Influence of cutting process mechanics on surface integrity and electrochemical behavior of OFHC copper

The authors gratefully acknowledge the support received from IC ARTS and CEA ValducSuperfinishing machining has a particular impact on cutting mechanics, surface integrity and local electrochemical behavior. In fact, material removal during this process induces geometrical, mechanical and micro-structural modifications in the machined surface and sub-surface. However, a conventional 3D cutting process is still complex to study in terms of analytical/numerical modeling and experimental process monitoring. So, researchers are wondering if a less intricate configuration such as orthogonal cutting would be able to provide information about surface integrity as close as possible to that one generated by a 3D cutting process. For that reason, in the present paper, two different machining configurations were compared: face turning and orthogonal cutting. The work material is oxygen free high conductivity copper (OFHC) and the cutting tools are uncoated cemented carbide. The research work was performed in three steps. In the first step, the process mechanics of superfinishing machining of OFHC copper was performed. In the second step, the surface integrity and the chemical behavior of the machined samples were analyzed. Finally, in the third step, correlations between input parameters and output measures were conducted using statistical techniques. Results show that when applying low ratios between the uncut chip thickness and the cutting edge radius, the surface integrity and cutting energy are highly affected by the ploughing phenomenon. Otherwise, the most relevant cutting parameter is the feed. In order to compare face turning with orthogonal cutting, a new geometrical parameter was introduced, which has a strong effect in the electrochemical behavior of the machined surface

Estudio del uso de neumáticos fuera de uso (NFU) como material para la construcción de terraplenes. Aplicación a la ampliación del vertedero de residuos controlado de les Borges Blanques (Lleida).

[ES] El TFG tiene como objetivo principal analizar la viabilidad para su uso de NFU como material para la construcción de terraplenes, con el fin de disminuir el riesgo que presentan para el medio ambiente. Se estudiará el comportamiento del NFU en los muros de contención mediante el análisis de la estabilidad de sus taludes y el estudio del asiento que experimentan. El estudio está mayormente orientado hacia una aplicación práctica de este tipo de material.Denguir, Y. (2021). Estudio del uso de neumáticos fuera de uso (NFU) como material para la construcción de terraplenes. Aplicación a la ampliación del vertedero de residuos controlado de les Borges Blanques (Lleida). Universitat Politècnica de València. http://hdl.handle.net/10251/173175TFG

Estudio sobre la presencia y distribución de contaminantes emergentes en los acuíferos detríticos del río Guadalhorce

Los contaminantes emergentes son compuestos que se utilizan de forma muy común en la sociedad actual y que están siendo constantemente liberados al medio ambiente. En la actualidad, a consecuencia de una falta de investigación y regulación legal, se sabe relativamente poco sobre los efectos que pueden tener estos contaminantes a largo plazo sobre la salud humana y ambiental. Algunos de los contaminantes emergentes que generan mayor preocupación son los fármacos (especialmente los antibióticos), las drogas de abuso, los pesticidas y los productos de higiene personal. El objetivo del presente estudio fue detectar la presencia de contaminantes emergentes, tanto en aguas superficiales como en aguas subterráneas de acuíferos aluviales de la cuenca del río Guadalhorce. Para ello se seleccionaron 32 puntos de muestreo (20 subterráneas y 12 superficiales) distribuidos a lo largo de las subcuencas que componen la zona de estudio. Los resultados revelan la presencia de contaminantes emergentes en todas las muestras analizadas. En las aguas superficiales se detectaron 19 contaminantes emergentes diferentes, principalmente fármacos, mientras que en las aguas subterráneas se hallaron 25 contaminantes emergentes diferentes, mayoritariamente plaguicidas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Complications of Minimally Invasive Left Ventricular Assistance Device Implantation

Indication of Ventricular assistance is advanced cardiac failure with maximal medical and surgical treatment has been used. The ventricular assistance has two main purposes: first, to maintain circulation by discharging the ventricle (s) untill to recovery, or to ensure patient survival by replacing cardiac function permanently or transitionally for patients waiting for heart Transplantation. The encouraging results of the partial or total artificial heart and the miniaturization of these devices allow their use in permanent implantation for patients with heart failure that is not eligible for heart transplantation. In left mono-ventricular assistance, blood is taken from the apex of the left ventricle (LV) and reinjected in the ascending aorta. The classic surgical approach is a total median sternotomy. Other minimally invasive approaches for the implantation or explanation of left ventricular assist devices have been published and have shown encouraging results. These alternatives currently play an important role in certain indications and in patients with heavy medical history. Nevertheless, the complications of the ventricular assistance even by minimally invasive approaches might be serious and represent a turning point in the life of the patients. In this chapter, we describe the implantation technique of left ventricular assistance device (LVAD) and we discuss its advantages and disadvantages including possible complications

Presencia y distribución de contaminantes emergentes en cuatro cuencas antropizadas del Sur de la Península Ibérica

El objetivo del presente estudio fue estudiar la presencia y distribución de contaminantes emergentes, tanto en aguas superficiales como en aguas subterráneas de acuíferos de cuatro cuencas del Sur de la Península Ibérica (Cuenca del río Guadalhorce (Málaga), Cuenca de la Laguna de Fuente de Piedra (Málaga), Cuenca del río Guadiaro (Málaga-Cádiz) y el acuífero detrítico de la Vega de Granada (Granada)). Para ello se seleccionaron casi 110 puntos de muestreo (77 subterráneas y 32 superficiales) distribuidas en cuatro cuencas que componen la zona de estudio. Los resultados revelan la presencia de contaminantes emergentes en todas las muestras analizadas. En las aguas superficiales se detectaron 33 contaminantes emergentes diferentes, principalmente fármacos, mientras que en las aguas subterráneas se hallaron 37 contaminantes emergentes diferentes, mayoritariamente plaguicidas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Endovascular management of an isolated common iliac artery aneurysm: a case report

Isolated iliac artery aneurysms are rare, and treatment by conventional surgery gives good results. Endovascular repair of such aneurysms has recently become the preferred form of treatment, provided the appropriate anatomy for endovascular repair exists. We report the case of a 60-year-old man admitted in our department for an aneurysm of the left primitive iliac artery revealed by intermittent claudication and treated by a covered stent after embolization of the hypogastric artery by an Amplatzer Vascular Plug with a good result. This case highlights the importance of preservation of the collaterals of the hypogastric artery when you treat such entity; in order to avoid transient gluteal claudication and sexual dysfunction

Multi-physical analysis of the electrochemical behaviour of OFHC copper surfaces obtained by orthogonal cutting

As mechanical, physical, and microstructural properties of metals can be significantly affected by the machining process, electrochemical properties and corrosion resistance are consequently altered. Manufacturers should control the impact of cutting conditions on surface integrity, as it will affect the component’s functional performance and life. This study addresses the case of orthogonal cutting of oxygen-free high conductivity (OFHC) copper. A set of experiments was performed and a statistical analysis was conducted to reveal the relationship between the cutting conditions and the surface integrity in terms of residual stresses, microstructure, plastic deformation and hardness, and the impact of those parameters on the electrochemical behavior. The physical origins of the observed phenomena are explained. The results show that the surface performance can be controlled by selecting the appropriate cutting conditions (e.g., reducing the tensile residual stress and roughness by more than 75%), such that the electrochemical behavior can be enhanced

Orthogonal cutting simulation of OFHC copper using a new constitutive model considering the state of stress and the microstructure effects

This work aims to develop an orthogonal cutting model for surface integrity prediction, which incorporates a new constitutive model of Oxygen Free High Conductivity (OFHC) copper. It accounts for the effects of the state of stress on the flow stress evolution up to fracture. Moreover, since surface integrity parameters are sensitive to the microstructure of the work material, this constitutive model highlights also the recrystallization effects on the flow stress. Orthogonal cutting model is validated using experimental designed cutting tests. More accurate predictions were obtained using this new constitutive model comparing to the classical Johnson-Cook model

A physical-based constitutive model for surface integrity prediction in machining of OFHC copper

Due to the rising interest in predicting machined surface integrity and sustainability, various models for metal cutting simulation have been developed. However, their accuracy depends deeply on the physical description of the machining process. This study aims to develop an orthogonal cutting model for surface integrity prediction, which includes a physical-based constitutive model of Oxygen Free High Conductivity (OFHC) copper. This constitutive model incorporates the effects of the state of stress and microstructure on the work material behavior, as well as a dislocation density-based model for surface integrity prediction. The coefficients of the constitutive model were identified through a hybrid experimental/numerical approach, consisting in mechanical tests, numerical simulations and an optimization-based algorithm. The orthogonal cutting model was simulated by FEM, using ALE formulation, and was validated by comparing predicted and measured results, including residual stresses, dislocation density and grain size. The model is then used to analyze the influence of the cutting parameters and cutting geometry on surface integrity, and its results are compared to those obtained by the Johnson-Cook model

Malignant hypertension secondary to iliac artery stenosis after kidney transplantation: a case report

Iliac artery stenosis is a rare complication after renal transplantation. This complication affects elderly patients and related to atheromatous disease. It mimics the same clinical presentation as a transplant renal artery stenosis or renal artery stenosis. This entity is can be responsible for serious complications such as renal dysfunction, malignant hypertension and acute pulmonary oedema. We present in this paper the case of a 51-year-old patient, who benefited 7 years early of renal transplantation, with a good initial result, and who was admitted actually for malignant hypertension and renal function impairment due to an iliac artery stenosis proximal to the renal transplant and who was treated with a stenting angioplasty of the external iliac artery with a mixed outcome. Our case highlights the importance of the early diagnosis and treatment of such complications to avoid definitive renal failure and permanent hypertension