A Suspension system is used to improve ride quality and comfort by absorbing energy with the use of a spring and shock absorber (damper) which are typically placed between the wheels of a vehicle, and the vehicle chassis. Vehicles that do not have wheels such as airplanes, helicopters, and boats must rely on other mechanisms and suspension system designs to improve the ride comfort for the occupants. Traveling in a high-speed boat can be one of the most violent rides for an occupant as these boats travel through rough seas at high speeds. When they crest waves and slam back to the water’s surface, a violent impact occurs. This event is known as a Wave Slam.
The impact energy associated with severe wave slams experienced in rough seas causes discomfort, fatigue, and injury. Advanced Materials and Devices, Inc. (AMAD) has developed a unique air-spring damper suspension system specifically designed for marine applications to reduce the energy transferred to occupants during a wave slam. This system improves absorbs energy in the vertical direction, improving ride comfort, and reducing the likelihood of injury for a seated occupant. The custom air-spring damper incorporates the air spring into the overall system, removing the need for an external accumulator, reducing the system’s space requirement and weight.
The suspension system was modeled as a 3 degree-of-freedom (DOF) mass spring damper system, with the DOF being the occupant's upper body, the occupant’s lower body, and the seat pan. This model takes into consideration the spring and damping rates of the air-spring damper, the seat cushion foam, and the occupant’s lower back. Characterization testing on AMAD’s damper test system provided the data to be used in biodynamic modeling.
The Dynamic Response Index (DRI) which is determined from the displacement between the upper body and lower body, or lower back compression, has been used to determine the effectiveness of the system on seated occupants with an acceleration input to the system from recorded high-speed boat rides. The DRI values are less than 7, which indicates the chance for occupant injury is very low. A DRI value >17.7 results in a 10% chance of occupant injury.
AMAD specializes in shock absorber design for custom applications ranging from bicycle shocks (dampers) to earthquake dampers. Contact us to find out more.