Parameter identification of a mechanical ductile damage using Artificial Neural Networks in sheet metal forming.

In this paper, we report on the developed and used of finite element methods, have been developed and used for sheet forming simulations since the 1970s, and have immensely contributed to ensure the success of concurrent design in the manufacturing process of sheets metal. During the forming operation, the Gurson–Tvergaard–Needleman (GTN) model was often employed to evaluate the ductile damage and fracture phenomena. GTN represents one of the most widely used ductile damage model. In this investigation, many experimental tests and finite element model computation are performed to predict the damage evolution in notched tensile specimen of sheet metal using the GTN model. The parameters in the GTN model are calibrated using an Artificial Neural Networks system and the results of the tensile test. In the experimental part, we used an optical measurement instruments in two phases: firstly during the tensile test, a digital image correlation method is applied to determinate the full-field displacements in the specimen surface. Secondly a profile projector is employed to evaluate the localization of deformation (formation of shear band) just before the specimen’s fracture. In the validation parts of this investigation, the experimental results of hydroforming part and Erichsen test are compared with their numerical finite element model taking into account the GTN model. A good correlation was observed between the two approaches

Chemical composition, antioxidant and antibacterial activities of extracts obtained from the roots bark of Arbutus andrachne L. a Lebanese tree.

Context and purpose of the study: The leaves, fruits, barks and roots of Arbutus andrachne L (A. andrachne), have been adopted to have high therapeutic value resulting from the presence of antioxidant compounds such as flavonoids, phenolic and tannins. In the present work, three extracts obtained from A. andrachne roots bark were evaluated for their antioxidant and antibacterial activities .The total phenolic content, flavonoid, condensed tannins and anthocyanins were determined in order to correlate them with the antioxidant activity of extracts.Main findings: The highest amounts of phenolic and tannins were found in the ethyl-acetate, while the anthocyanins ones were highly observed in the methanol-water extract. The lowest IC50 values for DPPH (0.6 µg/mL), and metal chelating assay (13.45µg/mL) were recorded in the ethyl-acetate extract and the methanolic one respetively. Gram positive bacteria (S. aureus and E. faecalis) were more susceptible to the antimicrobial potential of the methanol extract, while E.coli and P. aeruginosa as Gram negative bacteria turned out to be more resistant to the same extract. The ethyl-acetate extract was more effective on E. faecalis than on S. aureus; while E. coli and P. aeruginosa were the most resistant to this extract.Brief summary and potential implications: An appropriate dose of antioxidants derived from A. andrachne bark of the roots extracts in the human diet can help to avoid the risk of contracting diseases where ROS are involved in the pathogenesis. In fact, phenolic compounds in these extracts are among the natural antioxidants being studied by the scientific community due to their biological properties, e.g., antioxidant and antimicrobial activities

Chemical composition, antioxidant and antibacterial activities of extracts obtained from the roots bark of Arbutus andrachne L. a Lebanese tree.

Context and purpose of the study: The leaves, fruits, barks and roots of Arbutus andrachne L (A. andrachne), have been adopted to have high therapeutic value resulting from the presence of antioxidant compounds such as flavonoids, phenolic and tannins. In the present work, three extracts obtained from A. andrachne roots bark were evaluated for their antioxidant and antibacterial activities .The total phenolic content, flavonoid, condensed tannins and anthocyanins were determined in order to correlate them with the antioxidant activity of extracts.Main findings: The highest amounts of phenolic and tannins were found in the ethyl-acetate, while the anthocyanins ones were highly observed in the methanol-water extract. The lowest IC50 values for DPPH (0.6 µg/mL), and metal chelating assay (13.45µg/mL) were recorded in the ethyl-acetate extract and the methanolic one respetively. Gram positive bacteria (S. aureus and E. faecalis) were more susceptible to the antimicrobial potential of the methanol extract, while E.coli and P. aeruginosa as Gram negative bacteria turned out to be more resistant to the same extract. The ethyl-acetate extract was more effective on E. faecalis than on S. aureus; while E. coli and P. aeruginosa were the most resistant to this extract.Brief summary and potential implications: An appropriate dose of antioxidants derived from A. andrachne bark of the roots extracts in the human diet can help to avoid the risk of contracting diseases where ROS are involved in the pathogenesis. In fact, phenolic compounds in these extracts are among the natural antioxidants being studied by the scientific community due to their biological properties, e.g., antioxidant and antimicrobial activities