Saturday, 17 April 2010
Exploded Third Crane Design
The image below shows the exploded view of the third and final crane design. This image also contains a list of components and their quantities.
Tuesday, 13 April 2010
Crane Foot Base Options
The following image is a rendered picture of four potential crane foot base options.
These foot bases will be analysed from left to right:
- The first is the original foot base, as described by the previous CAD drawings. This foot base is quite basic and versatile, though since it will be supporting the crane foot on an angle it may be prone to slippage in wet conditions.
- The second is a revised foot base. This foot base has been slanted to the angle of the crane foot. The bottom has also been altered to have a series of groves, increasing the friction of the foot base with the ground. This design would greatly improve the stability of the crane, though would require a small flat surface to rest upon. It would also require orientating to the angle of the crane foot.
- The third design is a modified version of the previous design with all the same benefits over the original design. However this design has a reduced surface area of contact, thus the area beneath the foot base need not be as flat. This however may slightly reduce the stability of the crane, and this type also requires orientating.
- The final design is a spike design. This would be particularly useful in soft ground to help anchor the crane, however it would be useless on a solid surface such as concrete or tarmac.
In conclusion, I believe that since these foot bases have been designed to be removable, multiple types should be provided in the pack to suit different situations. I will take this matter up with the rest of the team in the next group meeting.
These foot bases will be analysed from left to right:
- The first is the original foot base, as described by the previous CAD drawings. This foot base is quite basic and versatile, though since it will be supporting the crane foot on an angle it may be prone to slippage in wet conditions.
- The second is a revised foot base. This foot base has been slanted to the angle of the crane foot. The bottom has also been altered to have a series of groves, increasing the friction of the foot base with the ground. This design would greatly improve the stability of the crane, though would require a small flat surface to rest upon. It would also require orientating to the angle of the crane foot.
- The third design is a modified version of the previous design with all the same benefits over the original design. However this design has a reduced surface area of contact, thus the area beneath the foot base need not be as flat. This however may slightly reduce the stability of the crane, and this type also requires orientating.
- The final design is a spike design. This would be particularly useful in soft ground to help anchor the crane, however it would be useless on a solid surface such as concrete or tarmac.
In conclusion, I believe that since these foot bases have been designed to be removable, multiple types should be provided in the pack to suit different situations. I will take this matter up with the rest of the team in the next group meeting.
Monday, 12 April 2010
Calculations for pins using the smallest and largest pins
Using the info mark published on hex bolts i decided to calculate the shear stress that would be experienced M12/ smallest bolt (largest stress) and the M36/ biggest bolt (smallest stress). I also calculated the stress on the leg pins by using the dimensions in mark's cad drawings. I found that the largest stress obtained was 92mpa when using the M12 bolts, which is not a problem as carbon steel generally has a shear stregnth of 42000psi = 289.5mpa.
Clevis Pin Types
Having chosen Clevis Pins as the type of beam pins, it is now important to decide on a type of pin. It would be of benefit if all pins and bolts in the kit were the same, thus reducing assembly time as any bolt would fit any hole.
The image below shows a selection of pin types. The most appropriate for this crane would be either the SAE pin or the Bent pin. Once the stress analysis on the legs has been completed I shall use that information to select an appropriate standard pin for this crane.
http://www.huyett.com/catalog/index.php?cPath=21_30&gclid=CLWA-cbKgaECFSEulAod7wabuA
The image below shows a selection of pin types. The most appropriate for this crane would be either the SAE pin or the Bent pin. Once the stress analysis on the legs has been completed I shall use that information to select an appropriate standard pin for this crane.
http://www.huyett.com/catalog/index.php?cPath=21_30&gclid=CLWA-cbKgaECFSEulAod7wabuA
Painting Safety Note
It is worth noting that since the legs are made from aluminium, it is necessary to adopt caution when choosing a primer paint. The following formula describes the oxidation of aluminium:
Fe2O3 + 2Al → 2Fe + Al2O3 + heat
When ignited, this reaction of aluminium and iron oxide produces liquid iron which can melt though almost anything. The military would call such a mixture thermite, and it would be used in incendiary devices.
This reaction would occur if the crane legs were painted with an iron oxide based primer paint such as Red Oxide. This particular type of paint is a common primer when painting metals, however it would be highly inappropriate to paint aluminium with it in a disaster zone where there would like be many large and uncontrolled fires.
The type of primer more suited to this environment would be an Epoxy Mastic metal primer or similar.
Fe2O3 + 2Al → 2Fe + Al2O3 + heat
When ignited, this reaction of aluminium and iron oxide produces liquid iron which can melt though almost anything. The military would call such a mixture thermite, and it would be used in incendiary devices.
This reaction would occur if the crane legs were painted with an iron oxide based primer paint such as Red Oxide. This particular type of paint is a common primer when painting metals, however it would be highly inappropriate to paint aluminium with it in a disaster zone where there would like be many large and uncontrolled fires.
The type of primer more suited to this environment would be an Epoxy Mastic metal primer or similar.
Potential Changes to Third Shoulder Design
The following image describes three possibilities for the third crane shoulder.
They are as follows:
-The one on the left is the design described in detail in my previous post
-The middle one is the same as the first, only with the top removed. This would reduce manufacturing cost and weight, though as the anchoring system of the shoulder to the beam is now essientially an open system, this woyuld significantly decrease the strength.
-The one on the right is a box design, essentially the same as the first design except in one solid block. This would increase the stability of the anchoring of the beam into the shoulder, though at the same time would significantly increase the cost of manufacture and the weight of the leg as a whole.
In conclusion I believe the original design is the most suitable, though in order to be certain this requires farther stress analysis to find the best design.
They are as follows:
-The one on the left is the design described in detail in my previous post
-The middle one is the same as the first, only with the top removed. This would reduce manufacturing cost and weight, though as the anchoring system of the shoulder to the beam is now essientially an open system, this woyuld significantly decrease the strength.
-The one on the right is a box design, essentially the same as the first design except in one solid block. This would increase the stability of the anchoring of the beam into the shoulder, though at the same time would significantly increase the cost of manufacture and the weight of the leg as a whole.
In conclusion I believe the original design is the most suitable, though in order to be certain this requires farther stress analysis to find the best design.
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