Welcome back! Sorry for the period of no updates as shortly after where I had left off, the looming end of semester tests was happening. As such I had to prepare for that which left me with no time to put together a blog on what I have done. As such I am quite enthusiastic about this blog as I have not written in a while. In today's blog post I will be covering 2 lessons where I have learnt about materials for design (MFD), design for materials (DFM) and sustainable design. So let's get right into it.
Up first is MFD. MFD was a module I had taken in year 1, due to that fact, the concepts taught this time around were a breeze to absorb and served as a nice refresher and reminder that concepts from other modules will be applicable in the course. As a summary, MFD is a process where an end result is desired aka a design and materials are selected based on the requirements of the design. For material selection we need to understand the 4 categories they are divided into.
- Mechanical Properties, e.g Hardness, Young's Modulus, Density, Ultimate Tensile Strength
- Thermal Properties, e.g Thermal conductivity, Specific Heat Capacity
- Fabrication Properties, e.g Ease of Machining, Viscosity, Availability
- Environmental Properties, e.g Corrosivity, Toxicity
Having understood the requirements a material can have, it is time to move onto the system which is used to pick the material best suited for the job, the COWS matrix. In previous blogs I have used the COWS matrix before. But for the benefit of those who do not understand what is COWS, let me explain.
Figure 1: Criteria Weightage for COWS Figure 2: COWS matrix for blade of razor
First of all, material criteria need to be selected from the list of properties we discussed above. Following that, a ranking of those criteria needs to be established as there are bound to be more important criteria. An example can be found in the above COWS matrix where the young's modulus was the main focus as the blade of a razor must be durable if anything else. Once the criteria and weightage is done, assign a number to each material based on how good they are in a certain criteria. Lastly, multiply the number with the percentage and tally up the total score. The highest score would be the material best suited for the job.
Next up is DFM. Although DFM might seem similar to MFD, they are different. In Design for Materials, both the design of a product and the material used for that product is taken into consideration, to see if any changes can be made to a product be it design or material wise in order to increase its effectiveness/ease of use. The given example was ceramic knives, which despite being similar in size to normal steel knives, stay sharp 10 times longer, are extremely light and are non-porous, which means they would prevent bacterial growth. However, ceramic knives are brittle and chip easily. I actually did not know that ceramics could be used to make knives, so the example was both interesting and educational.
After learning DFM, we were tasked to conduct research on a material and as a collective, my group decided on the Shape memory alloy material.
From our research, we found that there are several qualities that are useful about shape memory alloy:
- Capable of altering its shape back to its initial form
- Corrosion resistant
- Bio-compatible
These qualities have very real-world applications such as being able to be a one to one substitute for plastics in spectacle frames or metal used for the body of cars, however, the design of the car must be adjusted for shape memory alloy to replace metal.
Lastly I will briefly touch on sustainable design. Sustainability comes down to the materials used being:
- Non-toxic or recycled
- Made using energy efficient processes
- Have a long life-span (no degradation over long periods of time)
- Design for reuse and recycling. (e.g. easy to disassemble)
We decided that the top layer of our product can be made out of recycled plastic as its only requirement is to be structurally stable. We also altered the design of the product to be easily disassembled into two layers as it allows the product to be easily cleaned and hence reusable.
As always thank you for taking the time to read through my blog and learning vicariously through my experiences.
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