer needs to avoid.  Best method would be assume that the FEA is wrong until proven right by rigorous procedures and well-established norms. Email Contact

Contact us For:

  • Product Design
  • Finite Element Analysis
  • Analysis to test correlation
  • Failure Elimination
  • DFMEA
  • New Product Development
  • Safety Certification
  • Computational Fluid Dynamics
  • Value Engineering
  • GD&T Training
  • Training in FEA
  • SolidWorks CAD Software
  • Cosmos FEA Software
  • Vibration Problem

Trusted Specialists since 1993

EGS Computers India Private Limited
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Kodambakkam Chennai 600024 INDIA
Tel : +91-44-24803370 / 2372 0265
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Tel: +91 422 231 0268

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www.egsindia.com SolidWorks  Reseller  in  India

Geometric Dimensioning & Tolerancing

Drawings are the language of engineers.  Unless the design intent is protected and conveyed as manufacturable and measurable specifications, the drawing loses its importance and critical errors in manufacture or inspection could lead to disastrous product failures on the field.

It is wrongly understood that to improve product quality, tighter tolerances are a must.  This impression cannot be far from truth.  In addition to imposing tougher penalities on manufacturing the rejection rates lead to higher costs that could eventually lead to drastic reduction in profitability.  Needless to say, the drawings can make or break a company.
 
Geometric  Dimensioning  and  Tolerancing
Conventional +/- Tolerancing of a Hole (left) Vs GDandT Scheme (right)

For example, conventional tolerancing on the left would default to the tolerance on the notes in the drawing with a rectangular tolerance zone while the GD and T scheme on the right would result in a circular tolerance zone that maps the mating boundary with scope for bonus tolerance as the hole deviates from MMC to LMC.  With appropriate choice of tolerance, GD and T scheme would result in more tolerance than the conventional scheme (on the left) resulting in lesser cost and assuring assembly all the time !!  This is referred to as Functional GD and T.
Simple Steps in FEA to Validate Designs

W hen performing Finite Element Analysis the user is required to ensure that the Analysis is right before proceeding on Design Validation.

Cosmos Works provides a rich set of tools, for beginners and experts, to ensure that the results are qualified for further validation studies.  First step would be to ensure that the reaction forces and moments are the same as the loading considered.  Next would be to plot the Error Strain Energy Norm to obtain a mono-chromatic plot.  Deviation zones would represent the areas lacking in convergence requiring re-analysis with a refined mesh.  This Error plot is often mis-interpreted by the user as the Error in FEA.  This is not correct.

If assembly stresses due to fasteners are considered, then a simple calculation of axial bolt stresses and comparision against data probed on the stress plot would validate that the load path and system response are correct.

Directional stresses, when plotted, would provide a deeper insight into the stress contributors.  Cosmos Works provides the choice of co-ordinate system that could be used to obtain the desired directional stress components.

Are the stresses located close to loading or constraint zones?  If yes, then St. Venant's Principle is violated.  The part would then need to be analyzed in context of the assembly while transferring the loading and constraints to the contacting parts.  This is easily done in an assembly level analysis with automatic contact representation, inside Cosmos Works without any additional effort.

Once validated, Design Studies for a variety of design configurations can then be carried out in one-shot without the need for repeated analyses setup and re-runs.

Need more TIPS on using CosmosWorks? Contact EGS India
Did You Know?

Nature has endowed us with numerous mysteries that, when unravelled, would benefit mankind and society as a whole.  Power of observation, coupled with imagination and scientific temperament, leads to a deeper understanding of the secrets that Nature has to offer.  A spark of an idea inspired by nature  can lead to a discovery that benefits the whole world.  One such revelation came to Johann Christian Andreas Doppler who cherished observations of natural phenomena.

In his own words, "We know from general experience that a ship of moderately deep draught which is steering toward the oncoming waves has to receive, in the same period of time, more waves and with a greater impact than one which is not moving or is even moving along in the direction. If this is valid for the waves of water, then why should it not also be applied with necessary modification to air and ether waves?"

Stated in simple terms, when standing adjacent to a railway track, an observer notices a change in pitch or frequency of sound coming from a train whistle as the train approaches or moves away.

A change in the observed frequency of a wave, as of sound or light, occurring when the source and observer are in motion relative to each other, with the frequency increasing when the source and observer approach each other and decreasing when they move apart. The motion of the source causes a real shift in frequency of the wave, while the motion of the observer produces only an apparent shift in frequency. Also called Doppler shift

Study of the Doppler effect has benefitted Astronomy in understanding the Expansion of Universe in addition to estimating the temperature of Gaseous masses in the Universe.

Law enforcement agencies use Radars based on this principle to estimate travelling velocities of speeding motorists.

Laser Doppler Velocimeter and Acoustic Doppler Velocimeter are used to measure flow velocities in a non-intrusive manner.  Doppler shift of a target is used to ascertain the speed of a submarine in military applications.

Greatest benefit to humankind has been the velocity measurements associated with blood flow for monitoring valve function and areas.  Calculation of cardiac output, mitral valve regurgitation among others are regularly studied using this principle.  Doppler principle finds extensive use in Medical Ultrasonography of Neural and Obstetric diagnostics, immensely benefitting mankind .

While acknowledging the limitations of his calculations, Doppler had, in his publication referring to this phenomenon, admitted with remarkable foresight, "It is almost to be accepted with certainty that this will in the not too distant future offer astronomers a welcome means to determine the movements and distances of such stars which, because of their unmeasurable distances from us and the consequent smallness of the parallactic angles, until this moment hardly presented the hope of such measurements and determinations."

Discovery of this phenomenon had proved very important during the proposition of the Theory of Relativity by Albert Einstein later.  Little is known that one of the students interviewed by him for admission to the Royal Imperial University, Vienna, was Gregor Mendel who went on to become the father of modern genetics.

(Images Source: Kettering University)



Johann  Christian  Andreas  Doppler
Stationary Sound Source
Doppler  Effect
Source moving with velocity less than sound
Velocity  less  than  sound
Source moving with velocity greater than sound
Source  Velocity  greater  than  sound

Transition from AutoCAD to SolidWorks

Design Engineers are conversant with developing 2D Drawings using AutoCAD.  SolidWorks provides safe, accurate and reliable tools for re-use of existing 2D DWG files in addition to integrating the same with SolidWorks 3D and SolidWorks 2D drawings.

AutoCAD drawings can be inserted as an external reference inside SolidWorks drawings with link for automatic update, if required.  All layer information is retained intact while reading and writing DWG data.  SolidWorks also provides an independent drawing editing tool called DWGeditor for opening, editing and saving existing 2D DWG drawings.  DWGeditor provides a rich functionality to integrate existing LISP routines in addition to VBA for automation.

DWGGateway allows users to access DWG data written in later versions of AutoCAD format to be opened in earlier releases of AutoCAD.

DWGNavigator is useful to search and manage DWG files.

2D Command emulator is available in SolidWorks 3D Sketchmode for AutoCAD users conversant with commands.
DWGeditor
eDrawings

Engineering Community converges on SolidWorks at INTEC 2008 held at CODISSIA, Coimbatore

Entrepreneurs from the Engineering Industry got their Design Challenges addressed by SolidWorks in terms of Fit, Form and Function.  Wide ranging applications from start-up companies to large corporations were taken up for discussions and demonstrated with ease.

Integrated FEA and ability to validate design concepts were appreciated by the visitors in addition to the ease of use and migration of legacy DWG data.
 

SolidWorks  at  INTEC  2008
Interested in SolidWorks? Need Cosmos FEA? Require Solution to Problems? Refer Your friend
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Reviews:
Review Article
  • October 09, 2008
    Reviewed by 'Raj'
    It is a very good article for new product designers and developers in automotive sector. GD & T section is very simple to understand the concept of Geometric Dimensioning and Tolerancing techniques. Their web site http://www.egsindia.com is also carrying lot of informations and their old news letters. EGS India, Chennai is doing excellent work.
    I hope design engineers and new product developers will appreciate their efforts.

      Was this review helpful to you?   (Report this review as inappropriate)


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