Knowledge based cloud FE simulation of sheet metal forming processes

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques. This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material's forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions

Noninvasive predictors of presence and grade of esophageal varices in viral cirrhotic patients

Predicting the presence and the grade of varices by non-invasive methods is likely to predict the need for prophylactic beta blockers or endoscopicvariceal ligation. The factors related to the presence of varices are not  well-defined. Therefore, the present study has been undertaken to determine the appropriateness of the various factors in predicting the existence and also the grade of esophageal varices. Patients with  diagnosis of liver cirrhosis due to hepatitis C or B were included in a retrospective study between January 2001 and January 2010. All the  patients underwent detailed clinical evaluation, appropriate investigations, imaging studies (ultrasound with Doppler) and endoscopy at our center. Five variables considered relevant to the presence and grade of varices were tested using univariate and multivariate analysis (logistic regression). Three hundred and seventy two patients with viral liver cirrhosis were included, with 192 (51.6%) males. Platelet count and abundance of ascites were significantly associated with the presence of esophageal varices. However, abundance of ascites, prothrombin time, diameter of the spleen and portal vein were significantly associated with a large varice. In  multivariate analysis, platelet count inferior to 100000 was associated with presence of varices (p=0.04) and only abundance of ascites was associated with large varice. Low Platelet count (< or equal 100000) is associated with the presence of varices in viral cirrhotic patients and abundance of ascites is correlated with the presence of large varices

Springback analysis of AA5754 after hot stamping: experiments and FE modelling

In this paper, the springback of the aluminium alloy AA5754 under hot stamping conditions was characterised under stretch and pure bending conditions. It was found that elevated temperature stamping was beneficial for springback reduction, particularly when using hot dies. Using cold dies, the flange springback angle decreased by 9.7 % when the blank temperature was increased from 20 to 450 °C, compared to the 44.1 % springback reduction when hot dies were used. Various other forming conditions were also tested, the results of which were used to verify finite element (FE) simulations of the processes in order to consolidate the knowledge of springback. By analysing the tangential stress distributions along the formed part in the FE models, it was found that the springback angle is a linear function of the average through-thickness stress gradient, regardless of the forming conditions used

Knowledge Based Cloud FE simulation – data-driven material characterization guidelines for the hot stamping of aluminium alloys

The Knowledge Based Cloud FEA (KBC-FEA) simulation technique allows multi-objective FE simulations to be conducted on a cloud-computing environment, which effectively reduces computation time and expands the capability of FE simulation software. In this paper, a novel functional module was developed for the data mining of experimentally verified FE simulation results for metal forming processes obtained from KBC-FE. Through this functional module, the thermo-mechanical characteristics of a metal forming process were deduced, enabling a systematic and data-driven guideline for mechanical property characterization to be developed, which will directly guide the material tests for a metal forming process towards the most efficient and effective scheme. Successful application of this data-driven guideline would reduce the efforts for material characterization, leading to the development of more accurate material models, which in turn enhance the accuracy of FE simulations

THE USE OF NATURAL MATERIALS FOR THE TREATMENT OF LEACHATES OF THE AGADIR DUMP

Within the perspective of adopting effective solutions to the problems related to the burial of urban waste and its resulting harmful effects on both the environment and the human health, suitable actions should be taken to remedy the shortcomings of this somehow primitive method of waste disposal, namely those of the generated leachates. Because of their high pollutant load, leachates have to undergo a treatment of purification before being discharged into the environment.The focus of our study is to develop a simple technique to reduce the pollutant load of leachates in the technical burying center (TBC) of solid waste in Tamellast, Grand Agadir. This technique is based on the treatment of leachates through aeration followed by a percolation-infiltration on sand. The sand used is raw titaniferous sand (RTS) which is very abundant in the region of Agadir. Young leachate samples issued from fresh urban waste were collected at TBC, Tamellast. The physicochemical analyses of the young leachates show that their pH is very acidic, the values of conductivity are very important and greatly exceed the normal limit value specified for the discharges (2.7 mS / cm). The levels of biodegradable organic matter are important (the COD and BOD5 values are 17800 mg of O2 / L and 9100 mg of O2 / L, respectively). The aeration of leachate by injecting air has increased electrical conductivity due to the different chemical and biological reactions involved in the treatment. However, the values of COD and BOD5 have decreased. This decrease shows the significant effect of aeration on the reduction of polluting organic matter. The ratio BOD5 / COD is greater than 0.5 and shows that the treated leachate is of a very good biodegradability. After aeration, the young leachate was infiltrated by percolation on a sand column. The BOD5 value reached 280 mg of O2 / L (the BOD5 limit value of direct discharge = 300 mg of O2 / L) and the COD value is 540 mg of O2 / L (the limit value of direct release COD = 600 mg of O2 / L). The technique developed in this study led to high abatement rates (96.96% for COD and 97% for BOD5) in organic matter and lower COD and BOD5 values

Système de reconnaissance automatique de la parole Amazigh à base de la transcription en alphabet Tifinagh

Dans ce travail, nous présentons un système de reconnaissance automatique de la parole Amazigh basé sur la transcription en alphabet Tifinagh reconnue par l’Institut Royal de la Culture Amazigh (IRCAM ). Nous avons utilisé le modèle de Markov caché et on a fait une comparaison avec la méthode de programmation dynamique

Effect of melt conditioning on heat treatment and mechanical properties of AZ31 alloy strips produced by twin roll casting

In the present investigation, magnesium strips were produced by twin roll casting (TRC) and melt conditioned twin roll casting (MC-TRC) processes. Detailed optical microscopy studies were carried out on as-cast and homogenized TRC and MC-TRC strips. The results showed uniform, fine and equiaxed grain structure was observed for MC-TRC samples in as-cast condition. Whereas, coarse columnar grains with centreline segregation were observed in the case of as-cast TRC samples. The solidification mechanisms for TRC and MC-TRC have been found completely divergent. The homogenized TRC and MC-TRC samples were subjected to tensile test at elevated temperature (250-400 °C). At 250 °C, MC-TRC sample showed significant improvement in strength and ductility. However, at higher temperatures the tensile properties were almost comparable, despite of TRC samples having larger grains compared to MC-TRC samples. The mechanism of deformation has been explained by detailed fractures surface and sub-surface analysis carried out by scanning electron and optical microscopy. Homogenized MC-TRC samples were formed (hot stamping) into engineering component without any trace of crack on its surface. Whereas, TRC samples cracked in several places during hot stamping process.EPSRC – LiME, UK and Towards Affordable, Closed-Loop Recyclable Future Low Carbon Vehicle Structures – TARF-LCV(EP/I038616/1), Department of Mechanical Engineering, Imperial College London, UK, Mr. Steve Cook, Mr. Peter Lloyd, Mr. Graham Mitchell and Mr. Carmelo and BCAST, Brunel University London

Heavy Ion Carcinogenesis and Human Space Exploration

Prior to the human exploration of Mars or long duration stays on the Earth s moon, the risk of cancer and other diseases from space radiation must be accurately estimated and mitigated. Space radiation, comprised of energetic protons and heavy nuclei, has been show to produce distinct biological damage compared to radiation on Earth, leading to large uncertainties in the projection of cancer and other health risks, while obscuring evaluation of the effectiveness of possible countermeasures. Here, we describe how research in cancer radiobiology can support human missions to Mars and other planets