Composite Materials and Fibres

• Describe and calculate the mechanical properties of materials based on their chemistry and structure
• Explain and calculate the effect of defects on material strength, and identify the methods of obtaining strong fibres
• Describe the chemistry and structure, processing and properties of practically relevant fibres in composites (glass, carbon, cellulose, polyethylene)
• Explain scatter in strength of fibres by a statistical method (Weibull), and use the method to calculate the scale effects of fibre strength
• Convert between weight and volume fractions in composites, and understand the relationship between volume fractions of fibres, matrix and porosity, in composites with different fibre weight fractions
• Describe and calculate the load distribution and load transfer in unidirectional composites with continuous and non-continuous fibres
• Calculate stiffness of composites with a given composition and configuration, and design of composites in relation to specific property profiles
• Explain and calculate the strength of unidirectional composites with micromechanical models predicting single and multiple fracture
• Identify and estimate the work of fracture of unidirectional composites from the mechanisms of debonding, elastic stretching and fibre pull-out

Introduction to strong and light materials; theoretical maximum strength of materials; the effect of defects on practical lower strength; reinforcement of materials; principles of reinforcement with inclusions, in particular fibres; relevant fibres, their structure, fabrication, and properties; statistical analysis of fibre strength; volumetric composition of composite materials, in particular porosity; micromechanical models for composite materials; load transfer between fibre and matrix; critical fibre length; debonding and fibre pull-out energy for composite materials; single and multiple fracture; stiffness, strength and fracture energy for composite materials.

41015/41501/46410/46430/46440

Lectures, discussions, exercises