System Analyst Project Review

In general the project ran smoothly throughout the period, and due to a strict schedule the progress in which the project developed was smooth and of a quick pace. During the Easter holidays the work was carried on, despite a little communication issue, the level of work stayed constant.

Over the holiday period I was out of contact for the beginning of the holidays and it was only towards the end of the holidays that I was able to get in touch with any of the group. This slowed down the rather rapid pace that had been maintained for the beginning of the project slightly. However as soon as contact was re-established then I was able to get back up to speed with the rest of the group without any problem.

Our Materials Expert was absent for the first few weeks of the project, and after finally get a hold of him we found out it was due to illness. However apart from this little hiccup when the work was set he was able to perform at the level desired.

One of the major difficulties that arose for me was the continuous alterations of the beam, so therefore the amount of times the force analysis had to be done for each new design. The method would have been easier if a set model was created on a program like excel and the calculations could have been produced much quicker. However with the final design being of British Standards we were able to compare our calculations with benchmarks so we knew that the system would not fail and we weren't just taking a stab at it.

One of the main problems with the design was that the main component of the crane, the beam, was not collapsible so it could only be transported on either the top of the land rover type of 4x4 or on the landing booms of a helicopter, instead of in the loading bay with the actual kit. This is a restriction of the design but weighing that against critically weakening the design I believe it was the right path to take.

Overall the project went well and through the vigilance of the project manager, who made sure everything was to be done quickly and efficiently were able to complete the project without having to rush anything.

Revised Calculations

From the analysis done to work out how much length was needed for an object to move 4m maximum from one point to another it was calculated that the beam would have to be a minimum standard length of 5.5m

Revising the calculations done at an earlier date a delfection of 12.29mm was established with the same CSA.

Presentation

I have started on the presentation that is due next Wednesday. A few of the presentation slides have been completed and have been sent to the group Manager.

This is just a print screen of some of my initial workings

Machining Cost

One of the questions that needs to be answered is how much it is going to cos to make the crane. The beam is of a standard design and can be purchased pre-made and cut to the required length. However the legs must be specially made and a machining cost must be evaluated.

First and foremost we must look at the different types of tools that could be used to cut the aluminium into the specified dimensions.

High Speed Steel

This material was invented in the 19th century and was a massive improvement on the standard cutting tools of that time since they can function under higher speeds and hotter temperatures than standard steel tools. Out of all the tools researched this has the lowest range of cutting speeds, however it is still able to cut aluminium to a rough finish, but the life of the tool is significantly small when cutting this material. However the material is the cheapest type of tools looked at.

Cast Alloys

This material is a standard base metal (e.g. iron) which has been augmented with an alloying element (e.g. nickel, tungsten, chromium etc.). The reason for doing this is to improve the metals strength and reaction to heat. This group of cutting tools can operate at higher cutting speeds and temperatures than High Speed Steel, and the tool life is significantly higher. The price of these tools are also quite reasonable.

Carbides

Strong metal such as titanium are part of the this group of materials, and are used in some of the most extreme situations, for example they are used to construct the fuselage of space shuttles which are put under the most extreme temperature any material could be put through. In relation to cutting tools, this material is second only to certain ceramics in cutting speed and operating temperatures. The pieces are highly expensive though.

Price for Cast Alloy cutting tools = approx £20.00 (set of 11 cutting tools)

source: axminster tool centre

Ceramics

As mentioned before this the type of cutting tool that is second to none. Ceramic is the name given to most crystalline oxide structures, such as silicon carbide, saolin, titanium carbide. The strength of this material has been proven through the use in space shuttle re-entry shields, military ballistic vests, and heavy duty abrasives. Yet, as said with the carbides ceramics are very expensive to produce so the tool prices are very dear, but the tool life balances that out quite well.

By looking at this research it can be said that for the current project using Cast Alloy tools would be the most beneficial to the production of the cranes.

area of aluminium = 1.88 m^2

cutting speed = 1.1-1.8 m/sec (66-108 m/min)

life of cutting tool when cutting to a finished result = approx 175 mins

cost per cutting tool = £20/11 = £1.82 per tool

tool cost = £1.8/175mins = £0.01/min

minimum wage of machine operator = £6/per hour = £0.1/min

Machining Cost = Co x tm

Co = operator wage + overhead

overhead = life of tool + material able to be cut by tool per minute

tm = amount of time needed for task to be completed

Machining Cost = £241 per/min

This is quite a reasonable cost seing as the amount of material that can be machined within a minute will make up multiple kits.

source of calculations: Handbook of Material Selection, Myek Kutz, 2002 edition, published by John Wiley & Sons New York.

other sources:

http://en.wikipedia.org/wiki/Ceramic_materials

http://en.wikipedia.org/wiki/Carbide

http://www.thefreedictionary.com/alloy+cast+iron

http://www.wisegeek.com/what-is-high-speed-steel.htm

Beam Length Analysis

The beam length is determined on a few conditions and they are:

• The position of the struts at the base of the leg
• The dimensions of the object to be lifted

1/

The struts position is fixed in relation to the beam so therefore

length of leg at full extension = 1.145m

angle leg sits at = 30 degrees

s.t.f:

1.145 x sin 30 = 0.5725m

however the position of the leg in relation to the object is not that simple. Each leg is 120 degrees from each other and two of the legs sit 30 degrees from the plane which runs parallel with the leg itself.

s.t.f

0.5725 x sin 30 = 0.28625m = 286.25mm

2/

The dimensions of the material is not as big a problem as it would seem, because if we for example take the material to be of a cuboid nature (like in the load dimensions calculated) then if the worst case scenario set is that the material is 4.16m long then we can just work at a different angle by position the crane so we work on a plane with gives more room for the object to moved. However if we come upon a scenario where the material is the same distance no matter what way you take it, for example circular.

The volume of the worst case scenario = 0.3744m^3

s.t.f

pi x r^2 x l = 0.3744m^3

in the previous examples l = 450mm so it will be used in these calculations.

s.t.f

r = 0.515m

So from these two calculated results we can say that if the load has to be moved 4m then the length of the beam must be:

4m + 0.515m + (2 x 0.28625m) = 5.0875m

The beam has also got to have an extra 0.290m added to this length since it must sit in the shoulders. So therefore the overall minimum length needed is 5.3775m

With this it can be deduced that we need to use the standard length of 5.5m for the beam so that in the worst case scenario picking up the most common material.

Types of Transport

The kit is needed to be transported to the disaster site so there is a few criteria that needs to be fulfilled if it is to perform the task required.

• It must be able to carry the entire crane kit (including the beam)
• It must be able to carry all four people to the site
• It must be able to traverse very rough terrain
• It must be able to reach every site that the crane is needed in case the crane needs to be transported over long distances.

Car

They are widely used and comes in a variety of shapes and sizes. If the vehicle is of the right design then it can carry all the people required and should be able to traverse the environment with ease, especially if it has 4 wheel drive. Since most cars that would be chosen for this are of a moderate size and are quite nimble they should be able to reach most of the scenarios that it might come up against. The only drawback is that the internal storage space may not be sufficient to store the kit. The kit can be strapped to the top of the care but then there would be risk of damage since it is not protected by the vehicle.

Hovercraft

Hovercraft were designed so as all terrain vehicles; this is because the only thing between the vehicle and the ground is air so there is nothing it cannot traverse. The storage space and number of people which can be transported is dependant on the size and they range of single seated to ferry sized. The only downside to these vehicles is if the skirt of the hovercraft is damaged or one of the props powering the hover propellers is damaged then the vehicle would be useless and would take awhile to repair.

Van/Truck

Both modes of transport are big enough to store and transport the kit to wherever it needs, and both have sufficient engine power. The passenger space in both is not as could as the cars, however it would suffice. The only difference between the two is that in most cases the clearance between the ground and the chassis of the van is not a lot and may cause the vehicle to beach on a protruding bit of ground. The truck however has sufficient clearance and can reach most situations without duress.

Looking at the pros and cons of each mode of transport, the only one that full fills all the necessary requirements is the truck. So therefore the most obvious vehicle that should be encouraged to be used is such.

Beam Restrictions

It was brought up that since the beam could not be laid flat in the bed of a pick up truck the component should be split into sections and then packed with the rest in the kit. A few options were brought up, for example:

Joints Attachments

If the beam was cut into sections it would basically be put back together with joint attachments and screws and bolts. It would restrict the beam from rotating or pivoting in an unnatural manner and it would be easy to assemble and disassemble. The image below is a rough interpretation of the idea put foward.

Source: http://www.freepatentsonline.com/6802169-0-large.jpg

Pinned Joints

Probably the simplest idea that was produced. The beam could be split into sections and a male/female connection be cut into each section. Then each joint could be held together by a simple bolt and nut. This idea would be the quickest and most efficient way of splitting the beam. The idea does have flaws, one being that the restraints on the joint do not prevent the pieces from pivoting.

These ideas however all have one thing in common and that is that they will drastically increase the beams chances of failing. This is due to a phenomenon known as Stress Concentration.

Stick Welding

This is the strongest idea produced. If the beam was to transported to the event and when it is to be used, each part is welded together. When the beam is needed somewhere else the beam does not need to be separated again so it can be carried as a whole piece. This does however mean that a stick welding kit would be needed when the crane is being used and someone qualified would have to construct it, but stick welding is one of the quickest and simplest welding procedures it should not take too long to assemble.

http://static.howstuffworks.com/gif/stick-welding.jpg

All these ideas however have one thing in common, they would all increase the chances of failure massively. This is because of a phenomenon known as Stress concentration.

Stress Concentration

Definition: (mechanics) A condition in which a stress distribution has high localized stresses; usually induced by an abrupt change in the shape of a member; in the vicinity of notches, holes, changes in diameter of a shaft, and so forth, maximum stress is several times greater than where there is no geometrical discontinuity.

source: http://www.answers.com/topic/stress-concentration

If the beam was to be put into sections discontinuities in the geometry would have to be created and as stated would greatly increase the force applied to that point.

The Stress Concentration is measured as the Stress Concentration factor which is either calculated through theoretical methods or by using finite element methods. It calculates the stress along the axis of the discontinuity with stress applied on that point. The factor is a function of the geometry of the discontinuity and not the size, which means it does not matter how big it is, but of what shape it is.

Winch Impairment

Another issue that will arise is the track on which the winch will run will be distorted. This will either restrict or slow down the functioning of the crane, which in turn causes the crane to be unsafe and unreliable.

An example is a simple hole through a sample cause the force lines to distort in the manner shown below.

So in conclusion it would not be plausible to make the beam in sections to be put together otherwise it would undermine the quality of the crane, the safety of the people working with it and general sales of the product. The beams strength is dependant on it being one complete object

Transport Research

Probably the most common and most useful vehicles to use in an environment affected by a natural disaster would be a type of 4x4 pick up truck. However there are many different types to choose from.

Compact Pick up Trucks

This is the most common type of pick up truck on the marked, being that is the original type from when the design was first invented in the 60's. As it says in it's name the vehicle compact so it will be able to fit into situations that normal trucks wouldn't. However the bed is quite small and the cab only holds two people, however the other two people needed on the crane can sit in the bed anyhow.

Ford Ranger XLT 2009

Full-Size Pick up Trucks

This type of truck is designed to carry heavy loads and carry it over rough terrain. Most standard trucks of this nature can carry up to 450kg in the bed, and others can carry up to six times as much as that. The bed is usually designed to be around 1.2m x 2.4m in area. With rear wheel drive and 4 wheel drive as an optional, this truck can handle most terrain, especially if it is powered by a v10 engine. The largest type of this pick up truck are called "duallies" since they have 4 rear wheels, two on each side with an axle between. This would suit the requirements needed however the vehicle might be too cumbersome, and could get trapped in a tight squeeze.

Ford F-150 2007-2008 (extended)

Mid-Size Pick Up Trucks

This is the all rounder of the family. It has the advantages of being smaller than a full-size pick up truck and can carry the same load as one. It also has the option of having the bed in a longer, and wider style, the Toyota show has can come with a long bed 1.87m by 1.44m. The original models of these did not have the engine power needed to traverse extreme conditions, for example in an earthquake zone, however the newer models like the Toyota shown can come with a V6 engine. They have even more durability since they can also come with a double cab, which allows all four people to sit within the cab and not risk sitting in the bed with the gear.

Toyota Tacoma TRD 2001-2004 (extended cab)

Sports Utility Trucks (SUT)

The SUT is a cross breed between a Full-size pick up truck and a SUV (Sports Utility Vehicle). Where the cab is quite large so it can fit more people (up to 6 passengers) but it has a bed on the back designed for light or heavy loading. It would be very useful, however the design is a bit too much for what it is needed for and much would go to waste.

Dodge Ram 1500 crew cab

I believe looking at the choices the Mid-Size pick up truck is the best choices since it is the most adaptable out of all of them and even thought the bed is not as long as the full-size pick up it will suffice and it will be able to go into situations that it's larger brethren would not.

source: http://en.wikipedia.org/wiki/Pickup_truck#Types_of_pickups

This is the calculated deflection and characteristics of the beam when its length is 5m long. As you can see form the previous set it is heavier and has a larger deflection. So for the benefit of the design it would be beneficial to make the beam 4.7m long.

Revised Beam Analysis

This is the revised calculations of the beam as requested at a length of 4.7m with the specified CSA. I will get the calculations for 5m and the legs hopefully tomorrow.

System Calculations

These are the calculations that have been worked out for the design we chose.

Jason Harries - Initial Design

My train of thought was based on the idea of simplicity and for that reason I researched into the history of cranes and got some ideas from the Ancient Romans.

Pentospastos

This was a simple crane design that used a simple triangular frame and a block containing three pulleys which is attached to a manual winch. With this formation it could could lift over 1000kg.

The general design is simple and depending on the material used it could withstand the forces required of it.

However the design will not allow it move the load too far, so the design must be altered if it is to fullfill the required result.

Also places to peg the support cables may be hard to find in a disaster scenario.

Polyspastos

This is a crane of simlair design to the Pentospastos but on a larger scale. This one has multiple lines coming from the winch to pulley block which gives it the ability to lift more weight.

This design has the same flaws as the first one, and to lift the larger force either a large human force would be needed or a mechanical force would be needed to turn the winch.

The designs do not completely full fill the required specification but the idea can be modified so that it can perform as needed.

Meeting 2 (08/03/2010)

The register was taken and the same people from Meeting 1 were present.

Firstly discussed researched ideas that each group member looked at over the weekend.

Some ideas had some obvious flaws which may need to be remedied.

The group debated on the interpretation of the design brief and will take this up with Mr Thomson.

Meeting 1 (05/03/2010)

Meeting was had on recorded date and what was discussed was:
- Contact details between group members
- Setting up of blog
- Job allocations
- Minutes

The contact details were distributed between the members that attended, Jarrett Doherty was not present. As you can see the blog has been created so all of the members can access and contribute to it.

The Jobs were allocated as listed:

Sandra Donohoe - Project Manager
Mark Hawkins - Chief Designer
Jason Harries - Stress Analyst
Abdirahman Elmi - Finance Officer

The materials specialist has not been allocated due to the fact that Jarrett Doherty was not here, so therefore the job will be split between the current four unless a new member arises.

Chief Designer presented 5 sketches with initial ideas.

Project Manager has created a timetable so a record of meetings can be kept.

For the next meeting each member needs to research the current market.