Polyvinyl Chloride Foam Sandwich Engineering Essay

Many of the stuff could be used for the hull of the ground-effect machine based on the intent of its application.In the undertaking, the chief concern is to observe the landmines which is surely over land usage.Hull is the chief construction which the ground-effect machine floats over H2O or land and It supports the whole weight of the craft.The parts include trade floor, side panel forward, and trade panel untill the skirt line attachment.Five stuffs were listed among suited stuffs for the landmines sensing application and from these five stuffs, the best stuff will be selected for the hull.

-Aluminium Alloy

– Polyvinyl Chloride ( PVC ) froth sandwich ( Carbon skin Panel )

-HDPE

-Acrylonitrile butadiene cinnamene ( ABS )

-Balsa sandwich ( Glass Skin Panel )

The stuffs were listed by the commercially produced hull for boats and hovercraft.By far, hull for ships and ground-effect machine highlight the same mechanical and physical characteristics and it covers the interior portion of body.Hull demands exceptionally high strength-to-weight, therefore suitableness among 5 chief stuffs must be accounted singly.Since the ground-effect machine is remote-controlled and navigated by remote control system, the human weight job could be ignored and the elation of ground-effect machine could be optimized every bit far as possible and at the same time able to transport crutial burden like mine sensor and engine expeditiously.

In this range choice, balsa wood nucleus sandwich with the glass fiber skin panel is chosen as the best stuff that can be used to do hull.

ALuminium metal

Polyvinyl Chloride ( PVC ) froth sandwich ( Carbon skin Panel )

HDPE ( polypropene )

Acrylonitrile butadiene cinnamene ( ABS )

Balsa Wood sandwich ( Glass Skin Panel )

Density, ( kg/m3 )

2500-2900

28-32

939-960

1160-1210

90-110

Monetary value, ( RM/Kg )

5.414-8.773

43.04-86.08

4.973-5.526

7.32-14.13

35.57-57.39

Tensile Strength, ( Mpa )

58-550

0.8-0.9

20.7-44.8

27.6-55.2

8.5-10.5

Young, modulus, ( GPa )

68-82

0.028-0.032

0.621-0.896

1.86-2.76

2.1-2.5

Shear Modulus, ( GPa )

35-45

0.013-0.015

0.2177-0.3142

0.7-1.05

0.15-0.19

Compressive Strength, ( MPa )

130-150

0.28-0.32

18.6-24.8

44.8-51.7

3-5

Fracture Toughness ( MPa · m1/2 )

22-35

0.0014-0.0017

1.437-1.724

1.9-2.1

0.2-0.3

Table 1: Hull Material Selection Datasheet With Highlighted Chosen Material

Chosen Material Description

From the 5 pick of stuffs, balsa wood sandwich with glass fiber tegument said to be the best compared to other materials.The denseness of balsa wood is well low among 5 stuffs after PVC foam nucleus. HDPE and ABS found to hold excessively much different in weight compared to core stuff like PVC froth and ABS while aluminium metal seems to hold highest in weight.As the mark is to happen the visible radiation and strong stuff, eventhough PVC froth is lighter than Balsa wood, if there was a perennial impact, some of PVC froths could be brittle compared to Balsa wood while in this ground-effect machine design, the hull is the major portion that would ever doing high-stress contact with the land obstrucion like stones and impact quiver of engines.With the purpose is to observe a landmines, it is must be ensured that force per unit area contact with the land has to be every bit low as possible because if any exceptional force per unit area could take to explosion of landmines.Therefore, Balsa wood said to be lightest wood and able to defy continuos impact every bit good as practically used in trade modeling due to its less loft force to remain in air and first-class floatation.In footings of the strengthened tegument bed, Balsa wood surface by and large found to be easier to bond the laminate tegument because of nature of its wood where its capiliary action helps pull the rosin into the balsa and bring forth strong bond.By chosing Balsa wood, it is stronger in shear and compaction compared to PVC foam.In add-on, the Young Modulus indicates that balsa wood has low reaasonably low stiffness which is necessary for elastic bending whenever tons are imposed.Aluminium seems to hold really high Young Modulus which is really stiff whereas PVC is excessively low and non practically good for deformation.Balsa has really good UV resistant and the ground non to take ABS, HDPE and PVC is because, they are thermoplastic stuffs which are weaken over high temperature and tense UV visible radiation, that can ensue in serious impairment of physical, chemical, and mechanical belongingss.High degree of heat can hike up the embrittlement of stuff finally checking and since we want long operational life, the hull must be avoided from any debasement in stuff belongingss level that can cut down the dependability of hovercraft.Aluminium happens to be unsuitable in this ground-effect machine design because, the metallic component on aluminum may disrupt the signal and feedback of metal sensor where high degree of intervention can take to undetected landmines and this reduces effectiveness of of the chief intent of hovercraft.That is why the hull design should perchance insulate any metallic component by utilizing balsa wood core.Furthermore, balsa wood can be easy worked with simple film editing tools without impacting the strength which is necessary for case hole boring at line fond regard to attach the skirt.Balsa wood nucleus is light and able to defy high force per unit area burden and this makes the best pick to prolong engine burden and air thrust.The good acoustic soaking up gives the balsa wood ability to cut down the noise degree of hovering.Generally, the ground balsa wood is chosen instead than other stuffs is due to its handiness where it can be easy obtained in Asia and eventhough it is commercially produced in South America ( Ecuador ) , but now normally found in Asia like Indonesia and Thailand.Although HDPE, ABS and aluminum are slightly inexpensive, since they are unapplicable in this ground-effect machine hull design, the choice were shifted to PVC froth and Balsa wood and based on these two stuffs, Balsa wood is cheaper with most coveted belongingss surpass the PVC foam.Cost should be minimised but since this is non a mass production which is in little volume, a spot high cost on stuff choice could be tolerated for the interest of high quality hull design.

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Figure 1: Shear emphasis distribution on solid laminate and cored laminate based on applied burden

Core Laminated Fibre.

In the design type, the cored strucured stuff gives the best design to do hull of hovercraft.The grounds is because a cored laminate is lighter and stiffer than a solid fibreglass panel for case of the same weight and country. The nucleus stuff is really efficaciously moving as a emphasis web between the two teguments of laminated bonded. The rule is the same with the interior perpendicular subdivision of I-beam, which acts as a emphasis web for two outer subdivision of the I-beam. Essentially, in order cored laminate to flex, it need to be compressed on the tegument on the impact side and stretch the tegument on the opposite side and by connoting the nucleus, it greatly turned out the individual bed with tenseness on one side and compaction on the other side through the force that being transmitted to the nucleus material.The nucleus would absorb the shear and impact imposed in add-on to the extra structural value, cored laminate are really normally used. Through a sandwich, strength of chief nucleus stuff is optimised efficaciously. Generally, for nucleus such as balsa or froth, the laminated bed is in changeless contact with the full nucleus and hence during impact, the force is distributed over a broad country. In a sandwich panel ( tegument ) besides, the compaction strength of the nucleus helps forestall the construction from delaminating, pursing or clasping and many other similar failure.With Balsa wood being the best stuff selected, the bed which is strengthened glass fiber enhances the strength of core.Eventhough Carbon fiber is noted to be better than glass fiber, glass fiber is least expensive of fiber compared to carbon fiber and widely used in simple trade design due to good translucent effect.Other than that, glass fiber is really good electrical dielectric and it is of import in this design for the hull non to hold conduction so that the metal sensor which is extremely electical configurated to work without jobs like fickle pulsation due to bear down break on stuffs.

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Skirt Material Selection

Skirt of ground-effect machine is where the lowest portion of trade organic structure that closest to the land degree and must come in flexible sheet type of materials.It is said to be critically of import portion that governs the functionality of ground-effect machine alone.The air need to be contained so that the pressurized shock absorber can be produced in suspension.By commanding the sufficient force per unit area derived function of air shock absorber, the energy required to raise the ground-effect machine can be minimized therefore cut downing power ingestion every bit good as increasing other public presentation level.Degree of stableness public presentation must be conformed by the design by sing the right type of stuff chosen for skirt and its configuration.In the design, below are 5 normally used stuffs for skirt.

-polyethylene ( PE )

-Polychloroprene ( neoprene )

-polyurethane ( PU )

-Natural Rubber

-Ethyl-vinyl-acetate ( EVA )

Harmonizing to the type of skirt design like bag skirt, finger skirt ( segmented ) , angled jupe skirt or combination of any those 3, the stuffs that be used has to happen its suitabiity and lucifer to the intent of the design.Since the skirt must be the type of sheet and flexible, all the chief stuffs listed for testing are elastomer.It is unpractical to use other stuff types particularly metal and the flexibleness is really of import to plight the smoothness of working process.The stuffs choice must based on public presentation demand like high strength-to weight ratio, acceptable tensile and tear strength, cyclic tensile strength and compaction, air tight and opposition to scratch.

In this range of design, polyurethane is regarded as most suited to be used as skirt stuff on ground-effect machine.

Polyethylene ( PE )

Polychloroprene ( Neoprene )

Polyurethane ( PU )

Natural Rubber

Etyhl-Vinyl-acetate ( EVA )

Density, ( kg/m3 )

939-960

1230-1250

1120-1240

920-930

945-955

Monetary value, ( RM/Kg )

4.973-5.526

7.173-21.52

20.45-32.5

4.304-5.021

6.075-10.5

Tensile Strength, ( Mpa )

20.7-44.8

3.4-24

31-62

22-32

9.5-10

Young, modulus, ( GPa )

0.621-0.896

0.0007-0.002

1.31-2.07

0.0015-0.0021

0.007-0.009

Shear Modulus, ( GPa )

0.2177-0.3142

0.0002-0.007

0.4653-0.7352

0.0006-0.0008

0.002-0.003

Compressive Strength, ( MPa )

18.6-24.8

3.72-28.8

64.56-90.96

30

12-20

Fracture Toughness ( MPa · m1/2 )

1.437-1.724

0.1-0.3

1.837-4.969

0.2

0.3-0.5

Table 2: Skirt Material Selection Datasheet with Highlighted Chosen Material

Chosen Material Description

Polyurethane ( PU ) is the best stuff chosen because when compared to other stuffs like Neoprene, PE and EVA the weight is moderately good which is crutial for ground-effect machine weight where the point is to optimize the lower limit bareable weight.Eventhough natural gum elastic and PE seem good option for the skirt weight stuff but when sing snap, the application of skirt must hold the snap but high tensile and compressive burden strength.PU exploits the of import parts in stuff demand. With excessively low immature modulus could take to easy deform and the skirt finally speedy fail due to simple burden for illustration figured bass air thrust.The force of air inside the interior skirt ever vary with the thrust power and sometimes high and low.Due to this ground, the high immature modulus needed for stuff to defy this condition.In add-on, PU is used as it is the most demanded movie and sheet application due to long-run flexibleness at really low temperature and astonishing shelf life.This is really of import although it is rather expensive compared to other stuff, the long term dependable life should be primary mark instead than inexpensive stuff but unsustainable and easy to fail.Besides, in term of utmost environment, PU can be depended since it is good for high scratch resitant and high-wear application and these give PU ideal pick for skirt.With high lastingness, it has good UV resistant without yellowing and eventually embrittlement of stuff which is indispensable in skirt since the skirt must non see such behaviour to supply an effectual air shock absorber without leaking in air force per unit area for case tear due to brittle.If the air force per unit area leaking happened, the stableness of ground-effect machine is affected thereby air force per unit area can non be maintained on the land where it could lend to explosion of landmines.With good chracteristic of softie and strecthy PU is really easy fabricated without impacting the strength.It is said to be the most strongest elastomer.Produced with good translucent consequence, PU has advantage of beautiful tegument for aesthetic value for hovercraft.PU could be found most in assortment application in really broad scope and due to this, it is chosen because its availibility to obtained merely in common market in every state.

Rudder Material Selection

Rudder is used for commanding the ground-effect machine in turning and through the air flows at the back generated, the turning minute can be directed by maneuvering the rudder.It is an outside portion that is fastened usually by pivoted outside the hull.For the maneuvering procedure to efficaciously works, the aerofoil form of rudder must be symmetrical about the perpendicular centre plane.There are soo many stuff could be used for the rudder of ground-effect machine based on the velocity and manoeuvrability type within the range of ground-effect machine intent.In the design, the chief concern of rudder is to command the ground-effect machine motion at a low velocity as in this design the ground-effect machine merely merely to observe the landmines which are over land and non for high velocity action.The ground-effect machine must be stable with a low velocity oscitance so that the sensing of landmines can be improvised since fast velocity non advisable for effectual sensing signals.

-Brass

-Balsa Wood ( CFR skin panel )

-CFR ( epoxy matrix )

-Stainless Steel

-Bronze

Based on the most craft application either aircraft or Marine, if aluminum hulls used, the rudder should be choosen as aluminum rudder and if somehow GRP or composite hulls, rudder much more suited to be chosen between bronze, unstained steel or brass. As the design is targeted on metalless component, CFR ( epoxy matrix ) rudder likely to be the most suited material.The rudder is supposingly made of wood merely like the hulls.Historically, chromium steel steel has been preferred rudder stuff and the ground why stuff has been used as it was strong and non corrosive.For high public presentation applications nowadays complete C fiber rudder blade are normally used.

In this range of choice, solid CFR with exposy matrix is chosen as the best stuff for rudder that can be incorporated on ground-effect machine.

Brass

Balsa wood ( CFR laminate )

CFR ( C reenforce plastic-epoxy )

Stainless Steel

Bronze

Density, ( kg/m3 )

8184-8350

90-110

1500-1600

7700-8000

8500-9000

Monetary value, ( RM/Kg )

8.608-9.11

35.57-57.39

215-358

9.325-12.19

18.65-27.26

Tensile Strength, ( Mpa )

500-570

8.5-10.5

550-1050

515

140-800

Young, modulus, ( GPa )

97-103

2.1-2.5

69-150

190-210

70-120

Shear Modulus, ( GPa )

35.9-38.1

0.15-0.19

19-23.1

73-83

25-46

Compressive Strength, ( MPa )

150-160

3-5

542.1-656.8

1485-1815

65-700

Fracture Toughness ( MPa · m1/2 )

61.3-63.3

0.2-0.3

6.12-20

17-34

24-90

Table 3: Rudder Material Selection Datasheet with Highlighted Chosen Material

Chosen Material Description

The basic crutial consideration for the material choice on the rudder are reasonable weight, strength and stiffness.In the design procedure, the peculiar weight is regarded importantly.From 5 stuff accounted, Balsa wood ( CFR laminate ) shown the high decrease in weight compared to other material.To highlight the application of rudder, the weight of rudder must be non excessively heavy and excessively low where really low weight contributes easy quiver on the attachement and extremely sensitive motion where rudder motion should be smooth harmonizing to air thrust flux in order to hold easiness of maneuvering.Heavy rudder evidently unwanted because the weight on ground-effect machine must significantly moo for effectual lifting.CFR comes after Balsa wood where it s the 2nd lowest in weight based on the list and from comparing, this immense different sum of weight between chromium steel steel, bronze and brass devising CFR better to be integrated in the design.The best ground why to take CFR is because if compared to glaze fiber, C fibre which weighs less per given volume and is stronger both by weight and volume. For any metals behaviour, whenever they extremely are stressed, they begin to deform but still supply strength, unlike CFR, produced with good strength, it will take tonss about to 100 per centum of strength without lasting deformation.This is why the in aircraft technology, CFR is an ideal stuff for constituent that is contantly exposed to high burden like air force push. It is called resilient stuff and easy to organize into complex forms plus does non endure from metal weariness or corrosion.The same construct must be applied to rudder where high ductileness and stamina are imperative porperties.To have highest tenssile strength and immature modulus among 5 stuffs listed in the design, with obvious difference CFR proves that, it has high stamina degree and could absorb much energy upon high lading like force of air.Besides carbon fibre besides has better weariness life than most metals, and the rosins typically epoxy used to bond the fibres which offers highly good quiver damping.It is an advantage of CFR where the finishing surface is first-class when sanded carefully with smoothness and clear quality thereby improves aerodynamic by cut downing the retarding force of air flows. One good chracteristic of CFR has is that magnetic screening belongings where it does non disrupt but supplying way for the magnetic field which is necessary for metal sensor to work without false signal.Based on monetary value, the CFR is seemed to be highest yet due to the weight and other advantages, it is exceptionally of import for rudder stuff to set on ground-effect machine as it is worth the excess cost. The low care required for CFR compared to other stuff is another advantage that endorse this pick where initial high industry cost is better than high care cost.CFR is widely known for its popularity to be used in many application with limited production volume since the procedure to bring forth it is complicated.Nevertheless, it is familiar and easy obtained in many states including Malaysia.

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Figure 2: Carbon Fibre Reinforced with matrix epoxy

Fibre Special Review

Carbon fibre reinforced composite has several extremely alone traits that can be benefit in the design of advanced stuffs and systems particularly in ground-effect machine. The most common utilizations for C fiber are in applications are chiefly due to high strength-to-weight and high stiffness-to-weight are desirable. Use of it include in plantation, aeorspace, robotics, air current turbines, military constructions, fabricating constituent, and many others. The stamina can be enhanced when collated or combined with other materials.In peculiar utilizations, many extreme purpose make usage of C fiber in footings of its lastingness, every bit good as dependability in the instance of specialised C fibre. Furthermore, in basic mechanical belongingss, C fibre output a alone and beautiful surface coating for concluding products.The fiber that been reinforced which is embedded really can be modified in footings of choiceness of fiber and orientation on combination in order to acquire many agreement on the complexs which can bring forth different degree of belongingss and characteristic based on certain application.For illustration, some parts of fiber complexs can be really stiff and the other parts of fibre complexs can be so much flexible.All of those obtained by accommodation of fiber which is really interesting in bring forthing assortment of particular equipment.Dealing with C fiber required a high accomplishment degree and many complicated procedures to bring forth high structured stuffs for case, solid C sheet, sandwich laminate and tubing.