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The International Insurance Whiplash Protection Group (IIWPG) rating system has driven improvements in head restraint (head restraint) geometry and the addition of a dynamic test has helped address head restraint construction parameters. FMVSS 202a Static imposes more stringent requirements on backset and stiffness and the Dynamic option relaxes the potentially uncomfortable backset requirement if angular head movement can be limited to a specified level. These two requirements utilize different crash dummies and measurement parameters. The BioRID2 ATD (IIWPG) rewards a seat with good torso penetration to reduce neck loading. Seats with high comfort content tend to rate low. The Hybrid III-50 ATD (FMVSS) rewards limited lower torso penetration to reduce head rotation relative to the torso. Current production seats without active head restraints (AHR) are difficult to optimize to meet both the requirements of FMVSS 202a Dynamic and earn an IIWPG rating of Good.

Today trucks account for close to half of the US passenger vehicle market. And customers expect more and more from their trucks in terms of comfort and convenience features. The key to developing Best-in-Class comfort and convenience attributes lies in applying Ergonomic principles to the vehicle interior design. Lear Corporation has recently studied 4 truck interiors in the Sport Utility Market Segment focusing on Ergonomic design issues. This paper will review the Sport Utility study results and make interior design recommendations. In this market, functionality is of primary importance to customers. Using random samples of truck owners, we have examined the functionality of door panels, consoles, controls, cupholders, cargo covers and the rear cargo area. Several factors ranging from reach criteria, tactile feel and usability through operating efforts and the motion required to operate the various features were examined.

Continuing effort in measuring human vibration response results in a new design of vibration comfort dummy. The difference between this new dummy and other mechanical dummies is that (1) it uses a soft human-tissue like lower torso so it matches compliance better than the previous ones, and (2) it utilizes the spring and damping characteristics of the compliant lower torso. The lower torso is integrated with a spring-mass load simulating the top body of human so that the integrated dummy consists of two parts. This unique design greatly improves the accuracy and stability of transmissibility measurement and provides a direct application tool in seat prototype development. The results measured with dummy are compared with that measured with 3 human subjects in different percentiles and good match is found in the first transmissibility resonance and overall vibration response.

In order to more accurately simulate the load distributions and histories experienced by automotive seats in field use, more biofidelic motion and loading devices are needed. A new test dummy was developed by Lear Corporation and First Technology Safety Systems. This dummy uses exact skeletal geometry encased in a one-piece seamless mold with contours based on ASPECT data. A prototype was constructed and tested to demonstrate the efficacy of the concept. The skeleton and contour molds were created from CAD-generated rapid prototypes. The flesh was carefully formulated to have the mechanical properties of bulk muscular tissue in a state of moderate contraction, using data from the literature. This design allows much greater accuracy in reproducing human loads than was ever possible previously. The design has applications in durability, vibration and comfort testing.

Seats and carpets were evaluated for generating static charges on vehicle occupants. Active measures that eliminate or reduce static accumulation, and passive measures that dissipate static charge in a controlled manner were investigated. The active measures include using durable anti-static finishes or conductive filaments in seating fabrics. The passive measures include adopting conductive plastics in a steering wheel, seat belt buckle release button, or door opening handle. The effectiveness of these measures was tested in a low humidity environment.

Many studies have been done to objectively measure car seat foam properties and correlate them to comfort performance. Typically, the vibration characteristics (namely transmissibility) of the foam cushion are measured. It has been generally accepted that low natural frequency equates to better comfort. However, no subjective studies have been done to verify that humans can feel the vibration differences that are measured. Also, the measured differences of the foam may not be detectable once the foam is built into a complete seat. Three different foam formulations utilizing MDI (methylene diphenyl diisocyanate) and TDI (toluene diisocyanate) technology were evaluated for vibration characteristics. The foams were then submitted to subjective human testing and objective lab testing after being built into seats. The subjective testing was done using a typical ride and drive evaluation where people were interviewed about the comfort of the seat while driving over various road conditions.