How strong is an Aluminium Canopy?
Posted: Mon Mar 25, 2019 5:58 pm
We have been asking this question for a long time now, and at the beginning of the year we decided that we are going to find out... And we did..
Here is how it went down...
Ever wonder about the structural strength of your aluminium canopy? Will it maintain its structural integrity in case of a roll-over? Well this weekend we incorporated an experiment into the first Dust Series Qualifier of 2019 to determine how long an all aluminium canopy will last when you drive huge 4x4 vehicles over it. Will the doors still open and close, will the windows pop out? Will the canopy collapse? Will we make complete fools of ourselves? Will there be a cold beer to celebrate afterwards? These were some of the questions in the forefront of the minds of our guys and the canopy manufacturer.
In order for the experiment to be successful we determined that only 1 or maybe 2 vehicles need to drive over the canopy without the structure collapsing. This would mean that more or less 2 rollovers should be survived.
So we went in search of an aluminium canopy manufacturer who would be brave enough to put their product up for this experiment. One of the bigger manufacturers were on board immediately with grand plans on how they will tackle the problem and even build custom ramps to make things easier for the vehicles to get up and down from the canopy. Unfortunately as the time grew nearer, it seems like doubts were creeping in and less than 2 weeks before the great event, they pulled out. This left us without a canopy, and the hunt for a new supplier began all over again.
This time we got hooked up with Juan Fouche from Razorback canopies. Juan was slightly apprehensive about our whole idea to start off with, but we reassured him that we will do a test before the day of the event as a "proof of concept". With that we got hold of some ramps, adjusted them to fit and we ran our test 1 day before the time. Juan was sent a video clip and he was satisfied we are not just messing around. For this test we used Charles Muller's very fine V8 Hilux D/C bakkie which weighs in at 2.3 tons! Relief all around, now we can let this concept loose on the masses out there!
How did we do it? Firstly we decided to focus on the canopy structure and not so much the roof skin. As the roof skin is only there to keep the rain off you luggage and not to support a bunch of weight, especially not concentrated weight like 2 wheels on an axle carrying more than 1 ton. That is a LOT of PSI right there concentrated on an area not much bigger that 2 (or maybe 4) hand palms. We eliminated that by letting the vehicle run on a set of fibreglass traction grids, slightly elevated (48mm) above the roof skin. To make sure the weight of the vehicle gets transfered to the sides, we bolted a 48mm thick beam along the length of the roof on both the entry and exit side, on which we rested the grids. That had the roof skin sorted.
As a further safety mechanism, we placed supports, in the form of wooden pallets, on the inside of the canopy leaving about 7cm of space between the inside of the roof and the top of the supports. This was done just in case the roof skin, or one (or both) of the grids collapse, and the vehicle falls into the canopy. With the supports in place the vehicle could still be driven off the canopy, without the need for heavy lifting equipment. The 7cm gap would still allow for some flex in the roofskin, and in our test this was also about the amount of flex the grids allowed.
Satisfied that we catered for a complete canopy failure and safe vehicle recovery we were ready for the big day.
The first "obstacle" of the day was a weigh bridge exercise. Every vehicle drove onto a mobile weight pad to detemine the weight on the front and rear axle and a combined mass. The drivers had no idea at the time what this was for, but we had a plan.
At the very last obstacle, the drivers were lined up to drive over the canopy, and as every vehicle passed over the makes, and combined mass was recorded on the roofskin of the canopy in black permanent marker. All the spectators were waiting in anticipation for a spectacular collapse as eavh vehicle drove up, and when Gert in his 3.1 ton Patrol pulled up everybody thought "This is it!!". But alas, it wasnt. The canopy lived on to fight another day.
After all the vehicles crossed over, and all the weights were recorded we tallied it up and came to the total of 35 tons. Juan decided that we should remove the top most pallets from the inside supports, increasing the gap between the roof and supports by 20cm. We called for volunteers to drive over and Kobus volunteered his 4.5 D/C Land Cruiser to do the final run. To everybody's surprise the canopy held up, and with the support of the grids, there was almost no difference in the amount of flex on the roof skin. But as they say in the classics, "prevention is better than getting a crane in".
After all was said and done, all the windows were still in tact, and the doors openend and closed as per usual. There were some scuff marks on the sides where the ramps rubbed against it, and the roofskin was slightly warped, but after enduring 36 tons that is to be expected. The rivets holding the roofskin in place were all still 100 in tact as well. The only other damage was the sealant between the roofskin and the frame. That was destroyed as it pulled loose. So maybe the canopy will be slightly leaky, but it is still structurally intact.
As a world first, we can proudly say that the Razorback canopy passed with flying colours. The experiment was a huge success. With these results one can safely prove that an aluminium canopy will perform the same and even better in a roll over than a roll bar. Obviously this depends greatly on the manner of fitment, so that it does not seperate from the vehicle, but with sturdy fitment with the proper brackets and nuts and bolts, it should stay in place.
So here we have proved beyond a shadow of a doubt that a Razorback Aluminium Canopy can withstand the forces of 15 vehicles and a combined mass of almost 36 tons driving over it without structural damage. With the heaviest vehicle weighing in at 3.1 tons.
Well done to everybody involved, from Razorback for the canopy, Massametric who supplied the weigh bridge, Burnco and Allbilt for the use of their ramps and then the Team Offroad team who tested and executed the experiment. We cannot thank you guys enough.
Somewhere I heard a little birdie whistle in my ear that we might do this again next year.. with a newer model canopy.... We will keep you guys posted.
Here is how it went down...
Ever wonder about the structural strength of your aluminium canopy? Will it maintain its structural integrity in case of a roll-over? Well this weekend we incorporated an experiment into the first Dust Series Qualifier of 2019 to determine how long an all aluminium canopy will last when you drive huge 4x4 vehicles over it. Will the doors still open and close, will the windows pop out? Will the canopy collapse? Will we make complete fools of ourselves? Will there be a cold beer to celebrate afterwards? These were some of the questions in the forefront of the minds of our guys and the canopy manufacturer.
In order for the experiment to be successful we determined that only 1 or maybe 2 vehicles need to drive over the canopy without the structure collapsing. This would mean that more or less 2 rollovers should be survived.
So we went in search of an aluminium canopy manufacturer who would be brave enough to put their product up for this experiment. One of the bigger manufacturers were on board immediately with grand plans on how they will tackle the problem and even build custom ramps to make things easier for the vehicles to get up and down from the canopy. Unfortunately as the time grew nearer, it seems like doubts were creeping in and less than 2 weeks before the great event, they pulled out. This left us without a canopy, and the hunt for a new supplier began all over again.
This time we got hooked up with Juan Fouche from Razorback canopies. Juan was slightly apprehensive about our whole idea to start off with, but we reassured him that we will do a test before the day of the event as a "proof of concept". With that we got hold of some ramps, adjusted them to fit and we ran our test 1 day before the time. Juan was sent a video clip and he was satisfied we are not just messing around. For this test we used Charles Muller's very fine V8 Hilux D/C bakkie which weighs in at 2.3 tons! Relief all around, now we can let this concept loose on the masses out there!
How did we do it? Firstly we decided to focus on the canopy structure and not so much the roof skin. As the roof skin is only there to keep the rain off you luggage and not to support a bunch of weight, especially not concentrated weight like 2 wheels on an axle carrying more than 1 ton. That is a LOT of PSI right there concentrated on an area not much bigger that 2 (or maybe 4) hand palms. We eliminated that by letting the vehicle run on a set of fibreglass traction grids, slightly elevated (48mm) above the roof skin. To make sure the weight of the vehicle gets transfered to the sides, we bolted a 48mm thick beam along the length of the roof on both the entry and exit side, on which we rested the grids. That had the roof skin sorted.
As a further safety mechanism, we placed supports, in the form of wooden pallets, on the inside of the canopy leaving about 7cm of space between the inside of the roof and the top of the supports. This was done just in case the roof skin, or one (or both) of the grids collapse, and the vehicle falls into the canopy. With the supports in place the vehicle could still be driven off the canopy, without the need for heavy lifting equipment. The 7cm gap would still allow for some flex in the roofskin, and in our test this was also about the amount of flex the grids allowed.
Satisfied that we catered for a complete canopy failure and safe vehicle recovery we were ready for the big day.
The first "obstacle" of the day was a weigh bridge exercise. Every vehicle drove onto a mobile weight pad to detemine the weight on the front and rear axle and a combined mass. The drivers had no idea at the time what this was for, but we had a plan.
At the very last obstacle, the drivers were lined up to drive over the canopy, and as every vehicle passed over the makes, and combined mass was recorded on the roofskin of the canopy in black permanent marker. All the spectators were waiting in anticipation for a spectacular collapse as eavh vehicle drove up, and when Gert in his 3.1 ton Patrol pulled up everybody thought "This is it!!". But alas, it wasnt. The canopy lived on to fight another day.
After all the vehicles crossed over, and all the weights were recorded we tallied it up and came to the total of 35 tons. Juan decided that we should remove the top most pallets from the inside supports, increasing the gap between the roof and supports by 20cm. We called for volunteers to drive over and Kobus volunteered his 4.5 D/C Land Cruiser to do the final run. To everybody's surprise the canopy held up, and with the support of the grids, there was almost no difference in the amount of flex on the roof skin. But as they say in the classics, "prevention is better than getting a crane in".
After all was said and done, all the windows were still in tact, and the doors openend and closed as per usual. There were some scuff marks on the sides where the ramps rubbed against it, and the roofskin was slightly warped, but after enduring 36 tons that is to be expected. The rivets holding the roofskin in place were all still 100 in tact as well. The only other damage was the sealant between the roofskin and the frame. That was destroyed as it pulled loose. So maybe the canopy will be slightly leaky, but it is still structurally intact.
As a world first, we can proudly say that the Razorback canopy passed with flying colours. The experiment was a huge success. With these results one can safely prove that an aluminium canopy will perform the same and even better in a roll over than a roll bar. Obviously this depends greatly on the manner of fitment, so that it does not seperate from the vehicle, but with sturdy fitment with the proper brackets and nuts and bolts, it should stay in place.
So here we have proved beyond a shadow of a doubt that a Razorback Aluminium Canopy can withstand the forces of 15 vehicles and a combined mass of almost 36 tons driving over it without structural damage. With the heaviest vehicle weighing in at 3.1 tons.
Well done to everybody involved, from Razorback for the canopy, Massametric who supplied the weigh bridge, Burnco and Allbilt for the use of their ramps and then the Team Offroad team who tested and executed the experiment. We cannot thank you guys enough.
Somewhere I heard a little birdie whistle in my ear that we might do this again next year.. with a newer model canopy.... We will keep you guys posted.
