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In order to achieve the automatic call of any toolpath generation in 2.5 D pocket milling, new tool paths with offset parallel to the contour for any concave or convex polygonal shape are proposed in this article. Focus is given on several methods for addressing issues related to trajectory generation: the disappearance of edges when transitioning from one contour to another, the residual between passes, and the center of the pocket. A few selected test cases are presented for validation. The obtained results reveal that the approach introduced offers automatic toolpath generation for any polygonal shape and ensures efficient machining simulation without the appearance of material residues between passes in the corners or at the center of the pocket. [ABSTRACT FROM AUTHOR]

This paper presents a novel triangular strain-based element designed to address plane stress and strain, axisymmetric, and dynamic problems. The proposed element has four nodes, three of which are located at the vertices and one of which is located at the midpoint of the diagonal. The corner nodes have three essential external degrees of freedom (u, v, θ), while the central node has two degrees of freedom (u, v) on one of the triangle edges. A static condensation-based treatment of the central node is employed to streamline the model and reduce computational overhead. This triangular element is applicable to both linear and dynamic analyses. Its performance is evaluated using a suite of membrane and axisymmetric problems. The obtained results demonstrate the robustness and accuracy of the proposed element. [ABSTRACT FROM AUTHOR]

The present paper presents an investigation and analysis study of the effect of the head shapes of the impactor on the damages observed during low-velocity impact on T700/Epoxy composite laminate. Two types of impactors were investigated: hemispherical and flat-face. A new criterion based on the LARC05 damage model was linked as a LARC_VUMAT subroutine to simulate the impact and explore the effects of the head form shape through a three-dimensional finite element model. To properly analyze the problem, the history time of the mechanical responses, such as impact forces, bending, principal, and residual stresses, are highlighted and assessed. Additionally, a comparison with the experimental data found in the literature was performed to check the validity and accuracy of the considered finite element model. The damage occurring in the T700/Epoxy plates is illustrated for each impactor head shape. The mechanical response curves and all kinds of damage of the presented simulations are in perfect agreement with the experiments. The proposed VUMAT is efficient in the prediction of fiber kinking, matrix cracking, fiber splitting, and fiber tension of a laminate, and more importantly, it is easy to implement for other types of materials and the reproducibility of the analysis is assured. [ABSTRACT FROM AUTHOR]

This paper describes the development of a simple quadrilateral strain-based element for plane stress and strain problems. This element has five nodes, four located at its corners and one at the center. Each of the four corner nodes had two essential external degrees of freedom (u, v), while the center node had three degrees of freedom (u, v, ɵ); the static condensation method was used for the internal node. This element was used for both linear and dynamic analysis. Its performance was assessed using a variety of membrane and axisymmetric analysis problems. The obtained results demonstrated the good performance and accuracy of the proposed element. [ABSTRACT FROM AUTHOR]

The solar flux distribution on the Parabolic Trough Collector (PTC) absorber tube is extremely non-uniform, which causes non-uniform temperature distribution outside the absorber tube. Therefore, it generates high thermal stress which causes creep and fatigue damage. This presents a challenge to the efficiency and reliability of parabolic trough receivers. To override this problem, we have to homogenize the heat flux distribution and enhance the heat transfer in the receiver's absorber tube to improve the performance of the PTC. In this work, 3D thermal and thermal stress analyses of PTC receiver performance were investigated with a combination of Monte Carlo Ray-Trace (MCRT), Computational Fluid Dynamics (CFD) analysis, and thermal stress analysis using the static structural module of ANSYS. At first, we studied the effect of the receiver tube material (aluminium, copper, and stainless steel) on heat transfer. The temperature gradients and the thermal stresses were compared. Second, we studied the effect of the addition of nanoparticles on the working Heat Transfer Fluid (HTF), employing an Al2O3-H2O based nanofluid at various volume concentrations. To improve the thermal performance of the PTC, a nanoparticle volume concentration ratio of 1%-6% is required. The results show that the temperature gradients and thermal stresses of stainless steel are significantly higher than those of aluminium and copper. From the standpoint of thermal stress, copper is recommended as the tube receiver material. Using Al2O3 in water as an HTF increases the average output temperature by 2%, 6%, and 10% under volume concentrations of 0%, 2%, and 6% respectively. The study concluded that the thermal efficiency increases from 3% to 14% for nanoparticle volume fractions ranging from 2% to 6%. [ABSTRACT FROM AUTHOR]