Optimising the Performance of Complex Sociotechnical Systems in High-Stress, High-Speed Environments: The Formula 1 Pit Stop Test Case

In analysing the performance of complex sociotechnical systems, of particular interest is the inevitable and inherent variability that these systems exhibit, but can normally tolerate, in successfully operating in the real world. Knowing how that variability propagates and impacts the total function mix then allows an understanding of emergent behaviours. This interdependence, however, is not readily apparent from normal linear business process flow diagrams. An alternative approach to exploring the operability of complex systems, that addresses these limitations, is the functional resonance analysis method (FRAM). This is a way of visualising a system’s behaviour, by defining it as an array of functions, with all the interactions and interdependencies that are needed for it to work successfully. Until now this methodology has mainly been employed as a qualitative mind map. This paper describes a new development of the FRAM visualisation software that allows the quantification of the extent and effects of this functional variability. It then sets out to demonstrate its application in a practical, familiar test case. The example chosen is the complex sociotechnical system involved in a Formula 1 pit stop. This has shown the potential of the application and provided some interesting insights into the observed performances.

A new quick-stop device to study the chip formation mechanism in metal cutting: Computational and experimental investigation

Understanding the chip formation mechanisms during machining is an important factor to facilitate the choice of cutting tools and machining parameters. Despite the appearance of new sophisticated methods and advanced equipment, the technique so called quick-Stop Test (QST) remains efficient, less costly, and easier to apply in the investigation of chip formation in cutting process. In present paper a new Quick-Stop Device QSD is designed, numerically simulated, implemented, and tested. The reformed QST technique uses a QSD device which operates on the modified Charpy pendulum. Accordingly, design of new QSD is presented and deeply described, and 2D FE modeling of the new QST, including the application of the appropriate boundary conditions, has been carried out. Moreover, chip formation and morphology for different cutting conditions have been effectively simulated. Subsequently, quick stop cutting operations including metal cutting tests of high alloyed tool steel (AISI D2) using fabricated new QSD are performed. Preliminary results of quick-stop experiment from current investigation prove the effectiveness of the new designed QSD in matter of rigidity, safety, and absence of vibration, while providing a fast set up time and allowing extremely short workpiece-cutting tool separation time and guarantee the generation of chip with its root. The photomicrographs of chip root samples gathered from hard metal cutting experiments including various cutting speeds machining conditions, enables clear observation of segmented chip formation mechanisms, thereby, highly promising the new designed QSD for the purpose of investigation of the different cutting parameters influencing the chip formation and morphology.

New Perspectives Regarding the Chip Formation Process of Ti-6Al-4V

The mathematical, physical and morphological characteristics of the chip formation process during cutting of Ti-6Al-4V will be analyzed and presented in this paper. In recent years titanium has received more attention due to their unique material properties, such as light weight by height strength, small deformation at high temperatures, low brittleness at low temperatures, and nearly no oxidation at high temperatures, but with the disadvantage that it is difficult to machine. A lot of investigations have been conducted to solve the complex process of machining. But the real complex phenomena at the cutting edge can’t be explained with the help of simplified models. This paper presents a new mathematical-physical model describing the process mechanics leveraging two kinds of friction to explain the metal behavior to strain and stress with self-hardening or softening effects, and the dynamic chip formation behavior due to strain rate discontinuity. All these influencing parameters have an interdependent relationship; thus, they cannot be analyzed separately. The resultant deformation process leads to a grid deformation pattern in the relevant region of the transversal section of a chip that can be used for comparing the theoretical solution with the experimental result. This deformation pattern is the only characteristic that will not disappear after machining. As long as the theoretical results are found to be in agreement with the experimental data of the produced segmented chip, we can be sure, that the models integrating the friction conditions, strain-stress, and metallurgical conditions are correctly developed. In approaching these problems, it is difficult to choose the relevant machining conditions, because a “quick-stop” test is difficult to produce. The reason might be the existing contact conditions at the tool-chip interface, which has an intensive connection due to the diffusion process. Therefore, two different cutting velocities were chosen with the hope that the diffusion is not too intensive; (one slow velocity with vc = 12.5 m/min and a higher velocity with vc = 100 m/min). In addition, a photomicrograph of a chip was taken for the validation process between theoretical and experimental results. Furthermore, the existing temperatures in the contacting zone as well as in the chip formation area could be developed and are discussed and presented in this paper.

Methodology of Testing Foil Bearings in the Start-Stop Cycle in the Presence of a Working Medium - Stabilization of Temperature in the Test Chamber

The article presents the methodology of testing sliding bearings with a flexible shell, focusing on the issue of temperature increase during experiments for a specific time interval of the START-STOP test cycle. Selected material pairs, used in previous studies, were used in the experiment. The stand used for tests in the start-stop cycle was developed under the project POIG.01.03.01-00-027 / 08-00 at the Faculty of Technical Sciences UWM in Olsztyn.

Frequent Start-Stop Test Study of Graphene Coatings on Journal Bearings

In this study, the graphene was prepared by chemical vapor deposition (CVD) method, and then through thermal annealing technique it was firmly coated on and partly diffused into the inner surfaces of journal bearings made from aluminum bronze CuAl10Fe3. The journal bearings without graphene coatings were also prepared with made from aluminum bronze CuAl10Fe3 and tested under the same conditions as the references of comparison. Through frequent start-stop test, the changing laws of coefficient of friction (COF), power consumption, and back temperature rise and wear loss for each journal bearing with or without graphene coating were obtained. The test results showed that graphene coating could significantly reduce the power consumption and wear loss during the start and stop phases.

Methods of Research of Foil Bearings in START-STOP Cycle in the Presence of Working Medium

A method for testing sliding bearings with an elastic bearing liner was presented in the paper with a focus on the issue of selection of particular time intervals of the START-STOP test cycle. Then, results of the tests carried out according to the selected material combinations were presented. The working cycle of foil bearings tested on the test stand was performed in an automatic mode at the set number of sequences start-work-rundown-stop. Due to the highest use of sliding bearings during start and rundown of a machine, this type of tests is essential for selection of relevant sets of material for bearing elements. The article also presents the use of a thermo-visual camera for identification of additional thermal loads and manners of temperature stabilization in the test chamber.