Imperial College London

Dr Mazdak Ghajari

Faculty of EngineeringDyson School of Design Engineering

Reader in Brain Biomechanics



+44 (0)20 7594 9236m.ghajari Website




Dyson BuildingSouth Kensington Campus




Biomechanics of traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of death and disability in young people. TBI is caused by mechanical loading of the head in sports, road traffic collisions and falls. The relationship between head loading and the severity and pattern of brain injury is poorly understood. In collaboration with neurologists at the Brain Sciences Department at Imperial College, we have developed high-fidelity computational models of TBI to study this relationship. We are also developing tools for rapid prediction of brain injuries, which combined with sensing technologies, can provide novel information about brain injuries at a large scale. This can inform the design of protection systems, policies and guidelines and enhance injury response and diagnosis strategies.

This figure shows the contours of strain and strain rate within the brain during a fall, predicted with our computational model of TBI.

Contours of strain and strain rate within the brain during an occipital fall

Design of mitigation strategies

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Design and testing of mitigation strategies have not improved to keep up with the pace of improvement in our understanding of biomechanics of traumatic brain injury (TBI). To address this problem, we are developing new concepts, designs and test methods to eventually better protect the brain in real-world impact conditions.

The following image shows the contours of strain within the brain during oblique helmeted impacts, predicted with our computational model of TBI. The left image shows the performance of the reference helmet design and the right image shows the performance of the improved helmet design.

Left: reference helmet design, right: improved helmet design

Peridynamics for fracture analysis

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A new theory of continuum mechanics, called peridynamics, has enabled predicting complicated fracture phenomena in solids, e.g. crack nucleation, branching and coalescence. We have developed a new peridynamic material model to analyse fracture in anisotropic solids, such as ceramics and bone. This model has been implemented in our peridynamic code.

This figure shows crack propagation in an alumina microstructure predicted by using the anisotropic peridynamic model. You can see the effect of grain and grain boundary fracture energies on fracture pattern.Fracture pattern in an alumina microstructure