Andrew Rhead

Dr Andrew Rhead is a Lecturer in Composites in the Department of Mechanical Engineering.

His work focuses on the impact and damage tolerance of aerospace composite structures. He is particularly interested in the detection and modelling of mechanisms of failure and Non-Destructive evaluation (NDE) of impact damage.

Andrew graduated with a MSci(MMath) with a focus on Dynamical Systems, specifically Mechanics, Control theory, Chaos theory, Fluid dynamics, Fractals and Quantum mechanics, from the University of Bristol in July 2006.

He obtained a PhD on the Analysis and optimisation of damage tolerant, post-buckled composite laminates from the University of Bath in 2009. His research was sponsored by GWR and Airbus.

Between November 2009 and April 2010, Andrew was awarded an EPSRC grant for improving departmental use of Digital Image Correlation (DIC) and Ultrasonic C-scan equipment.

Andrew's six-month research project in 2010 on analysing and optimising the damage tolerance of stiffeners subject to in-plane impact was funded by Airbus and was used to confirm allowable strain in the structure of the Airbus A350-XWB wing.

Between 2010 and 2012 Andrew worked on ABBSTRACT 2 – EPSRC, an Airbus and GKN funded project assessing the feasibility of using curved fibres to manufacture aerospace components.

Andrew provided experimentally validated analytical models for the damage tolerance of curved fibre structures that can be used in conjunction with minimum mass optimisation tools.

Research

During the manufacture and operation of an aircraft, layered Carbon Fibre Reinforced Plastic (CFRP) components are subject to a variety of low-energy impacts.

These impacts typically leave minor surface indentations that go unnoticed during routine inspections. However, dangerous internal damage is also created which can lead to catastrophic failure when loaded.

The lack of damage tolerance of composite structures is one of the greatest barriers to improvement of airframe structural efficiency; a critical driver for increasing fuel efficiency and reducing emissions.

Andrew's research has focused on assessing the residual strength of impact damaged composite laminates and has been supported by the EPSRC, Airbus and latterly by GKN Aerospace.

Topics include:

• Development of unique, computationally efficient, analytical modelling tools for the calculation of the compression after impact strength of composite laminates under both static and fatigue loading. This work has been applied to a range of aerospace structures and the tools have been shown to be at least as accurate and an order of magnitude more computationally efficient than commercial finite element approaches.
• Implementation of state-of-the-art Non Destructive Testing (NDT) and application of the above models led to the discovery that coupon level tests, upon which current empirical industry approaches to damage tolerance rely, do not always provide a correct representation of the damage tolerance of a full composite structure. This is a consequence of the fact that coupon tests do not account for the effects of interaction of local failure mechanisms with global component deformation and boundaries.
• Illumination, during research on steered fibre laminates, of deficiencies in the underlying theory used in commercial Finite Element approaches to the buckling of surface plies, especially in regions where surface plies have high Poisson’s ratios or show coupling of in-plane loading to twisting deformation.

Interested in supervising students studying:

• Aerospace composites
• Damage tolerance of aerospace structures
• Impact of aerospace structures