Computational modeling is widely used to support the design of profile extrusion dies. However, despite the viscoelastic nature of the polymer melts, the majority of the computational approaches resort to inelastic models. With the aim of assessing the accuracy of the approach usually employed on the modeling of profile extrusion dies, this work aims at comparing the behavior of profile extrusion dies when interrelated viscoelastic (elastic) and generalized Newtonian (inelastic) constitutive models are used. For this purpose, the polymer melt employed in the study was experimentally characterized, being the data collected used to fit a nonlinear multimode viscoelastic (elastic) Giesekus constitutive model. Subsequently, the fitted model was used to generate the material shear flow curve, which was then used to fit a Bird‐Carreau (inelastic) constitutive model. The numerical studies undertaken were focused on the extrusion die of two profiles: a simple one, with a rectangular cross‐section, and a complex swimming pool cover profile. The results obtained showed that in realistic case studies, the effect of elasticity might be relevant, even when modeling just the flow in the extrusion die flow channel and, thus, should be considered when designing profile extrusion dies.

Nowadays, titanium and its alloys are widely utilized in various industrial parts in such areas as the petrochemical, medical, and automotive industries; However, due to structural considerations, application is problematic in cases of joining. Ti 4Al 2V is a new type of titanium alloy, that in point of structure is near to the α-series, which have many applications in critical conditions (moisture, steam, temperature, etc.). One of the main drawbacks of titanium is the welding of this alloy; however, friction stir welding has been found to be a good method in joining solid materials, especially titanium and its alloys. In this research, the effective parameter of spindle rotational rate has been varied through the process and its effect on the mechanical properties was examined.

The present work focuses on the extensional rheometry test, performed with the Sentmanat extensional rheometer (SER) device, and its main objectives are: (i) to establish the modelling requirements, such as the geometry of the computational domain, initial and boundary conditions, appropriate case setup, and (ii) to investigate the effect of self-induced errors, namely on the sample dimensions and test temperature, on the extensional viscosity obtained through the extensional rheometry tests. The definition of the modelling setup also comprised the selection of the appropriate mesh refinement level to model the process and the conclusion that gravity can be neglected without affecting the numerical predictions. The subsequent study allowed us to conclude that the errors on the sample dimensions have similar effects, originating differences on the extensional viscosity proportional to the induced variations. On the other hand, errors of a similar order of magnitude on the test temperature promote a significant difference in the predicted extensional viscosity.

The present work aims to investigate the effect of the parameters of the laser machining process and laser line angle to injection direction of sample plastics on the electrical resistance of Polymethyl Methyl Methacrylate (PMMA)/Multi-Wall Carbon Nanotubes (MWCNT) Nano-composite. The laser machining process was performed on the samples considering a combination of power, feed rate, and laser line angle with respect to to the direction of melted flow parameters. According to the obtained results from electrical resistance and magnetic properties measurements, this was demonstrated that the laser line angle to the direction of melted flow does not statistically, and physically affect the electrical resistance of the composite. And increasing laser machining power leads to electrical resistance reduction. On another hand, feed rate enhancement (with fixed lasering power) causes increasing the electrical resistance. Moreover, this is found out that laser machining does not significantly affect the magnetic properties of the samples.