Week 4 Assignment

The week 4 lesson is asynchronous, and we were given time to revisit a module that we had taken in our first year: Materials for Design. In Materials for Design, we learned how to classify materials into different categories based on their physical and chemical properties, and select the most suitable material for a product based on the given product function, taking into account the functional, aesthetic and ecological requirements.

The design process of a product involves selecting a material, specifying the shape of the product, and choosing a manufacturing process.

For the asynchronous assignment in week 4, we have been tasked to select materials for a reusable face-shield for medical workers to protect them against the COVID-19 virus. Our scope involves the transparent sheet and the support for the forehead.

1. Define the product function

Figure 1. Function of a face shield

The reusable face-shield protects wearers and the people they interact with against accidental fluid splashes and droplets by preventing water droplets from coming into contact with the user, as the COVID-19 virus is transmitted through these droplets. It is made of two components: the transparent sheet and the forehead support.


2. Define the product requirement

Component: Transparent Sheet
  • It will come into contact with water droplets.
    • It should be water-resistant/waterproof.
  • It will be sanitised with alcohol-based wipes or any other chemical-based cleaning agent.
    • It should not react with whatever is being used to clean it (unreactive).
  • It will be supported by the user’s head.
    • It should be light.
    • It should also be flexible.
  • The user will be wearing it while going about their everyday lives
    • It should allow the user to see through the shield to see what they are doing.
Component: Forehead Support
  • It will be in contact with the user’s forehead.
    • It should be soft.
  • It will be supported by the user’s head.
    • It should be light.
Other requirements
  • It should be able to be used by the frontline workers without cost being a major setback.
  • It should be able to be used a few times before discarding it to prevent too much waste.
  • It should be easy to construct so that it can be made with ease without needing any special machinery.


3. Translate the requirements into material properties


Component: Transparent Sheet
Figure 2. Requirements for the transparent sheet of the face-shield to work

Component: Forehead Support
Figure 3. Requirements for the forehead support of the face-shield to work

Other requirements
Figure 4. Other desirable qualities of a good face shield



4. Identify probable candidates

Component: Transparent Sheet

  • Metals are ruled out since they have high densities, which is the opposite of what we want.
  • We can consider polymers as the probable candidate material.
    • Probable candidates are polycarbonate, polyethylene terephthalate (PET) and polyvinyl chloride (PVC) for the face shield.

Component: Forehead Support

  • Metals are ruled out since they have high densities, which is the opposite of what we want.
  • Ceramics are also ruled out since they are hard.
  • We can consider polymers as the probable candidate material.
    • Probable candidates are polycarbonate, polyethylene terephthalate (PET) and polyvinyl chloride (PVC) for the forehead support.

5. Select the most suitable material

Component: Transparent Sheet
Figure 5. Relevant properties of materials shortlisted for the transparent sheet

Component: Forehead Support
Figure 6. Relevant properties of materials shortlisted for the forehead support

Other requirements
Figure 7. Other relevant properties of the materials shortlisted

COWS Matrix for Transparent Sheet
Figure 8. COWS Decision Matrix for the Transparent Sheet

With polycarbonate having scored the highest of 235, this material is selected as the material for the transparent sheet.

COWS Matrix for Forehead Support
Figure 9. COWS Decision Matrix for the Forehead Support

With PET having scored the highest of 270, this material is selected as the material for the forehead support.

Comments

  1. Chua Poh HuiJune 20, 2021 at 6:51 PM

    You provided a detailed analysis on the material selection. Good job.

    ReplyDelete

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