1. Fracture of Brittle Lattice Structures
Author: Robert Tanner
Supervisor: Professor Martyn Pavier
05 July 2016
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2. Contents
• Aims and objectives
• Background information
• Test specimens
• Methods
• Results
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3. Aims and objectives
• To produce a literature review on available information
on the fracture of brittle lattice structures
• To design experiments that will demonstrate brittle
fracture of solid and lattice structures
• To perform the experiments and analyse the resulting
data
• To determine if the fracture mechanics approach is valid
when applied to a brittle lattice structure
Aims and objectives 3
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4. Background Information
• What is a lattice?
• Cellular solids
Background information 4
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• 𝐾𝐼𝑐 = 𝑓 𝜎, 𝑎, 𝑊
• 𝐾𝐼𝑐 = 𝑓 ഥ𝜌, 𝜎𝑓, 𝐿
5. Background information 5
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• Material failure: stress and strength
• Brittle failure
• Theoretical strength and actual strength
• Hierarchical structure
7. • Useless
• Overcomplicated
• Can the fracture mechanics approach predict the
failure of a brittle material under plane strain
conditions containing a large lattice structure
with cracks?
Background information 7
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8. Test specimens
• PMMA
Test specimens 8
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• Thick
• Waterjet cutter
• Lattice structure
• Circular unit cells
• Crack-hole geometries
• Observations and measurements
10. Experimental phase
• Material properties
• Mount in testing machine
• Tension
• Load-displacement data
• Critical crack lengths
• FEA and LEFM
Experimental phase 10
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