EGS India Product Design Newsletter - February 2008 Edition
EGS India Newsletter February 2008
Read the complete story ...
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.
"Imagination is more important than Knowledge "
- Albert Einstein
Element Thought For The Day
| 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.
- Product Design
- Finite Element
- Analysis to test correlation
- Failure Elimination
- New Product Development
- Safety Certification
- Computational Fluid Dynamics
- Value Engineering
- GD&T Training
- Training in FEA
- SolidWorks CAD
- Cosmos FEA
- Vibration Problem
Trusted Specialists since 1993
EGS Computers India
New No 90 Old No 342 Arcot Road
Kodambakkam Chennai 600024 INDIA
Tel : +91-44-24803370 / 2372 0265
Telefax : +91-44-24844227
1/1 B. R. Nagar, Trichy Road, Opposite Coimbatore Stock Exchange,
Singanallur Post, Coimbatore 641050 INDIA
Tel: +91 422 231 0268
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.
+/- 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.
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
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
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
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
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
(Images Source: Kettering University)
Stationary Sound Source
Source moving with velocity less than sound
Source moving with velocity greater than
AutoCAD to SolidWorks
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.
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
For more discussions, follow this link
- 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.