Project: Development of Visual based non destructive Evaluation systems for Composite material Damage detection

Background_x000D_Composite materials are becoming increasingly used across a broad range of industries where designers can capitalise and exploit key properties such as specific stiffness, strength and durability. However, there reCOs a degree of apprehension from prospective end users on the effect of damage on both short and long term performance. In contrast to metals, damage in composite materials can be difficult to detect and this can potentially have serious consequences from a safety and long term asset management perspective._x000D__x000D_Fitness for purpose is often gauged from periodic inspections that are carried out by personnel who have received dedicated training and are specialists in the techniques of damage detection. Many high-tech methods are available to detect damage but the most common reCOs visual inspection._x000D__x000D_Current Status_x000D_In order to address the concerns of end users and to promote confidence in the use of composite materials in engineering structures, EPL Composite Solutions Ltd (SME) set out to build on existing Non-Destructive Evaluation (NDE) techniques by developing a simple, low cost, visual based damage detection technique that would enable COtenance engineers (unfamiliar with composite materials and NDE) to rapidly identify and quantify any damage to a composite structure , thereby enabling decisions to be made regarding further detailed inspection or repair/replacement of the structure. _x000D__x000D_Several visual-based damage identifiers for composite structures have been developed by EPL through their previous basic research activity. These systems are based around the microencapsulation of certain chemical compounds that react to a damage initiating event by diffusing themselves within the composite laminate; the resulting dispersed chemicals forming a mark or “bruise” within the composite. The distribution of microcapsules is such that the whole structure (or just a part of it depending on the style used) possesses the ability to indicate damage. Impact tests have shown that a conspicuous bruise can be produced that would alert personnel that a thorough examination is advised._x000D__x000D_Prototype systems were successfully developed that were compatible with hand lamination and vacuum infusion manufacturing methods. Throughout the project, industrial interest was, and reCOs, high. Examples of the results from this work can be seen in Annex A._x000D__x000D_Next Phase_x000D_Whilst it has been shown that a system can be developed that when incorporated into a glass/polyester composite laminate shows visible signs of impact damage, this has only been achieved in prototype form and using prototype facilities. In order to commercialise this system, much work is required to create a rugged product that can be used in the broad range of manufacturing processes and with as wide a range of materials as possible. Applied research and demonstration is required in order to determine the exact nature of the bruise formation; to optimise the chemistry of the bruise forming agents (for different resin systems, to create different coloured or indeed UV bruises for different products); to develop the encapsulate to tailor the rupture strengths to suit product requirements from low-end industrial composites through to structural aerospace grade composites._x000D__x000D_The aim of the next phase is to develop the underlying technology into a robust and commercial product for the composite market that provide simple, low cost, visual based damage indication systems that can be incorporated into a wide range of composite materials and products using a variety of manufacturing processes._x000D__x000D_Specific objectives of this programme include:_x000D_(i) Development of damage indication systems and ensure robustness and "fitness for purpose"._x000D_(ii) Determine and optimise the range of bruisable materials for each respective composite material type (glass, aramind, carbon reinforcement - epoxy, vinylester, polyester, bismaleimide resins)._x000D_(iii) Establishing the capability of the damage indication systems. i.e. can the systems show level of damage or can they be designed to only show at a certain damage level?_x000D_(iv) Developing a range of products that can be “tailored” to rupture at different loads/pressures, so that the systems can be used in a wide variety of end uses (from low end industrial products to structural aerospace components)_x000D_(v) Evaluating and developing system compatibility with different composite material types and manufacturing processes._x000D_(vi) Performing an extensive mechanical and durability testing programme to create a performance envelope._x000D_(vii) Development of guidelines on the interpretation of results and repair requirements_x000D_(viii) Manufacture and critical evaluation of up to 3 case study articles_x000D_

Acronym ViECoDam (Reference Number: 5158)
Duration 01/09/2010 - 31/08/2013
Project Topic A suite of simple, low cost, visual based damage indication systems will be developed that can be incorporated into composite structures providing them with an integrated health monitoring capability. This will greatly aid industry in terms of efficiency, safety and asset management - through life.
Project Results
(after finalisation)
The results of this project have been positive with the great majority of the objectives and deliverables having been successfully met. The CO result of the project is the development of products that, when inserted into a composite component during manufacture, cause that composite part to have the ability to show, the locations of damage within the composite laminate. This damage indicating product is not suitable for all composite materials or all manufacturing processes but has been shown to work for a wide variety of them and is generally likely to show an impact event. It is intended to be used to highlight the potential damaged area more easily by visual inspection and compared to other NDT technology._x000D_A range of systems have been developed that cover the different potential industries and components that would benefit from such an invention. All of the products are based around the microencapsulation of a damage indicating component. These damage indicating components can be categorised as:_x000D_• visual dye-based fluids_x000D_• ultraviolet fluorescent systems_x000D_• two component colour forming systems_x000D__x000D_To incorporate these capsules into a composite component, the microencapsulated damage indicators are applied onto very thin, two dimensional substrates that can be easily incorporated into products using a range of traditional composite manufacturing techniques. Processes where it has been possible to introduce this damage indicating system include vacuum infusion, hand lamination, autoclave pre-pregs and filament winding.
Network Eurostars
Call Eurostars Cut-Off 3

Project partner

Number Name Role Country
4 EPL Composite Solutions Ltd Coordinator United Kingdom
4 Aeroconcept Ingenieurgesellschaft für Luftfahrttechnik und Faserverbundtechnologie mbH Partner Germany
4 DWI at RWTH Aachen e.V. Partner Germany
4 Institut fuer Kunststoffverarbeitung in Industrie und Handwerk an der RWTH Aachen Partner Germany