Mechanical Behaviour ofMechanical Behaviour of Highly Packed Particulate Composites

Henry TanySchool of Engineering, University of Aberdeen, UK

Highly Packed Particulate Composites (HPPCs)

Five topics on the “Mechanical Behaviour of “Highly Packed Particulate Composites” (HPPCs)

1. Microstructure of Highly Packed Particulate CompositesComposites

2. Interface Cohesive Law3. Network Formation and Percolation Modelling3. Network Formation and Percolation Modelling4. Materials Point Method and X‐Ray tomography5. Catastrophic Behaviours under Loading5. Catastrophic Behaviours under Loading

Mechanical Behaviour of Highly Packed particulate Composites (HPPCs)g y ac ed pa t cu ate Co pos tes ( Cs)

1 Microstructure of HPPCs1. Microstructure of HPPCs

Structured Food

One of the greatest challenges in the food industries is to develop products that can fracture in a pre‐designed way so that they can provide the required function. 

Sedimentary Rock

Sedimentary rocks are made of sediments cemented or compacted together by a particular force or process over time.

P ti l i 50

Mudstone, 泥岩Conglomerate , 砾岩 Sandstone, 砂岩

S di t k l t th ti fl d

Particle size < 50mg ,砾岩Particle size > 2mm Particle size < 0.05‐2mm

Sedimentary rocks cover almost the entire ocean floor and about three‐quarters of the Earth's surface land area

Multiple Sizes

Plants

bamboo poplar eucalypt pine

Cellular Structure of Wood

bamboo poplar eucalypt pine

Mayo, Evans, Chen, Lagerstrom, 2009, Journal of Physics

FoamMaterialsFoam Materials

Nacre

砖‐泥巴网络结构

organic biopolymerbiopolymer

Brick‐and‐mortar like network. 

Li X, Huang Z (2009) Unveiling the Formation 

aragonite platelets

Mechanism of Pseudo‐Single‐Crystal Aragonite Platelets in Nacre, Phys Rev Lett.

Hierarchical Organization in Nacre

crystal /biological binderBrick‐mortar network biological binderBrick mortar network

Nacre

Luz and Mano , 2009

Brick‐mortar network

Plastic Bonded Energetic Materialg

coarse particlesp(~250 m)

fine particles (~8m) 

High volume fraction ~93%g

High specific surface of interface

Bimodal Size Distribution

Safety in Nuclear Decommissioning

Partnership with Sellafield Ltd Decommissioning, Cumbria, 2007 -p g, ,

Explosive charges placed under the cooling towers of Calder Hall Plant

Controlled collapse of each tower.(World Nuclear News)cooling towers of Calder Hall Plant.

A d t di f th iti it f l i t f d t l

(World Nuclear News)

An understanding of the sensitivity of explosives at a fundamental level is important for safety in nuclear decommissioning.

Solid Propellant Rocket

DDT: normal surface burning‐>explosion

Catastrophic interface debonding‐> formation of hotspot

Microstructure of solid propellant material.Id l 1999

Center for Simulation of Advanced Rockets, UIUC

Ide et al., 1999• Ignition and combustion of composite energetic materials• Solid mechanics of propellant, case, insulation, and nozzle• Fluid dynamics of interior flow and exhaust plume

Pressure – Burn – Microstructure

Combustion chamber

Solid propellant

BurningBurning surface

Relatively small defects, like debonded interfaces and cracks, can lead to catastrophic failure.

Summary y

Several typical Highly Packed Particulate Composites (HPPCs)