For each of the four scenarios below, choose a suitable material for the application, and give reasons for that choice.
Across the four scenarios you should use 1 metal, 1 ceramic, 1 polymer, and 1 composite material choice.
For each choice, your answer should:
State the preferred chosen material for that application, or similar possible alternatives.
Explain the atomic structure of the chosen material
Describe the properties of the material which are relevant to the application, and how your chosen material meets those properties.
Consider possible failure mechanisms for the application, and how your material choice minimise these risks
To achieve a merit:
Consider any impact of hysteresis for any relevant application
To achieve a distinction:
Justify your material choice using appropriate selection charts.
SCENARIOS:
Application 1 - The design of rails (tracks) for a new railway line
Application 2 - The design of vibration blocks to be used on a large industrial, rotating machinery.
Application 3 -A sports company is looking to design a pole to be used in pole vault competitions
Application 4 - A tool company is looking to design a new cutting tool for higher temperature applications
Full Answer Section
- Durability: To resist wear and tear from constant use and exposure to the elements.
- Weldability: To facilitate the joining of rails.
Failure Mechanisms and Material Choice:
- Fatigue Failure: Steel's high fatigue strength and toughness help mitigate this risk.
- Wear: Hardening treatments can improve wear resistance.
- Corrosion: Regular maintenance and protective coatings can reduce corrosion.
Application 2: Vibration Isolation Blocks
Material Choice: Elastomer (e.g., natural rubber, silicone rubber, or neoprene)
Atomic Structure: Long chains of polymer molecules with cross-linking to provide elasticity.
Relevant Properties:
- Elasticity: To absorb and dissipate vibrational energy.
- Durability: To withstand repeated stress and environmental factors.
- Resistance to Fatigue: To maintain its properties over time.
- Chemical Resistance: To resist degradation from oils, fuels, and other chemicals.
Failure Mechanisms and Material Choice:
- Fatigue Failure: Elastomers, especially those with high molecular weight, exhibit good fatigue resistance.
- Thermal Degradation: Choosing a heat-resistant elastomer can mitigate this risk.
Application 3: Pole Vault Pole
Material Choice: Carbon Fiber Composite
Atomic Structure: A composite material consisting of carbon fibers embedded in a polymer matrix (e.g., epoxy resin).
Relevant Properties:
- High Strength-to-Weight Ratio: Essential for maximizing vaulting height.
- Stiffness: To provide the necessary rigidity for support.
- Elasticity: To store and release energy during the vault.
- Durability: To withstand repeated use and impact loads.
Failure Mechanisms and Material Choice:
- Fiber Failure: High-quality carbon fibers with optimal orientation can minimize this risk.
- Matrix Failure: A strong and durable polymer matrix is crucial.
- Delamination: Proper manufacturing processes and quality control can prevent delamination.
Application 4: High-Temperature Cutting Tool
Material Choice: Ceramic (e.g., tungsten carbide or ceramic-metal composite)
Atomic Structure: Crystalline structure with strong covalent bonds.
Relevant Properties:
- High Hardness: To maintain a sharp cutting edge.
- High Temperature Resistance: To withstand the heat generated during cutting.
- Wear Resistance: To minimize tool wear and maintain cutting efficiency.
- Thermal Shock Resistance: To resist sudden temperature changes.
Failure Mechanisms and Material Choice:
- Thermal Shock: Ceramic materials, especially those with fine-grained microstructure, exhibit good thermal shock resistance.
- Wear: A hard, wear-resistant coating can further improve tool life.