notes on diffusion, deformation processes

uni/mmme/1029_materials_and_manufacturing/materials.md

@@ -27,17 +27,17 @@ tags: [ uni, nottingham, mechanical, engineering, mmme1029, materials ]
   usually associated wit structural and mechanical properties or long standing chemical effects like
   corrosion:
 
-    - fossil fuels
-    - hydroelectric
-    - oil from shale and tar
-    - sands
-    - coal gasification
-    - liquefaction
-    - geothermal energy
-    - wind power
-    - bomass conversion
-    - solar cells
-    - nuclear reactors
+  - fossil fuels
+  - hydroelectric
+  - oil from shale and tar
+  - sands
+  - coal gasification
+  - liquefaction
+  - geothermal energy
+  - wind power
+  - bomass conversion
+  - solar cells
+  - nuclear reactors
 
 ### Applications of Energy-Related Materials
 
@@ -1140,7 +1140,74 @@ You can apply the Arrhenius equation for all thermally activated diffusion:
 
 $$D = D_0 \exp{\left( - \frac{Q}{RT} \right)}$$
 
-where $Q$ is the activation energy and $R$ is the ideal gas constant (8.31 J k$^{-1}$ mol$^{-1}$).
+where $D$ is the diffusion coefficient, $D_0$ is the frequency factor, $Q$ is the activation energy,
+$R$ is the ideal gas constant (8.31 J k$^{-1}$ mol$^{-1}$).
+
+You can find the diffusion distance, $x$, with the following equation:
+
+$$x ~ \sqrt{Dt}$$
+
+![](./images/vimscrot-2022-02-28T20:31:12,395307966+00:00.png)
+
+
+# Materials in Sustainable Transport
+
+- Concerns over use of fossil fuels, climate change
+- Const of energy
+- Energy use in making and moving vehicles
+- Rising energy prices mean cost of fuel is comparable to cost of car
+- 1/4 of energy used in UK is to transport goods and people
+- Legislation and voluntary targets set by EU to improve fuel efficiency
+- In 2015 average CO2 emmisions as 130 g / km
+- Engine powerhas gone up significantly from 2001 to 2018 (~30%) yet engine displracement has gone
+  down ~10% and CO2 emissions down ~18% while weight has gone up ~10%
+
+## Is the car emissions reduction target significant?
+
+Overall CO2 emissions in 2016 is 466 Megatonnes.
+
+Does a reduction from 130 g / km to 95 g / km (a 35 g/km reduction) make a significant difference?
+
+There are 33 million registered cars in the uk.
+
+If they average around 8000 miles each (~13000 km) per year that's a ~15 Megatonne reduction,
+or about 3% of the annual C02 emmissions, a significant reduction.
+
+## Materials in Cars
+
+- Most of the energy used by cars is during driving (71%)
+- This means the mass of the vehicle has a great effect on its emmissions across a lifetime
+- The body, suspension, drivetrain, and interior all contribute roughly a quarter to the mass of the
+  car
+- However, the mass of cars are increasing
+
+### Material Substitution
+
+- The material will likely have performance requirements:
+
+  - It may need to be a physical size
+  - It may need to operate at certain temperatures
+  - It may need to bear a certain load
+
+- The component mustalso be designed for convenient manufacturing, assembly, servicing, disposal,
+  remanufacturing and/or disassembly
+
+#### Case Study --- 2012 Honda Accord
+
+- Body --- opted to stay with steel --- aluminium intense and multi-material approaches were both
+  rejected due to higher costs and limitations in manufacturing and assembly.
+  Recyclability was also noted as an issue due to different grades of aluminium needing to be
+  separated at end of life.
+- Doors and bonnets --- move to aluminium from steel --- more costly but the mass savings made this
+  option worth it
+- Wiring --- aluminium to copper --- lower mass for same conductivity, copper is more expensive
+  (I think)
+- Seats --- steel to composites or magnesium structural components --- very high weight savings
+
+## Choosing a Material
+
+
+
 
 # Glossary