The physics that states ‘energy efficiency of cars is inversely proportional to kerb weight’ has led automotive manufacturers to look at lighter materials. Recent pressure to do this has come indirectly from a push to reduce emissions leading to the adoption of electric vehicle technology. The downside to electric vehicles though is their extra weight compared to similarly powered combustion vehicles, due to heavy electric motors and battery packs. In fact electric vehicles are usually 125 % heavier than their combustion powered equivalents. Resistance to adopting light weight materials has always been cost because consumers do not wish to pay the extra. Things will undoubtedly change as regulations and initiatives are introduced, such as the UK’s Industrial Smart Strategy that states OEMs have to reduce carbon emissions of their models to 95g/km in 2020 and 75g in 2025. Current level is 140g/km.
Although lighter weight materials are desirable their mechanical properties are often inferior to cheaper but heavier materials such as steel. For example magnesium is 75% lighter than steel and 33% lighter than aluminium but has low creep resistance at high temperature and therefore needs to be alloyed with a rare-earth metal to improve mechanical properties, which also adds to cost ! Developing new processing methods though could potentially overcome some of these strength issues. One process is superplastic forming which can add mechanical strength but is presently quite costly. Composites with high strength and stiffness ratios, and lightweight are credible solutions and the technology is always moving forward. They can be manufactured as one piece with a reinforced matrix material with different regions of reinforcement, for efficient design.
To conclude, pressure is on for manufacturers to reduce emissions and move to electric vehicles that perform comparably to traditional combustion engine vehicles, but weight is one of the issues and a work in progress to reduce this to increase energy efficiency and performance within commercial limits.
Hope you enjoyed the blog and that you have a good month
All the best
“A lie gets halfway around the world before the truth has a chance to get its pants on.”
Winston S. Churchill
“Going to church doesn’t make you a Christian any more than going to a garage makes you an automobile.”
ps If you have enjoyed the blog please forward to those who might be interested, many thanks in advance, Mike