Introduction What Are Daleks Engineering Essay

Originally mutated posterities of Kaleds of the planet Skaro, the Daleks are an evil, shockable race who starred as the Doctor ‘s greatest enemy through most of the Dr. Who series. Although Daleks can look to be entirely robotic, a biological being resides in the Dalek armor and controls it from within. Losing most of the android abilities, the beings grew really much dependant on the Dalek shell. Therefore, the Dalek armor was built and improved throughout the series to supply them with protection, mobility, arms and the necessary life conditions [ 1 ] , [ 2 ] .http: //www.themindrobber.co.uk/dvd-3d/new-series-dalek-dvd.gif

As can be seen in Figure 1, a Dalek resembles a “ human-sized peppershaker ” consisting of three chief subdivisions ;

The top rotating dome which enable the Dalek to see through its mechanical eyestalk. Two talker visible radiations are besides attached to the dome, enabling communicating with other Daleks and existences.

The middle housed the arms including a operator arm and a gun stick which could be interchanged with several other arms fond regards.

Figure – DalekThe underside shell was the primary agencies of travel, protection and general lodging of the mutant inside [ 1 ] , [ 2 ] .

Dalek Body – Its Function

The chief map of the skirt-like underside shell is to house all the equipment inside it and back up the top and middle, whilst protecting the animal interior. For this ground, this sturdy and stiff construction should be able to defy the several signifiers of onslaught the Daleks are normally exposed to. Throughout the series, it is believed that no arm can damage the Dalek unless it is one developed by the Daleks themselves. Therefore, the Daleks are said to be vulnerable to high energy explosives, high-octane energy arms, photon beams, machine guns, intense sonic beams and other arms made out of the same high-performance stuff used for the casing itself. In ulterior versions, Daleks besides had force-fields that were able to debar slugs, doing them to wholly lose the shell [ 1 ] , [ 2 ] . However, in this assignment, it is assumed that the force-fields were produced by another constituent of the Dalek, holding no consequence on the map of the organic structure.

It is said that on the planet Skaro ( Figure 2 ) , sulfuric acid frequently precipitates. This means that the Dalek shell should besides be able to defy such caustic environments whilst protecting the interior [ 3 ] .

Figure – Planet SkaroThe shell used to besides be responsible to provide the power to the machine. In earlier versions of the Daleks, inactive electricity transmitted through the conductive floors of the Dalek City was used to externally power the Dalek. Therefore, this required the shell to be conductive itself. However, ulterior developments allowed for the installing of dishes onto the dorsum of the Dalek to roll up energy from external radio detection and rangings. Internal power supplies besides featured in other theoretical accounts [ 1 ] , [ 2 ] . In this assignment, the ulterior versions of the Daleks are considered where the shell will non be needfully conductive. hypertext transfer protocol: //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Skaro.jpg/250px-Skaro.jpg

In the beginning, mobility of the Daleks was besides dependent on the shell. In earlier theoretical accounts, Daleks could merely travel by a gliding gesture on degree conductive floors. However, vibrating and even winging and going through infinite and clip were developed in subsequently theoretical accounts [ 1 ] , [ 2 ] . Therefore, it is assumed that as power supply is independent of the shell, even mobility is taken attention of by other equipment. However, lightweight shells will be favorable so that power consumed is kept low.

Constraints

Specifying the maps of the constituent for which a suited stuff is to be chosen is the first measure in the material choice procedure. Thus, after specifying the maps of the Dalek shell above, the following measure is to put the needed restraints on the stuff belongingss. These restraints can be formulated through research by both association and synthesis methods.

Research on Dr. Who TV series resulted that the stuff of the Dalek shell was either “ Dalekanium metal ” or a poly-carbide. This fictional Dalekanium metal is strong and tough plenty to be unassailable and besides resist the bulk of the optical masers and bombs. The metal is electrically conductive so that electrical power could be taken in from the conductive milieus [ 4 ] . Thus through association, it was concluded that a similar stuff would be ideal for pick due to its bullet-resistance.

Since no distinct belongingss of Dalekanium could be found, stuffs used for similar applications were searched for. It was concluded that the above maps of the Dalek organic structure casing call for a stuff with vehicle armor features. Armored vehicles can utilize several stuffs for protection against high velocity impacts ; these include steels, Aluminium, Titanium, ceramics and complexs.

Brown McFarlane [ 5 ] have developed the Miilux scope of steel armor home bases, offering equal protection for such vehicles. The particular steels in the Miilux scope consist of several debasing elements such as Chromium, Molybdenum, Nickel and Silicon, which give the steels good mechanical and physical belongingss. The full set of belongingss can be seen in Appendix A.

Bing a comparatively new stuff, Kevlar [ 6 ] , an aramid fiber embedded in a polymer matrix, besides has really good physical and mechanical belongingss which make it suited for vehicle armor, and therefore Dalek shell.

However, Daleks are susceptible to acidic environments which therefore require corrosion immune stuffs for their organic structure.

Based on the sets of belongingss these armour stuffs offer, the undermentioned restraints were set for the choice of a competitory and perchance superior stuff for the Dalek organic structure.

The chosen stuff should be comparatively lightweight so that power consumed during traveling will be reduced. Therefore, the denseness ( ) should at least be lower than that of steel i.e. less than 7800 kgm-3 to accomplish a lighter stuff and construction.

Since the organic structure is responsible to keep the equipment in its topographic point, stiffness and rigidness is of import. Therefore, the Young ‘s modulus ( E ) should at least be 90 GPa.

Sing the form of the shell and the inactive tonss it has to defy, the stuff should hold a sensible value of compressive strength. Therefore, the compressive strength ( ) should be at least more than ( or similar to ) that of an aramid fiber epoxy complex, i.e. more than 100 MPa.

The tensile strength ( ) should be at least more than 500 MPa, midway between the two armor stuffs considered. Note that the tensile strength was chosen as a restraint over output strength since it is assumed that inactive normal forces will non make those high magnitudes while it wo n’t count if the shell deforms a spot if it is impacted by a larger force, given that the stuff will non fracture or present a jeopardy to the being indoors.

Bing susceptible to impacts, the stuff should besides be tough plenty to defy such sudden forces. Through ciphering the stamina, GC [ 7 ] , for both steel and Kevlar, it was found that the new stuff selected should hold a stamina of at least 45 kJm-2. The line of lower limit needed stamina, M1, was plotted on a Fracture Toughness – Young ‘s Modulus belongings chart, Chart 1, were the step of evident break surface energy was used as in Equation 1 [ 7 ] .

Finally, since on the planet Skaro, acidic rain is a common precipitation signifier, the Dalek shells should be immune to such strong acids. As a restraint, the stuff to be chosen should at least have limited usage in weak and strong acids

Using CES EduPack 2011 package [ 8 ] , the above bounds were inputted and Chart 1 was developed as shown hereunder. At this phase, all the technology stuffs were screened such that merely a sum of 94 stuffs resulted to go through the given restraints.

Chart – Fracture stamina vs. Young ‘s Modulus Materials Selection Chart

Prospective Materials

From Chart 1, the following five suited stuffs were chosen. These all passed from the set of restraints listed before while ranking top as the lightest from their sub-class ( complexs, chromium steel steels, Ti alloys etc ) .

[ CFRP ] High strength C fibre/Cyanate ester composite – Quasi-isotropic laminate fabricated from unidirectional prepreg tape. Such composite is typically used in ballistic capsules and aircrafts and in similar high public presentation applications. Its chief advantage is its high strength to burden ratio.

[ Ti metal ] Ti-6Al-4V, Titanium alpha-beta metal – A solution treated and aged Titanium metal. Such metals are used in aerospace applications, chemical technology and in the medical industry. Their advantages include high strengths, comparatively low densenesss, and the possibility of high operating temperatures.

[ Zr-Sn metal ] Zr704 Zirconium-tin metal – A shaped Zirconium-tin metal with 1.5 % Sn, known to be an industrial class. Zr704 metal is typically used in chemical processing equipment, heat money changers and the similar. Its first-class corrosion opposition in most environments defines it from most other stuffs.

[ Stainless Steel ] AISI 446 Ferritic chromium steel steel – A wrought and annealed ferritic chromium steel steel. Due to its low monetary value scope and really good belongingss including high corrosion opposition and strength, this chromium steel steel is a widely used stuff for several applications particularly when covering with caustic environments.

[ Ni-Co-Cr metal ] IN-100 Nickel-Cobalt-Chromium metal – The as cast Nickel-cobalt-chromium metal is used for really similar applications as the above, having chiefly in aircraft engines and chemical processing equipment. Some outstanding features of this Nickel alloy include its high strength, good corrosion opposition and first-class weariness opposition over a broad scope of temperatures [ 9 ] .

Table 1 shows some of the belongingss of the chosen five stuffs [ 8 ] .

Table – Material belongingss of the five suited stuffs

Property

CFRP

Ti metal

Zr-Sn metal

Stainless Steel

Ni-Co-Cr metal

Density ( kgm-3 )

1620 – 1670

4410 – 4450

6500 – 6650

7400 – 7600

7650 – 7850

Price ( a‚¬kg-1 )

143.51 – 174.71

38.44 – 42.30

46.92 – 51.66

2.5 – 2.75

36.21 – 39.82

Young ‘s Modulus ( GPa )

101 – 115

110 – 117

92 – 100

195 – 205

210 – 220

Tensile Strength ( MPa )

607 – 738

896 – 1140

410 – 500

480 – 615

790 – 1120

Compressive Strength ( MPa )

317 – 415

758 – 1120

240 – 380

275 – 350

655 – 935

Elongation ( % strain )

0.53 – 0.73

10 – 12

14 – 20

13 – 20

5 – 12

Hardness – Vickers ( HV )

10.5 – 21.5

380 – 420

140 – 200

190 – 225

340 – 420

Poisson ‘s Ratio

0.31 – 0.33

0.31 – 0.323

0.35 – 0.38

0.275 – 0.285

0.3 – 0.33

Fracture Toughness ( MPam0.5 )

54.6 – 83

82 – 100

115 – 150

72 – 122

120 – 150

Toughness ( kJm-2 )

19.49 – 52.07

43.44 – 69.40

95.83 – 181.16

19.68 – 59.87

49.21 – 82.42

Lastingness: Water

Excellent

Excellent

Excellent

Excellent

Excellent

Lastingness: Ultraviolet radiation

Good

Excellent

Excellent

Excellent

Excellent

Lastingness: Weak acids

Excellent

Excellent

Excellent

Excellent

Excellent

Lastingness: Strong acids

Limited usage

Acceptable

Excellent

Acceptable

Acceptable

Material Processing Energy ( MJ/kg )

20.9

13.5

3.19

2.91

10.3

Procedure Zone ( I?m )

1.74 – 5.95

1.65 – 3.96

16.8 – 42.6

4.36 – 20.6

3.65 – 11.5

Aims

After testing was carried out to extinguish unserviceable stuffs and the five prospective stuffs were chosen as in the old subdivision, a set of aims were formulated so that the best stuff for the application at manus could be chosen. The aims set are listed below.

To be even stronger under onslaught, the stuff chosen should hold a high tensile strength ( ) . Thus the first aim, in no peculiar order, is to maximise.

For mobility with minimal power ingestion, the stuff should hold a low denseness ( ) . Maximizing will guarantee that a lightweight stuff is chosen.

Since a batch of Daleks have to be manufactured, another aim is to minimise cost ( C ) , therefore to maximise. However, non much importance can be given to this nonsubjective since stuffs in other planets might hold different costs depending on their copiousness in that peculiar planet.

A high stamina ( GC ) is besides ideal since the automatons are normally exposed to warfare. This rendered another aim to maximise GC.

Due to the incidence of acidic rain on planet Skaro, the stuff should hold the highest corrosion opposition possible particularly against strong acids. Maximizing this corrosion opposition was set as another aim.

Finally, for the maps identified before, it is besides ideal for the stuff to give before break instead than break before output ( i.e. the stuff should non be brittle ) . This can be determined by the size of the procedure zone, Dy ( Equation 2 ) [ 7 ] . Thus Dy should be maximized.

Material Selection Methods

After puting up the aims, the Modified Digital Logic Method was foremost used to put the weights on each stuff belongings that is to be maximized, as can be seen in Table 2. Therefore, the wanted stuff belongingss were compared with each other, one at a clip. When a stuff belongings was deemed to be more of import than another, a mark of 3 was given, while a mark of 1 was given to the less of import belongings. Alternatively, if the belongingss had equal importance, each was given a mark of 2. The tonss were so added for each belongings and the comparative accent coefficient was obtained.

Such method enabled comparative importance to be given to the aims indentified. The modified digital logic was used over the normal digital logic ( where merely a 1 or a 0 can be given during comparing ) so that no material belongings would stop up with a concluding weight of 0, and tantamount importance between two peculiar belongingss could be given. Furthermore, such method was used so that the weights given would non be excessively subjective or even given about indiscriminately.

The obtained coefficients were so employed in the normalized weighted superior method, Table 3, to choose the concluding stuff of pick based on the aims. After happening the mean value of each stuff belongings from Table 1, the normalized belongings value ( N ) was worked out. This value was so multiplied by the obtained weights in Table 2 and the consequences of each stuff added up. This method therefore eventually ranked the stuffs harmonizing to the nonsubjective set and the given weightings.

Final Material Choice

The concluding measure of the material choice procedure is to analyze the consequences obtained from the normalized weighted ranking. Therefore, upon analyzing Table 3, it is clear that with the given restraints, aims and weightings, Zirconium-tin metal will be the best pick of stuff for this application.

In fact, looking at both Table 1 and Table 3, it can be clearly noted that this metal has the highest stamina, ductileness and corrosion opposition from the originally chosen five stuffs. This will do the casing more bullet-resistant and more immune to caustic debasement. On the other manus, it ranked 3rd and 4th in the denseness and cost aims severally, while ranking last when it came to tensile strength. Yet, these last three aims were non given much weight on the concluding determination. This caused Zr-Sn metal to still rank foremost from the chosen stuffs.

Other than the belongingss mentioned above, Zirconium alloys besides have good welding abilities and it is besides reclaimable [ 10 ] . Such first-class stuff belongingss allow these metals to be used in heat money changers, atomic facings and other applications where strong acids and alkali tend to be abundant.

A stuff with possible competitory belongingss to the above pick would be ferritic chromium steel steel. Its chief advantages would be its really low cost, good ductileness and good corrosion opposition particularly in sulfuric ambiances [ 11 ] . Apart from that, fabricating engineerings for chromium steel steels has developed a great trade on planet Earth and would likely be much easier to fabricating than Zirconium-tin metal. However, being created on planet Skaro, cognition on fabrication might change well from one race and conditions to another, doing Zr-Sn metal perchance a more economic option.

Table – Modified Digital Logic Method

Goals

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

No. of Positive Decisions

Relative Emphasis Coefficient

Tensile Strength

2

3

1

1

2

9

0.15

Density

2

3

1

1

2

9

0.15

Cost

1

1

1

1

2

6

0.1

Stamina

3

3

3

3

3

15

0.25

Procedure Zone

3

3

3

1

2

12

0.2

Corrosion opposition

2

2

2

1

2

9

0.15

Entire

60

1

Table – Normalized Leaden Ranking Method

Material

Tensile Strength

1/Density

1/Cost

Stamina

Procedure zone

Corrosion Resistance

Mark

Nitrogen

W 0.15

Nitrogen

W 0.15

Nitrogen

W 0.1

Nitrogen

W 0.25

Nitrogen

W 0.2

Nitrogen

W 0.15

CFRP

0.66

0.099

1.00

0.150

0.02

0.002

0.26

0.065

0.13

0.026

0.33

0.050

0.392

Ti Alloy

1.00

0.150

0.37

0.056

0.07

0.007

0.41

0.103

0.09

0.018

0.67

0.101

0.435

Zr-Sn Alloy

0.45

0.068

0.25

0.038

0.05

0.005

1.00

0.250

1.00

0.200

1.00

0.15

0.711

Stainless Steel

0.54

0.081

0.22

0.033

1.00

0.100

0.29

0.073

0.42

0.084

0.67

0.101

0.472

Ni-Co-Cr Alloy

0.94

0.141

0.21

0.032

0.07

0.007

0.48

0.120

0.26

0.052

0.67

0.101

0.453

9Note: Average values of the stuff belongingss from Table 1 were considered. N – Normalised value. W – Normalised value multiplied by the weights obtained in Table 2.