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Focus
on Fatigue |
MoreVision has developed a number of programs to post-process finite element
results, calculate fatigue damage and to plot damage directly onto the FE
mesh. The assessments cover code of practices used in many countries (UK -
BS7608, France -UIC 515-4 Goodman Diagram, German DIN 15 018, Swedish Volvo
standards) |
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Experimental Methods |
MoreVision strain gauge testing compliments its analysis services. |
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Software
Success |
MoreVision has sold
its innovative
engineering calculation software Research Engineers Inc. for worldwide distribution. The product has already earned MoreVision a
DTI SMART award for innovation. |
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| Composite
Analysis |
MoreVision
has extensive experience in the modelling composite materials. |
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Dynamic
Analysis |
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Avoid resonance by performing a dynamic analysis. |
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Plastic
Analysis |
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What
happens when stress rises above yield? - it may not be as
severe a situation as you think. |
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  On-track
Testing |
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 Within hours
we began to gain an understanding of the problem using a simple finite
element model. This showed that the bracket was particularly
susceptible to lateral loading. We gained enough understanding of the
bracket fatigue prone areas to position number of strain gauges for an
investigative on track test.
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 The test
train was taken onto the track in a number of configurations (cardan
shaft attached, removed and freewheeling). This would help us
determine the relative magnitudes of possible fatigue mechanisms. A
spotlight was quickly thrown on the importance of low magnitude but
high frequency stresses arising from cardan shaft's out of balance
forces. This problem could only get worse with time as the cardan
shaft wears.
The problem was exacerbated by the dynamic response of the motor
rubber mounts whose resonant frequencies coincided with typical line
running speeds. |
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 The waterfall
plot below shows the strain results in the frequency domain (response
is plotted against frequency [x] and speed [y]). It shows the
maximum response at the same frequency as the cardan shaft rotational
frequency. |
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The set of three graphs opposite show strain verses time as the train
accelerates from 0 to 200kmph. The top
graph shows the raw signal (unfiltered); the middle graph shows the high
frequency content of the signal (mainly associated with rotation of
the cardan shaft); the bottom graph shows the low frequency content of
the raw signal (mainly associated with motor torque effects). Both
high frequency and low frequency signals had an influence on fatigue
life of the bracket. |
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On-track testing helped us to:
• understand the most important fatigue driving mechanisms.
• understand the importance of cardan shaft
loading and the dynamic response of the motor on its resilient rubber
mounts.
• determine stress signals for input to crack growth models. This
forms the basis of an inspection regime to guarantee passenger safety.
• redefine new loadcases to develop a long term solution.
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Next>
<Back |
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Top
Software Tools |
MoreVision
have some 20 years experience of problem solving with ANSYS®. They
have developed a library of macros and software tools customizing
ANSYS for specific problems. |
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Bolted Joint Analysis |
 MoreVision uses 'Boltcalc' software
in conjunction with FEA for fast & accurate assessments. |
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Partnering
Client Design Teams |
 Will it fall off? Is it strong
enough? How long will it last? These are the questions on the minds of many
designers. MoreVision can team up to perform simple strength assessments to
allow designers to move forward with the confidence that their designs will
ultimately satisfy structural criteria. |
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Independent
Design Audits |
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A
fresh pair of eyes can offer an new insight into design critical
problems. |
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Fixed
Price Contracts |
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Whenever
possible MoreVision offers fixed price contracts from the outset of a
project. |
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Failure
Investigations |
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Simply strengthening an area
may not give you the results you want and could make the problem worse.
Before a solution can even be considered it is imperative that the mechanics
of the failure are completely understood. |
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Can
we live with cracks? |
 Let MoreVision help you decide using their custom PD6493 software. |
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Too
Hot to Handle? |
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MoreVision
helps clients solve temperature problems. |
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Stress
Overload? |
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Use
MoreVision to offload work when you're too busy to cope. |
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