木材、金屬與合金：練習題

Which of the following metals is classified as a non-ferrous alloy?

Which of the following ferrous metals is characterized by a high carbon content (typically 2% to 4%), providing excellent compressive strength and fluidity for casting, but resulting in low malleability and poor impact resistance?

A designer is specified to use reactive glass for the external windows of a high-end corporate office. What is the primary functional advantage of this modern material compared to photo-chromic materials in this context?

Which hardwood is commonly specified for the manufacture of high-quality architectural models and light-weight prototypes due to its exceptionally low density and high strength-to-weight ratio?

A designer is developing a tactile pressure sensor for a robotic limb. They require a smart material that behaves as an electrical insulator in its relaxed state but becomes a conductor when physical pressure is applied. Which material is most suitable?

A designer is developing a reusable coffee cup that must withstand high temperatures without losing its shape. Compare the suitability of Polypropylene (PP) and Acrylic for this application based on their thermoplastic properties and safety.

Discuss the technical benefits of using Glass Fibre Reinforced Plastic (GRP) for the hull of a small boat, referring to the material\'s strength-to-weight ratio and its chemical resistance to saltwater.

Compare the malleability and ductility of copper and cast iron, explaining why one is more suitable for wire manufacture.

A high-performance automotive company is developing a new lightweight structural component for a vehicle chassis. They are choosing between using duralumin (an aluminium alloy) and Carbon Fibre Reinforced Plastic (CFRP).

(a) Evaluate the use of CFRP for this application, specifically discussing how its strength-to-weight ratio and stiffness compare to duralumin. (3 points)

(b) Explain how the lamination process used in the manufacture of CFRP allows designers to manipulate the directional strength of the component. (2 points)

A high-performance aerospace manufacturer is redesigning a component that was previously made from Duralumin. They are considering replacing it with Carbon Fibre Reinforced Plastic (CFRP) to improve fuel efficiency and performance.

(a) Evaluate the use of CFRP over Duralumin for this application, with specific reference to two mechanical performance characteristics. (2 points)

(b) The component must withstand significant impact during landing. Explain why a designer might be concerned about using a composite like CFRP in this scenario compared to a metal alloy, referring to the material's toughness and failure mode. (2 points)

(c) Modern aircraft often utilise Shape Memory Alloys (SMA) in wing assembly. Explain the unique functional characteristic of SMAs and how they respond to external stimuli. (2 points)