Chapter 20 - Improving Functionality

What type of mechanical force is a pulling force that stretches a material?

Tension is a pulling force that stretches a material.

What type of mechanical force is a pushing force that squashes a material?

Compression is a pushing force that squashes a material.

Which force causes layers of a material to slide over one another?

Shear is a force that causes layers to slide over one another.

A twisting force applied to a material is known as what?

A twisting force is known as torsion.

What is bending in the context of mechanical forces?

Bending is a combination of tension and compression caused by a load applied to a material.

What is the primary purpose of strengthening a material?

The purpose of strengthening is to improve a material's load-bearing capacity and reduce the risk of deformation or failure.

Name one method used for strengthening a material.

One method is to increase the material's thickness or select a stronger, higher-grade material.

How can features like ribs, gussets, or brackets improve a product's functionality?

They can be added to increase strength at key points as a method of strengthening.

What does reinforcing mean in product design?

Reinforcing means adding additional material or components to improve the strength or durability of a product.

What material is commonly used to reinforce concrete?

Steel rebar is commonly placed inside concrete to reinforce it.

How are polymers reinforced to create composites?

Glass fibres or carbon fibres are added to polymers to create reinforced composites.

What is the primary purpose of reinforcing a material?

The purpose of reinforcing is to enhance strength and resistance to forces, particularly tension and bending.

What is the main goal of stiffening a material?

The goal of stiffening is to increase a material's rigidity so it resists bending or flexing.

What technique is used to stiffen sheet metal or textiles along their edges?

Forming folded edges or hems is a technique used to stiffen sheet materials and textiles.

How can the stiffness of card or sheet materials be increased without adding much material?

Adding corrugation increases the stiffness of card or sheet materials.

What is webbing and what is its main function?

Webbing is a strong woven material used to distribute loads over a larger area.

In what common product would you find webbing used to spread tension evenly?

Webbing is used in products like backpacks, seatbelts, and straps.

What is the process of laminating?

Laminating involves bonding two or more layers of material together to improve performance.

How is plywood constructed to increase its strength and stability?

In plywood, layers of wood are arranged with alternating grain directions at 90 degrees to each other.

What is the purpose of fabric interfacing in textiles?

Fabric interfacing is used to add stiffness, structure, or strength to fabrics, and to reinforce them.

Where in a garment is fabric interfacing typically applied?

Interfacing is typically applied to collars, cuffs, and waistbands to help them retain their shape.

How does folding or bending a flat material improve its properties?

Shaping materials by folding or bending can significantly increase their structural strength and rigidity.

In the context of packaging, what is a net?

A net is a 2D layout that, when cut and folded, creates a 3D shape.

In composite materials, what is the role of the matrix?

The matrix acts as a binder, holding the reinforcement materials together.

In composite materials, what is the role of the reinforcement?

The reinforcement is added to provide strength or other useful properties to the composite.

In Oriented Strand Board (OSB), what materials serve as the matrix and reinforcement?

In OSB, the matrix is resin adhesive and the reinforcement is strands of softwood timber.

What are the components of Wood Plastic Composite (WPC)?

WPC is made from wood fibres or flour (reinforcement) and thermoplastic polymers (matrix).

What property makes Cement Bonded Particle Board (CBPB) suitable for building panels?

CBPB is fire-resistant due to the Portland cement matrix.

What is the main benefit of plywood's cross-laminated structure compared to solid timber?

Plywood's structure provides uniform strength, stability, and resistance to warping in all directions.

What is 'Yakisugi'?

Yakisugi is a traditional Japanese method of preserving timber by charring its surface.

How does charring the surface of timber in the Yakisugi method protect it?

The layer of carbon created is resistant to decay, water, insects, and even fire.

What is the purpose of steam bending timber?

Steam bending uses heat and moisture to make wood soft and bendable, so it can be shaped without snapping.

Why is timber for outdoor use often pressure-treated with preservatives?

It is treated to protect it from rot, fungal decay, and insect attack.

What is kerfing?

Kerfing is a structural modification technique where closely spaced cuts are made partially through timber to allow it to bend.

How does laminating thin strips of timber create curved shapes?

Thin strips or veneers are glued together and clamped to a bending jig, holding their new shape once the glue dries.

Why is a knot considered a weak point in a piece of timber?

A knot is a weak point because the grain is disrupted, and it can split or crack easily under stress.

What is the purpose of interlocking joints, such as a comb joint, in timber construction?

Interlocking joints create strong connections by fitting pieces together, often increasing the surface area for gluing.

What is glulam and how is it constructed?

Glulam is an engineered timber made by gluing layers of timber together with the grain running in the same direction.

The method of reinforcing a frame structure by creating triangles is called _.

triangulation

What are corner braces or plates used for in timber frames?

Corner braces or plates are added to strengthen right-angle joints and provide structural support.

What materials form Carbon Fibre Reinforced Plastic (CRP)?

CRP is made from layers of woven carbon fibres (reinforcement) and resin (matrix).

What are the key properties of Kevlar that make it suitable for bulletproof vests?

Kevlar is a tough, high-strength, and lightweight material.

What is the difference between laminating and quilting in textiles?

Laminating bonds layers of different materials (e.g., fabric and foam), while quilting stitches layers of fabric with wadding in between.

What is the purpose of adding UV stabilisers to the polymer used for outdoor flags?

UV stabilisers are added to prevent the polymer from degrading in sunlight.

What is the main purpose of heat setting synthetic fabrics?

Heat setting is used to permanently fix the fabric's shape, set features like pleats, and reduce shrinkage.

What is calendering in textile and paper production?

Calendering is a finishing process that uses heated rollers to press and smooth the material, making it denser, stronger, and often glossier.

How can a PTFE coating enhance the properties of a school uniform?

A PTFE coating can be applied to act as a stain repellent, making the uniform easier to clean and maintain.

How do rivets improve the structural integrity of jeans?

Rivets are small metal fasteners used to reinforce high-stress areas like pocket corners to prevent tearing.

What is boning in garment construction?

Boning is where thin strips of metal or polymer are sewn into fabric channels to provide shape, support, and rigidity, as seen in corsets.

What is the function of a gusset in a garment?

A gusset is an extra piece of fabric sewn into a seam to provide a wider range of motion and prevent tearing under stress.

What is an alloy?

An alloy is a material made by combining two or more elements, where at least one of them is a metal.

What two metals are combined to make the alloy brass?

Brass is an alloy of copper and zinc.

Why is stainless steel, an alloy of iron and chromium, used for medical instruments?

Stainless steel is strong, corrosion-resistant, and non-porous, which makes it hygienic and easy to sterilise.

What is the purpose of adding carbon to iron to make steel?

Adding carbon to iron increases its strength and hardness, with higher carbon content resulting in harder steel.

What is the heat treatment process of annealing?

Annealing involves heating a metal and then cooling it slowly to make it softer, less brittle, and easier to work with.

Describe the process of hardening a metal.

Hardening involves heating a metal and then cooling it quickly (quenching), which makes it very hard but also brittle.

Why is a metal typically tempered after it has been hardened?

Tempering is done to reduce the brittleness and improve the toughness of the metal while retaining most of its hardness.

What is galvanising?

Galvanising is a process that involves coating steel with a layer of zinc to act as a protective barrier against corrosion.

How does anodising protect aluminium?

Anodising uses an electric current to create a thick, hard oxide layer on the surface of aluminium, making it more resistant to corrosion.

What is the purpose of adding folded edges (flanges) to sheet metal?

Adding folded edges increases the strength and stiffness along those edges, making the component more rigid.

How does a fillet weld reinforce a metal joint?

A fillet weld joins parts at an angle and adds extra weld material to the corner, which reinforces the joint and increases its strength.

What is the matrix and reinforcement in Glass-Reinforced Plastic (GRP)?

In GRP, the matrix is a resin (a polymer) and the reinforcement is glass fibres.

In polymer manufacturing, what does encapsulation mean?

Encapsulation means fully enclosing a component, such as a sheet of paper, within a polymer layer for protection.

What type of additive is mixed with a polymer to increase its flexibility?

A plasticiser is an additive used to increase the flexibility of a polymer.

What is the purpose of adding stabilisers to polymers used for outdoor products like garden chairs?

Stabilisers are added to prevent polymers from becoming faded and brittle due to UV light from the sun.

What happens during the curing of a thermosetting polymer?

During curing, a chemical reaction called cross-linking forms strong, permanent bonds between the polymer chains, setting the material into a rigid state.

Why can thermosetting polymers not be reshaped after curing?

The permanent cross-links formed during curing create a rigid structure that does not soften when reheated.

How can ribbing be incorporated into an injection-moulded polymer product to improve it?

Ribbing adds wall-to-wall material to provide extra strength and prevent bending or warping.

How does the design of a blow-moulded PET bottle prevent it from collapsing?

Indentations, ridges, or rings are moulded into the sides of the bottle to provide strength and structural integrity.

Describe the structure of corrugated polypropylene sheet.

It consists of a fluted (wavy) inner layer sandwiched between two flat outer layers of material.

What is the advantage of a honeycomb structure, as seen in Nomex core?

The hexagonal cells spread loads evenly in all directions, providing high strength and rigidity with very low weight.

What is the main role of the 'matrix' in a paper-based composite like papier-mâché?

In papier-mâché, the matrix is the diluted glue that holds the paper fibres (reinforcement) together.

How does using multiple plies enhance the properties of toilet paper?

Bonding multiple thin layers (plies) together improves the strength, softness, and absorbency of the paper.

What is the purpose of adding a silicone coating to baking paper?

A silicone coating is applied to baking paper to provide a non-stick surface.

How does calendering improve the properties of paper used for magazines?

Calendering uses heat and pressure to compress the paper fibres, making the paper denser, stronger, smoother, and glossier.

In packaging design, what are interlocking tabs used for?

Interlocking tabs lock into slots to hold the shape of a flat-pack package, reducing the need for adhesives and improving structural integrity.

How do gussets improve the functionality of a paper bag?

Gussets are additional folded sections that allow the bag to expand, increasing its volume and improving how it distributes the load.