Sponsored by: ARCCA, Inc.

Fall 2003

ARCCA Support Team Members:

• Michael Barraclough
• Nicholas Mazzocchi
• Robert McKellar
• Giovanni Migliaccio

Project History

ARCCA, Incorporated requested an analysis of an A-pillar from a Sports Utility Vehicle (SUV) to be conducted. This analysis will be used to determine the component’s baseline performance. Strength improvements are to be incorporated in a modified design which will increase the component’s compressive strength by a minimum factor of six. The modified component must retain the overall shape of the existing design and must not exceed 150% of the component’s original weight.

ARCCA, Incorporated currently focuses much attention towards crash survival. Within the past decade, ARCCA’s disciplines have grown extensively in the fields of forensic accounting, cause and affect, statistical analysis, courtroom logistics, and many other technical areas associated with vehicle crash survival. Projects conducted by the firm require both the identification of a problem source as well as recommendations for improvement established through technical analysis.

The roof structure of SUVs has been identified as major concern in vehicle rollovers. The necessity for improvement of SUV roof structures has been addressed due to SUV’s greater propensity to rollover than passenger cars. Less than four inches of space exists between a passenger’s head and the roof during a rollover if the seat restraints (lap buckle, should strap, etc.) work properly. Any compression of the roof structure decreases the survival space of the passenger which may result in fatal injury.

The roof structure may be divided into several subcomponents which must maintain structural integrity during a rollover. Since the driver’s seat must always be occupied during vehicle operation, analysis of the front portion of an SUV has a high priority. Two main components designed to maintain vertical survival space in the front portion of an SUV are the A-pillars and the windshield. Though the windshield provides great compressive strength properties, the glass usually does not remain intact throughout majority of an accident due to its brittle behavior. Therefore it is logical to analyze the A-pillar first, and conduct further analysis on other roof structure components at a later date.

The roof structure of an SUV must not exceed deformation of 0.127 m when a load 1.5 times the weight of the unloaded vehicle is applied to the roof’s edge, as indicated in vehicle test standard §571.216. Therefore the A-pillar must be currently designed to withstand a force of at least 1 G. The majority of rollover accidents are lower acceleration, long duration events when compared to frontal or other vehicle impact orientations. Rollover acceleration levels are well within human tolerance ranges, therefore rollover accidents are survivable for a properly restrained occupant with a preserved occupant space. A 6 fold increase in component strength is being used as an initial starting point for roof strength improvement.