Imperial College London

John P. Dear MA PhD CEng FIMechE CPhys FInstP

Faculty of EngineeringDepartment of Mechanical Engineering

Professor of Mechanical Engineering
 
 
 
//

Contact

 

+44 (0)20 7594 7086j.dear Website

 
 
//

Location

 

520City and Guilds BuildingSouth Kensington Campus

//

Summary

 

Composite Materials - MECH97051

Aims

Introduction; what are composites, where they find use now and in the future. Definitions. History and Future; why the market for advanced composite materials is expected to grow by well over an order of magnitude in the coming decade

Materials; what goes into a composite and how are they made? Reinforcement types: Fibres, particles, nanomaterials. Matrix materials; thermosets, thermoplastics, metals, ceramics. Reinforcement architectures: UD, woven, non-crimp fabrics, braided, 3D woven and random.
Micromechanics of FRPs; why do composites behave the way they do? Weight and volume fractions. Analytical models for elastic properties Analytical models for strength
Macromechanics of a ply. Ply numbering and notation conventions. Stress and strain vectors plus transformations review. Dealing with shear stiffness in engineering vs tensor forms. Symmetry, anisotropy and orthotropy. Elastic properties of an orthotropic ply. Hygrothermal strains. Strength of an orthotropic ply
Macromechanics of a laminate. Forces and moments. Strains and curvature. Mechanics of a laminate; constructing the ABD matrix. Effect of layup on coupling bending and twisting. Effective elastic properties of a laminate
Macromechanics; failure criteria. Max strain. Max stress. Tsai-Hill and Tsai-Wu. PPFA and damage based models. WWFE review
Micromechanics of particle filled composites. Eshelby’s method of inclusions. Halpin-Tsai. Hashin-Strihkman. Numerical homogenisation of unit cells  
Toughening mechanisms. Brittle material toughening mechanisms. Toughening through inducing plasticity; Huang-Kinloch model. Plastic zone size; toughening in bulk vs composite materials. Fibre bridging. Initiation vs propagation fracture toughness within laminates.
Curing; Main hardener classes for epoxies. Models for cure kinetics. Determining constants for kinetic models using DSC. Rheology of resin systems vs state of cure
Defects; Effect of porosity. Sources and sinks in liquid vs prepreg processing. Scaling effects; Darcy’s law. Effect of pressure on porosity; critical conditions for bubble growth. Debulk and cure cycle design principles; keeping volatiles in solution
Fibre (mis)alignment; real vs idealised fibre and tow paths in textile based composites. Misalignment at the tow level. Misalignment at the fibre level. Real vs idealised misalignment in models. Effect of random vs regular packing idealisations

Role

Course Leader

Composite Materials - MECH97067

Aims

Introduction; what are composites, where they find use now and in the future. Definitions. History and Future; why the market for advanced composite materials is expected to grow by well over an order of magnitude in the coming decade

Materials; what goes into a composite and how are they made? Reinforcement types: Fibres, particles, nanomaterials. Matrix materials; thermosets, thermoplastics, metals, ceramics. Reinforcement architectures: UD, woven, non-crimp fabrics, braided, 3D woven and random.
Micromechanics of FRPs; why do composites behave the way they do? Weight and volume fractions. Analytical models for elastic properties Analytical models for strength
Macromechanics of a ply. Ply numbering and notation conventions. Stress and strain vectors plus transformations review. Dealing with shear stiffness in engineering vs tensor forms. Symmetry, anisotropy and orthotropy. Elastic properties of an orthotropic ply. Hygrothermal strains. Strength of an orthotropic ply
Macromechanics of a laminate. Forces and moments. Strains and curvature. Mechanics of a laminate; constructing the ABD matrix. Effect of layup on coupling bending and twisting. Effective elastic properties of a laminate
Macromechanics; failure criteria. Max strain. Max stress. Tsai-Hill and Tsai-Wu. PPFA and damage based models. WWFE review
Micromechanics of particle filled composites. Eshelby’s method of inclusions. Halpin-Tsai. Hashin-Strihkman. Numerical homogenisation of unit cells  
Toughening mechanisms. Brittle material toughening mechanisms. Toughening through inducing plasticity; Huang-Kinloch model. Plastic zone size; toughening in bulk vs composite materials. Fibre bridging. Initiation vs propagation fracture toughness within laminates.
Curing; Main hardener classes for epoxies. Models for cure kinetics. Determining constants for kinetic models using DSC. Rheology of resin systems vs state of cure
Defects; Effect of porosity. Sources and sinks in liquid vs prepreg processing. Scaling effects; Darcy’s law. Effect of pressure on porosity; critical conditions for bubble growth. Debulk and cure cycle design principles; keeping volatiles in solution
Fibre (mis)alignment; real vs idealised fibre and tow paths in textile based composites. Misalignment at the tow level. Misalignment at the fibre level. Real vs idealised misalignment in models. Effect of random vs regular packing idealisations

Role

Course Leader

Dynamics - MECH50008

Aims

To enable students to master essential basic topics in vibrations and dynamics

ECTS units: 5

 

Role

Tutor