bicycle helmet final

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INTRODUCTION INTRODUCTION - A bicycle helmet is a helmet intended to be worm while riding a bicycle. - They are designed to attenuate impacts to the skull of a cyclist in falls while minimizing side effects to the such as interference with peripheral vision. - A cycle helmet should be light in weight and should provide adequate ventilation because cycling can be an intense aerobic activity which significantly raises body temperature and the head in particular needs to be able to regulate its temperature.

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Page 1: Bicycle Helmet Final

INTRODUCTIONINTRODUCTION-A bicycle helmet is a helmet intended to be worm while riding a bicycle.

- They are designed to attenuate impacts to the skull of a cyclist in falls while minimizing side effects to the such as interference with peripheral vision.

- A cycle helmet should be light in weight and should provide adequate ventilation because cycling can be an intense aerobic activity which significantly raises body temperature and the head in particular needs to be able to regulate its temperature.

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Bicycle Helmet

Bicycle Helmet

Material selection for Bicycle Helmet

Polystyrene foam closed cell (0.050)

Cork

Balsa, ultra low density, perpendicular to grain

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The material selection for The material selection for bicycle helmetbicycle helmet

Figure 1 : The ability of a foam to absorb energy is measured by the product

eD. sc(0.25). Materials above the selection line absorb the most energy per unit volume.

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Figure 2 : shows a chart with the same axes as figure 2, but this time selects foams which absorb energy below the plateau stress of 0.9 MPa (the constraint determined by the load on the skull).

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Figure 3: shows those materials that pass both stages and are therefore viable candidates. They are Expanded Polystyrene with a density of 0.05 Mg/m3 - EPS (0.05), Cork and ultra low density Balsa wood (see the selection results below).

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Denstiy; 1050 kg/meter3

Density determines both weight and the materials ability to absorb impact. Studies show that a lower density matieral will not only be lighter in weight, but will aslo be able to withstand more force upon impact.

Young's Modulus: 3000-3600 Mpa        The Young's Modulus (or Elastic Modulus) describes the stress and strain apacity of an object. A larger number indicates that the object will deform less under greater force.

Tensile Strength: 46-60 Mpa

Melting Point : 240°C

Decomposition ± 2000

Expanded Polystyrene• 5 -10% gaseos blowing agents                 +

• 90 - 95% Polystyrene or Styrofoam

• EPS is omni-directional and will provide the same protection from all directions of impact.

Expanded Polystyrene Basic Statistics

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Polystyrene : Why is it the best choice ?Polystyrene : Why is it the best choice ?

- Polystyrene is an aromatic polymer made from the aromatic monomer styrene.

- Polystyrene is a thermoplastic substance which is in solid (glassy) state at room temperature.

- Heated when above glass transition temperature (Molding or extrusion).Solid again when it cools.

- Polystyrene can be recycled and the number ‘6’ as its recycle symbol.

- It is abundant as a form of pollution in the outdoor environment particularly.

Polystyrene's chemical formula is (C8H8)n; it contains the chemical element, carbon and

hydrogen..

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Cork

- Cork material is an impermeable,buoyant material.

- Cork is composed of suberin a hydrophobic substance and

because of its impermeability,buoyancy,elasticity and fire

resistance.

- It is a good insulator it can reduce the energy required for heating.

- Some of the property ranges of the composites are density (400–

1500 kg/m³), compressive strength (1–26 MPa) and flexural

strength (0.5–4.0 MPa).

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Balsa-Known as Ochroma pyramidale. -Balsa is the softest commercial hardwood. Balsa lumber is very soft and light with coarse open grain.

- The density of dry balsa wood ranges from 40–340 kg/m³ (2.5-21 lb/ft³), with a typical density of about 160 kg/m³ (10 lb/ft³).

-Balsa wood is used to make very light, stiff structures. Balsa wood is often used as a core material in composites.

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Material considerationMaterial consideration

•The importance of a safe and reliable bike helmet is immeasurable. Scientists can, however, The importance of a safe and reliable bike helmet is immeasurable. Scientists can, however, measure the durability, affectiveness, and strength of the material that make up the inside of measure the durability, affectiveness, and strength of the material that make up the inside of helmets is difficult. helmets is difficult.

•They tested a series of materials, including low density cork, balsa wood, and Aluminum SiC , They tested a series of materials, including low density cork, balsa wood, and Aluminum SiC , for the ability to withstand force, impact, time, and the elements of wind, rain, snow, and ultra-for the ability to withstand force, impact, time, and the elements of wind, rain, snow, and ultra-violet rays. violet rays.

•Expanded PolystyreneExpanded Polystyrene

• The material that was strongest in all of these categories .The material that was strongest in all of these categories .

• low-density foam material that helps to prolong and soften the impact of the cranium low-density foam material that helps to prolong and soften the impact of the cranium on the ground.on the ground.

•Bicyclists only need to know that helmets made with EPS must be replaced after a crash or Bicyclists only need to know that helmets made with EPS must be replaced after a crash or after being subjected to a great amount of force. EPS loses its strength after one impact.after being subjected to a great amount of force. EPS loses its strength after one impact.

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Manufacturing TechniqueManufacturing Technique

•Helmet shells are made by blow moulding, vacuum moulding or injection mouldingHelmet shells are made by blow moulding, vacuum moulding or injection moulding

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Design ConsiderationDesign Consideration

•about the tolerable impact the head can handleabout the tolerable impact the head can handle

• the soft linings provide as protection, and the exterior protection from punctures.the soft linings provide as protection, and the exterior protection from punctures.

•Wearing a helmet to protects headWearing a helmet to protects head

•. It could basically be a life saver if get into an accident.. It could basically be a life saver if get into an accident.

•Helmets act as a protection device for your head .Helmets act as a protection device for your head .

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Environment considerationEnvironment consideration

EPSEPS•Used polystyrene has no impact on the environment even in landfill sites or in incineratorsUsed polystyrene has no impact on the environment even in landfill sites or in incinerators

•No contain substances that could pollute the air or soilNo contain substances that could pollute the air or soil

•EPS not only recyclable but it poses no risk to either health or the environmentEPS not only recyclable but it poses no risk to either health or the environment

Cork and BalsaCork and Balsa•Not harm to the environment because its is organic materialNot harm to the environment because its is organic material

•Produce from plantsProduce from plants

•Can be dispose naturallyCan be dispose naturally

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THANK YOUTHANK YOU