Development of penetration resistance in the survival cell of a Formula 1 racing car

Abstract

The success of composite materials in providing stiffness efficiencies and weight reduction in Formula 1 cars is well documented. Much of the sport’s improved safety record in recent years derives from the controlled fracture behaviour of composite materials. Research and understanding of the impact and fracture behaviour of these materials has enabled the design of a sophisticated driver protection system into the vehicles’ structure at minimum weight penalty. The chassis itself has evolved into a “survival cell” capable of tolerating damage from minor incidents whilst at the same time being able to protect the driver in the event of a major impact. Combined with this are specialised structural devices designed to absorb large amounts of energy per unit mass by controlled fracture and disintegration. A number of safety issues were raised by injuries caused to drivers by Foreign Object Damage. This generally involved penetration of the survival cell by broken pieces from theirs or other competitors’ vehicles. In an attempt to combat this potentially very dangerous occurrence, a “side intrusion” test was been introduced. Each team is required to submit a panel for testing which is representative of the construction of their monocoque. The centre of the panel is loaded by a special device. A minimum load must be reached prior to full penetration, coupled with the absorption of a minimum amount of energy. The pass criteria for the test also stipulate a non-catastrophic failure mode. The introduction of mandatory safety tests has resulted in chassis design becoming increasingly dominated by strength considerations. The fracture mechanics of the composite materials used strongly influence the ability of the structure to meet the requirements of the regulations. The penetration test tends to be periodically made more stringent (as indeed are the other safety tests) requiring greater loads and energy absorption. The various factors involved in resisting penetration of the survival cell are discussed along with a review of the appropriateness of the test to increased survivability of the driver.