Co-authors​ :

 Nawres AL-RAMAHI (SWEDEN), Patrik FERNBERG (SWEDEN), Roberts JOFFE  

In this work, a thorough investigation of the electrical behavior of carbon fiber (CF) composite was conducted using both, experimental and numerical methods. The focus was on using CF composite as a source of heat for anti-icing of structures (e.g. the blade of the wind turbine). The aim of the study was to gain a better understanding of how different layer orientations and sample dimensions affect the electrical resistance of the composite and amount of heat it produces. For the experimental part, rectangular composite samples with varying layer orientations ([02]T, [902]T, [45]T, [0/90]T, [45/-45]T, [0/45/-45/90]T) and dimensions were used. Metal electrodes were integrated along the two opposing ends of the plate. The electrical resistance and temperature increase in the plates were measured and analyzed. To simulate this behavior a numerical model using the finite element method with Thermal-Electric element was used. The performance of the carbon fiber composite laminate under electrical load was predicted. Good agreement between experimental results and numerical simulations was obtained. It was found that the plate with [02]T exhibited the lowest electrical resistance compared to other directions. Accordingly, the [02]T showed the highest heat generation capacity compared to other layups with the circuit configuration studied. The electrical resistance of [45/-45]T and [0/90]T, were higher than resistance of [02]T by 80% and 97% respectively. While, the [0/45/-45/90]T showed only a 2% difference in resistance in absolute numbers but if normalized with thickness this difference increased to 102%. Notably, the 90° layer alone demonstrated a very high electrical resistance, approximately 2000 times higher than that of the 0° layer. This is expected, since ideally, no electrical current should pass through the 90° layer. However, due to the waviness of carbon fibers and inter-fiber contact points, current may flow from one fiber to another in 90° layer. This inter-fiber behavior also results in the electric conductance of the out-of-plane direction being very similar to that of the transverse direction. Furthermore, it was observed that the temperature increase for the 0° plate was approximately twice as high as that for the other composites under the same applied electrical current. Consequently, lower electrical voltage (less than 25% of the value compared to laminates with different layup) needed to be applied to the 0° plate to achieve the same temperature increment as for the other laminates. Thus, the current study concludes that the prepreg-based UD lamina with 0° fiber orientation is best suited for electrical and thermal applications. However, the specific design should also consider factors like mechanical and thermal loads, expected location, direction of damage. This study provides valuable insights into the electrical behavior of carbon fiber composite, helping to provide good suggestions for applications in various industries.