You might have seen the picture of the Japanese wooden electric car in today's Metro newspaper. Not so stylish you are probably thinking, but some people really like to have a car made from wood - like this man from Ukraine.
Well, perhaps that is also a bit too much for most people's tastes. ...but how about cruising around town in one of these...
If you keep your eyes peeled you might still spot an iconic Morris Minor Traveller on a UK road...or one of the wooden framed Morgan sports cars.
You might be thinking the days of wood for making car bodies are long gone, but you could be very wrong. There is a lot of research going on into natural composite materials that use plant fibres and chemicals (including wood) to make materials that have high performance but also better environmental credentials.
Showing posts with label technology. Show all posts
Showing posts with label technology. Show all posts
Friday, 20 June 2008
Friday, 8 February 2008
Is it wood, is it bricks or is it lego?
Time to practice your French with this post. One of the big new things coming over from continental Europe is "massive wood construction". This is an extension of the idea of a traditional log cabin - in which the walls are solid wood - but updated with modern hi-tech manufacturing methods. So instead of irregular round logs you have nice regular building blocks.
This provides very good insulation keeping the heat in and the noise from outside out. It's also greener than conventional fired clay bricks - which require more energy to make and produce more carbon dioxide in the process.
Obviously it requires an awful lot of wood, but the good thing is that cheaper, low quality, wood can be used. As there is so much of it, the force is shared over a bigger area, meaning it doesn't have to be nearly as strong or as stiff as the wood used in a timber frame building.
You might see this type of construction more often in the next few years for buildings like schools and hotels.
The first video is an explanation (in French) of one particular system of massive wood construction (there are others). Notice the computer controlled robotic cutting and drilling machines. Wood manufacturing really is like this in the 21st century.
The second video, which has no sound, shows the same system being used to actually construct a building. Notice how accurately the pieces fit together thanks to the precision manufacturing.
This provides very good insulation keeping the heat in and the noise from outside out. It's also greener than conventional fired clay bricks - which require more energy to make and produce more carbon dioxide in the process.
Obviously it requires an awful lot of wood, but the good thing is that cheaper, low quality, wood can be used. As there is so much of it, the force is shared over a bigger area, meaning it doesn't have to be nearly as strong or as stiff as the wood used in a timber frame building.
You might see this type of construction more often in the next few years for buildings like schools and hotels.
The first video is an explanation (in French) of one particular system of massive wood construction (there are others). Notice the computer controlled robotic cutting and drilling machines. Wood manufacturing really is like this in the 21st century.
The second video, which has no sound, shows the same system being used to actually construct a building. Notice how accurately the pieces fit together thanks to the precision manufacturing.
Sunday, 25 November 2007
Careers in the timber industry
The UK's multipurpose forests provide environmentally friendly materials for all sorts of things and there are a vast array of different types of job out there.
For more information on jobs visit The Doorway and A Job In.
For more information on jobs visit The Doorway and A Job In.
Wednesday, 7 November 2007
Measuring stiffness with sound
It is very useful to know the engineering properties of the timber in logs before they are sent to the sawmill. Time and energy spent sawing up a log and kiln drying the battens is wasted if that timber later fails to meet the grade for construction. It would be much better to put that log to another use.
The science of sound allows us to do just that. The speed of sound through any material is related to the material's stiffness. In fact, stiffness equals density times the speed of sound squared.
That means if we can measure the speed of sound and the density we can calculate stiffness.
To do this we measure how long it takes the sound to travel from one end of the piece of timber to the other. Then it’s simply a case of speed equals distance divided by time. To explore the science further why not look at our whack-a-stick simulation or read about our exhibit at the Royal Society Summer Science Fair 2007?
This was one of the first videos we made. Annie and Heraa had just started their Nuffield Science Bursaries and we were practicing using the video camera. It just so happened that on the day, Peter Carter from Fibregen was visiting the laboratory to talk about his acoustic testing tool with John and Andy from the SIRT project.
We decided it was a good opportunity to make a short video, so Annie and Heraa asked Peter how it worked and we videoed Annie doing a demonstration.
This tool, the HM200, is called the Director, but people also call it the "Hitman". It is designed to work in busy, noisy timber yards but in the quiet of your own home or classroom you can make your own "non-destructive acoustic testing device". All you need is a microphone and a computer with some software that will analyse the frequency of sound. We have found that the free software called Audacity can do this well enough for a demonstration.
When you hit the end of the wooden batten with a hammer, the main sound you can hear is the sound of the first mode of resonance. The frequency of the first mode of resonance is the time it takes the sound to travel along the batten, bounce off the end and travel back down the length of the batten. This means the wavelength of the first mode of resonance is twice the length of the batten.
It sounds complicated at first, but it’s actually quite simple. All you need to do is hit the piece of timber and analyse the sound to find out what frequency it was mainly made off. So long as everything is working as it should, that is your first mode frequency.
To calculate the speed of sound in the timber:
(Speed of sound) = (wavelength) x (frequency) = 2 x (batten length) x (frequency)
And to calculate stiffness:
(Stiffness) = (density) x (speed of sound) x (speed of sound)
Here is some proof that we did not fake anything for the video. We took the audio recorded from the video and opened it in Audacity (we've extracted the sound of the hammer strikes so you can do this yourself). We then selected the sound of the hammer strike and selected "plot spectrum" from the "analyze" menu.
What we want to look at is the frequency spectrum – that's the graph with frequency on the horizontal axis and the level on the vertical axis. The higher the level the more of that frequency there is in the sound.
The sound contains lots of different frequencies, but we are mainly interested in the highest peak. This is a frequency of 554 Hz.
And if we look at what the figure on the laptop in the video it says 558 Hz. Pretty close huh?
Did you notice the time on the laptop clock? We don't work that late! That was New Zealand time. The laptop was Peter's and that's where he lives.
The science of sound allows us to do just that. The speed of sound through any material is related to the material's stiffness. In fact, stiffness equals density times the speed of sound squared.
That means if we can measure the speed of sound and the density we can calculate stiffness.
To do this we measure how long it takes the sound to travel from one end of the piece of timber to the other. Then it’s simply a case of speed equals distance divided by time. To explore the science further why not look at our whack-a-stick simulation or read about our exhibit at the Royal Society Summer Science Fair 2007?
This was one of the first videos we made. Annie and Heraa had just started their Nuffield Science Bursaries and we were practicing using the video camera. It just so happened that on the day, Peter Carter from Fibregen was visiting the laboratory to talk about his acoustic testing tool with John and Andy from the SIRT project.
We decided it was a good opportunity to make a short video, so Annie and Heraa asked Peter how it worked and we videoed Annie doing a demonstration.
This tool, the HM200, is called the Director, but people also call it the "Hitman". It is designed to work in busy, noisy timber yards but in the quiet of your own home or classroom you can make your own "non-destructive acoustic testing device". All you need is a microphone and a computer with some software that will analyse the frequency of sound. We have found that the free software called Audacity can do this well enough for a demonstration.
When you hit the end of the wooden batten with a hammer, the main sound you can hear is the sound of the first mode of resonance. The frequency of the first mode of resonance is the time it takes the sound to travel along the batten, bounce off the end and travel back down the length of the batten. This means the wavelength of the first mode of resonance is twice the length of the batten.
It sounds complicated at first, but it’s actually quite simple. All you need to do is hit the piece of timber and analyse the sound to find out what frequency it was mainly made off. So long as everything is working as it should, that is your first mode frequency.
To calculate the speed of sound in the timber:
(Speed of sound) = (wavelength) x (frequency) = 2 x (batten length) x (frequency)
And to calculate stiffness:
(Stiffness) = (density) x (speed of sound) x (speed of sound)
Here is some proof that we did not fake anything for the video. We took the audio recorded from the video and opened it in Audacity (we've extracted the sound of the hammer strikes so you can do this yourself). We then selected the sound of the hammer strike and selected "plot spectrum" from the "analyze" menu.
What we want to look at is the frequency spectrum – that's the graph with frequency on the horizontal axis and the level on the vertical axis. The higher the level the more of that frequency there is in the sound.
The sound contains lots of different frequencies, but we are mainly interested in the highest peak. This is a frequency of 554 Hz.
And if we look at what the figure on the laptop in the video it says 558 Hz. Pretty close huh?
Did you notice the time on the laptop clock? We don't work that late! That was New Zealand time. The laptop was Peter's and that's where he lives.
Sunday, 28 October 2007
How trees are harvested
Think you know what a lumberjack is? A big guy with a beard, a checked shirt and an axe? Possibly saving girls in red hoods from wolves dressed as grandmothers? Well think again...
For starters the people (men and women) who take down the trees are called loggers or harvesters...and its all part of forest management, which also includes tree planting, silviculture, landscaping and a range of other 'forest operations'.
Technology has changed the job considerably from the days of yore. Chainsaws started to replace axes back in the 1920s, but these days most of the trees grown for timber in countries like the UK are felled by machines a bit like the ones you see on construction sites. These machines can cut a tree, strip the branches and cut the logs to length in a matter of seconds...plus they have a lot of other fancy gadgets too...like GPS to locate the trees marked for felling. Other types of specialised machines are used to get the logs to the road and on to the sawmills.
All this is done while causing minimum damage to the forest floor and to young trees. The forest owners don't want their future timber crops to be put at risk...or any income they get from other uses of the forests such as recreation and tourism.
In some areas the land is so inaccessible that other methods have to be used, such as horses and helicopters ...or even submarines and machines that walk on legs!
For starters the people (men and women) who take down the trees are called loggers or harvesters...and its all part of forest management, which also includes tree planting, silviculture, landscaping and a range of other 'forest operations'.
Technology has changed the job considerably from the days of yore. Chainsaws started to replace axes back in the 1920s, but these days most of the trees grown for timber in countries like the UK are felled by machines a bit like the ones you see on construction sites. These machines can cut a tree, strip the branches and cut the logs to length in a matter of seconds...plus they have a lot of other fancy gadgets too...like GPS to locate the trees marked for felling. Other types of specialised machines are used to get the logs to the road and on to the sawmills.
All this is done while causing minimum damage to the forest floor and to young trees. The forest owners don't want their future timber crops to be put at risk...or any income they get from other uses of the forests such as recreation and tourism.
In some areas the land is so inaccessible that other methods have to be used, such as horses and helicopters ...or even submarines and machines that walk on legs!
Wednesday, 17 October 2007
Trebuchets
Words cannot describe how much we love catapults. Some work because of the springiness of the wood (its elasticity) and some rely on its strength. The awesome trebuchet is in the second category.
Trebuchets work as huge levers. The short arm of the lever has a large counterweight on it and the longer arm has the projectile - which weighs a lot less. The potential energy of the counterweight is turned into kinetic energy of the small projectile. It's all in the physics - the bread and butter for engineers.
Warwick Castle has the world's largest. Check out their website with loads of historical facts and a flash game you can play.
If you're looking for a woodwork project why not try building your own mini trebuchet ...like these kids did. The cola bottle is so cool! (8 minutes in)
Be safe though...not like the 'eccentric' guy in the third video!
Trebuchets work as huge levers. The short arm of the lever has a large counterweight on it and the longer arm has the projectile - which weighs a lot less. The potential energy of the counterweight is turned into kinetic energy of the small projectile. It's all in the physics - the bread and butter for engineers.
Warwick Castle has the world's largest. Check out their website with loads of historical facts and a flash game you can play.
If you're looking for a woodwork project why not try building your own mini trebuchet ...like these kids did. The cola bottle is so cool! (8 minutes in)
Be safe though...not like the 'eccentric' guy in the third video!
Friday, 12 October 2007
Wood shrinkage
This is a delightfully retro video looking at the microstructure of pine wood and why it shrinks when it dries. It gets quite complicated with the terminology but has good visuals that help show how things work even if you don't understand the words. The things that look like air bubbles are meant to represent water droplets.
You might also want to look at our video about the chemistry of wood (on the firrs webpage).
You might also want to look at our video about the chemistry of wood (on the firrs webpage).
Wednesday, 10 October 2007
Pykrete
Pykrete is a frozen mixture of water and wood fibre. Normal ice has very little tensile strength - it's brittle and cracks easily. The wood fibre helps spread the stress and bind together the ice making it many many times stronger.
It seems like a strange curiosity...but these days it is common to mix wood fibre with other materials like plastic and glue to make "composite materials" with improved properties.
It seems like a strange curiosity...but these days it is common to mix wood fibre with other materials like plastic and glue to make "composite materials" with improved properties.
Helicopter logging
There a several ways to get timber out of the forest, but perhaps the most spectacular method is by helicopter. This video shows a helicopter in action in Canada where the large distances and remoteness of the forests make this a viable option. It has been tried in the UK...the first time was in 1956 at Glenduror, near Fort William by the Forestry Commission.
Traditional timber frame 2
Here is a nice contrast to the "traditional timber frame 1" video. Again it's a class of students in the USA, but this time they are using modern machine tools for their carpentry. The most interesting bit is towards the end where you can briefly see some computer controlled robotic saws in action.
Friday, 5 October 2007
The walking harvester
A Finnish company owned by John Deere has developed a tree harvesting machine that walks through the forest like something out of a science fiction film. Even the wheeled and tracked harvesting machines are like a cross between a space ship and a sports 4x4.
The machine is useful in areas with difficult terrain ...where land has been turned to forestry because it can't be used for much else. Notice how lightly it treads...allowing forests to be managed for timber with the minimum of environmental impact.
The video shows the harvester in slow motion - it would be interesting to see how quickly it can really move!
Subscribe to:
Posts (Atom)
