Some observations regarding the vibrational environment in child safety seats

A growing issue in the area of vehicular ride comfort is that of child safe ty seats. Postural, thermal and vibrational comfort considerations are find ing their way into child seat design. This paper makes some observations re garding the current state of child safety seat design, then goes on to pres ent the results of vibration tests performed over two road surfaces using t wo child seats and two children. The vibration levels measured at the inter faces between the children and their seats were found to be higher than the vibration levels between the driver and the driver's seat. Calculated powe r spectral densities and acceleration transmissibility functions showed tha t the vibration transmission characteristics of the coupled system consisti ng of the automobile seat, child seat and child were different from those o f the driver/seat system. Whereas, automobile seats normally reduce vibrati onal disturbances at most frequencies, the child seats tested amplified vib ration at most frequencies up to 60 Hz. (C) 2000 Elsevier Science Ltd. All rights reserved.