Neuro-Fuzzy Model for the Prediction and Classification of the Fused Zone Levels of Imperfections in Ti6Al4V Alloy Butt Weld

Weld imperfections are tolerable defects as stated from the international standard. Nevertheless they can produce a set of drawbacks like difficulty to assembly, reworking, limited fatigue life, and surface imperfections. In this paper Ti6Al4V titanium butt welds were produced by CO2laser welding. The following tolerable defects were analysed: weld undercut, excess weld metal, excessive penetration, incomplete filled groove, root concavity, and lack of penetration. A neuro-fuzzy model for the prediction and classification of the defects in the fused zone was built up using the experimental data. Weld imperfections were connected to the welding parameters by feed forward neural networks. Then the imperfections were clustered using the C-means fuzzy clustering algorithm. The clusters were named after the ISO standard classification of the levels of imperfection for electron and laser beam welding of aluminium alloys and steels. Finally, a single-value metric was proposed for the assessment of the overall bead geometry quality. It combined an index for each defect and functioned according to the criterion "the-smallest-the-best.

fe analysis of low density hemp epoxy composites produced by a new continuous process

Abstract This paper aims to present a new grid composite structure obtained by stacking hemp fabric layers impregnated by resin using a new continuous process. Both the process feasibility and the mechanical properties of the obtained specimens were investigated in terms of tensile and flexural response. In addition, the effect of the superimposition error of the layers, that can affect the density and the mechanical properties of the produced bio-composites, was studied both experimentally and numerically by finite element models (FEM). The results showed that the process is able to produce low density composites possessing interesting specific mechanical properties with a good level of repeatability

CFRPs drilling: comparison among holes produced by different drilling strategies

Abstract The drilling process of CFRPs is the most commonly employed machining operation owing to the need for joining these structures. However, these materials are prone to delaminate during the process and the presence of these defects can be a cause of rejection of these components. Therefore, this paper aims on the study of alternative drilling strategies such as: the orbital and a new drilling strategy (called circular drilling) to reduce the delaminations extension. Holes 8 mm in diameter were obtained by using different drilling strategies and cutting conditions and their influence on the cutting forces and delamination factor was studied

Recyclability Process of Standard and Foamed Gypsum

n/

Impact behaviour of a new Hemp/Carbon sandwich structure

Abstract This paper aims to present a new sandwich structure comprising of a grid hemp core and carbon skins. Two typology of hemp cores (7 and 8 mm in thickness) that mainly differ in the density values (0.36 and 0.63 g/cm3) were produced by an ad hoc manufacturing process and adopted to produce the sandwich structures under investigation. Aiming to extend the use of natural fibre composites (NFCs) for applications where high impact resistance is required and to replace common materials used as cores with more eco-friendly ones like the proposed hemp core, low velocity impact (LVI) tests and non-destructive (ND) tests were carried out

Selection of Optimal Process Parameters for Wire Arc Additive Manufacturing

Abstract This paper is about the optimal selection of process parameters for Wire Arc Additive Manufacturing technology, an emerging solution for additive production of metal parts. In particular, the selection of the process parameters is based on the evolution of the microstructure and on the mechanical properties of the final samples obtained through the successive deposition weld beads of a ER70S-6 steel, according to the AWS legislation. The feed rate and the heat input during the deposition of the weld beads have been varied, in order to understand how the temperature reached by the samples can affect the final product mechanical characteristics. The final cooling has been carried in calm air at room temperature and between the deposition of a weld bead and the following one it has been imposed a pause of 60s. The tests on mechanical properties carried out have been: A full experimental campaign that includes: macrographic observations, micrographic observations and Vickers microhardness. The analysis of these tests has highligthed that by varying the process parameters, the samples do not have substantial differences between them. Instead, a microstructure that evolves from pearlitic-ferritic grains until bainitic lamellae along the vertical direction of the samples has been observed by micrographic analysis and confirmed by microhardness measurements

A model for evaluation of laser welding efficiency and quality using an artificial neural network and fuzzy logic

A model for evaluation of laser welding efficiency and quality using an artificial neural network and fuzzy logi