Aeroelastic Effects in Multibody Dynamics

To enable a realistic assessment of the aeroelastic phenomena of aircraft, a simultaneous application of computational fluid dynamics (CFD), computational structural mechanics and flight mechanics has to be performed. Each discipline has developed powerful specialized tools which have to be adapted for multidisciplinary applications. The combination of CFD and elastic multibody systems is well suited for the simulation of a range of aircraft applications, especially for aircraft ground dynamics. Approaches to a coupling of elastic multibody systems and computational fluid dynamics have been performed using close coupling, that is a modal approach, and loose coupling, that is by co-simulation. In the article the applied programs and the coupling methods are presented. Advantages and limits of using multibody simulation as compared to the direct use of FEA methods for the representation of structural dynamics are discussed. Results of coupled steady and unsteady simulations are presented. Finally, an approach to the aeroelastic trim problem is shown.     

Overview of Coupling of Multibody and Control Engineering Tools

The role of Computer Aided Engineering in vehicle development has been significantly increased during the last decade. Specialised simulation tools became very complex, however, growing demands on complexity and particularly interdisciplinarity of vehicles and their simulation models have led to a number of approaches trying either to develop multidisciplinary simulation tools or to connect various specialised simulation tools by interfaces. This paper addresses some aspects of interconnection of the specialised simulation tools as one possibility for simulating complex mechatronic vehicle systems. It classifies the interfaces between specialised software packages in general, mentions some historical development of the interfacing and further discusses the examples of the implemented couplings between the Multibody System codes and Computer Aided Control Engineering tools. Finally, the performance of selected interfaces is compared on an example simulation of a controlled vehicle suspension.     

Wheel/rail interface management in heavy haul railway operations—applying science and technology

The primary objective of the paper is to review science and technologies that have been developed by various scientists and engineers over the years and that have made it possible to push the limits within the wheel/rail interface in the heavy haul railway environment. After describing the wheel/rail stress-state and its consequences, preventative and corrective measures that can assist in optimising wheel and rail life, and thus reduce costs, are reviewed. The significant contribution of measurement and monitoring technologies to quantify the stress-state of the wheel/rail system is highlighted. Finally, a brief review of the fundamentals of contact mechanics, vehicle dynamics and wheel/rail interface analysis software is given.     

Stabilization of Passenger Car-Caravan Combination Using Four Wheel Steering Control

This study aims to stabilize the trailer at high speed. The behavior of passenger cars with four wheel steering system, vehicles with rear wheel steering and of trailer and passenger car are similar. This is regarded as an optimal regulator problem with linear equation of motion, and a state variables feedback control system is adopted. The problem of stability at high speed on a straight course can be solved. Therefore, the passenger car-trailer system can be stabilized. Furthermore, this study indicates the way forward to stabilize a passenger car-trailer system.     

Labour relations in the Hong Kong merchant navy

This paper discusses the role of ratings' and officers unions, and that of boarding-house keepers, in relation to the recruitment and supply of seamen for the Hong Kong Merchant Navy     

On the Performance Capabilities of Active Automobile Suspension Systems of Limited Bandwidth

Using methods established in earlier work, calculations are carried out to reveal the influence of actuator bandwidth on the performance capabilities of a class of active suspension system for automobiles. The suspension consists of an actuator in series with a spring, the combination being in parallel with a passive damper, and the system is modelled as a single wheel station traversing a random road. The results indicate that a system with a 3 Hz bandwidth actuator and variable damping will have excellent ride performance qualities over a wide range of road roughness conditions. Since such a system can be expected to be easily adaptable to the running conditions, to provide good static and dynamic attitude control, to be capable of contributing to good steering control responses and to be inexpensive in terms of capital and energy consumption costs compared with most of the active systems which have previously been discussed, it is suggested that it is a prime candidate for further study and practical development.     

Delay processes at unsignalised junctions: The interrelation between geometric and queueing delay

The interrelation between geometric delay—the delay caused by the need for isolated vehicles to slow down to negotiate a junction—and the queueing delay due to vehicle-vehicle interactions is considered. The delay elements present in measurements of geometric delay are identified, and some overlap is seen with those normally included in the service mechanisms in queueing models. The total delay per vehicle is not, therefore, the sum of the measured geometric delay and the queueing delay. Although the geometric delay can be redefined so as to eliminate the overlap, it is not then measurable. A framework is developed in which the relationships between the “pure” and measured geometric delay and the queueing delay are expressed for the population mean values. Approximate expressions are developed for the elements of delay. The framework is extended to allow queueing delays to be represented by time-dependent functions allowing approximately for non-randomness in arrival and departure patterns and service time differences between queueing and non-queueing vehicles. Numerically, geometric delay elements constitute a significant proportion of total delay except at traffic intensities approaching unity. In this region time-dependent effects dominate the queueing process.