Problem Solving Skills Deconstructed And Implemented In An Adaptive Learning Tool

The development of problem-solving skills is an important subject in engineering curricula. Helping novice students develop such skills can be challenging because problem solving is a complex skill in the sense that it is accompanied with an internal thinking process that many experts are even unaware of doing. From a combination of literature and a thinking-aloud exercise with the entire teaching team, a scheme with building blocks and strategies that are commonly used by engineers was constructed. In addition to commonly named steps such as Identify/Define, Plan/Choose, Carry Out/Do and Look back/Inspect the scheme refines the first step into multiple interdependent building blocks, emphasizes the need for critical reflection at each point as well as the possible need to return to previous steps at any time. Moreover, multiple correct solution paths can be followed in solving a problem. To address this and to empower the students in their divergent thinking processes when solving a problem, an innovative intra-exercise adaptive e-learning tool was created. The anywhere-anytime availability enables for virtual and remote learning in the post-COVID world. In the learning tool students can choose between different solution paths, after firstly identifying the correct context, parameters etc. This paper describes the process of defining the building blocks, resulting strategy scheme and implementation of the building blocks in the adaptive e-learning tool. Initial findings indicate that the strategy scheme consisting of building blocks and the adaptive e-learning tool help students in developing their problem-solving skills

Critical evaluation of the FeeNi, FeeTi and FeeNieTi alloy systems

The FeeNieTi alloy system has been evaluated, together with FeeNi and FeeTi binary subsystems, to provide reliable information for applications and in view of a thermodynamic modelling of the system. Available literature has been critically evaluated, mainly considering phase constitution and phase equilibria, thermochemical and diffusion data, as well as ab initio atomistic calculations. A discussion of the presently available CALPHAD-type thermodynamic assessments is also presented. Finally, new experimental investigations needed to solve uncertain and contradictory data are suggested

Thermodynamic Modeling of the Fe-Ni-Ti System: A Multiple Sublattice Approach (Thermodynamische modellering van het Fe-Ni-Ti systeem: een formalisme met meerdere subroosters)

Fe-Ni-Ti legeringen zijn zeer geschikt voor verscheidene technologische toepassingen. Elk van de samenstellende elementen vormt de basis van een brede waaier aan legeringen, zoals staalsoorten, Ni-gebaseerde superlegeringen en Ti legeringen met hoge sterkte en laag soortelijk gewicht. Deze legeringen zijn vaak samengesteld uit meer dan tien elementen. Toch vormt het Fe-Ni-Tisysteem reeds de basis voor de modellering. Specifieke toepassingen van Fe-Ni-Ti legeringen zijn geheugenlegeringen en materialen voor de opslag van waterstof.In de context van de Europese COST 535 actie (THALU-THermodynamics of ALUminides) wordt het ternaire Fe-Ni-Ti systeem bestudeerd en gemodelleerd aan de hand van de CALPHAD methode. Deze studie bestaat uit twee delen. Eerst worden de gepaste thermodynamische modellen geselecteerd voor de modellering van de verschillende fasen (zowel stabiele als metastabiele fasen). De orde-wanorde relatie die tussen een aantal van deze fasen (bijvoorbeeld A1, L1_0 en L1_2) bestaat wordt hierbij beschouwd. De geselecteerde modellen zijn consistent voor alle fasen in het quaternaire Al-Fe-Ni-Ti systeem. Wanordelijke fasen en de vloeistoffase worden in alle deelsystemen gemodelleerd met het reguliere oplossingsmodel. Intermetallische fasen worden gemodelleerd met meerdere subroosters. Het subroosterformalisme laat toe de orde-wanorde relatie tussen de verschillende geordende en ongeordende configuraties van de kubisch ruimtegecenterde (krg) en kubisch vlakgecenterde (kvg) fasen in rekening te brengen. De aandacht gaat daarbij vooral uit naar het modelleren van de bcc fasen met 4 subroosters, waarbij de Gibbs vrije energie van de ongeordende bcc fase geschreven wordt als functie van de vormingsenergieën van de geordende verbindingen.In het tweede deel van deze thesis wordt op basis van de geselecteerde oplossingsmodellen succesvol een volledige thermodynamische beschrijving van het ternarie Fe-Ni-Ti bekomen. Hierbij wordt gebruik gemaakt van kritisch geëvalueerde data uit de literatuur en van nieuwe experimentele data die gegenereerd werden binnen de Europese COST 535 actie THALU.status: publishe

Relation between water penetration behavior and product quality in water-assisted injection molding (WAIM) at different process parameters

Measurements of water pressure and water volume flow rate during water injection were related to both the part weight and a visual inspection of part cross-section at different process settings. It was found that the residual wall thickness (RWT) as well as the formation of part defects end on the polymer resistance, since the variation of this latter leads to a change in both the water bubble width and velocity. Therefore, product quality depends on process parameters such as water volume flow rate and water injection delay time, which have an influence on this polymer resistance.status: publishe

Defect Occurrence in Water-Assisted Injection-Molded Products: Definition and Responsible Formation Mechanisms

This study starts with the definition of different defects that occur in water-assisted injection-molded products to which subsequently responsible formation mechanisms are attributed. It is seen that the four different defect types in the current experimental setup—irregular residual wall, void, double wall, and no residual wall—are either formed by different mechanisms or by the same mechanism of which the extent decides on the actual defect type. The current insights into the occurring part defects are used in the second part of this study to explain the influence of process and material parameters on the defect occurrence in a reference experiment. The presence as well as the extent of a formation mechanism is here further linked to the water and/or polymer properties/conditions, which exist during water penetration. The water and melt temperature, water holding pressure, and the presence of nucleating agents in the polymer melt were therefore varied within the predefined reference setting. The influence on the nature and location of the part defects was investigated with a qualitative defect analysis. It is found that the proposed definitions and mechanisms are able to explain experimentally observed changes in defect occurrence physically, with which the existing indistinctness in the literature can be elucidated as well.status: publishe

The Influence of Melt and Process Parameters on the Quality and Occurrence of Part Defects in Water-assisted Injection Molded Tubes

This study investigates the influence of melt and process parameters on the quality of water-assisted injection molded tubes. The influence was determined by the aid of a design of experiments (DOE) for both a HDPE and a PP resin. This design was carried out on two different cavities, in which the residual wall thickness (RWT) and the part weight were set as response functions. This was combined with a visual inspection of the part sum face to detect correlations in the occurrence of part defects such as fingering and double wall. It was found that the water injection delay time and the water volume flow rate have the largest influence on the RWT and part weight. Moreover, the shear viscosity of the applied material determines the width and shape of the water bubble and consequently the RWT and part weight. In addition, process parameters such as melt temperature, water hold time and water volume flow rate as well as melt parameters such as shear viscosity have an influence on the formation of part defects.status: publishe

Variotherm spuitgieten voor het optimaliseren van het breukgedrag van een sierkader uit polycarbonaat

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Occurrence of Part Defects in Water-Assisted Injection Molded Products

Water-assisted injection molding (WAIM) is one of the latest techniques to produce hollow or partially hollow products. A shorter cycle time in combination with a lower material and process cost are the main advantages. However, the occurrence of part defects remains unresolved. This study investigated the influence of the polymer shrinkage behavior on the occurrence of the part defects. Therefore, two polypropylene resins were used of which one resin was filled with nucleating agents, whereas the other was unfilled. The results cleared out that the presence of nucleating agents, inducing a higher polymer shrinkage, leads to a higher amount of part defects.status: publishe

Formation of part defects in water-assisted injection molding (WAIM): influence of process and material parameters

Water-assisted injection molding (WAIM) enables the production of hollow or partially hollow products, having a higher quality and lower process cost when compared to products produced with other and earlier developed plastic processing techniques. However, the occurrence of (unwanted) defects in the final product is one of the current limitations of the WAIM process, for which in available research until now no clear explanations exists. In this study, the influence of process and material parameters on the occurrence of part defects was examined in a pre-defined reference experiment. With a qualitative defect analysis, it was found that within the reference setting a high water temperature, a low melt temperature and water holding pressure as well as the addition of nucleating agents are more favorable. The experimentally observed changes in defect occurrence, under influence of the applied parameter variation, can herewith be explained with the proposed definitions of the different defect types and their responsible formation mechanisms. In this way, the principle mechanisms behind the formation of part defects are enclosed in these definitions and mechanisms, which hence contribute to a more fundamental understanding of the WAIM process.status: publishe

Construction of modified embedded atom method potentials for the study of the bulk phase behaviour in binary Pt-Rh, Pt-Pd, Pd-Rh and ternary Pt-Pd-Rh alloys

A first attempt is made to simulate the solid part of the phase diagram of the ternary Pt-Pd-Rh system. To this end, Monte Carlo (MC) simulations are combined with the Modified Embedded Atom Method (MEAM) and optimised parameters entirely based on Density Functional Theory (DFT) data. This MEAM potential is first validated by calculating the heat of mixing or the demixing phase boundary for the binary subsystems Pt-Rh, Pt-Pd and Pd-Rh. For the disordered alloy systems Pt-Rh and Pt-Pd, the MC/MEAM simulation results show a slightly exothermic heat of mixing, thereby contradicting any demixing behaviour, in agreement with other theoretical results. For the Pd-Rh system the experimentally observed demixing region is very well reproduced by the MC/MEAM simulations. The extrapolation of the MEAM potentials to ternary systems is next validated by comparing DFT calculations for the energy of formation of ordered Pt-Pd-Rh compounds with the corresponding MEAM energies. Finally, the validated potential is used for the calculation of the ternary phase diagram at 600 K. (C) 2008 Elsevier Ltd. All rights reserved.status: publishe