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NEWS

Motovated Design & Analysis Newsletter - February 2009

Hello everyone,

Welcome to 2009! This is shaping up to be a challenging year for many businesses, but also a year of development and opportunities. Already this year, Motovated has had a big opportunity to support jet sprint driver Peter Caughey, and we won a world championship!

Motovated is also seeing a lot of companies looking at cost reduction initiatives. These include changing materials and manufacturing processes, reducing raw materials, improving processes to eliminate bottlenecks, and providing for easier assembly and transportation. As they say, "Necessity is the mother of invention", and with the current economic climate it is becoming more necessary to reduce product costs.

Also in this issue we have another design tip, a puzzle and answers to last issue's puzzle question. We hope you've all had a good start to the year, we look forward to working with you and seeing what this year will bring.

Greg Morehouse
General Manager
Engineering Analyst

JetSprint World Champs 2008 - Motovated & Peter Caughey Racing win the world title

Motovated has had a busy start to the year with our support and sponsorship of Kiwi Peter Caughey in his bid to take on the world at the JetSprint Championship, held here in New Zealand last month.

Peter Caughey's World Superboat Caughey raced to his third World Superboat title in style with a winning time of 45.52 seconds, beating fellow Kiwi Leighton Minnell (47.18 seconds), who raced in Caughey's previous Sprintec boat.

We are very proud to support a team with such an enthusiasm for racing and engineering, and look forward to working alongside them this year as they prepare for the 2009 World Championship in Australia.

You can find all the race details, photos and video footage on our website

Motovated's 2009 Desktop Calendar

Our 2009 calendars have now been posted out, we hope you're enjoying them. If your copy hasn't arrived yet, please drop us an email at sharyn.laing@motovated.co.nz and we will send one out to you.

Motovated 2009 Calendar

Tips & Tricks - which weld is the best?

Fillet Weld

Weld 1: standard fillet weld

Combination Groove and Fillet Weld

Weld 2: combination groove and external fillet weld

(images sourced from Welding Magazine) - you can read the full article here.

A fillet weld is used to attach a gear to a shaft, which is subject to a high torsional load. When the design is modified for a larger machine, a bigger shaft is used to carry the increased torque.

The engineer initially specifies a 25mm fillet weld to attach the larger gear, but then decides to add a groove weld as a precautionary measure. The weld specification is changed to a 25mm groove weld with a 25mm external fillet weld.

Which weld is the strongest in torsion?

Fillet Weld
Fillet and Combination Groove Weld Stress Results

By carrying out a simple Finite Element Analysis (FEA), we found that the Von Mises stresses are almost identical in the two welds. The weld stress in the combination groove weld was only marginally lower than the fillet weld stress. You can view the stress results for both welds by clicking on the picture opposite.

The main point to note here is that the addition of the groove weld increases the production costs of the shaft, and does not significantly increase the load carrying capacity of the weld. Instead it adds time and cost to the manufacturing process, with little (if any) return on added weld strength.

Blodgett even indicates that according to hand calculations, the groove weld actually decreases the load carrying capacity...but we believe our FEA!

Did you know...

Ingenious!

The verb "to engineer" is derived from the French word 'ingenierie' and means
"to be ingenious"

Outsmart your colleagues...

Here's a problem for all the fishermen out there:

You’re sitting in a boat afloat on a pond... You're sitting in a boat afloat on a pond with no inlet or outlet. You've found a nice fishing spot, and you throw the boat's anchor over the side into the water.

Does the water level in the pond rise, fall, or stay the same?

Send your correct answer to competition@motovated.co.nz to be in with a chance of winning a $50 Mitre 10 voucher.

Answer to last issue's puzzle

The last puzzle of 2008 was about finding a defective bulb in a string of Christmas lights in the minimum number of steps. The correct answer for a string of 64 bulbs is 6 tests. Well done to everyone who got this right. The method is outlined below:

Measure the current using a test meter, test by 'halves'. Test the first 32, if current flows through this half of the line, the trouble must be in the second half. Then test across 16 of the remaining 32; if there is a meter reading, the problem is in the last 16. Continue halving down to two bulbs, one of which is bad, then one more test will give the answer.

Testing by halves

For the bonus points, the number of tests (N) required for any number (x) of bulbs is:

N = ln(x)/ln(2)

Congratulations to Ravi Kandula from AuCom Electronics Ltd, a Mitre 10 voucher is on its way to you.

Thanks for your time and support. We look forward to working with you and continuing to provide the best engineering services possible.

Greg and the team at Motovated.

"engineering your vision"