3.2.2
Timber
Torsion and Shear Force
Torsion and Shear Force
Materials can be manipulated to resist and work with forces and stresses.
Torsion with woods
Torsion with woods
- Wood has very good torsional strength but there are often issues with ensuring that the wood does not warp under moisture and differing conditions.
- Some scaffolding boards have metal brackets that hold and prevent the wood timber from warping and increasing its torsional strength.
- It goes without saying that torsional strength is key when being used for scaffolding
Hardwoods and softwoods
Hardwoods and softwoods
- Hardwood materials that are dense and have close grains that make them less likely to warp compared to softwoods.
- However, softwoods are used with metal brackets as they are more sustainable and they are more economical.
Shear force with woods
Shear force with woods
- Wood, especially close grain hardwoods, resist shear force.
- Some softwoods are weaker but generally speaking, can withstand shear forces just as well.
Affecting shear force
Affecting shear force
- Knots and looser grains reduce the strength of wood which directly affects its ability to resist shear force.
- If moisture is increased you will weaken the ability for the timber to withstand shear forces.
- If plywood is not glued and laminated properly, its ability to withstand sheer force will be reduced greatly.
Tension, Compression and Bending
Tension, Compression and Bending
Materials can be manipulated to resist and work with forces and stresses.
Tension
Tension
- The tensile strength of wood is very high due to its grain and structure.
- Moisture, over time, can affect the tensile strength.
- Wood is a good choice for when tensile strength is needed, but wood is 30% stronger in compression than tension.
Compression
Compression
- Wood is excellent for compression.
- Moisture content can severely affect its ability to withstand compression which results in an ineffective piece of timber/wood.
- Wood, when working in the direction of the grain, can withstand compression well. However, if pushed too far, hardwood will fail.
Bending
Bending
- Bending, as a force, can be desirable in certain situations.
- Often Aeroply is used (as it is a thin laminated sheet) with water and heat. Bending can be used to show off how curves can be used with wood.
Kerfing
Kerfing
- Bending can also be achieved through kerfing.
- Kerfing is creating half slots through the use of a saw. Glue is applied once the wood is bent.
1Core Technical Principles
1.1New & Emerging Technologies
1.2Energy Generation & Storage
1.3Developments in New Materials
1.4Systems Approach to Designing
1.5Mechanical Devices
1.6Materials Categories
2Paper & Board: Specialist Technical Principles
2.1Selection of Materials
2.2Paper & Board: Forces & Stresses
2.3Paper & Board: Ecological & Social Footprint
2.4Paper & Board: Sources & Origins
2.5Paper & Board: Using Materials
2.6Paper & Board: Stock Forms, Types & Sizes
2.7Paper & Board: Scales of Production
2.8Paper & Board: Specialist Techniques & Processes
2.9Paper & Board: Surface Treatments & Finishes
3Timber: Specialist Technical Principles
3.1Timber: Selection of Materials
3.2Timber: Forces & Stresses
3.3Timber: Ecological & Social Footprint
3.4Timber: Sources & Origins
3.5Timber: Using Materials
3.6Timber: Stock Forms, Types & Sizes
3.7Timber: Scales of Production
3.8Timber: Specialist Techniques & Processes
3.9Timber: Surface Treatments & Finishes
4Metal: Specialist Technical Principles
4.1Metals: Selection of Materials
4.2Metals: Forces & Stresses
4.3Metals: Ecological & Social Footprint
4.4Metals: Sources & Origins
4.5Metals: Alloy-Based Materials
4.6Metals: Using Materials
4.7Metals: Scales of Production
4.8Metals: Specialist Techniques & Processes
4.9Metals: Quality Control
4.10Metals: Surface Treatments & Finishes
5Polymers: Specialist Technical Principles
5.1Polymers
5.2Polymer Categories
5.3Polymer Forms
5.4Polymer Production, Techniques & Quality Control
6Textiles: Specialist Technical Principles
6.1Textile Materials
6.2Selection of Materials
6.3Forces & Stresses
7Designing & Making Principles
7.1Investigation & Data
7.2Environmental, Social & Economic Challenges
7.3The Work of Others
7.4Design Strategies
7.5Communication of Design Ideas
7.6Prototype Development
7.7Selection of Materials
7.8Tolerances
7.9Material Management
7.10Specialist Equipment
7.11Specialist Techniques & Processes
Jump to other topics
1Core Technical Principles
1.1New & Emerging Technologies
1.2Energy Generation & Storage
1.3Developments in New Materials
1.4Systems Approach to Designing
1.5Mechanical Devices
1.6Materials Categories
2Paper & Board: Specialist Technical Principles
2.1Selection of Materials
2.2Paper & Board: Forces & Stresses
2.3Paper & Board: Ecological & Social Footprint
2.4Paper & Board: Sources & Origins
2.5Paper & Board: Using Materials
2.6Paper & Board: Stock Forms, Types & Sizes
2.7Paper & Board: Scales of Production
2.8Paper & Board: Specialist Techniques & Processes
2.9Paper & Board: Surface Treatments & Finishes
3Timber: Specialist Technical Principles
3.1Timber: Selection of Materials
3.2Timber: Forces & Stresses
3.3Timber: Ecological & Social Footprint
3.4Timber: Sources & Origins
3.5Timber: Using Materials
3.6Timber: Stock Forms, Types & Sizes
3.7Timber: Scales of Production
3.8Timber: Specialist Techniques & Processes
3.9Timber: Surface Treatments & Finishes
4Metal: Specialist Technical Principles
4.1Metals: Selection of Materials
4.2Metals: Forces & Stresses
4.3Metals: Ecological & Social Footprint
4.4Metals: Sources & Origins
4.5Metals: Alloy-Based Materials
4.6Metals: Using Materials
4.7Metals: Scales of Production
4.8Metals: Specialist Techniques & Processes
4.9Metals: Quality Control
4.10Metals: Surface Treatments & Finishes
5Polymers: Specialist Technical Principles
5.1Polymers
5.2Polymer Categories
5.3Polymer Forms
5.4Polymer Production, Techniques & Quality Control
6Textiles: Specialist Technical Principles
6.1Textile Materials
6.2Selection of Materials
6.3Forces & Stresses
7Designing & Making Principles
7.1Investigation & Data
7.2Environmental, Social & Economic Challenges
7.3The Work of Others
7.4Design Strategies
7.5Communication of Design Ideas
7.6Prototype Development
7.7Selection of Materials
7.8Tolerances
7.9Material Management
7.10Specialist Equipment
7.11Specialist Techniques & Processes
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