DIM - FABDIS - Artículos de revistas

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Impact response of advance combat helmet pad systems
(Elsevier Ltd, 2023-11-01) Rodríguez Millán, Marcos; Rubio Díaz, Ignacio; Burpo, F. J.; Olmedo Marcos, Álvaro; Loya Lorenzo, José Antonio; Parker, K. K.; Miguélez Garrido, María Henar; Ministerio de Economía y Competitividad (España); Ministerio de Universidades (España)
Combat helmets are designed to protect against ballistic threats and fragments of explosive devices. There are numerous types of helmet comfort foams available. However, pad systems have not been evaluated in combat helmets to understand to what extent they mitigate head accelerations. In this work, different pad systems are studied to analyze the ballistic performance of combat helmets using a Hybrid III dummy equipped with longitudinal accelerometers at the head and a neck simulator. The tests are conducted with 9 mm Full Metal Jacket (FMJ) projectiles according to the performance requirements III-A of the NIJ 0106.01 standard. This experimental methodology allows the evaluation of brain and neck injuries. The thicker bicomponent polyurethane foams and the honeycomb configuration provided the best results in terms of mitigating brain damage due to accelerations applying different criteria (PLA, WSTC, HIC). However, it was concluded that there is no cervical injury or cranial fracture risk for any of the cases studied.
An experimental and numerical investigation to characterize an aerospace composite material with open-hole using non-destructive techniques
(MDPI, 2020-08-01) Feito Sánchez, Norberto; Calvo Orozco, Jose Vicente; Belda González, Ricardo; Giner, Eugenio; Ministerio de Ciencia, Innovación y Universidades (España)
In this study, the open-hole quasi-static tensile and fatigue loading behavior of a multidirectional CFRP thick laminate, representative of laminates used in the aerospace industry, is studied. Non-destructive techniques such as infrared thermographic (IRT) and digital image correlation (DIC) are used to analyze the behavior of this material. We aim at characterizing the influence of the manufacturing defects and the stress concentrator through the temperature variation and strain distribution during fatigue and quasi-static tests. On the one hand, the fatigue specimens were tested in two main perpendicular directions of the laminate. The results revealed that manufacturing defects such as fiber waviness can have a major impact than open-hole stress concentrator on raising the material temperature and causing fracture. In addition, the number of plies with fibers oriented in the load direction can drastically reduce the temperature increment in the laminate. On the other hand, the quasi-static tensile tests showed that the strain distribution around the hole is able to predict the crack initiation and progression in the external plies. Finally, the experimental quasi-static tests were numerically simulated using the finite element method showing good agreement between the numerical and experimental results.
Dynamic behavior of aluminum alloy AW 5005 undergoing interfacial friction and specimen configuration in split hopkinson pressure bar system at high strain rates and temperatures
(MDPI, 2020-10-02) Bendarma, Amine; Jankowiak, Tomasz; Rusinek, Alexis; Lodygowski, Tomasz; Jia, Bin; Miguélez Garrido, María Henar; Klosak, Maciej
In this paper, experimental and numerical results of an aluminum alloy’s mechanical behavior are discussed. Over a wide range of strain rates (10−4 s−1 ≤ έ ≤ 103 s−1) the influence of the loading impact, velocity and temperature on the dynamic response of the material was analyzed. The interface friction effect on the material’s dynamic response is examined using a split Hopkinson pressure bar (SHPB) in a high temperature experiment using finite element analysis (FEA). The effect of different friction conditions between the specimen and the transmitted/incident bars in the SHPB system was examined using cylinder bulk specimens and cylinder plates defined with four-layer configurations. The results of these tests alongside the presented numerical simulations allow a better understanding of the phenomenon and reduces (minimizes) errors during compression tests at high and low strain rates with temperatures ranging from 21 to 300 °C.
Modular 3-D-printed education tool for blind and visually impaired students oriented to net structures
(IEEE, 2023-02) Domínguez Reyes, Ricardo; Moreno López, Lourdes; Muñoz Sánchez, Ana; Ruiz Mezcua, María Belén; Savoini Cardiel, Begoña
Contribution: This article presents the design, creation, testing, and results after the use of a 3-D-printed educational tool that helped a blind student learning electric circuits theory in higher education. Background: Educational tools oriented to visually impaired and blind students in higher education are limited or even nonexistent in the STEM area. Previous developments on the field present in the literature, including other 3-D printing solutions, have been revised and compared to the proposed educational tool. Intended Outcomes: The tool was tested by a blind student in order to test the potential of the design to achieve a better understanding of the topology and performance of electric circuits. The main purpose of the tool described in this work is helping to increase the resources available in the field of teaching students with visual impairments. Application Design: 3-D technology has the potential to be used to create accessibility tools for visually impaired and blind individuals. Modular systems can be used to create complex structures using simple elements. A modular 3-D-printed tool was fabricated to help blind and visually impaired students to learn net structures. Findings: The 3-D tool has allowed the blind student to work autonomously in the study of simple electric circuits and supplies the teacher with a resource to communicate with the student in an easy and fast way. Updated design can be used to describe more complex net structures that can be applied to most electric circuits despite their complexity. The use of the modular system provided the blind student with a direct representation of the whole subject, even when it involved a great amount of graphical information and manipulation.
Some practical considerations for compression failure characterization of open-cell polyurethane foams using digital image correlation
(MDPI, 2020-08-01) Belda, Ricardo; Megías, Raquel; Feito Sánchez, Norberto; Vercher Martínez, Ana; Giner, Eugenio; Ministerio de Ciencia, Innovación y Universidades (España); Generalitat Valenciana
Background: Open-cell polyurethane foam mechanical behavior is highly influenced by microstructure. The determination of the failure mechanisms and the characterization of the deformation modes involved at the micro scale is relevant for accurate failure modeling. Methods: We use digital image correlation (DIC) to investigate strain fields of open-cell polyurethane foams of three different densities submitted to compression testing. We analyze the effect of some DIC parameters on the failure pattern definition and the equivalent strain magnification at the apparent ultimate point. Moreover, we explore speckle versus non-speckle approaches and discuss the importance of determining the pattern quality to perform the displacement correlation. Results: DIC accurately characterizes the failure patterns. A variation in the subset size has a relevant effect on the strain magnification values. Step size effect magnitude depends on the subset size. The pattern matching criterion presented little influence (3.5%) on the strain magnification. Conclusion: The current work provides a comprehensive analysis of the influence of some DIC parameters on compression failure characterization of foamed structures. It highlights that changes of subset and step sizes have a significant effect on the failure pattern definition and the strain magnification values, while the pattern matching criterion and the use of speckle have a minor influence on the results. Moreover, this work stands out that the determination of the pattern quality has a major importance for texture analysis. The in-depth, detailed study carried out with samples of three different apparent densities is a useful guide for DIC users as regards texture correlation and foamed structures.
Experimental and numerical analyses of ballistic resistance evaluation of combat helmet using Hybrid III headform
(Elsevier, 2023-09-01) Rodríguez Millán, Marcos; Rubio Díaz, Ignacio; Burpo, F. J.; Tse, Kwong Ming; Olmedo, A.; Loya Lorenzo, José Antonio; Parker, K. K.; Miguélez Garrido, María Henar; Ministerio de Economía y Competitividad (España); Ministerio de Universidades (España)
Combat helmets are the primary system for protecting the head against ballistic impacts. Generally, combat helmets have been evaluated using a ballistic plasticine head surrogate based on international standards. More realistic human head models have recently been introduced to assess combat helmet performance considering biomechanical requirements. In this work, the Hybrid III dummy head and neck has been introduced to evaluate the performance of the combat helmet against the ballistic impact of live ammunition at different impact locations, considering two different thicknesses of the padding system. A numerical model including a helmet and a Hybrid III head and neck, is developed and validated with our experimental data. The results reveal the influence of the location, where the rear impact leads to the highest risk of brain damage. The effect of pad thickness is closely related to the energy absorbed by the helmet, the backface deformation (BFD), the contact force and the acceleration measured on the head.
Fiber-optic pyrometer for very localized temperature measurements in a turning process
(IEEE, 2017-03) Tapetado Moraleda, Alberto; Díaz Álvarez, José; Miguélez Garrido, María Henar; Vázquez García, María Carmen; Comunidad de Madrid; Ministerio de Economía y Competitividad (España)
A fiber-optic two-color pyrometer based on glass multimode fibers with 62.5 μm diameter and 0.275 numerical aperture is used for localized temperature measurements in turning processes. Operation wavelengths improve temperature measurement accuracy. The system is capable of measuring temperature in the range from 300 to 650 °C in a surface area below 0.16 mm 2 . Numerical simulation of the calibration curves including manufacturer tolerances are reported, showing good agreement with the experimental results. Temperature evolution is performed in a lathe at different feed rates and cutting speeds at an Inconel 718 turning process, using a glass fiber-optic sensor embedded into a modified tool member. The results are used to in-process prevent premature failure of the components related to the fatigue and validate feed rates recommended by the tool manufacturer.
Machine learning approach in non-intrusive monitoring of tool wear evolution in massive CFRP automatic drilling processes in the aircraft industry
(Elsevier, 2022-10) Domínguez-Monferrer, C.; Fernández-Pérez, J.; Santos, Raul de; Miguélez Garrido, María Henar; Cantero Guisández, José Luis; Comunidad de Madrid; Ministerio de Ciencia e Innovación (España); Ministerio de Educación, Cultura y Deporte (España)
This research presents an analysis of real production data of an automatic drilling industrial system and emphasizes its ability as a process control indicator in terms of tool wear. In particular, the study is framed in Carbon-fiber-reinforced polymer composites (CFRPs) drilling operations carried out at Airbus facilities. The industrial process data were directly collected from the manufacturing plant in Getafe (in the Madrid-Spain region) and come from three different sources: spindle power consumption signals, obtained from the internal instrumentation of the machine, cutting tools wear analysis, and hole quality inspection. The main goal is to use different machining features such as tool accumulated cutting time, together with signal features to feed Machine Learning (ML) algorithms to predict tool wear. To address the inherent variability of complex production systems, it has been proposed a specific methodology that is applicable to control machining operations. The approach includes data collection, data pre-processing, and the application of Linear Regression, k-Nearest Neighbors, and Random Forest ML algorithms. As an outcome to be predicted, a novel qualitative scale of the general condition of the drill is proposed. The predictive models show promising results bearing in mind the quality and quantity of the available data – up to 3500 holes drilled with 8 diamond-coated tungsten carbide tools under different work conditions (number of layers, thickness, and others). The relevance of the benchmarks defined as representative features of the spindle power consumption as well as other machining-related parameters and their relationship with tool wear has been discussed. The Random Forest model gets the best results, being the most interesting variables the accumulated cutting time and the maximum spindle power consumption, and the most irrelevant, the number of parts to be drilled.
Combined analysis of wear mechanisms and delamination in CFRP drilling
(Elsevier, 2021-01-01) Fernández Pérez, Juan; Díaz Álvarez, José; Miguélez Garrido, María Henar; Cantero Guisández, José Luis; Ministerio de Economía y Competitividad (España)
Carbon-fiber-reinforced polymer composites (CFRPs) are widely used in industry due to their outstandingmechanical properties combined with reduced density and good corrosion and fatigue resistance. Although composite components are manufactured near net shape, further machining operations are required. Drillingis the most common operation, involving a significant percentage of the total production cost. This study ana-lyzes the influence of cutting parameters on tool wear mechanisms and machining-induced damage in CFRP drilling with diamond-coated carbide tools. The wear mechanism is a combination of localized detachmentsof the diamond coating on the rake surface and the subsequent abrasive wear of the carbide substrate. Themain contribution of this paper is a combined analysis of tool wear, delamination, and machining forces, ori-ented to the optimization of the cutting parameters, cutting tool utilization, and real-time control of these drilling processes.
CFRP drilling process control based on spindle power consumption from real production data in the aircraft industry
(Elsevier, 2022) Domínguez Monferrer, Carlos; Fernández Pérez, Juan; Santos Garcia, Raul De; Miguélez Garrido, María Henar; Cantero Guisández, José Luis; Comunidad de Madrid; Ministerio de Educación, Cultura y Deporte (España)
Ongoing challenges in advanced manufacturing highlight the need of improved control of the production system, higher production speed, lower tool wear, top quality standards together with reduced material waste to minimize associated costs, time and environmental footprint. The organization of production resources through the integration of data along the value chain using Information Technologies is required to achieve these challenges. Thus, the emergence of the fourth industry revolution brings with it the organization of productive resources through computational intelligence and connectivity. This research seeks to analyze the spindle power consumption in Carbon-fiber-reinforced polymer composites (CFRPs) drilling operations as a process control indicator in terms of tool wear. This signal stands out among others available because it can be obtained in real time, with high quality and through a non-intrusive methodology. In particular, the study is framed in the real production system in factories of Airbus. The industrial process data were directly collected from the manufacturing plant in Getafe (in the Madrid-Spain region) and correspond to more than 3000 holes drilled with diamond-coated tungsten carbide tools. The variability of machining conditions in the aeronautical component drilling process and inherent noise level of signals obtained in industrial environments required the development of a data wrangling methodology to structure and clean the information. As a result, different magnitudes were obtained from spindle power consumption signal related to tool wear with low levels of dependence on drilling conditions. The conclusions of this work are directly applicable to the control of industrial production systems within the framework of Industry 4.0, searching new improvement opportunities through Data analytics and Artificial Intelligence such as tool breakage detection or the optimization of cycle times.
Crack morphology in lattice-core specimens made of biopolymer via fused deposition modelling
(Elsevier, 2022) Alvarez Blanco, Mario; Arias Blanco, Adrian; Infante García, Diego; Marco Esteban, Miguel; Giner, Eugenio; Comunidad de Madrid; Ministerio de Ciencia e Innovación (España)
During the last decades, it has been shown how additive manufacturing is becoming a cost-efficient alternative to produce customized parts or prototyping with traditional manufacturing processes. However, the integrity assessment of 3D printing technology parts is still challenging due to the huge number of parameters involved during the process along with the lack of industry standards. Therefore, further investigations are required to optimize the in-service behaviour of additive manufacturing parts. The objective of this work is to analyse the failure of components made from additive manufacturing under three-point bending tests in terms of crack morphology and strength. Specimens were made by a biopolymer (polylactic acid, PLA) via fused deposition modelling with different infill core densities. Next, three-point bending tests were carried out at a low strain rate under monotonic loading. In addition, three-dimensional digital image correlation was applied during tests in order to track the exterior full-field displacement and strain and output crack trajectories. The results are analysed in terms of fracture morphology and flexural strength of the post-mortem specimens, and they show the high impact of process parameters in the mechanical behaviour and failure of components made from additive manufacturing.
Estimation of thermal effects in dry drilling of Ti6Al4V
(Elsevier, 2015) Díaz Álvarez, Antonio; Cruz Hernández, Jesús Alberto de la; Díaz Álvarez, José; Cantero Guisández, José Luis; Ministerio de Economía y Competitividad (España)
This work focuses on the dry drilling of titanium alloy Ti6Al4V. The main objective is establishing a methodology to quantify the heat generated in the material, and the heat fluxes towards it during a machining process. For the thermal effects determination in the machined material, a tridimensional finite element model of drilling was developed. The numerical model was validated experimentally. From the thermal distributions obtained numerically, the heat that acts on the material due to the action of the edges of the tool it is determined.
Numerical modelling of the thermal effects on material in drilling processes Ti6Al4V alloy
(Elsevier, 2015) Díaz Álvarez, José; Cruz Hernández, Jesús Alberto de la; Díaz Álvarez, Antonio; Cantero Guisández, José Luis; Ministerio de Economía y Competitividad (España)
It has been developed a bidimensional finite element model, which considers the thermal analysis of the material during the dry drilling of Ti6Al4V. Thermal loads that affect material have been calculated based on three-dimensional numerical models and the evolution of the torque experimentally measured in dry drilling of Ti6Al4V. Results of the numerical model have been compared with temperature values reached in the material at 1 mm from drill wall that was obtained experimentally. The developed numerical model to determine the evolution of the temperature in the material obtained during the drilling process gives relevant information for the control of thermal damage due to machining.
Estimation of the reinforcement factor [epsilon] for calculating the transverse stiffness E2 with the Halpin-Tsai equations using the finite element method
(Elsevier, 2015-06-01) Giner, Eugenio; Vercher Martínez, Ana; Marco Esteban, Miguel; Arango, Camila; Ministerio de Economía y Competitividad (España)
In this work, an estimation of the reinforcement factor [epsilon] of the Halpin–Tsai equations used to calculate the transverse stiffness E[subíndice 2] is provided. An improved estimation of the value [epsilon]=2 originally proposed by Halpin and Tsai is given through a set of finite element analyses that consider randomly distributed unidirectional fibers for different volume fractions. The analysis overcomes the original hypothesis of a square array distribution of fibers in the transverse plane. It is concluded that a value of [epsilon]=1.5 is a better estimation for the usual volume fractions found in practice for a unidirectional lamina of fiber reinforced composites.
Engineering Graduate Studies for Public Security Professionals: the Bachelor Thesis at the End of the Studies
(International University of Logistics and Transport in Wrocław, Poland, 2014-10-01) Loya Lorenzo, José Antonio; Moure Colón, Fernando; Moreno Sánchez, Carlos Edgar; Rodríguez Millán, Marcos; Moral, Anselmo del; Verón, Emilio José; Miguélez Garrido, María Henar
This work presents the latest results concerning the Bachelor Thesis developed at the end of the fourth course in the Security Engineering Degree. A combined approach has been selected applying technological issues to crime problems, and also attending to legal and social aspects involved
Bending of Euler-Bernoulli beams using Eringen's integral formulation: A paradox resolved
(Elsevier BV., 2016-02-01) Fernández-Sáez, José; Zaera, Ramón; Loya Lorenzo, José Antonio; Reddy, JN; Ministerio de Economía y Competitividad (España)
The Eringen nonlocal theory of elasticity formulated in differential form has been widely used to address problems in which size effect cannot be disregarded in micro- and nano-structured solids and nano-structures. However, this formulation shows some inconsistencies that are not completely understood. In this paper we formulate the problem of the static bending of Euler-Bernoulli beams using the Eringen integral constitutive equation. It is shown that, in general, the Eringen model in differential form is not equivalent to the Eringen model in integral form, and a general method to solve the problem rigorously in integral form is proposed. Beams with different boundary and load conditions are analyzed and the results are compared with those derived from the differential approach showing that they are different in general. With this integral formulation, the paradox that appears when solving the cantilever beam with the differential form of the Eringen model (increase in stiffness with the nonlocal parameter) is solved, which is one of the main contributions of the present work.
Orientation of propagating crack paths emanating from fretting-fatigue contact problems
(Gruppo Italiano Frattura, 2016-01-01) Giner, Eugenio; Díaz Álvarez, José; Marco Esteban, Miguel; Miguélez Garrido, María Henar; Ministerio de Economía y Competitividad (España)
In this work, the orientation and propagation of cracks in fretting fatigue problems is analyzed numerically using the finite element method (FEM) and the extended finite element method (X- FEM). The analysis is performed by means of a 2D model of a complete-contact fretting problem, consisting of two square indenters pressed onto a specimen subjected to cyclic fatigue. For the simulation, we allow for crack face contact in the implementation during the corresponding parts of the fatigue cycle. The problem is highly nonlinear and non-proportional and we make use of the so-called minimum shear stress range orientation criterion, min(Delta tau), proposed by the authors in previous works. This criterion is introduced to predict the crack path in each step of the crack growth simulation. The objective of the work is to detect which is the relevant parameter affecting the crack path orientation. A parametric study of some a priori relevant magnitudes is carried out, such as normal load on the indenters, bulk load on the specimen, stress ratio and relative stiffness of the indenter and specimen materials. Contrary to previous expectations, it is shown that the relative magnitude of the applied loads has no significant effect. However, it is found that the stiffness of the indenter material with respect to the specimen material has the greatest effect. A simple explanation of this behavior is also provided.
Theories and analyses of functionally graded circular plates
(Elsevier BV., 2021-07-01) Reddy, JN.; Ruocco, Eugenio; Loya Lorenzo, José Antonio; Neves, Ana M.A.
This paper presents the governing equations and analytical solutions of the classical and shear deformation theories of functionally graded axisymmetric circular plates. The classical, first-order, and third-order shear deformation theories are presented, accounting for through-thickness variation of two-constituent functionally graded material, modified couple stress effect, and the von Kármán nonlinearity. Analytical solutions for bending of the linear theories, some of which are not readily available in the literature, are included to show the influence of the material variation, boundary conditions, and loads.
Experimental analysis of special tool geometries when drilling woven and multidirectional CFRPs
(2016-01-01) Feito Sánchez, Norberto; Díaz Álvarez, Antonio; Cantero Guisández, José Luis; Rodríguez Millán, Marcos; Miguélez Garrido, María Henar; Ministerio de Economía y Competitividad (España)
Drilling is one of the most frequent machining operations for carbon fiber-reinforced polymer composites, carried out prior to assembly between structural components using mechanical joining. Delamination is the main damage mechanism involved during carbon fiber-reinforced polymer composite drilling causing an elevated percentage of workpiece rejection. Tool geometry strongly influences drilling performance. In this paper, an original work dealing with the comparison between three recently developed configurations (Brad center, Step drill and Reamer drills) in terms of drilling forces and delamination both for woven and tape carbon fiber-reinforced polymers is presented. Reamer drill showed the best results concerning productivity and delamination. Strong differences were found when hole quality obtained in tape and woven composite was compared: multidirectional composite presented poorer hole quality than woven composite under the same cutting conditions. The analysis of variance was developed in order to analyze the influence of each parameter showing the importance of feed rate on surface damage.
On the use of the theory of critical distances with mesh control for fretting fatigue lifetime assessment
(Elsevier, 2020-02-01) Zabala, Alaitz; Infante García, Diego; Giner, E.; Goel, Saurav; Endrino, J.L.; Llavori, Iñigo; Ministerio de Ciencia, Innovación y Universidades (España)
This work analyses the viability of the theory of critical distances (TCD) using mesh control for fretting fatigue lifetime assessment. More than seven hundred sets of simulations were performed by taking seventy different experimental tests reported previously in the literature. The outcome of the present study suggests that the TCD mesh control method can be extended to fretting fatigue problems by the reasonable assumption of setting the right element size proportional to critical distance. In this study, a significant computational time reduction of up to 97% was obtained. Thus, this study provides a simple method to design complex 3D industrial components subjected to fretting fatigue phenomena using finite element analysis efficiently without requiring complex remeshing techniques.

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