Determination of representative loading conditions for effective semitrailer design

Obtaining a representative loading spectrum that corresponds well to the reality is still one of the greatest challenges for fatigue life calculations and optimal design of the trailer body. A good qualitative and quantitative knowledge of the spectrum leads to more efficient usage of material, a better design of connection points and an overall decrease of the weight of the trailer, which finally results in a significant decrease in the price of a ton of cargo per km. Despite that, the approach is nowadays mostly based on the experience and rules of thumb. It typically results in over-dimensioning of some parts while other parts remain vulnerable to failure due to unknown loading patterns. This paper describes a generic approach to solve the problems mentioned above applied in a research project named FORWARD (Fuel Optimized trailer Referring to Well Assessed Realistic Design loads). The project lasted two years and was carried out in cooperation with several different trailer manufacturers and 1st tier suppliers. The loading history of more than 1000 hours for five trailer types were captured in the shape of strains, accelerations and velocities of various elements of the trailers, enabling reconstruction of the loading in terms of forces and moments acting on the wheels and kingpin. Parallel to this extensive test-campaign, a novel generic physics-based computational approach was developed to predict selected loads encountered during common manoeuvres to all trailer types. The computational approach was validated against test-data and resulted in creating a generic multi-body library applicable for all trailer types, and an automated post-processing routine for the large amount of test-data

Assesment of Dutch longer and heavier vehicles with a performance based approach and its applicability to Europe

The volume of goods transported as well as the number of commercial vehicles in Europe has increased substantially over the past decade. The sixteen years old European directive on vehicle weights and dimensions does not fully reflect on these circumstances and allows commercial vehicles up to 18.75m of length and weight of 44t for international transport. As the Dutch experience reveals, the legalization of longer and heavier vehicles (LHV) on highways makes transportation of goods more efficient, sustainable and is applicable even in highly populated regions. This paper is benchmarking the performance of all currently used Dutch LHV combinations, two potential LHV concepts satisfying the logistic needs, and conventional European combinations using the Australian performance based approach. Furthermore it discusses applicability of performance based standards to Europe as an alternative to current prescriptive legislation and shows that performance of LHV’s can differ very much

Full vehicle ABS braking using the SWIFT rigid ring tyre model

In recent years, at the Delft University of Technology and TNO-Automotive and in conjunction with an industrial consortium, a pragmatic tyre model has been developed going by the name SWIFT, which is geared to the analysis of tyre oscillations and its effects on vehicle behaviour. The SWIFT tyre model has been designed to cover in-plane, out-of-plane and combined higher order dynamic tyre performance. It can be regarded as an extension of the Magic Formula pragmatic tyre model, up to a range of at least about 70 Hz. This paper describes the application of the SWIFT tyre model to full vehicle ABS braking. First, the model is used to derive the single tyre response to road undulations and brake torque step input, both being very much of relevance to ABS braking. This includes a survey of the sensitivity of the dynamic tyre parameters regarding the first, rigid belt, eigenfrequencies and the relative damping. Next, the response of a quarter vehicle to similar input is discussed with specific emphasis on the added value of the dynamic characteristics of the SWIFT model in comparison to steady state and transient tyre models. Finally, full vehicle ABS controlled braking on an even road is considered for various road friction values and vehicle speed