# Failure Detection within Composite Materials in System Engineering Applications
## 6 Failure Detection  
This study proposes a novel live failure detection technique for better monitoring the fracture of a hockey stick made of CF composite. The lower third of the hockey shaft can be highlighted as the most likely fracture area, due to the low position of the player's hand during a slap shot. Thus, this area will be targeted in the design. The novel live failure detection method uses an LED or buzzet attached to a copper wire circuit inserted in theply stack or on the inner and outer surfaces of the ply stacks. The LED/buzzet will be triggered when the hockey stick is overextended owing to the copper wire breaking [1]. Due to composite's structural complexity, circuit properties may be determined by a variety of parameters based on composite flex number, or the extent of flex supplied per bound of force [36]. Figure 6 (left picture) depicts the notion failures monitoring system based on copper wire is depicted in Figure 6 (left picture). The copper wire circuit is shown by the dark lines. Similarly, Figure 6 (right image) shows failure detection mechanism within the lower section of a drone 3.2 mm National Electrical Manufacturers Association (NEMA) flame retardant (FR) frame. Woven fiberglass fabric with an epoxy resin binder makes up this composite material. Again, the detection comprises a copper makeup on the upper layer, a simple task with printed circuit board (PCB) manufacturing processes. Recent discoveries surrounding laser induced graphitisation (LIG) display promising results at producing graphene an allotrope of carbon arranged in a two-dimensional honeycomb lattice on pine. To produce high-quality graphene, pine wood was chosen because of its lignocellulosic which is cross-linked structure, as compared to wood which has less amount of lignin complex organic polymer material. In wood, lignin is responsible for the formation of cell walls that are stiff. Similar to the polyimide (PI) method, a typical commercial carbon dioxide laser (CO\({}_{2}\)) at ambient temperature and pressure can be used. To keep the pine from burning, argon or helium must be used to create an inert environment. [PERSON] et al. claim that converting wood into graphene brings alternative paths for the production of LIG from materials other than polyimide [37]. This certainly is true of potential low-cost live failure monitoring of possible wood composites with conventional  
Figure 6: The concept system for failure detection. readily available equipment. Interestingly, such lasers are typically accompanied by air assist nozzles that blow compressed air on the laser site when in operation to clear the debris and prevent burning under non LIG intended applications such as engraving and cutting. A possible but as yet untested solution to requiring an inert atmosphere such as a sealed unit for production of LIG on wood would be to replace the compressed air supply with the inert gas, similar to how welders operate. This would greatly reduce the constraints required and open up graphene production on large samples, such as wooden structures. This would be beneficial to having laser produced electrically conductive patterns etched on structures in which to monitor live failure of wood composites. It would be necessary however, to ensure a basic level of protection of the laser etched graphene by such means as a suitable lacquer or finishing paint. The inherent electrically conductive properties of CF and recent advancements in graphene production on high lignin woods offers potential interesting opportunities yet to be exploited from composites when viewed from a system engineering perspective. With electrically conductive materials in place or conductive pattens being simple to etch on surfaces, it is entirely feasible to create fundamental components seen in electronics industry within the structure of the composite. Previous success has been achieved at pre detecting complete structural failure before the event with use of a thin enamelled copper wire embedded within carbon fibres.