Proceedings of the Institution of Mechanical Engineers,Part D: Journal of Automobile Engineering

The relative influence of various heavy vehicle design features on road-damaging potential is discussed. Testing procedures that could be used to measure the road-damaging potential of heavy vehicles are examined. A validated vehicle simulation is used to examine some of the characteristics of dynamic tyre forces generated by typical leaf sprung and air sprung articulated heavy vehicles for typical highway conditions. The proposed EC suspension test is simulated and the results compared with dynamic tyre forces generated under highway conditions. It is concluded that the road-damaging potential of a vehicle cannot be assessed by the simplistic parametric measurement of the proposed EC test. It is questionable whether a vehicle that passes the test will be any more ‘road friendly’ than one that fails.

During a robotic materials handling operation, the position and orientation of the workpiece must remain fixed with respect to the coordinate frame of the gripper when the robot arm moves from one point to another. This is achieved if all degrees of freedom of the workpiece relative to the gripper are eliminated by placing appropriate constraints on its movements. Deciding how to constrain an object forms an important part of the design of gripping devices. In this paper, the rules for analysing the state of constraint of an object are reviewed. This is followed by a discussion of a procedure for synthesizing stable constraint configurations for a wide variety of object shapes. Finally, examples are provided to illustrate the application of the proposed procedure in the case of two simple objects.

The generation of systems of contacts for stably holding a workpiece is a task requiring knowledge of a large number of rules about rigid-body constraint. A knowledge-based expert system has been developed to automate this process. The system is capable of synthesizing valid constraint configurations for a wide range of workpieces. Its ultimate use is to generate contact profiles for robot gripper jaws based on these constraint configurations. The system is described in this paper, which also gives a brief overview of expert systems in general and of the particular development tool adopted.

A technique is described which allows the aerodynamic characteristics of the cross wind gusts that are commonly experienced by passenger vehicles to be correctly represented in wind tunnels. This characterization includes the modelling of wind strength and direction, gust duration and the cross wind boundary layer. The technique uses conventional wind tunnel model and instrumentation configurations and relies upon a second nozzle and shutter arrangement to give complete control over the profile and duration of the cross wind gust. Data from some initial proving tests are presented to demonstrate the potential of the method.

Progressive strategic, organizational and product actions taken by the Japanese automotive manufacturers during the past two decades have gained them leadership in almost every benchmark of competitive and industrial competence. From this vantage point, they stand poised to alter the nature of the market during the 1990's through the introduction of a proliferation of low-volume niche products with very short life spans. Two-year automobile product cycles are within their competence now.

The paper outlines the implications of introducing such severely compressed product cycles in a European context. These were exposed by a determined attempt to match Japanese methods and techniques over a period of eleven years. Attaining the goal affected every aspect of the business and its external interfaces. The resultant new company ethos and culture is described. Future evolutionary developments are signposted.

The paper describes a computational and experimental study of the application of advanced ceramic materials for thermal insulation of the swirl chamber of the passenger car IDI diesel engine. Four ceramic materials, having a wide range of physical properties, were evaluated. These were syalon 101, aluminium titanate, reaction bonded silicon nitride (RBSN) and tetragonal zirconia polycrystals (TZP). A detailed finite element study was carried out in support of component design which examined parameters such as heat flux, operating temperature, thermal and assembly stresses and evaluated the requirements for interference fits between metallic and ceramic components. Experimental work was initially carried out on a steady state dynamometer test stand and later supported by vehicle tests on a chassis dynamometer and test track.

The investigation has shown that current engineering ceramic materials have the potential for application in engine combustion chambers. A total of 254 hours of engine testing with ceramic chambers was achieved without catastrophic engine failure. Engine performance was unchanged by the adoption of a thermally insulated swirl chamber, probably because the increase in swirl chamber surface temperature obtained (increased from 660 to about 850°C at full load) was insufficient to modify the thermodynamic cycle. Hydrocarbon emissions were generally increased, however; this was due in part to the difficulty of sealing the air gap behind the ceramic chamber at the fuel injector and glow plug interfaces.

The paper describes a parametric study of valve system dynamics using a single cam-follower system model. The effect of the choice of damping coefficients and the degree of flexibility of the camshaft on the valve motion are highlighted.

The paraffin oil admixtures with some Mo-S complexes were evaluated as potential EP lubricant additives in the ‘four-ball test’ using 12.7 mm diameter steel balls of different compositions. The oil-soluble additive, bis(oxinato)-μ-oxo-μ-sulphido-dioxomolybdenum (V), was found to be quite effective against the steel balls of different compositions. The tribochemistry and topography of the used ball specimens were examined by means of scanning auger electron spectroscopy and scanning electron microscopy respectively.