The main limitation of the existing technology in bonding repair of aerospace structures lies in the inability of the repair control systems to assess the actual material state and integrate the available tools (simulations, measurements, experience and knowledge) into an intelligent material-based control system.
To circumvent these limitations, the SENARIO project proposed the development of a revolutionary sensing system linked to intelligent process control equipment and reliable methodologies of aero structures component maintenance.
The proposed system consisted of:
- a portable curing process console with blanket-mounted dielectric sensors;
- wireless non-intrusive dielectric sensors for monitoring adhesive state;
- reliable laser technology for increased automation;
- optical sensors complementing the dielectric sensors;
- thermo mechanical monitoring set-up;
- intelligent process guidance system for co-cured components;
- integrated multi-zone repair control unit, and;
- application of bonded repairs with reliability, controlled quality and certification potential.
The proposed novel multi-zone integrated process control scheme gains full benefit from the use of multi-sensory devices and the deployment of existing process knowledge (cure and stress development). The scheme enables in situ monitoring of bonded repair and resulting adhesion quality through the repair process, while offering a potential tool for non-intrusive structural health monitoring.
The main innovations reside in:
- the use of durable dielectric sensors in the repair process for real-time assessment of in-patch conditions;
- the wire-free dielectric sensor capable of measuring remotely changes in adhesive electrical properties;
- intelligent process guidance algorithm for optimal repair process conditions in co-curing applications;
- the interface between thermomechanical process simulation tools, process actuators and composites multi-sensory monitoring tools.
The proposed novel multi-zone integrated process control scheme gains full benefit from the use of multi-sensory devices and the deployment of existing process knowledge (including cure and stress development) and enables the in situ monitoring of the bonded repair and the resulting adhesion quality at any stage in the process, while offering a potential tool for non-intrusive structural health monitoring.
Given the successful implementation of the scheme, the repair process uncertainty can be minimised or even eliminated, thus contributing to the easier certification and standardisation of the repair procedures. The global nature of the multi-sensor and multi-zone control scheme allows the single-step repair processes. This involves treating and co-curing the adhesive and reinforcing the composite using portable and usable repair systems, leading to increased safety and weight saving in the aircraft.
The project results resolve significant problems for two groups of end-users:
- for the aerospace component manufacturers and repair centres: the lack of standard, online and in situ information on and control of the bonding process and quality, and
- for the manufacturers of process and repair support systems: the missing link between the advanced industrial simulation and control systems and the developing material and process monitoring technology.