The evolution of the composite bat

The evolution of the graphite and plastic bats began in 1985. These new bats had the strength of aluminum and the performance of wood. They did not perform nearly as well as the more popular aluminum single-walled bats, however, despite being very strong and withstanding heavy abuse.

About 10 years later, Miken introduced carbon fibre bats into the market. History repeated itself when the bats failed to outperform aluminum bats on the market.

In 2001, the Louisville Slugger Genesis all-composite slow-pitch softball bat achieved the #1 ranking in Performance at the 2001 Bat Wars. Composite softball bats were now competing with the best available aluminum bats. There were, however, problems with durability – the early Genesis bats (model SB34) were notorious for breaking after 50 or so good hits. The second generation Genesis (model SB103) had a slightly thicker wall and was more durable, but had a slight sacrifice in performance.

By then the point had been made: it was possible to design and manufacturer a composite bat that could perform as well as the best aluminum bats. Today there is a wide variety of composite choices from several manufacturers. The majority of composite bats are slow-pitch bat models, and in the slow-pitch game composites definitely reign supreme.

How the composite bat works

Composite materials have a distinct advantage over aluminum in that they are anisotropic, which means that the elastic properties of a composite material are not the same in all directions. By changing the weave angle of the composite material fabric, the stiffness along both the bat length and barrel can be modified independently of each other.

One way to increase the performance of a bat is to enhance what is known as the trampoline effect of the barrel. The barrel of the bat essentially acts as a spring during the bat-ball collision. If the barrel spring is very stiff, then the ball compresses a great deal upon impact and loses a significant amount of energy in the process of compression and re-expansion. However, if the barrel of the bat is made softer, then the barrel compresses more, the ball compresses less, and the ball loses less energy during the collision. Furthermore, the energy which was temporarily stored in the barrel spring is returned to the ball and the ball speed is greatly increased after the collision.

By adjusting the stiffness of the barrel, a manufacturer is able to "tune" the trampoline effect of a bat to increase or decrease performance as desired.

Composite materials provide a manufacturer with a very wide range of possibilities to design a bat to a targeted performance and/or feel.