Engineering Studies- HSC Course Essay Example

bending because it is quite stiff due to its hard nature (mentioned in paragraph 1).

Regrettably, due to steels exceptional stiffness, it is has very low shock abortion, making a steel frame rather uncomfortable to ride. When joining comes into consideration, steel loud have to be one of the easiest to fabricate. There is an abundant amount of joining methods for steel, such as brazing or welding. Once welded it can still be modified to a large degree. Overall, it is rather inexpensive, also has excessive tempering properties; it allows this immensely tough alloy to be affordable. Cost is low, high strength, easy to join and will last lengthy amounts of time.

Sadly it is considerably heavy, corrodes easily and would be uncomfortable to ride (no shock absorption). (http://en. Wisped. Org/wick/Heat_treating)( http://en. Wisped. Org/wick/ Reynolds_Cycle_Technology) (www. Plainclothesman. Mom, 201 3) Reynolds XSL 00 Reynolds X 100 is an alloy made up of the elements Aluminum and Lithium (4. 2% L I), this alloy is not as strong as steel (in some cases it contains copper, zirconium & magnesium). Aluminum is widely used in modern day society, not so much a bike frame component but as power lines, lightweight transformed, and some cars.

So it is widely available, and although aluminum on its own cannot compete, the alloy 'X 100' is a contender. In this alloy, the combination of aluminum and lithium create relatively good strength. The strength of OXIDE, although not steel quality is still strong, they use efferent methods after the alloy is created to give it strength. Two of the methods that are used to prepare the alloy for a bike frame are

strain hardening and precipitation hardening. Even with these hardening techniques, it is thought to be one-third the strength of steel. With the added lithium, aluminum becomes less dense and the stiffness is steeply increased.

The strength of this alloy is questionable, but with this lack of strength comes another property, it is extremely light. When it comes to bike frames weight is obviously exceedingly important, and this alloy happens to be weightless in imprison to steel. The amazing thing about 'Reynolds X 100' is that instead of deteriorating over time it will in fact begin to harden over lengthy amounts of time (age hardening). A topic related to strength is resistance to corrosion, and unlike 'Reynolds 853', Reynolds X 100 has an exceptionally great resistance to rust.

Aluminum is known for stopping rust as it forms an oxide layer over its surface, preventing the start of decay. The element aluminum is noted for its terrible resistance to fatigue, and aluminum going under stress for lengthy amounts of time will amount to ever damage. This is a trait one would think removes it completely from a bike frame, but with the addition of lithium that changes. The inclusion of lithium in Reynolds X 100 makes sure to block any dislocations within the alloys crystal structure, giving it an outstanding fatigue resistance.

Reynolds X 100 as stated in paragraph one & two has a lack of strength compared to steel. The best way to deal with this is to increase the tubular diameter making it ovular that makes up the bike frame, hence also making sure that it is very resistant to bending. Though these enlarged and

irregular sections are difficult to design and employ, the added stiffness to the frame is extensive. Un like steel, we see that XSL 00 (due to aluminum) has tremendous shock absorption, making the ride of a 'Reynolds XSL 00' frame much more comfortable. X 100 is a seemingly average alloy, when it comes to joining it follows this path.

To join aluminum it is naturally difficult to welded, and more complicated difficult processes must be used (inert gases are required to join members (MIX)). Conclusively 'Reynolds XSL 00' is more expensive than steel, due to its large percentage Of aluminum, yet still not greatly expensive. In an ethical sense, the production of these bikes will not be wasteful, as aluminum is recyclable. It has great weight, very resistant to forms of decay and resistance to fatigue. Unfortunately, it is very difficult to repair, as the joining methods take large amounts of time and are very costly. (http://www. Dade. Com/products, 201 2) Titanium Alloy There are many different titanium alloys, but by far the most common is It al-IV (http://character. Ides. Com/), this alloy would be most suited to a bike frame. It AI-IV consists of titanium, aluminum, and vanadium (6% AAA, 4% V). This titanium alloy is amazing, as it has only half the density of steel, yet remains significantly strong. Titanium is far superior in strength to aluminum and just below that of steel. Titanium has been viewed as an extremely hardy strong metal for many years, how this will compare to its ability in a bike frame, is to be discussed.

It's known that It al IV, because of the large percentage of

titanium, it is a very stiff alloy, though surprisingly it is very shock absorbent (an. N. M. En. Wisped. Org/Vicki). The level of shock absorption makes this alloy for a comfortable ride, though this is the case strength is not effected, strong & comfortable. When it comes to fatigue resistance titanium is exceptional, it will last similar periods Of time to aluminum. Not only does it have good fatigue resistance but it also has a great level of corrosion resistance. These aspects make it an exceptional choice, and with this in mind could be perfect for a bike frame.

With its strength and fatigue resistance, this alloy comes hand in hand with great resistance to forms of bending, yet it is able to absorb shock effectively. The limitations of the It al-IV alloy, are the methods required to form and fabricate with it. Although it seemed to be the perfect choice, titanium alloys fall short of the mark. Weld cracking is very common when dealing with titanium; extreme care must be taken while DIG welding (Tungsten inert gas) is undertaken. The complication of these methods and the delicacy in which the alloy must be dealt with, slow the entire process and its negatives begin to outweigh the positives.

There are limited options of fabrication methods with It al-IV; ones that are preferred are expensive and burdensome, such as Hot Stochastic Pressing (HIP). Once it has been finished and the end product test damaged, the damage is very challenging and laborious to fix. (http:// en. Wisped. Org/wick/Titanium_powder) Regrettably, titanium is simply not an option for this small company, if they Were to produce a thousand bikes

it would not be feasible. Although the technical aspect of this alloy seems perfect, the formalities destroy its perfect image.

The cost would be immense and the time going into production would simply be too long. The alloy is time consuming to join, difficult to repair, very hard and limited tampering properties and of course the extensive cost involved. (http://www. Sewer. Ca/, 2014) (http://en. Wisped. Org/weightlifting_alloy, 2013) 7005 Aluminum Alloy 7005 Aluminum is an alloy that is made up of many different elements, all of which affect its properties. These elements include Chromium (0. 06-0. 2%), Copper (0. 10%), Iron (0. 40%), Manganese (0. 2-0. 7%), Silicon (0. 35%), Titanium (0. 01-0. 06%), Zinc (4-5%), and Zirconium (0. 8-0. 2%) (http://en. Wisped. Org/ wick/7005_minimum_alloy). Unlike some of the other alloys, sass's primary use is bicycle frames. Being an aluminum alloy, it is naturally very similar to 'Reynolds XSL DO'. Though the base metal is the same, there are still differences; sadly, for 7005 they are not good. When it comes to strength, this alloy is less than great, even though its primary use is bike frames. To increase its strength 7005 can be age hardened as well as work hardened (similar to XSL 00), apparently, on average these methods increase its hardness by around 15-20%.

Though this huge increase in strength occurs, this alloy is inferior to the 'Reynolds XIII', (http:// www. Cybercafés. Com/lists/Reynolds-XSL 001). Other than these varying strengths, 7005 & XSL 00 are practically the same alloys. All the properties are the same and its uses and advantages are the same (including the negatives). The only other difference between these two alloys is

the reported extreme ease of fabrication. The only reason stated as to why 7005 is used to make bike frames is that is can be welded and modified with extreme ease.

The outcome of this analysis is bleak for 7005, as it simply cannot compete. As the pricing is the same for XSL 00, this Aluminum alloy is practically obsolete. Without the same strength, it quickly loses any ground it had on XSL 00. To use this alloy when another option is available, with the name properties just with added strength, 7005 should not be considered. If this small company produced its bikes with this material, it would be using an archaic design, wasting large amounts of money on 7005 when X 100 is available. This is the first alloy in the selection to which the answer is a definite no.

A graph depicting steel vs. aluminum (http://endless-sphere. Com/) Carbon fiber Carbon fiber is the only alternative that is not an alloy, making it a strange choice for a bike frame. Carbon fiber is a very exclusive material, produced by strands of carbon being glued together with epoxy (a class of reactive Olympus) (http://en. Wisped. Org/wick/Epoxy). This fiber has some amazingly good properties such as its great strength. The strength of carbon fiber greatly depends on the way in which it is formed, obviously the better you want its strength, the more it will cost.

Its strength and stiffness are properties of the fiber that apply to force laterally, adding huge amounts of strength. Another amazing property that can relate to bending resistance and strength is that of carbon fibers horizontal flexibility. When a force

is applied horizontally, carbon fiber actually has the ability to stretch out, absorbing stress. The design of a carbon fiber bike would involve complex engineering, because Of the differing vertical and horizontal features. The engineer must carefully calculate where the fiber should be vertical (strength) & horizontal (shock absorption).

Despite carbon fibers brilliant strength, it is unlike the steels, very light; in fact, it is the lightest of all the contending materials. (http://compartmentalizing. Wordless. Com/) The fatigue resistance of carbon fiber is not an issue, because it is not a metal. This means it is completely void of any rust, decay, or reaction with air or water. Unfortunately it means it also cannot be tampered with, what you see it what you get, there is no changing that. The bending of carbon fiber is difficult, and could result in breakages due to its firm nature.

Thankfully, it is optimal for unconventional shapes, perfect for a recumbent bike frame. Carbon fiber is terrible at absorbing any shock, because it is very brittle, meaning it would not be the most pleasant ride (rather jolly). The undoing of carbon fiber is in the cost, just as titanium, though it also has a nasty surprise. This fiber will not bend, and it will never show signs of cake points Or bending sections. Instead, carbon fiber will UN-expectantly and rather suddenly snap (like a twig, very brittle), words that have been used to describe this failure are catastrophic & disastrous.

This is obviously a precursor to some appalling accidents, some of which the small company may be responsible. This point makes carbon fiber a less attractive material that the equally

expensive titanium, and although it is an extremely useful product, bike frames may not be the best decision. Also the creation of carbon fiber is not yet an ethical act as there is still no known way to recycle it. To recap, the positives are no fatigue or rust (carbon fiber is not a metal) and can be engineering accordingly. It is extremely light yet still maintains its amazing strength and shock absorption (this can be changed, modified, and controlled).

Negatively it is still very expensive and a small bike company would struggle to afford such costs. The other huge fault is that is can fail with very little warning, causing the potential for serious injury or in a worst-case scenario death. 41 30 Chromium Molybdenum Steel 4130 chrome molly steel (for short) is an alloy very similar to that of Reynolds 853', and does not really exceed it in any way. The elements that are often melded into 4130 are manganese (0. 4-0. 6%), phosphorus (0. 025%), sulfur (0. 025%), and silicon (0. 15-0. 35%).

The base elements have percentages of 0. 8-1 . 10% (chromium) & 0. 15-0. 25% (molybdenum), both used as strengthening agents (http://mad. Zoom. Com/article. Asps? Articled=5742). When it comes to strength, this alloy is almost identical to 853 yet still not as strong. The strength is improved using heat treatment methods, similar to that of Reynolds. The alloy is best worked/machined in normal tempered notations, slightly increasing strength. When this alloy has been hardened, the ease as which you can work it is very low, much like the other steel alloys.

Though this alloy has better strength than most

steels today, it still is not up to the standard of 853, as previously mention. The fatigue resistance of this steel matches that of 853. When it comes to corrosion chrome molly steel is rather good. For a steel it is very resistance to decay in the form of rust, this can be attributed to the relatively high chromium percentage. The most known aspect of this steel is the ease in which it can be joined. The reason for this effortless joining is the alloys low carbon content (around 0. 3%); meaning fusion welding can easily be implemented.

In addition, a property that has been recognized is its brilliant ductility, (http:// www. Teammates. Com/4130-alloy-steel-socio-and-sheet. HTML). Reynolds 853 has better strength than 41 30, but because of this, chrome molly steel has a higher 'modulus' of elasticity. This simply leads to 4130 having greater bending resistance, this takes us to another problem. Unfortunately as we know, this means its less shock absorbent, 853 was already lacking this property, and 4130 is even worse. In conclusion, it can be drawn that 41 30 Chromium-Molybdenum Steel is very similar to 'Reynolds 853'.

Chrome molly steel is actually more expensive that 853, this is thanks to its comparatively high production costs. Like most steels, 4130 is sadly quite heavy and absorbs minimal amounts Of shock. Fortunately, it has high resistance to fatigue and bending and it can be conveniently welded due to fusion welding. It has high strength like most steels, but also has high corrosion resistance, which is rare. (http://Achaean. Lox. In/, 201 1) Rest Its Reynolds 853 is an all-round steel, it is also relatively cheap, which

is a huge bonus for the small company.

The properties that make this steel an option are its strength, resistance to bending and fatigue. It can also be welded very easily; unfortunately, it is heavy and lacks the appropriate corrosion resistance. Reynolds XSL O This Aluminum alloy is a great candidate for this small company. However, it lacks strength, compensated by the design of oval shaped members it is not a problem. Unlike steel, this alloy has brilliant corrosion resistance due to it being aluminum. A huge factor is its shock absorption, making it the most comfortable ride. Additionally this alloy is only slightly more expensive than 853.

It AI IV has an amazing list of properties; it almost seems like a perfect solution. It is very strong, has resistance to bending, and is still a comfortable ride. It has good resistance to decay (corrosion, rust), also showing great fatigue resistance. Titanium alloys just are not an option for this small company, as cost is just too much. It also take more time and money to join and fabricate the bikes (as titanium is hard to join). 7005 Aluminum 005 is not an option from the start; it would be a waste of time and money for the company to use this alloy.

It is practically the same as XSL 00, but XIII out performs it in almost every way. Reynolds XIII has better strength, corrosion, and bending resistance. Carbon Fiber Carbon fiber is a seemingly great candidate, as it cannot corrode or fatigue with considerable resistance to bending. However, it is very light (the lightest of all options), it still can does not hit

the mark, it has some major limitations. It is much too expensive for a small company such as this, and as previously scudded has the potential to fail suddenly and catastrophically.

Its production would be the least ethical of all, as it cannot be recycled like all other choices. 41 30 Chromium Molybdenum Steel 41 30 is not a good choice, as it is the inferior of Reynolds 853. Not only is it worse that 853, it is also more expensive. The only advantage is its improved corrosion resistance from added elements. Though all these materials have their positives and negatives, it is evident that some are better than others. Even though there are these outstanding options, it is still necessary to compare them, finding the best choice, as the rape on page 10 demonstrates.

With this table it becomes easier to find the right choice of material for a recumbent bike frame, such as the one this small company is after. Table of Materials: Properties (http://www. Doctor. Com/docs/, 2011 ) Conclusion Its becomes apparent that some of these materials are simply not up to standard, either being to expensive or having a major flaw. Therefore, we can eliminate a few candidates from the selection before it begins. The first two alloys that can be removed are 7005 Aluminum alloy and 4130 Chromium Molybdenum steel, the reason for this is simple.

Although the properties of these alloys do in fact suit the job, there are superior alloys in the selection (Reynolds 853 and XIII) that out match them. This means these alloys have no need to be in the selection process as they are already

outmatched. There are two more materials that can be removed from the line-up, there are only a few reasons why they are not suitable, but those reasons pose strong cases. The first of which is the titanium alloy (It al IV), even though its properties are seemingly perfect, the cost that the 'small' Company would have to undertake is just too great.

Carbon Fiber is a seemingly good choice, until you take into consideration the cost and the difficulty of joining. A huge factor into why it is not a candidate for selection is also its tendency to fail without warning, which has major safety implications. With these materials removed from consideration only two remain, Reynolds 853 and Reynolds X 100. This could be a leading factor in why the Reynolds Bike Company is one of leading bike manufactures in the world. It holds two of the best alloys for creating bikes in a relatively large selection of materials. Between Reynolds 853 and X 100, one does stand out, due to the negative repertories.

The fact that we are looking for a material suited to creating 'recumbent' bikes X 100 stands out as the best alloy. Looking at Reynolds 853 we see it is a very heavy alloy and with recumbent bikes already having a lot of added weight it is a definite negative. The purpose of a recumbent is to have an enjoyable leisurely ride, with the lack of shock absorption this would simply not be the case. A bike of this weight would be very hard to maneuver and would take much too long to brake (to heavy). Clearly making X 100 the

better choice in bike frame, out of the six suggested materials.