Time filter

Source Type

San Sebastián de los Reyes, Spain

Cicero S.,University of Cantabria | Madrazo V.,Fundacion Centro Tecnologico Of Componentes Ctc | Garcia T.,University of Cantabria
Theoretical and Applied Fracture Mechanics | Year: 2015

This paper analyses the structural integrity of components containing U-shaped notches by combining Failure Assessment Diagrams and the Line Method correction for notch effects. With this objective, the experimental results obtained in 555 fracture tests are homogeneously evaluated in the same Failure Assessment Diagram, with and without applying the Line Method notch corrections, and covering a wide range of materials such as PMMA, Al7075-T651, four different structural steels (S275JR, S355J2, S460M and S690Q) tested at different temperatures from the lower shelf up to the ductile-to-brittle transition zone, and two rocks (granite and limestone). It is demonstrated that the proposed methodology generally produces significant reductions in the conservatism associated to notch effects, yet providing safe predictions. © 2015 Elsevier Ltd. Source

Cicero S.,University of Cantabria | Garcia T.,University of Cantabria | Madrazo V.,Fundacion Centro Tecnologico Of Componentes Ctc
Engineering Failure Analysis | Year: 2015

This paper provides a structural integrity assessment methodology for the analysis of ferritic steels containing notch-type defects and operating within their ductile-to-brittle transition zone. The methodology, based on the use of Failure Assessment Diagrams and the novel concept of the Notch Master Curve, has been applied to 323 experimental results performed on four different steels (S275JR, S355J2, S460M and S690Q), six different notch radii (from 0 mm up to 2.0 mm), two different types of specimens (CT and SENB), and three different temperatures within the corresponding ductile-to-brittle transition zone. The results validate the proposed assessment methodology. © 2015 Elsevier Inc. Source

Cicero S.,University of Cantabria | Garcia T.,University of Cantabria | Madrazo V.,Fundacion Centro Tecnologico Of Componentes Ctc
Theoretical and Applied Fracture Mechanics | Year: 2015

This paper analyses the capacity of the Line Method to provide evaluations of the apparent fracture toughness, which is the fracture resistance exhibited by materials in notched conditions. With this aim, the experimental results obtained in 555 fracture tests are homogeneously presented and compared to the Line Method evaluations. It is remarked that the Line Method provides adequate estimates of the apparent fracture toughness, and also that it conveniently addresses the physics of the notch effect. All this makes the Line Method a valuable scientific and engineering tool for the fracture assessment of materials containing notches. © 2015 Elsevier Ltd. Source

Bascones R.,Fundacion Centro Tecnologico Of Componentes Ctc | Gorrochategui I.,Fundacion Centro Tecnologico Of Componentes Ctc | Alvarez J.A.,University of Cantabria
Engineering Failure Analysis | Year: 2010

The aim of this analysis is to identify and to study the phenomena which have produced the failure of a rubber drying machine speed reducer output shaft. The machine has suffered several failures during its operating life and different materials for the same shaft have been tested. At the time of initiation of the analysis there was no evidence that a change of material or a change of geometry could avoid the appeared problem.An experimental analysis and a theoretical evidence study have been made from the knowledge of the machine operating conditions. The observations of the laboratory have identified the mechanisms which have produced the fracture of the shaft and have verified the quality of the used material. Through this identification, a study which justifies the failure in regards to the initiation and propagation phenomena implied in the fracture has been performed. The analysis of laboratory has included hardness tests, optical microscopy and SEM. The theoretical study has been based in the fatigue and fracture methodology recently developed by the European Fitness-for-Service Network [1].The laboratory observations and the theoretical study are consistent and both demonstrate the same causes of failure and justify the life cycle of the shaft subject to its actual operating conditions. © 2009 Elsevier Ltd. Source

Falco G.,Istituto Superiore Mario Boella | Gutierrez M.C.-C.,Fundacion Centro Tecnologico Of Componentes Ctc | Serna E.P.,Acorde Technologies S.A. Acorde | Zacchello F.,Aermatica SPA Aermatica | Bories S.,French Atomic Energy Commission
27th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS 2014 | Year: 2014

This paper shows the design and development of a truly low cost attitude determination and navigation system based primarily on non-dedicated mass market GNSS receivers and antennas, aided by MEMS inertial sensors. GNSS/INS integration combines the advantages of absolute satellite-based positioning with the high dynamic performance and data rates of inertial sensors, having become the standard approach in navigation systems for Unmanned Aerial Vehicles (UAV) among other applications. We have used a Tightly-Coupled (TC) algorithm aimed at the integration of GPS and INS devices, designed to exploit the measurements provided by four GNSS receivers and a MEMS IMU. This task is accomplished by forming double differences (DD) of carrier-phase measurements and properly solving the ambiguities on-the-fly. The robustness of the algorithm is enhanced by exploiting unambiguous DD of code-phase observables or un-differenced pseudoranges when carrier phase ambiguity fix is not reliable. In order to limit the unwanted effects of vibration, the INS raw samples (i.e. gyro and accelerometer measurements) are passed through a proper low-pass filter before being used by the fusion algorithm. Furthermore, we have constrained the TC algorithm with the heading information obtained from the DD carrier-phase measurements of four GNSS receivers that are available in the final system. These carrier-phase measurements need to be processed and their ambiguities solved before becoming usable, for which proper integer ambiguity resolution methods are described too. Achieving the realization of the first prototype relies on advances beyond the state-of-the-art in the fields of multi-receiver GNSS-based attitude determination, inertial MEMS/GNSS data fusion and precise calibration of properly selected GNSS antennas. All these advances aim at optimizing the cost, weight, size and power consumption of the overall system to enable its use in one of the most demanding applications as is the control and navigation of small UAV. The feasibility of a real-time implementation has been demonstrated. We have run the designed TC algorithm first onboard a car for validating the implementation by gathering real data in different user configurations (i.e. static and dynamic) and environmental scenarios (open- sky, urban canyon, etc.). For performance evaluation of the real-time system the prototype was mounted onboard the target UAV as a sample case of aerial applications. Copyright © (2014) by the Institute of Navigation. All rights reserved. Source

Discover hidden collaborations