This research investigates formulation, compounding and thin-wall injection moulding of Polypropylene/clay nanocomposites (PPCNs) prepared using conventional melt-state processes. An independent study on single screw extrusion dynamics using Design of Experiments (DoE) was performed first. Then the optimum formulation of PPCNs and compounding conditions were determined using this strategy. The outcomes from the DoE study were then applied to produce PPCN compounds for the subsequent study of thin-wall injection moulding, for which a novel four-cavity injection moulding system was designed using CAD software and a new moulding tool was constructed based upon this design. Subsequently, the effects of moulding conditions, nanoclay concentration and wall thickness on the injection moulded PPCN parts were investigated. Moreover, simulation of the injection moulding process was carried out to compare the predicted performance with that obtained in practice by measurement of real-time data using an in-cavity pressure sensor. For the selected materials, the optimum formulation is 4 wt% organoclay (DK4), 4 wt% compatibiliser (Polybond 3200, PPgMA) and 1.5 wt% co-intercalant (erucamide), as the maximum interlayer spacing of clay can be achieved in the selected experimental range. Furthermore, DoE investigations determined that a screw speed of 159 rpm and a feed rate of 5.4 kg/h are the optimum compounding conditions for the twin screw extruder used to obtain the highest tensile modulus and yield strength from the PPCN compounds. The optimised formulation of PPCNs and compounding conditions were adopted to manufacture PPCN materials for the study of thin-wall injection moulding. In the selected processing window, tensile modulus and yield strength increase significantly with decreasing injection speed, due to shear-induced orientation effects, exemplified by a significantly increased frozen layer thickness observed by optical microscopy (OM) and Moldflow® simulation. Furthermore, the TEM images indicate a strong orientation of clay particles in the flow direction, so the PPCN test pieces cut parallel to the flow direction have 36.4% higher tensile modulus and 13.6 % higher yield strength than those cut perpendicular to the flow direction, demonstrating the effects of shear induced orientation on the tensile properties of thin-wall injection moulded PPCN parts. In comparison to injection speed, mould temperature has very limited effects in the selected range investigated (25-55 °C), in this study. The changes in moulding conditions show no distinctive effects on PP crystallinity and intercalation behaviour of clay. Impact toughness of thin wall injection moulded PPCN parts is not significantly affected by either the changes in moulding conditions or clay concentration (1-5 %). The SEM images show no clear difference between the fracture surfaces of PPCN samples with different clay concentrations. TEM and XRD results suggest that higher intercalation but lower exfoliation is achieved in PPCN parts with higher clay content. The composites in the thin sections (at the end of flow) have 34 % higher tensile modulus and 11 % higher yield strength than in the thicker sections, although the thin sections show reduced d001 values. This is attributed to the significantly enhanced shear-induced particle/molecular orientation and more highly oriented frozen layer, according to TEM, OM and process simulation results. In terms of the reduced d001 values in the thin sections, it is proposed that the extreme shear conditions in the thin sections stretch the PP chains in the clay galleries to a much higher level, compaction of clay stacks occurs as less interspacing is needed to accommodate the stretched chains, but rapid cooling allows no time for the chains to relax and expand the galleries back. Overall, data obtained from both actual moulding and simulation indicate that injection speed is of utmost importance to the thin-wall injection moulding process, development of microstructure, and thus the resulting properties of the moulded PPCN parts, in the selected experimental ranges of this research.

Die Weiterentwicklung von Verbrennungsmotoren ist geprägt von einer Steigerung der Effizienz, optimaler Betriebslaststeuerung, einer Absenkung des spezifischen Verbrauchs und der Erfüllung geltender Abgasemissionsgesetzgebung. Die Optimierung des Ladungswechsels spielt dabei eine entscheidende Rolle. Eine Möglichkeit den Ladungswechsel optimal zu beeinflussen, ist der Einsatz von variablen Ventiltrieben zur Veränderung der Ventilhubbewegung sowie zur Verstellung der Steuerzeiten. thyssenkrupp Dynamic Components entwickelt und stellt Schiebenockensysteme als diskret schaltbare Ventiltriebsysteme her, welche die verschiedenen Ventilhubanforderungen über unterschiedliche Nockenprofile auf dem Schiebeelement nebeneinander abbilden können. Im Entwicklungs- und Auslegungsprozesses kommt eine Simulation des Bewegungs-, Beschleunigungs- und Abbremsverhaltens sowie der Kraftverläufe beim Verstellvorgang mittels einer Mehrkörpersimulation (MKS) in der Software alaska/ModellerStudio zum Einsatz. In diesem Beitrag wird das MKS-Modell des Schiebelements sowie der Abgleich des Modells mit Versuchen vorgestellt. Es folgt eine Darstellung von Optimierungsmöglichkeiten bereits in der Simulationsumgebung, bei denen die Kontaktnormalkräfte und Beschleunigungen in mehreren Iterationsschleifen auf den gewünschten Anwendungsfall angepasst werden können. Unter Berücksichtigung der Fertigungs- und Lagertoleranzen sowie des Verschleißverhaltens kann das System mit diesem Simulationstool bereits virtuell abgeprüft werden. / The advancement of internal combustion engines is characterized by an increase in efficiency, optimum operating load control, a reduction in specific consumption and compliance with applicable exhaust emission legislation. Optimization of the charge change plays a decisive role in this. One way of optimally influencing the charge change is to use variable valve trains to change the valve lift and adjust the timing. thyssenkrupp Dynamic Components develops and manufactures sliding cam systems as discretely switchable valve train systems that can feature the various valve lift requirements side by side via different cam profiles on the sliding element. A simulation of the motion, acceleration and deceleration behavior as well as the force curves during the sliding process by means of a multi-body simulation (MBS) in the alaska/ModellerStudio is applied in the development and design process. This presentation shows the MBS model of the sliding cam and the comparison of the model with test results. Various optimization options in the simulation environment present, how the contact normal forces and accelerations can be adapted in several iteration loops to the desired application. Taking into account the manufacturing and bearing tolerances as well as the wear behavior, this simulation tool allows to virtually check the sliding cam system.