My final topic of discussion today deals with a very in depth dissertation I recently came across (L.T. Harper, Discontinuous Carbon Fibre Composites for Automotive Applications, The University of Nottingham, UK). The author goes into great detail about the feasibility of carbon fiber composites in the automotive industry, how they will work and what will be the challenges faced by their integration into the market.
However, the section which caught my attention dealt with the dent resistance of recently developed composites compared to the current standard steel. Specifically, steel was compared to six different types of composites which are either in production or under consideration to be placed in production by the automotive industry. Below is a graph which is in L.T. Harper's paper, which shows each material and its dent threshold (the amount of displacement needed in order to create a visible dent).
The dotted horizontal line indicates when there is a visible dent and the far left curve is that of steel. Steel will have a noticeable dent when displaced by 0.5 mm. The composite with the lowest displacement will not have a dent until 2.2 mm of displacement and the strongest composite is over 3 mm. Although the composites tested have a dent performance around 6 times that of steel, Harper mentions that their cost is around 39 times more than steel. My concern is that manufacturers might be asking too much from future components with the current technology. Is there a reason why there is such a large leap in strength? Would the final product work just as fine with a composite which dents at 1 mm of displacement? I strongly believe in baby steps in order to create a successful movement. There are plenty of other factors that composite developers can focus on, such as how to repair a dent in a composite. I am pretty positive most body shops are not too familiar with how to repair a $1500 carbon fiber bumper after you backed into a light pole. All I am suggesting is to slow down and get the little things right and gradually increase from there, when the little things are done correctly, the big things fall into place.