Motovated > News > Newsletter February 2011

Hi everyone,

To all our friends and colleagues affected by last weeks devastating earthquake, our thoughts are with you. Our Business Development Manager Jonathan Prince has developed an excellent synopsis of the quake below, with some great links to follow if you're interested in why it was so much more damaging than "the big one" six months ago.

We were unfortunately just above the epicentre and, despite an office which looked like a warzone, we were able to get up and running as soon as power was restored. This is a real testament to fall-back planning, redundancy and excellent back-up processes! Many thanks to Graham and the crew at Computer Troubleshooters - Avonside.

Enjoy the read, which also includes our regular jokes and puzzles, and another tips & tricks feature.

Finally, I'd like to point out that while the level of acceptable risk is different for every client and product, every product must be "fit for purpose". At Motovated we work with all of our clients to determine the level of design & analysis appropriate for their project, to ensure that the product is both cost-effective and fit for purpose.

Greg Morehouse
Managing Director
Engineering Analyst
greg@motovated.co.nz

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The Canterbury Quake: Round 2

I was going to write an article in this month's newsletter outlining how good analysis can go a long way to eliminating failures in the field. But, after last week, one thing that really hit home is that there's only so much you can do! Whilst many of the buildings that collapsed in our city were older and maybe didn't comply to modern building codes, that certainly wasn't the case across the board. It hit home for me the reality of designing to an appropriate standard and how sometimes, even with the best laid plans, things can still turn to custard!

One of the biggest issues in analysing something for potential failures is making absolutely sure that you understand what the potential failure modes really are, and then perform sufficient simulation to suit those modes. Wherever possible, we like to use existing standards and engineer to those standards, however, there are times when failure modes can occur that are well outside of even these.

As I understand it, the Earthquake the 22nd Feb 2011 measured up to 2.2 g at one location (220% of the acceleration due to gravity at Heathcote Valley Primary School, scarily enough) with the shaking exceeding 1.8 g (180% g) in the city centre. This exceeds the design strength of most buildings. 124% g is regarded as "Extreme" shaking (higher than "Violent") (see image opposite).

According to one seismic engineer, the force of the quake was "statistically unlikely" to occur more than once in 1000 years, with a PGA (Peak Ground Acceleration) greater than many modern buildings were designed to withstand. By comparison, the Sept 2010 quake - in which damage was predominately to pre-1970s buildings - exerted 65% of the design loading on buildings. For a great explanation of the difference in earthquake intensity compared to the "big one" of six months ago, follow this link: http://en.wikipedia.org/wiki/2011_Christchurch_earthquake

I understand that this would have flattened most cities around the world and it was only NZ's strict building codes that meant more of the city didn't disintegrate. The interesting point for me here is that design is always a compromise: strength vs. cost vs. likelihood of failure, and sometimes there's very little that can be done to completely eliminate all risk even with the best intentions.

At Motovated Design & Analysis we certainly hope to add that extra piece of mind when it comes to the uncertainty of design, but at the end of the day there are sometimes forces and events way beyond our control, and beyond the scope of even the best design standards.

Kia Kaha Christchurch!

Jonathan Prince
Business Development Manager
Cell: 021 582 199
jonathan.prince@motovated.co.nz

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Tips & Tricks - Zinc Coatings

When your steel product requires a surface finish that will be corrosion-resistant, there are a number of options. Perhaps the first coating that comes to mind is some form of zinc. But within the zinc category, you can still choose from zinc electroplating, hot-dip galvanising, mechanical plating, and zinc flake processes, and that's without discussing zinc-rich paints. So, which is the one you want to use? Zinc electroplating is the most common and as a result, inexpensive. The downside is that it produces thin coatings (around 10 microns) which won't last and hydrogen embrittlement does occur. However, this is a good option for small parts with tight tolerances, such as small fasteners. Mechanical plating and zinc flake can produce a similar coating thickness but without the embrittlement and with improved corrosion-resistance. During mechanical plating, the zinc is added to a tumbling barrel in metallic powder form and 'cold welds' to the part. The zinc flake process spins the part in a liquid suspension of zinc, which is followed by curing in a furnace. Mechanical plating is of course limited by the size of the barrel. Mechanical plating and zinc flake coating are less well known and have been developed for specific applications. Hot-dip galvanising is a great option where the highest corrosion-resistance is desired and you are not worried about dimensional variation. Coatings of over 50 microns are applied by passing the steel part through a molten bath of zinc. The strength of the steel is somewhat reduced due to the high temperature of the liquid which is important to keep in mind in high strength applications. To read more about zinc plating, see the following links:
	Surface Coatings Hot-dip galvanising Eng-Tips Forum Discussion Zinc galvanising vs. zinc plating
Bevan Hoyt Design Engineer Motovated Design & Analysis

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JOKE: Job Interview Techniques

Take the prospective employees you are trying to place and put them in a room with only a table and two chairs. Leave them alone for two hours, without any instruction. At the end of that time, go back and see what they are doing.

If they are writing up the experience, send them to the Technical Documents team. If they have taken the table apart, put them in Engineering. If they try to tell you it's not as bad as it looks, send them to Marketing. If they are sleeping, they are Management material. If they mention what a good price we got for the table and chairs, put them into Purchasing. If they are wearing green sunglasses and need a haircut, Computer Information Systems is their niche. If they don't even look up when you enter the room, assign them to Security.

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Outsmart your colleagues...

A checkerboard is a square that has been divided up into 64 smaller squares by straight lines at right angles. How many squares are there on a checkerboard? The answer is not 64 or 65. BONUS: How could you work out how many squares there are on any sized square board?
Send your correct answer to competition@motovated.co.nz to be in with a chance of winning a $50 Mitre 10 voucher.

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Answers to last issue's puzzle

Check your answer to December issue's question here: The correct answer is:

You should switch your choice of door - this will double the probability of winning the car from 1/3 to 2/3.

You can read details of the full solution here.

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Last issue's puzzle winner...

Congratulations to Kylie Robinson from Igtimi Limited, a $50 Mitre 10 voucher is on its way to you.

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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"