Richard Trask | University of Bath (original) (raw)

Papers by Richard Trask

Link to publication record in Explore Bristol Research PDF-document This is the author accepted m... more Link to publication record in Explore Bristol Research PDF-document This is the author accepted manuscript (AAM). The final published version (version of record) is available online via ASME at http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2663128. Please refer to any applicable terms of use of the publisher.

Composites Part A-applied Science and Manufacturing, 2012

An investigation is described concerning the interaction of propagating inter-laminar cracks with... more An investigation is described concerning the interaction of propagating inter-laminar cracks with embedded strips of interleaved materials in E-glass fibre reinforced epoxy composite. The approach deploys inter-ply strips of thermoplastic film, chopped aramid fibres, pre-impregnated fibre reinforced tape and thermosetting adhesive film, ahead of the crack path on the mid-plane of end loaded split (ELS) specimens promoting energy absorbing mechanisms,

ICSHM 2013: Proceedings of the 4th International Conference on Self-Healing Materials, Ghent, Belgium, June 16-20, 2013, Jun 16, 2013

Composites Science and Technology, Nov 1, 2016

Stringer debonding within stiffened, assembled aerospace structures is one of the most critical d... more Stringer debonding within stiffened, assembled aerospace structures is one of the most critical damage scenarios that can occur in such structures. As a result, a degree of redundancy is inherently built-in to the design process of skin-stringer configurations to mitigate against premature and inservice failure. Introducing a "self-healing" solution for stringer run-out configurations has the benefit of mitigating and controlling damage initiation, and by introducing this concept there is great potential to reduce excessive conservative safety margins that could ultimately lead to more lightweight designs. Vascular self-healing technology has been successfully implemented into a simplified strap lap specimen, showing that the introduction of a vascular microchannel reduces the strength by 15% but has little effect on the stiffness. Upon delivery and cure of epoxy-based self-healing agents full recovery of the mechanical properties was observed. This self-healing approach has been further implemented into industrially relevant, larger stringer run-out panels as a feasibility study, in which no knockdown to mechanical properties caused by the embedded vascular microchannels has been observed, this study has also shown similar promising results in terms of performance recovery.

Synthetic smart systems often lack the simplicity of material construction and the complexity in ... more Synthetic smart systems often lack the simplicity of material construction and the complexity in functionality when compared to biological systems. In nature, versatility and functionality is a consequence of controlled placement of ‘building blocks’ at nano and micro-scale and the resulting multifunctional hierarchical structures. The design and arrangement of these building blocks are programmed into the organisms through billions of years of evolution. In the current scientific drive to towards 4D materials, more-often-than-not the simple building blocks are being overlooked in favour of complex strategies and expensive systems to realise synthetic morphing. In comparison, this project is focussed on developing sustainable and cost-effective smart material systems following the design rules that we observe in nature. The potential of paper as a cost-effective, sustainable and programmable smart material is the focus of this investigation. A paper inspired cellulose-hydrogel smart...

IEEE Transactions on Transportation Electrification, 2021

Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, 2020

Search and rescue craft have to endure the toughest conditions to save lives at sea. The design, ... more Search and rescue craft have to endure the toughest conditions to save lives at sea. The design, resourcing, operation and support of a search and rescue fleet requires state-of-the-art technology and an ability to react to and exploit cutting edge research and foment future research agenda. This article reviews the unique relationships that exist between the Royal National Lifeboat Institution and academia to drive engineering innovations to the forefront of Royal National Lifeboat Institution’s search and rescue craft and in particular the legacy of the Advanced Technology Partnership.

Multifunctional Materials, 2019

Multifunctional composites offer the ability to increase the efficiency, autonomy and lifespan of... more Multifunctional composites offer the ability to increase the efficiency, autonomy and lifespan of a structure by performing functions that would have been considered by designers as mutually exclusive. In the present perspective paper, a subclass of multifunctional composites is considered: metamaterials. In this perspective, a multifunctional composite is defined as ‘made of two or more materials that perform two or more functions in a manner that is constructive to the overall purpose of the structure’ where there is no differentiation between structural or non-structural functions. Equally, we define metamaterials are a class of man-made structures that display properties that are opposite to those typically found in nature. These ‘engineered’ architected materials continue to revisit and extend the boundaries of traditional materials science, opening up a wealth of new opportunities impacting on all aspects of human life. In our work, multifunctional metamaterials are delineated...

Composites Part A: Applied Science and Manufacturing, 2018

A finite element methodology to predict the behaviour of Dyneema® HB26 fibre composites at quasis... more A finite element methodology to predict the behaviour of Dyneema® HB26 fibre composites at quasistatic rates of deformation, under low velocity drop weight impact, and high velocity ballistic impact has been developed. A homogenised sub-laminate approach separated by cohesive tied contacts was employed. The modelling approach uses readily available material models within LS-DYNA, and is validated against experimental observations in literature. Plane-strain beam models provide accurate mechanisms of deformation, largely controlled through Mode II cohesive interface properties and kink band formation. Low velocity drop weight impact models of HB26 give force-deflection within 10% of new experimental observations, with in-plane shear strain contour plots from models directly compared with experimental Digital Image Correlation (DIC). Ballistic impact models utilising rate effects and damage showed similar modes of deformation and failure to that observed in literature, and provide a good approximation for ballistic limit under 600 m/s impact speed.

Journal of The Royal Society Interface, 2019

In Nature, despite the diversity of materials, patterns and structural designs, the majority of b... more In Nature, despite the diversity of materials, patterns and structural designs, the majority of biomineralized systems share a common feature: the incorporation of multiple sets of discrete elements across different length scales. This paper is the first to assess whether the design features observed in the hexactinellid sea sponge Euplectella aspergillum can be transferred and implemented for the development of new structurally efficient engineering architectures manufactured by three-dimensional (3D) additive manufacturing (AM). We present an investigation into the design and survival strategies found in the biological system and evaluate their translation into a scaled engineering analogue assessed experimentally and through finite-element (FE) simulations. Discrete sections of the skeletal lattice were evaluated and tested in an in situ compression fixture using micro-computed tomography (μCT). This methodology permitted the characterization of the hierarchical organization of t...

Smart Materials and Structures, 2015

The effect of including hollow channels (vascules) within cross-ply laminates on static tensile p... more The effect of including hollow channels (vascules) within cross-ply laminates on static tensile properties and fatigue performance is investigated. No change in mechanical properties or damage formation is observed when a single vascule is included in the 0/90 interface, representing 0.5% of the cross sectional area within the specimen. During tensile loading, matrix cracks develop in the 90°layers leading to a reduction of stiffness and strength (defined as the loss of linearity) and a healing agent is injected through the vascules in order to heal them and mitigate the caused degradation. Two different healing agents, a commercial low viscosity epoxy resin (RT151, Resintech) and a toughened epoxy blend (bespoke, in-house formulation) have been used to successfully recover stiffness under static loading conditions. The RT151 system recovered 75% of the initial failure strength, whereas the toughened epoxy blend achieved a recovery of 67%. Under fatigue conditions, post healing, a rapid decay of stiffness was observed as the healed damage reopened within the first 2500 cycles. This was caused by the high fatigue loading intensity, which was near the static failure strength of the healing resin. However, the potential for ameliorating (via self-healing or autonomous repair) more diffuse transverse matrix damage via a vascular network has been shown.

Journal of Materials Science, 2016

Shape-changing materials open an entirely new solution space for a wide range of disciplines: fro... more Shape-changing materials open an entirely new solution space for a wide range of disciplines: from architecture that responds to the environment and medical devices that unpack inside the body, to passive sensors and novel robotic actuators. While synthetic shape-changing materials are still in their infancy, studies of biological morphing materials have revealed key paradigms and features which underlie efficient natural shape-change. Here, we review some of these insights and how they have been, or may be, translated to artificial solutions. We focus on soft matter due to its prevalence in nature, compatibility with users and potential for novel design. Initially, we review examples of natural shape-changing materials-skeletal muscle, tendons and plant tissues-and compare with synthetic examples with similar methods of operation. Stimuli to motion are outlined in general principle, with examples of their use and potential in manufactured systems. Anisotropy is identified as a crucial element in directing shape-change to fulfil designed tasks, and some manufacturing routes to its achievement are highlighted. We conclude with potential directions for future work, including the simultaneous development of materials and manufacturing techniques and the hierarchical combination of effects at multiple length scales.

Fibre reinforced polymer composite materials are becoming more widely adopted for high performanc... more Fibre reinforced polymer composite materials are becoming more widely adopted for high performance industrial applications. The hierarchical nature of these materials offers a unique opportunity to incorporate multi-functionality whilst maintaining their excellent mechanical properties. Ideally, multifunctional composites can be configured to mimic natural biological systems. For example, the fabrication of an embedded array of hollow channels in the form of a vascular network can be utilised to provide a variety of functions, including self-healing, thermal management or sensing and actuation [1]. Previous research has shown that vascular integration into FRP laminates can be achieved through incorporation of material in-situ (hollow glass fibres [2] or polyether ether ketone (PEEK) tubing [1]), or through a "lost-wax" process using solder [3,4]. This study considers a novel manufacturing method for hollow channel fabrication, with the intention of limiting damage to the FRP laminates during post-cure channel manufacture, using Polylactic Acid (PLA) coated Nichrome wires to produce vascular networks running through multiple levels of the FRP ply stack. Low voltage resistive heating of the Nichrome wires enables their removal from the FRP post cure, even in complex shapes. The successful manufacture of an Animalia inspired network design was achieved within a glass fibre reinforced polymer (GFRP) panel. Furthermore, for panels subjected to steady state heating, the branched network displayed far greater cooling potential than the parallel channel design. This suggests the possibility to manufacture more complex networks within FRP laminate structures, facilitating their multi-functionality, namely for thermal management or self-healing applications.

Locally stiffened or 'stringer'-skin composite structures are extensively used for lightweight ap... more Locally stiffened or 'stringer'-skin composite structures are extensively used for lightweight applications in the aerospace industry. Due to localised stiffening, stress concentrations arise which can initiate damage e.g. debonding or delamination, within the composite structure. Critically, this damage can propagate under fatigue loading compromising the structural integrity of the component. To mitigate against this risk, significant safety margins are used within the design phase, which limit the potential weight savings offered by the application of advanced fibre reinforced composites.

A qualitative study on the influence of an embedded vascular network on the structural performanc... more A qualitative study on the influence of an embedded vascular network on the structural performance of a FRP composite laminate is presented. This study includes: methods of forming such vascular networks in laminates; characterisation of laminate cross-sections; FE analysis for failure initiation and validation of the FE results via mechanical testing.

Multifunctional Materials, 2020

This perspective details the grand challenges of designing and manufacturing multifunctional mate... more This perspective details the grand challenges of designing and manufacturing multifunctional materials to impart autonomous property recovery. The susceptibility of advanced engineering composites to brittle fracture has led to the emergence of self-healing materials. This functionality has been demonstrated in bulk polymers and fibre-reinforced composites; most recently through the addition of vascular networks into the host material. These network systems enable the healing agents to be transported over long distances and provide a means by which both the resin and hardener can be replenished, thus overcoming the inherent limitations of capsule-based systems. To date, vascule fabrication methods include machining, fugitive scaffold processes, a lost-wax process and the vaporisation of sacrificial components, but recent developments in additive manufacturing (AM) technologies have paved the way for more efficient, bio-inspired vascular designs (VDs) to be realised. This perspective...

Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation and Control of Adaptive Systems; Structural Health Monitoring; Keynote Presentation

A new approach to self-healing systems is presented that aims to overcome the inherent drawbacks ... more A new approach to self-healing systems is presented that aims to overcome the inherent drawbacks of conventional liquid resin based healing systems within composites. Finite embedded systems offer limited healing potential for small volume delaminations and as such cannot effectively heal large damage volumes often associated with shear damaged sandwich panel structures or debonding between skin and core. An expanding polymer based approach aims to overcome such limitations. The mechanical and physical properties of a prepared polyepoxide foam are investigated and how the inclusion of a carbon fibre reinforcement within the foam affects processability and performance. The healing efficiency of different polymer foams to heal damaged structures is also investigated. A secondary investigation is also presented that aimed to overcome the drawbacks associated with the requirement for stoichiometric mixing of two part healing agents, or for healing agent to come into direct contact with ...

This paper lays out a technique whereby delamination growth in a GFRP panel subjected to a low ve... more This paper lays out a technique whereby delamination growth in a GFRP panel subjected to a low velocity impact is compartmenatlised using discrete thermoplastic film rings. By comparing the compartmentalised configurations with an unmodified baseline panels the thermoplastic film rings have been shown to suppress delamination crack growth at the desired interfaces and effectively prevented any growth beyond the outer diameter of the rings. This has resulted in the reduction of the damage footprint areas by up to 38% and an improved compression after impact (CAI) strength of up to 18% relative to a baseline panel.