HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
REGISTER   |   LOGIN   |   HELP
Blogs
CAD/CAM Corner
Spring-Free Trampoline Coming to a Backyard Near You
12/20/2013

Dr. Keith Alexander and the University of Canterbury develop the world's first spring-less trampoline using finite element analysis (FEA).
Dr. Keith Alexander and the University of Canterbury develop the world’s first spring-less trampoline using finite element analysis (FEA).

Return to Article

View Comments: Threaded|Newest First|Oldest First
tekochip
User Rank
Platinum
Performance
tekochip   12/20/2013 10:57:15 AM
NO RATINGS
That looks like a real slick redesign, the real question would be the performance.

mrdon
User Rank
Gold
Re: Performance
mrdon   12/21/2013 3:07:33 PM
NO RATINGS
tekochip

I agree. Curious about the cost of this trampoline in addition to the performance. Also, wondering when will this new product hit the marketplace for purchase.

Nancy Golden
User Rank
Platinum
Cost
Nancy Golden   12/20/2013 12:03:53 PM
NO RATINGS
I agree with tekochip - it does look like a slick design, but I would think cost would be a huge factor for marketability. It seems that the cost to manufacture this type of trampoline would be exponential...

Habib Tariq
User Rank
Iron
Re: Cost
Habib Tariq   12/22/2013 2:11:05 AM
NO RATINGS
Yes cost does play a very key role in the overall delivery of the project, but it does not seem like a very expensive product(considering the parts used). Majority of the cost would have been in the researching part, but now that they have come out with a final design, I think producing it on large scale should not be very expensive.

TJ McDermott
User Rank
Blogger
Re: Cost
TJ McDermott   12/22/2013 7:47:38 PM
NO RATINGS
Ah, Nancy, what price do you put on safety? (and that's said tongue in cheek).

With more research, the complex ball-socket connections might give way to something simpler in order to bring the cost down.

I agree with you - the concept is brilliant but will be difficult to sell.

Tom-R
User Rank
Gold
Re: Cost
Tom-R   12/23/2013 9:38:49 AM
NO RATINGS
Safety is the objective, but I don't see how this addresses falling off the trampoline. You still need a net around it, and this design doesn't have a frame to mount one to. Yes you can use one without a net, but the manufactured better have one available; if only for liability reasons. I can only imagine a separate framework for a net and wonder how it would be padded, and designed to prevent gaps between it and the new trampoline design. I understand the safety improvement of no exposed springs, but don't see how it addresses the other major safety concerns stated in the article. It could be less safe, overall.

GTOlover
User Rank
Platinum
Safety?
GTOlover   12/20/2013 1:10:55 PM
NO RATINGS
So this is all being designed with safety in mind. What happens if one of those fiberglass poles breaks? It seems that the ground is a lot farther away and falling off the edge might hurt a bit more!

Besides, if I am on a trampoline, it is expected that I am on a high risk device. However, I weigh the risk to the fun factor.

naperlou
User Rank
Blogger
Visualize
naperlou   12/20/2013 1:29:33 PM
NO RATINGS
Cabe, this is a great design.  I don't about the cost, but it fits the bill. 

One thing I did notice was that the picture did not really give me a good idea of how it was put together until I read the article.  It is interesting how you need both together since this is such a departure.

Nancy Golden
User Rank
Platinum
Design Question
Nancy Golden   12/22/2013 1:08:09 PM
NO RATINGS
One thing about the design that puzzles me...if you are using a ball and socket then it is going to have a point where it has a "stop" to it - whereas a spring just continues to stretch and give more and more. This becomes especially evident with heavier weight. I wonder how this design would compare with springs in that regard?

Battar
User Rank
Platinum
Re: Design Question
Battar   12/23/2013 9:22:42 AM
NO RATINGS
If you want all the gory details in poorly written English, look up US patent 8303469 - It's all there, with some drawings and explanations.

jlawton
User Rank
Gold
Dazed and confused
jlawton   12/23/2013 9:47:44 AM
NO RATINGS
How this works isn't obvious to me at all, it looks as if the participant would be subjected to a degree of angular momentum around the vertical axis on each bounce, unlike a standard trampoline. Somebody please clarify how this thing works, will you?

shrimper53
User Rank
Gold
The reinvention of the "tramp"
shrimper53   12/23/2013 10:16:14 AM
NO RATINGS
Very interesting , and out-of-the -box thinking on the developer's part......... what we really need is VIDEO... to demonstrate exactly how this thing performs and reacts....

It would seem that the top surface would be subject to some rotation however slight, which would then cause the participant to acquire some rotatation also.   Talk about a whole new aspect to the adventure....

Sadly , this is also another illustration of the nanny-state mentality towards trying to eliminate all risk from everything....I do not wish to imply that such fundamental product improvements are not possible, and should not be pursued.  The several comments regarding how a net enclosure would work, and how the thing will actually propel you into the air, whether rotational or angular motion is introduced, etc. point out that often there are unintended consequences to a seemingly good idea.

Let's hope DN can find us some video..... I am very intriqued!

jlawton
User Rank
Gold
Re: Dazed and confused
jlawton   12/23/2013 10:39:31 AM
NO RATINGS
The issue with vertical angular momentum is that a forward or back somersault (or a number of them) is one of the most common moves to be performed on a trampoline, and that requires that angular momentum occurs around one of the horizontal axes. If there is already angular momentum around a vertical axis (ie at right angles to the horizontal axis) then the net rotation would be around some vector sum of the angular momenta ie at some intermediate angle, which could be EXTREMELY difficult for the performer to adequately manage, and would make it almost impossible to do normal stunts at the competition level. Not promising at all.

Mark Ravonsheed
User Rank
Iron
Good group engineering project
Mark Ravonsheed   12/23/2013 10:30:09 AM
NO RATINGS
This seems to be a great design and as far as safety is concerned, if this unit reduces the total reported injuries to half, then there should not be any discussion about the cost (as long as it is reasonable)

Cost- when the final prototype is approved, then here we come China.

The article did not cover much, may be I missed a more detail one somewhere. It mentioned 3 areas of safety, but except the springs, nothing else was mentioned. Categories: 1- springs 2- metal frame, 3-ground all around.  Items 2 and 3 were left out.

Here are my comments and questions:

Fiberglass- durable, sturdy to a point, repairable, hard, brittle and could easily be shaped. I am aware of flexible type and some use isopthalic flex resin rather than acetone to achieve stronger, clearer and more flexible material, but what ever material they are made up, it must be subjected to tensile and stress test for such an application. (which I am sure it has been done)

What happens if one rod breaks? Will the pieces start flying or break and stay intact?

What would be the minimum bending angle or what is the length of each rod?

Have each rod sitting in it´s own ball/socket housing (fixed or removable) on the frame, doesn´t each require lubrication on the frame and under the mat?

If breakge is a problem, then have they invented a ball/socket housing that can rotate on another "whatever" that is free to move up to 360 deg. in X,Y and Z axis without breaking the rod?

How does rust and corrosion will effect the ball/socket housing? Steel and higher grade material could be used, then what about the cost?

To what distance to the frame will the rods support the mat? Another words, if the mat is sitting up 100 mm above the frame, then will the rods bend horizontally or lower?

.

.

.

I had a lot more questions and dissection to do, but decided to stop as I see this looks good as a project for a graduating student to learn a lot about safety, materials and effect of outside environment, but as final consumer product, well we need to wait and see.

 

paulzad
User Rank
Iron
Re: Good group engineering project
paulzad   12/23/2013 11:43:42 AM
NO RATINGS
All of this engineering is well and good but has anyone considered the practicality of making those rods from fiberglas and the issue of sun exposure and breakage? Has anyone ever touched a ski pole made of fiberglas after it has seen a few years of use? I suggest you don't try it, because if you slide your hand down the length of a fiberglas rod after it has been used and flexed for several years you will embed hundreds of tiny slivers of fiberglas into your hand ---needless to say very very very painful and good luck getting them out....impossible. 

Mark Ravonsheed
User Rank
Iron
Re: Good group engineering project
Mark Ravonsheed   12/23/2013 2:40:31 PM
NO RATINGS
Please see below.

Ramesh Panday has given a clear explanation of this material.

http://cr4.globalspec.com/thread/45573

 

Ramesh Panday

Hi All,

Glass-reinforced plastic

Glass-reinforced plastic (GRP),[1] also known as glass fiber-reinforced plastic (GFRP),[2] is a fiber reinforced polymer made of a plastic matrix reinforced by fine fibers made of glass. It is also known as GFK (for Glasfaserverstärkter Kunststoff), or simply by the name of the reinforcing fibers themselves: fiberglass.

GRP is a lightweight, strong material with very many uses, including boats, automobiles, water tanks, roofing, pipes and cladding.

The plastic matrix may be epoxy, a thermosetting plastic (most often polyester or vinylester) or thermoplastic.

Fibre Reinforced Plastics (FRP)

Fibre-reinforced polymers/plastics is a recently developed material for strengthening of RC and masonry structure. This is an advanced material and most of the development in its application in structural retrofitting has taken place in the last two decades. It has been found to be a replacement of steel plate bonding and is very effective in strengthening of columns by exterior wrapping. The main advantage of FRP is its high strength to weight ratio and high corrosion resistance. FRP plates can be 2 to 10 times stronger than steel plates, while their weight is just 20% of that of steel. However, at present, their cost is high. FRP composites are formed by embedding a continuous fibre matrix in a resin matrix. The resin matrix binds the fibre together and also provides bond between concrete and FRP.

The commonly used fibres are Carbon fibres, Glass fibres and Aramid fibres and the commonly used resins are polyester, vinyl ester and epoxy. FRP is named after the fibre used, e.g. Carbon Fibre Reinforced Polymer (CFRP), Glass Fibre Reinforced Polymer (GFRP), and Aramid Fibre Reinforced Polymer (AFRP).

The fibres are available in two forms

(i) Unidirectional tow sheet, and

(ii) (ii) Woven fabric.

The application of resin can be in-situ or in the form of prefabrication of FRP plates and other shapes by pultrusion. The in-situ application is by wet lay-up of a woven fabric or tow plate immersed in resin. This method is more versatile as it can be used on any shape. On the other hand, prefabrication results in better quality control. The manufacturers supply these materials as a package and each brand has specific method of application, which is to be followed carefully. Specialized firms have developed in India also, which take up the complete execution work and supply of material. It is important to note the difference between the properties of steel and FRP and it should be understood that FRP cannot be treated as reinforcement in conventional RC design methods

Mark Ravonsheed
User Rank
Iron
Good group engineering project
Mark Ravonsheed   12/23/2013 2:23:17 PM
NO RATINGS
The more I read and analyze the project, it seems that the inventor thought of the idea as another invention regardless of practicality or the cost for the end user.

See : http://en.wikipedia.org/wiki/Keith_Vivian_Alexander

The gentleman is an inventor and this unit has been available since 1999. Being in such a position, receiving grants and sponsorship is much easier for him than any high school teacher. As I mentioned earlier, this must have been a project for a group of young engineers.

Larger picture could be seen here:

http://upload.wikimedia.org/wikipedia/commons/9/9b/SF40_full_opencomp.jpg

bobjengr
User Rank
Platinum
SPRING-FREE TRAMPOLINE
bobjengr   12/23/2013 2:38:21 PM
NO RATINGS
 When our kids were small, we purchased a trampoline as a Christmas present.  They loved it.  It was the center of attraction for days to come, THEN, one Sunday evening I heard a blood-curdling scream.  Our oldest son lost his balance, fell and hit his head. Eight (8) stitches later, we returned home from the ER all the wiser.  He actually hit the supporting bar and not the springs.  I feel the springs are the lesser evil in the design.   If there was some alternative to that support I would love to see it.   

etmax
User Rank
Gold
Spring free (not really, just not conventional)
etmax   12/23/2013 11:57:30 PM
NO RATINGS
I think I've seen one of these, or one very much like it. My only question would be how much circular twist occurs during compression, and what it means to the user??

Springfree
User Rank
Iron
Re: Spring free (not really, just not conventional)
Springfree   12/24/2013 12:23:11 AM
NO RATINGS
Hi Everyone,

Thank you for your comments on the Springfree Trampoline design.

This product launched to consumers ten years ago and there are literally thousands of happy families with Springfree Trampolines in their backyards all over the world.

We now sell and distribute into 29 countries including Canada and the US as well as Australia and New Zealand.

For those of you wanting more information and keen to see the product in action, our website contains a great deal of material and some good video footage presented by Dr Alexander. The following link will take you to the Safety Features part of our site where you'll see most of the design features in action.

http://www.springfreetrampoline.com.au/safety-benefits

Thanks again and I hope you have a chance to experience a Springfree Trampoline sometime soon. Our customer satisfaction and feedback is a real life testament to the difference that good design can make to the safety of products like trampolines.

Nichole Kelly

Springfree Trampoline Australia 

Partner Zone
More Blogs from CAD/CAM Corner
The Business Advantage Group recently released its 2014 Worldwide CAD Trends Survey, announcing both a prospective increase in the cloud-based CAD industry and the anticipated incorporation of 3D printing.
Easel was created with beginners in mind. It acts as sort of a gateway app that takes novices from project inception to actual milling in just five minutes.
Autodesk, a leader in 3D design solutions, announced earlier this month that it has completed its acquisition of Delcam, a leading supplier of CAD/CAM manufacturing software, in its efforts to expand the company’s manufacturing software capabilities.
3D Systems absorbs Xerox’s Solid Ink Engineering to further expand its 3D printer prowess.
Texas Instruments' Webench is vying to win the Golden Mousetrap Award in the Analysis & Calculation Software category, but it is up against some pretty tough competition from Mentor Graphics, COMSOL, and aPriori Inc.
Design News Webinar Series
3/27/2014 11:00 a.m. California / 2:00 p.m. New York / 7:00 p.m. London
2/27/2014 11:00 a.m. California / 2:00 p.m. New York / 7:00 p.m. London
12/18/2013 Available On Demand
11/20/2013 Available On Demand
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Apr 21 - 25, Creating & Testing Your First RTOS Application Using MQX
SEMESTERS: 1  |  2  |  3  |  4  |  5


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: April 29 - Day 1
Sponsored by maxon precision motors
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service