Numerical Modelling of Ballistic Impact Response at Low Velocity in Aramid Fabrics

[EN] In this study, the effect of the impact angle of a projectile during low-velocity impact on Kevlar fabrics has been investigated using a simplified numerical model. The implementation of mesoscale models is complex and usually involves long computation time, in contrast to the practical industry needs to obtain accurate results rapidly. In addition, when the simulation includes more than one layer of composite ply, the computational time increases even in the case of hybrid models. With the goal of providing useful and rapid prediction tools to the industry, a simplified model has been developed in this work. The model offers an advantage in the reduced computational time compared to a full 3D model (around a 90% faster). The proposed model has been validated against equivalent experimental and numerical results reported in the literature with acceptable deviations and accuracies for design requirements. The proposed numerical model allows the study of the influence of the geometry on the impact response of the composite. Finally, after a parametric study related to the number of layers and angle of impact, using a response surface methodology, a mechanistic model and a surface diagram have been presented in order to help with the calculation of the ballistic limit.This research was funded by the Ministry of Economy and Competitiveness from Spain, grant number BES-2012-055162 and the international collaborations subprogram under the reference EEBB-I-2016-11586.Feito-Sánchez, N.; Loya, J.; Muñoz-Sánchez, A.; Das, R. (2019). Numerical Modelling of Ballistic Impact Response at Low Velocity in Aramid Fabrics. Materials. 12(13):1-15. https://doi.org/10.3390/ma121320871151213Tabiei, A., & Nilakantan, G. (2008). Ballistic Impact of Dry Woven Fabric Composites: A Review. Applied Mechanics Reviews, 61(1). doi:10.1115/1.2821711Lim, C. ., Tan, V. B. ., & Cheong, C. . (2002). 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Modeling the effects of yarn material properties and friction on the ballistic impact of a plain-weave fabric. Composite Structures, 89(4), 556-566. doi:10.1016/j.compstruct.2008.11.012Nilakantan, G., Keefe, M., Wetzel, E. D., Bogetti, T. A., & Gillespie, J. W. (2011). Computational modeling of the probabilistic impact response of flexible fabrics. Composite Structures, 93(12), 3163-3174. doi:10.1016/j.compstruct.2011.06.013Nilakantan, G., & Gillespie, J. W. (2012). Ballistic impact modeling of woven fabrics considering yarn strength, friction, projectile impact location, and fabric boundary condition effects. Composite Structures, 94(12), 3624-3634. doi:10.1016/j.compstruct.2012.05.030Nilakantan, G., Wetzel, E. D., Bogetti, T. A., & Gillespie, J. W. (2012). Finite element analysis of projectile size and shape effects on the probabilistic penetration response of high strength fabrics. 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Computational Materials Science, 50(7), 2172-2184. doi:10.1016/j.commatsci.2011.02.029Lozano-Mínguez, E., Palomar, M., Infante-García, D., Rupérez, M. J., & Giner, E. (2018). Assessment of mechanical properties of human head tissues for trauma modelling. International Journal for Numerical Methods in Biomedical Engineering, 34(5), e2962. doi:10.1002/cnm.2962Palomar, M., Lozano-Mínguez, E., Rodríguez-Millán, M., Miguélez, M. H., & Giner, E. (2018). Relevant factors in the design of composite ballistic helmets. Composite Structures, 201, 49-61. doi:10.1016/j.compstruct.2018.05.076Moure, M. M., Feito, N., Aranda-Ruiz, J., Loya, J. A., & Rodriguez-Millan, M. (2019). On the characterization and modelling of high-performance para-aramid fabrics. Composite Structures, 212, 326-337. doi:10.1016/j.compstruct.2019.01.049Abtew, M. A., Boussu, F., Bruniaux, P., Loghin, C., & Cristian, I. (2019). Ballistic impact mechanisms – A review on textiles and fibre-reinforced composites impact responses. Composite Structures, 223, 110966. doi:10.1016/j.compstruct.2019.11096

Analysis of the Machinability of Carbon Fiber Composite Materials in Function of Tool Wear and Cutting Parameters Using the Artificial Neural Network Approach

[EN] Local delamination is the most undesirable damage associated with drilling carbon fiber reinforced composite materials (CFRPs). This defect reduces the structural integrity of the material, which affects the residual strength of the assembled components. A positive correlation between delamination extension and thrust force during the drilling process is reported in literature. The abrasive effect of the carbon fibers modifies the geometry of the fresh tool, which increases the thrust force and, in consequence, the induced damage in the workpiece. Using a control system based on an artificial neural network (ANN), an analysis of the influence of the tool wear in the thrust force during the drilling of CFRP laminate to reduce the damage is developed. The spindle speed, feed rate, and drill point angle are also included as input parameters of the study. The training and testing of the ANN model are carried out with experimental drilling tests using uncoated carbide helicoidal tools. The data were trained using error-back propagation-training algorithm (EBPTA). The use of the neural network rapidly provides results of the thrust force evolution in function of the tool wear and cutting parameters. The obtained results can be used by the industry as a guide to control the impact of the wear of the tool in the quality of the finished workpiece.The Ministry of Economy and Competitiveness of Spain, projects DPI2017-89197-C2-1-R and DPI2017-89197-C2-2-R] and the Ministry of Science, Innovation and Universities, grant number [FJCI-2017-34910], funded this research.Feito-Sánchez, N.; Muñoz-Sánchez, A.; Diaz-Alvarez, A.; Loya, J. (2019). Analysis of the Machinability of Carbon Fiber Composite Materials in Function of Tool Wear and Cutting Parameters Using the Artificial Neural Network Approach. 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International Journal of Machine Tools and Manufacture, 46(12-13), 1403-1416. doi:10.1016/j.ijmachtools.2005.10.004Hocheng, H., & Tsao, C. C. (2005). The path towards delamination-free drilling of composite materials. Journal of Materials Processing Technology, 167(2-3), 251-264. doi:10.1016/j.jmatprotec.2005.06.039Davim, J. ., & Reis, P. (2003). Study of delamination in drilling carbon fiber reinforced plastics (CFRP) using design experiments. Composite Structures, 59(4), 481-487. doi:10.1016/s0263-8223(02)00257-xSardiñas, R. Q., Reis, P., & Davim, J. P. (2006). Multi-objective optimization of cutting parameters for drilling laminate composite materials by using genetic algorithms. Composites Science and Technology, 66(15), 3083-3088. doi:10.1016/j.compscitech.2006.05.003Fernandes, M., & Cook, C. (2006). Drilling of carbon composites using a one shot drill bit. Part I: Five stage representation of drilling and factors affecting maximum force and torque. International Journal of Machine Tools and Manufacture, 46(1), 70-75. doi:10.1016/j.ijmachtools.2005.03.015Fernandes, M., & Cook, C. (2006). Drilling of carbon composites using a one shot drill bit. Part II: empirical modeling of maximum thrust force. International Journal of Machine Tools and Manufacture, 46(1), 76-79. doi:10.1016/j.ijmachtools.2005.03.016Feito, N., Diaz-Álvarez, A., Cantero, J. L., Rodríguez-Millán, M., & Miguélez, H. (2015). Experimental analysis of special tool geometries when drilling woven and multidirectional CFRPs. Journal of Reinforced Plastics and Composites, 35(1), 33-55. doi:10.1177/0731684415612931Feito, N., Díaz-Álvarez, J., Díaz-Álvarez, A., Cantero, J., & Miguélez, M. (2014). Experimental Analysis of the Influence of Drill Point Angle and Wear on the Drilling of Woven CFRPs. Materials, 7(6), 4258-4271. doi:10.3390/ma7064258Iliescu, D., Gehin, D., Gutierrez, M. E., & Girot, F. (2010). Modeling and tool wear in drilling of CFRP. International Journal of Machine Tools and Manufacture, 50(2), 204-213. doi:10.1016/j.ijmachtools.2009.10.004Abrão, A. M., Rubio, J. C. C., Faria, P. E., & Davim, J. P. (2008). The effect of cutting tool geometry on thrust force and delamination when drilling glass fibre reinforced plastic composite. Materials & Design, 29(2), 508-513. doi:10.1016/j.matdes.2007.01.016Rawat, S., & Attia, H. (2009). Wear mechanisms and tool life management of WC–Co drills during dry high speed drilling of woven carbon fibre composites. Wear, 267(5-8), 1022-1030. doi:10.1016/j.wear.2009.01.031Fernández-Pérez, J., Cantero, J. L., Díaz-Álvarez, J., & Miguélez, M. H. (2017). Influence of cutting parameters on tool wear and hole quality in composite aerospace components drilling. Composite Structures, 178, 157-161. doi:10.1016/j.compstruct.2017.06.043Tsao, C. C., & Hocheng, H. (2007). Effect of tool wear on delamination in drilling composite materials. International Journal of Mechanical Sciences, 49(8), 983-988. doi:10.1016/j.ijmecsci.2007.01.001Chen, W.-C. (1997). Some experimental investigations in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates. International Journal of Machine Tools and Manufacture, 37(8), 1097-1108. doi:10.1016/s0890-6955(96)00095-8Murphy, C., Byrne, G., & Gilchrist, M. D. (2002). The performance of coated tungsten carbide drills when machining carbon fibre-reinforced epoxy composite materials. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 216(2), 143-152. doi:10.1243/0954405021519735Fernández-Pérez, J., Cantero, J., Díaz-Álvarez, J., & Miguélez, M. (2019). Hybrid Composite-Metal Stack Drilling with Different Minimum Quantity Lubrication Levels. Materials, 12(3), 448. doi:10.3390/ma12030448Tsao, C. ., & Hocheng, H. (2004). Taguchi analysis of delamination associated with various drill bits in drilling of composite material. International Journal of Machine Tools and Manufacture, 44(10), 1085-1090. doi:10.1016/j.ijmachtools.2004.02.019Palanikumar, K., Prakash, S., & Shanmugam, K. (2008). Evaluation of Delamination in Drilling GFRP Composites. Materials and Manufacturing Processes, 23(8), 858-864. doi:10.1080/10426910802385026Mohan, N. S., Kulkarni, S. M., & Ramachandra, A. (2007). Delamination analysis in drilling process of glass fiber reinforced plastic (GFRP) composite materials. Journal of Materials Processing Technology, 186(1-3), 265-271. doi:10.1016/j.jmatprotec.2006.12.043Srinivasa Rao, B., Rudramoorthy, R., Srinivas, S., & Nageswara Rao, B. (2008). Effect of drilling induced damage on notched tensile and pin bearing strengths of woven GFR-epoxy composites. Materials Science and Engineering: A, 472(1-2), 347-352. doi:10.1016/j.msea.2007.03.023Enemuoh, E. U., El-Gizawy, A. S., & Chukwujekwu Okafor, A. (2001). An approach for development of damage-free drilling of carbon fiber reinforced thermosets. International Journal of Machine Tools and Manufacture, 41(12), 1795-1814. doi:10.1016/s0890-6955(01)00035-9Saravanan, M., Ramalingam, D., Manikandan, G., & Kaarthikeyen, R. R. (2012). Multi Objective Optimization of Drilling Parameters Using Genetic Algorithm. Procedia Engineering, 38, 197-207. doi:10.1016/j.proeng.2012.06.027Feito, N., Milani, A. S., & Muñoz-Sánchez, A. (2015). Drilling optimization of woven CFRP laminates under different tool wear conditions: a multi-objective design of experiments approach. Structural and Multidisciplinary Optimization, 53(2), 239-251. doi:10.1007/s00158-015-1324-yKrishnaraj, V., Prabukarthi, A., Ramanathan, A., Elanghovan, N., Senthil Kumar, M., Zitoune, R., & Davim, J. P. (2012). Optimization of machining parameters at high speed drilling of carbon fiber reinforced plastic (CFRP) laminates. Composites Part B: Engineering, 43(4), 1791-1799. doi:10.1016/j.compositesb.2012.01.007Krishnamoorthy, A., Rajendra Boopathy, S., Palanikumar, K., & Paulo Davim, J. (2012). Application of grey fuzzy logic for the optimization of drilling parameters for CFRP composites with multiple performance characteristics. Measurement, 45(5), 1286-1296. doi:10.1016/j.measurement.2012.01.008Abhishek, K., Datta, S., & Mahapatra, S. S. (2014). Optimization of thrust, torque, entry, and exist delamination factor during drilling of CFRP composites. The International Journal of Advanced Manufacturing Technology, 76(1-4), 401-416. doi:10.1007/s00170-014-6199-3El Kadi, H. (2006). Modeling the mechanical behavior of fiber-reinforced polymeric composite materials using artificial neural networks—A review. Composite Structures, 73(1), 1-23. doi:10.1016/j.compstruct.2005.01.020Altinkok, N., & Koker, R. (2004). Neural network approach to prediction of bending strength and hardening behaviour of particulate reinforced (Al–Si–Mg)-aluminium matrix composites. Materials & Design, 25(7), 595-602. doi:10.1016/j.matdes.2004.02.014Karnik, S. R., Gaitonde, V. N., Rubio, J. C., Correia, A. E., Abrão, A. M., & Davim, J. P. (2008). Delamination analysis in high speed drilling of carbon fiber reinforced plastics (CFRP) using artificial neural network model. Materials & Design, 29(9), 1768-1776. doi:10.1016/j.matdes.2008.03.014Altinkok, N., & Koker, R. (2006). Modelling of the prediction of tensile and density properties in particle reinforced metal matrix composites by using neural networks. Materials & Design, 27(8), 625-631. doi:10.1016/j.matdes.2005.01.005Stone, R., & Krishnamurthy, K. (1996). A neural network thrust force controller to minimize delamination during drilling of graphite-epoxy laminates. International Journal of Machine Tools and Manufacture, 36(9), 985-1003. doi:10.1016/0890-6955(96)00013-2Kuo, C.-F. J., Chang, C.-D., Su, T.-L., & Fu, C.-T. (2008). Optimization of the Dyeing Process and Prediction of Quality Characteristics on Elastic Fiber Blending Fabrics. Polymer-Plastics Technology and Engineering, 47(7), 678-687. doi:10.1080/03602550802129569Chen, W.-C., Fu, G.-L., Tai, P.-H., & Deng, W.-J. (2009). Process parameter optimization for MIMO plastic injection molding via soft computing. Expert Systems with Applications, 36(2), 1114-1122. doi:10.1016/j.eswa.2007.10.020Ko, Y.-D., Moon, P., Kim, C. E., Ham, M.-H., Myoung, J.-M., & Yun, I. (2009). Modeling and optimization of the growth rate for ZnO thin films using neural networks and genetic algorithms. Expert Systems with Applications, 36(2), 4061-4066. doi:10.1016/j.eswa.2008.03.010Faraz, A., Biermann, D., & Weinert, K. (2009). Cutting edge rounding: An innovative tool wear criterion in drilling CFRP composite laminates. International Journal of Machine Tools and Manufacture, 49(15), 1185-1196. doi:10.1016/j.ijmachtools.2009.08.002Ashrafi, H. R., Jalal, M., & Garmsiri, K. (2010). Prediction of load–displacement curve of concrete reinforced by composite fibers (steel and polymeric) using artificial neural network. Expert Systems with Applications, 37(12), 7663-7668. doi:10.1016/j.eswa.2010.04.076Levenberg, K. (1944). A method for the solution of certain non-linear problems in least squares. Quarterly of Applied Mathematics, 2(2), 164-168. doi:10.1090/qam/10666Khashaba, U. A., El-Sonbaty, I. A., Selmy, A. I., & Megahed, A. A. (2010). Machinability analysis in drilling woven GFR/epoxy composites: Part II – Effect of drill wear. Composites Part A: Applied Science and Manufacturing, 41(9), 1130-1137. doi:10.1016/j.compositesa.2010.04.011Heisel, U., & Pfeifroth, T. (2012). Influence of Point Angle on Drill Hole Quality and Machining Forces When Drilling CFRP. Procedia CIRP, 1, 471-476. doi:10.1016/j.procir.2012.04.084Díaz-Álvarez, A., Díaz-Álvarez, J., Santiuste, C., & Miguélez, M. H. (2019). Experimental and numerical analysis of the influence of drill point angle when drilling biocomposites. Composite Structures, 209, 700-709. doi:10.1016/j.compstruct.2018.11.01

Crack-front propagation during three-point-bending tests of polymethyl-methacrylate beams

Crack-front evolution in polymethyl-methacrylate (PMMA) beams was measured during quasi-static three-point-bending tests performed on a universal testing machine. A high-speed camera was used to record the crack-front propagation process through the specimen thickness and to determine the instantaneous crack-length during the test, considering the effect of different initial notch lengths and loading-point displacement rates. The average steady crack-propagation speed was also calculated and correlated with the stored elastic energy, and these results have been compared with those reported by other authors for different test conditions. This experimental technique appears to be suitable to determine the influence of the test conditions on the crack-propagation speed of PMMA specimens.Facultad de Ingenierí

Dependence of polytetrafluoroethylene reflectance on thickness at visible and ultraviolet wavelengths in air

Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. However, the reflectance of PTFE is a function of its thickness. In this work, we investigate this dependence in air for light of wavelengths 260 nm and 450 nm using two complementary methods. We find that PTFE reflectance for thicknesses from 5 mm to 10 mm ranges from 92.5% to 94.5% at 450 nm, and from 90.0% to 92.0% at 260 nm. We also see that the reflectance of PTFE of a given thickness can vary by as much as 2.7% within the same piece of material. Finally, we show that placing a specular reflector behind the PTFE can recover the loss of reflectance in the visible without introducing a specular component in the reflectance

Numerical simulation of dynamic four-bending-tests using a modified Split Hopkinson Pressure Bar

In this work, we present a three-dimensional full numerical simulation of the dynamic four-point bending test performed in a modified split Pressure Hopkinson Bar (SHPB). The study is mainly focused on the obtaining of the dynamic Stress Intensity Factor (SIF) from the displacement of the contact points between the specimen and the bars or, alternatively, from the Crack Mouth Opening Displacements (CMOD) assuming that the relationship between these variables and the SIF deduced for static conditions is applicable to the dynamic one. The results derived from the two analysed methods are compared with those obtained from the direct numerical calculation. We conclude that both procedures lead to adequate estimations of the temporal evolution of the SIF, although the best results are achieved through the CMOD. However, the application of this method requires more complex experimental equipment

Determination of the dynamic stress intensity factor of a specimen under one-point bending from the measurement of the load-point displacement

The use of dynamic one-point bending tests as an alternative to three-point bending tests allows fracture properties such as dynamic initiation fracture toughness to be obtained at high strain rate. To perform this kind of test, experimental devices based on modifications of the Hopkinson bar can be used. Several authors have been proposed simplified procedures to obtain the dynamic stress intensity factor, $K_{I}(t)$, considering the specimen as a Timoshenko cracked beam subjected to a concentrated load at the central cross-section. The disadvantage of this procedure is that normally it is difficult to measure the force applied to the specimen in the above-mentioned tests. Here a simplified method is proposed for the calculation of $K_{I}(t),$ based on an analysis of the behaviour of a Timoshenko cracked beam, knowing the displacement of the point of loading, which can be measured more accurately than the applied load. The results were compared with those of a finite element numerical simulation and good agreement was found

On the bulk modulus and natural frequency of fullerene and nanotube carbon structures obtained with a beam based method

In this work, the natural frequency of vibration and Bulk modulus under hydrostatic pressure conditions of carbon nanotubes and fullerenes are investigated. For this purpose, three-dimensional finite element modelling is used in order to evaluate the vibration characteristics and radial stiffness for different nanotube and fullerene sizes. The atomistic method implemented in this work is based on the notion that nanotubes, or fullerenes, are geometrical frame-like structures where the primary bonds between two neighbouring atoms act like load-bearing beam members, whereas an individual atom acts as the joint of the related load-bearing system. The current numerical simulations results are compared with data reported by other authors, highlighting the greater simplicity and the lower computational cost of the model implemented in this work compared to other molecular dynamics models, maintaining accuracy in the results provided.Fil: Braun, Matias Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería; ArgentinaFil: Aranda Ruiz, J.. Universidad Carlos III de Madrid. Instituto de Salud; EspañaFil: Rodríguez Millán, M.. Universidad Carlos III de Madrid. Instituto de Salud; EspañaFil: Loya, J.A.. Universidad Carlos III de Madrid. Instituto de Salud; Españ