Search Results

Currently, the chassis assembly contributes about 73 percent of the overall weight of a 14.63 m long haul trailer. This paper presents alternative design concepts for the structural floor of a van trailer utilizing sandwich panels with various material and geometric characteristics of the core layer in order to reduce its weight significantly below that of the current design configuration. The main objective of the new designs is to achieve optimal tradeoffs between the overall structural weight and the flexural stiffness of the floor. Various preliminary design concepts of the core designs were compared on the basis of a single section of the core structure. Six different designs were analyzed by weight, maximum displacement and maximum stress under bending and torsion loads. Each concept was kept uniform by length, thickness, loading and boundary conditions. Each design concept was examined through testing of scaled model for floor assemblies.

Recent advances in Metal Matrix Composites have made them ready for transition to large-volume production and commercialization. Such new materials seem to allow the fabrication of higher quality parts at less than 50 percent of the weight as compared to steel. The increasing requirements of weight savings and extended durability motivated the potential application of MMC technology into the heavy vehicle market. However, significant technical barriers such as joining are likely to hinder the broad applications of MMC materials in heavy vehicles. The focus of this paper is to examine the feasibility of manufacturing and the behavior of bolted joint connections made from aluminum matrix reinforced with Silicon Carbide (SiC) particles. Two reinforcement ratios: 20% and 45% were considered in this study. The first part of the paper concentrates on experimental evaluation of bolted MMC joints.

Emissions from light duty vehicles have traditionally been measured using a chassis dynamometer, while heavy duty testing has been based on engine dynamometers. However, the need for in-use vehicle emissions data has led to the development of two transportable heavy duty chassis dynamometers capable of testing buses and heavy trucks. A test cycle has been developed for Class 8 trucks, which typically have unsyncronized transmissions. This test cycle has five peaks, each consisting of an acceleration, cruise period, and deceleration, with speeds and acceleration requirements that can be met by virtually all vehicles in common service. Termed the “WVU 5 peak truck test”, this 8 km (5 mile) cycle has been used to evaluate the emissions from diesel and ethanol powered over-the-road tractors and from diesel and ethanol powered snow plows, all with Detroit Diesel 6V92 engines.

A study to determine whether performance-based brake testing technologies can improve the safety of our highways and roadways through more effective or efficient inspections of brakes of on-the-road commercial vehicles is being sponsored by FHWA/DOT-OMC. A key objective of the study is to determine how the results from performance-based “inspections” compare with results obtained through traditional visual methods, such as those recommended by the Commercial Vehicle Safety Alliance (CVSA). Data from joint inspections (i.e., CVSA and performance-based inspections on the same vehicle), obtained over approximately a one year period, have been analyzed. Description of three of the performance-based technologies and preliminary results from approximately 1,400 joint inspections are covered in this paper.

There is recent interest in examining whether performance-based brake tests are advantageous compared to presently used visual inspections for safety checks of on-the-road commercial vehicles. In this first of a series of two papers, the basic features of visual inspections and performance-based brake tests are presented and discussed. It is shown that the visual inspection method is inherently “predictive” in nature and therefore conservative. A performance-based brake test is objective but not predictive. The performance based test may reveal safety-related defects only for the specific vehicle load configuration and operating condition. The presentation is concluded with a discussion of what may be required for future enforceable use of performance-based brake testing devices for “on the road” inspections of commercial vehicles. In the short term, use of performance based testing will depend on correlation of test results with presently enforceable visual methods or standards.

Speed-time and video data were logged for tractor-trailers performing local deliveries in Akron, OH. and Richmond, VA. in order to develop an emissions test schedule that represented real truck use. The data bank developed using these logging techniques was used to create a Yard cycle, a Freeway cycle and a City-Suburban cycle by the concatenation of microtrips. The City-Suburban driving cycle was converted to a driving route, in which the truck under test would perform at maximum acceleration during certain portions of the test schedule. This new route was used to characterize the emissions of a 1982 Ford tractor with a Cummins 14 liter, 350 hp engine and a 1998 International tractor with a Cummins 14 liter, 435 hp engine. Emissions levels were found to be repeatable with one driver and the driver-to-driver variation of NOx was under 4%, although the driver-to-driver variations of CO and PM were higher.