Numerical analysis of rheological and tribological behavior influence on 16MnCr5 forging fibering

International audienceThe present research work is focus on the influence of the rheological constitutive equation and friction law formulation on 16MnCr5 forging fibering. Numerical analysis using FE Forge® and Abaqus code show the importance of the rheological softening terms on the metals fibers morphology and position coordinate. Calibration of friction law and sensitivity of softening parameters corresponding to a Hansel-Spittel rheological equation have been studied. © 2016 Author(s)

An optimal forward extrusion device proposed for numerical and experimental analysis of materials tribological properties corresponding to bulk forming processes

International audienceThis paper concerns the design and the analysis of an optimal forward extrusion die used in order to characterize and to identify the tribological properties corresponding to real contact conditions which occur during bulk plastic forming processes. The main idea is to find the friction parameters by a two-step inverse analysis method applied to a Finite Element Model of the extrusion process. A compression test, using a special dumbbell specimen, is also performed in order to describe correctly the real rheological behaviour of the material. Experimental upsetting and extrusion tests are carried out for an AA5083 aluminium alloy and the corresponding rheological and friction coefficients are identified using only the recorded load-stroke curves. Experimental analysis of the contact surfaces, validation of the obtained results and influence of the friction on the local mechanical and microstructural properties of the material are performed via tribometer tests, micro-hardness measurements and EBSD characterization

Model of dynamic compression tests on hydraulic testing machines: Influence of dynamic phenomena

The forming process simulation requires models describing the materials behaviour at large strains and at strain rates up to hundreds of s$^{-1}$. The major difficulty then encountered is that few experimental tests enable to reach these two criteria. For a few years, several studies have been carried out on hydraulic machines provided with a dynamic jack. However, for higher strain rates tests, the load measurement is disturbed by the response of the experimental set-up and oscillations appear. In this article, the experimental test is developed and a finite element model of the set-up is introduced

Optimizing the storage of chemotherapeutics for ophthalmic oncology: Stability of topotecan solution for intravitreal injection

Background: Intravitreal administration of topotecan shows activity against tumor vitreous seeding in the conservative treatment of retinoblastoma, a malignant tumor originated in the retina of small children. Adequate storage of the intravitreal topotecan solution would allow immediate availability for patients at health care institutions. The goal of the work was to address the stability of the intravitreal topotecan formulation upon reconstitution. Materials and methods: Intravitreal topotecan solutions were reconstituted (at a concentration of 0.2 mg topotecan in 1 mL saline solution vehicle, aliquoted in 1 mL plastic syringes) and stored either frozen or at room temperature for different times. Topotecan content was analyzed at time zero and at different conditions using a high performance liquid chromatography method to quantify topotecan lactone (active) and to detect its pH-dependent hydrolysis product, the open carboxylate. Results:. We found that intravitreal topotecan syringes remained stable at room temperature at least for 24 h, at least for 167 days upon stored frozen at −20°C, and up to 8 h after thawing at day 6. The degradation carboxylate product did not appear in the analyzed thawed samples during the whole study. Conclusions: This study confirms the stability of frozen intravitreal topotecan syringes and will help optimize the use of this chemotherapy modality at institutions with low resources. Storage of aliquots will also help reduce personnel exposure to chemotherapy at hospital pharmacies.Fil: Bossacoma, F.. Hospital Sant Joan de Deu Barcelona; España. Hospital Fundació Salut Empordà; EspañaFil: Cuadrado Vilanova, M.. Hospital Sant Joan de Deu Barcelona; EspañaFil: Vinent, J.. Hospital Sant Joan de Deu Barcelona; EspañaFil: Correa, M.G.. Hospital Sant Joan de Deu Barcelona; EspañaFil: Gavrus, D.. Hospital Sant Joan de Deu Barcelona; EspañaFil: Castillo Ecija, H.. Hospital Sant Joan de Deu Barcelona; EspañaFil: Catala Mora, J.. Hospital Sant Joan de Deu Barcelona; EspañaFil: Mora, J.. Hospital Sant Joan de Deu Barcelona; EspañaFil: Schaiquevich, Paula Susana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Chantada, Guillermo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina. Hospital Sant Joan de Deu Barcelona; EspañaFil: Montero Carcaboso, Angel. Hospital Sant Joan de Deu Barcelona; Españ