The drive for ever-increasing efficiency has lead researchers from West Virginia University to look into long-haul trailers as an area where improvements can be made.
With 73% of the weight of 14.6-m (48-ft) trailers being in the chassis, floor, and structural materials, these were the targets of a study presented at the SAE Commercial Vehicle Engineering Congress, with several designs analyzed for energy savings.
Current van trailers use 35-mm (1.4-in) oak floor panels on steel I-beams set 0.3 m (1 ft) apart. This layout has great potential for integrated structural weight savings using composite materials. Four alternative designs were tested using a variety of materials. The initial alternative uses the same floor plan but substitutes lighter materials for the steel I-beams. This solution can reduce the weight by 66% when using magnesium alloy or 69% when using a carbon-carbon composite.
Three other alternatives were studied: fiberglass faceplates and a core of C-channel crossbeams, fiberglass faceplates with a core of hollow tubes, and a sandwich floor with a homogeneous, lightweight core.
To test the four alternatives, a prototype trailer was constructed that enabled the team to assess the joining methods and material selections. Fiberglass and aluminum were the primary materials tested, bonded together so as not to damage the structure of the fiberglass. The trailer prototype was designed with a modular structure with removable segments that can be taken out in case of damage or to minimize empty weight if the trailer is not carrying a full load.
The findings of the study indicate that sandwich panels allow for light weight and a variety of core materials, and carbon-carbon composites allow the largest weight savings. The team also devised fastener-less joining methods specifically for trailers.
The fuel savings for both the reduced weight and the joining configurations of the prototype were predicted in terms of fuel used to move one ton of freight 1000 miles. The weight savings over the traditional model varied from 47 to 60%, depending on which of the four alternative materials was used, and showed 5.7 to 7% savings in fuel consumption.