An experimental and computational study for predictive assessment of material failure

The destructive effects of current and emerging exploding threats are routinely reported from current conflicts around the world. Protective structures and platforms, commonly consisting of materials such as High Hard Steel (HHS), are used to reduce the catastrophic effect of these threats. Although full scale blast trials are conducted to assess the protection level provided by a range of armour technologies against blast loading, the fundamental cause of brittle failure during overmatch is not well understood.

As a consequence, it is also not possible to reliably predict the outcome of blast events against high hard steel through Finite Element Analysis (FEA) methods. An increased understanding of the behaviour of HHS under extreme dynamic loading is essential to improve numerical simulation of such structures. This project will investigate armour steel failure mechanisms across length scales to understand their influence on macroscale performance and to inform the FEA material models used to predict armour performance against threats, known and emerging.

Initially, the successful candidate will identify the critical data capture steps for accurate prediction of material failure in macroscale blast assessments. The current test methods will be trialled, benchmarked and optimised, incorporating enhanced novel, dynamic, diagnostic tools to accurately capture failure modes. Fundamental microstructural characterisation techniques will also be used to interrogate the failed material and enhance understanding of failure. This knowledge will be used to parametrise damage/failure models for use in FEA and these models will be used to predict the outcome for a wide range of load conditions against various thicknesses of protection material. The experimental and numerical results will be combined to generate a numerical tool to predict rupture of materials under blast loading. Machine Learning techniques will also be investigated throughout the project to rapidly assess the large experimental and numerical datasets. The student will also receive training in industrial placements from numerical modelling, materials and armour practitioners.

• To develop a criteria of failure for the materials selected. This will involve the identification and development of novel experimental techniques to obtain high resolution structural images of the failed material during the blast event.
• To understand and quantify the evolution of failure during a blast loading event, this will include the development of high-quality testing and evaluation of instrumentation to examine dynamic failure in real time.
• A numerical replication of brittle steel failure will be developed. Models will be developed that underpin the fundamental physical measurements that have been acquired from the experimental trials which will include varying any features observed at the microscale.

• Cranfield Defence and Security (CDS) provide unique educational opportunities to the Defence and security sectors of both public and private sector organisations.
• Access to explosive ranges, explosive laboratories, ballistic ranges and an onsite armoury. These are unique research facilities that will enable this project to develop world leading research and networking opportunities that are not possible elsewhere in the UK.

• Throughout the project, the student will undertake a series of industrial placements, to work alongside SMEs in armour, materials and FEA. This will significantly enhance the student experience and enable unique networking opportunities with one of the leading Defence Research Establishments in the UK. Within these placements the student will have access to devoted high performance computing facilities, training on blast codes that are not commercially available and probabilistic modelling.
• Experimental explosive trials are a rare capability which this studentship offers there are only one or two universities in the country that offer this type of unique experimental facility.
• Conferences will be supported during this studentship. 

Based at the UK Defence Academy at Shrivenham in Oxfordshire and at Cranfield University Bedfordshire, CDS is the academic provider to the UK Ministry of Defence for postgraduate education at the Defence Academy, training in engineering, science, acquisition, management and leadership.

• Application deadline06 Sep 2023
• Award type(s)PhD
• Start dateAs soon as possible
• Duration of awardFull-time 4 years
• EligibilityUK
• Reference numberCDS054

Applicants should have a first- or second-class UK honours degree or MSc equivalent in a related discipline. We encourage applications from all groups and are committed to equality, diversity and inclusion.

Fully-funded studentship

Studentship will provide a stipend of £17,668 tax free plus fees for up to four years. To be eligible for the funding the applicant must be a UK national.

If you are eligible to apply for this studentship, please complete the online application form.

For information about applications please contact: [email protected]

NOTE: Contact information will be the admissions office as standard.