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Öğe Crash test simulation of a modified thrie-beam high containment level guardrail under NCHRP Report 350 TL 4-12 conditions(Inderscience Enterprises Ltd, 2006) Cansiz, Omer F.; Atahan, Ali O.This paper describes details of a computer simulation study performed on a modified thrie-beam high containment level guardrail designated as SGR09b. Because the SGR09b guardrail system is the only high containment guardrail system passing the NCHRP Report 350 TL4 requirements in its class, developing an accurate finite element model for this guardrail is deemed to be a significant contribution towards enhancement of computer-simulated virtual roadside safety. research. For this reason, a detailed finite element model of the SGR09b guardrail system has been developed and subjected to 8000 kg single unit truck impact under NCHRP Report TL4 conditions. The fidelity of the simulation study was evaluated using the full-scale crash test results. As in the full-scale crash test, in the finite element simulation study, the guardrail system successfully contained and redirected the 8000 kg single unit truck. Based on the crash test results, it was determined that the finite element models for both the SGR09b guardrail system and the 8000 kg single unit truck are fairly accurate and can be used with confidence in further computer-simulated virtual roadside safety research.Öğe Crashworthiness evaluation of an intercity coach against rollover accidents(Inderscience Enterprises Ltd, 2011) Guler, Mehmet A.; Atahan, Ali O.; Bayram, B.Rollover accidents can result in serious consequences to vehicle occupants if necessary safety measures are not taken. Two significant measures that can be implemented to minimise occupant injury risk during vehicular rollover events are structural adequacy of the vehicle against crushing and occupant protection by using passive protective devices, such as safety belts and air bags. The aim of this study is to evaluate the structural resistance and passenger injury risks and compare the effectiveness of safety belt usage during a simulated rollover event. In this study, a 13 m long TEMSA bus was used as the vehicle. A total of eight occupants were placed in the critical places of the bus by considering the structurally weakest sections. Three different occupant protection cases were considered: (i) no safety belt; (ii) two-point safety belt and (iii) three-point safety belt. A standard rollover procedure was simulated using non-linear finite element code LS-DYNA. Head and neck injury criteria were used for all three cases to evaluate the effectiveness of seat belt usage on occupant protection. Simulation results clearly illustrated that if occupants had no seat belt protection they suffered serious risk of injuries. Moreover, two-and three-point safety belts provided somewhat similar protection levels for most of the occupants. On the basis of findings, use of two-point safety belts in all the seats of the TEMSA buses was recommended because of their ease of handling.Öğe Crumb rubber in concrete: Static and dynamic evaluation(Elsevier Sci Ltd, 2012) Atahan, Ali O.; Yucel, Ayhan OnerIn this study, six different concrete mix designs containing various amounts of coarse and fine crumb rubber were tested for properties important to concrete safety barriers. Eighteen samples - three of each mix design - were tested under static compression to determine the compressive strength and elastic modulus values. Another eighteen samples were subjected to dynamic drop tests to assess the effect of rubber on energy dissipation. Test results show that increasing the amount of rubber decreases the compressive strength and elastic modulus of the concrete, while significantly increasing impact time and energy dissipation capacity. It was determined that replacing 20-40% of aggregates with crumb rubber creates concrete mixes that would be useful for concrete safety barriers in locations where strength, fracture resistance and energy dissipation are required. Finally, concrete mixes with greater than 60% of aggregates replaced by crumb rubber would be useful for concrete impact attenuators in locations where low impact severity is of ultimate importance, and fracture or fragmentation upon impact is acceptable. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Design and validation of a 30,000 kg heavy goods vehicle using LS-DYNA(Amer Soc Mechanical Engineers, 2005) Atahan, Ali O.; Bonin, Guido; El-Gindy, MoustafaExtraordinary developments in virtual crash testing research have been achieved during the past decade. Advancements in hardware and software technology along with improvements in computation mechanics and increased number of full-scale crash tests contributed positively to the development of more realistic finite element models. Use of complex finite element codes based on computational mechanics principles allowed the virtual reproduction of real world problems. Regarding roadside safety, the design phase was, until now, based on the use of simplified analysis, unable to describe accurately the complexity of vehicle impacts against safety hardware. Modeling details, such as geometry, constitutive laws of the materials, rigid, kinematic and other links between bodies, definition and characterization of contact surfaces are necessary to build an accurate finite element model for an impact problem. This set of information is needed for each different body involved in the event; making the development of a complete model very much demanding. Once a part (subset) of the entire model has been accurately validated against real experimental data, it can be used again and again in other analogous models.Öğe Development of a draft heavy vehicle rear underride guard specification(American Society of Mechanical Engineers (ASME), 2006) Atahan, Ali O.; El-Gindy, Moustafa; Bonin, Guido; Allen, JamesThis paper summarizes results of a large research program intended to develop a draft rear underride guard specification for heavy vehicles. Results of a series of laboratory and full-scale crash tests performed at the Transport Canada Research Center were used in the development of these specifications. A total of eleven full-scale crash tests was carried out to evaluate the effectiveness of different underride guards. The first ten of these tests were performed on a simulated trailer attached guard. Four different underride guard designs were used in these ten full-scale crash tests. Three different vehicle models traveling at 48, 56 and 65 km/h speeds were used to impact underride guards head on. Results of the first ten crash tests show that the currently used US FMVSS 223 standard is far from adequate in preventing the occurrance of rear underride. Based on findings obtained from these crash tests, an improved guard design was developed and tested using a 16-meter trailer. This final crash test verified the effectiveness of improved guard design in reducing the undesirable effects of rear underride crashes. Based on the results, a draft heavy vehicle rear underride guard specification was developed. Copyright © 2006 by ASME.Öğe Development of European End-Treatment TWINY Using Simulation and Crash Testing(Asce-Amer Soc Civil Engineers, 2008) Atahan, Ali O.; Bonin, Guido; Cicinnati, Luigi; Yasarer, Hakan I.In this study, a simple guardrail end treatment, called TWINY, designed particularly for use with a thrie-beam guardrail system is developed. In the first phase, the system is designed and analyzed using a versatile, highly nonlinear finite-element analysis program LS-DYNA. Two different crashes involving a head on impact and a 15 S angle impact are simulated using LS-DYNA. In both simulations, a nominal 900 kg car traveling at 80 km/h is used to impact the end treatment as outlined in European Crash Testing Guidelines EN1317 section 4. Based on the successful simulation results, both tests are repeated in a crash test facility in Germany to substantiate simulation predictions. Full-scale crash testing results compared favorably with those obtained from LS-DYNA simulation. Based on the results, a final full-scale crash testing was carried out on the system to fully verify its compliance with the EN1317 section 4. A 1,300 kg compact car traveling at 80 km/ h impacted the end terminal at its midlength at an angle of 15 S. The vehicle is successfully redirected with minimal damage to both vehicle and terminal. Based on the simulation and full-scale crash test results, it can be concluded that TWINY is a promising end treatment for steel thrie-beam guardrail terminals and can be implemented at the European Highway System with confidence.Öğe EVALUATION OF VERTICAL WALL-TO-GUARDRAIL TRANSITION(Amer Soc Mechanical Engineers, 2009) Atahan, Ali O.; Bonin, Guido; El-Gindy, MoustafaTransition barriers are used to connect longitudinal barriers that have different stiffnesses. They are designed to provide a gradual increase in stiffness towards the stiffer barrier section. In this study, a W-beam rail and a W-beam rubrail transition connecting a rigid bridge rail to a semi-rigid guardrail was evaluated using numerical and experimental methods. First, a finite element model of the transition design was constructed and validated using a 2000 kg pickup truck impact. Then, a series of vehicle models, i.e., 900 kg compact automobile, 8000 kg single unit truck and finally 30,000 kg heavy truck was used to evaluate the impact performance of the same transition design numerically. Simulation results predict that the double W-beam transition barrier performs acceptably in containing and redirecting all vehicles except 30,000 kg heavy truck. Occupant injury criteria were also found to be acceptable for all the cases, except 30,000 kg truck impact. Performing further simulations with vehicle sizes heavier than 8,000 kg that exist in crash testing guidelines is recommended to evaluate the acceptability limit of existing W-beam rail and a W-beam rubrail transition.Öğe Evaluation of vertical wall-to-guardrail transition(2008) Atahan, Ali O.; Bonin, Guido; El-Gindy, MoustafaTransition barriers are used to connect longitudinal barriers that have different stiffnesses. They are designed to provide a gradual increase in stiffness towards the stiffer barrier section. In this study, a W-beam rail and a W-beam rubrail transition connecting a rigid bridge rail to a semi-rigid guardrail was evaluated using numerical and experimental methods. First, a finite element model of the transition design was constructed and validated using a 2000 kg pickup truck impact. Then, a series of vehicle models, i.e., 900 kg compact automobile, 8000 kg single unit truck and finally 30,000 kg heavy truck was used to evaluate the impact performance of the same transition design numerically. Simulation results predict that the double W-beam transition barrier performs acceptably in containing and redirecting all vehicles except 30,000 kg heavy truck. Occupant injury criteria were also found to be acceptable for all the cases, except 30,000 kg truck impact. Performing further simulations with vehicle sizes heavier than 8,000 kg that exist in crash testing guidelines is recommended to evaluate the acceptability limit of existing W-beam rail and a W-beam rubrail transition. Copyright © 2008 by ASME.Öğe Laboratory and field evaluation of recycled content sign posts(Elsevier Science Bv, 2013) Atahan, Ali O.; Yucel, Ayhan O.This paper summarizes results of an experimental study intended to evaluate performance of recycled content sign posts. A total of 23 sign posts, circular, rectangular and square shaped, obtained from 13 different manufacturers were evaluated using laboratory and field tests. Full-scale specimens were used in order to account for size effects and the non-homogeneous nature of the materials. Static tests, such as flexure, hydrothermic cycling, density, creep, warpage and dynamic pendulum impact tests were used to make conclusive decisions regarding their suitability. Conventionally used wooden sign post was also included in the experimental program to provide baseline performances for the material evaluation. Static and dynamic test results demonstrated that some recycled sign posts could be suitable alternatives to conventional wooden post. Full-scale crash testing is strongly recommended to substantiate experimental findings. (C) 2013 Elsevier B.V. All rights reserved.Öğe A rear-end protection device for heavy vehicles(American Society of Mechanical Engineers (ASME), 2003) Atahan, Ali O.; Joshi, Abhishek S.; El-Gindy, MoustafaRear underride crashes, particularly with heavy vehicles, constitute a serious safety concern for passenger cars. Several solutions to this emerging concern have been proposed by responsible agencies. Recent rear-end crashes with heavy vehicles show that a properly used rear underride guard devices can slow down impacting vehicle in a controlled manner. Moreover, with the use of these devices, the severity of crashes can be reduced and loss of lives can be prevented. In this paper, a special underride guard device is designed for heavy vehicle use. The height of the device from ground and support conditions are varied to evaluate and compare the crash performances. Finite element models of these particular designs are constructed and models are impacted by a passenger car model traveling at two different speeds of 48 km/h and 64 km/h. LS-DYNA, a non-linear finite element code capable of analyzing large deformations is used for the analysis. Vehicle decelerations, energy dissipations and passenger car crush characteristics are compared to determine the acceptability of each design. Based on the simulation study, an optimum height from ground and support condition are determined for acceptable impact performance for heavy vehicle mounted rear-end underride guard devices against passenger vehicle impacts.Öğe Retrofit of an existing Italian bridge rail for H4a containment level using simulation(Inderscience Enterprises Ltd, 2009) Bonin, Guido; Cantisani, Giuseppe; Ranzo, Alessandro; Loprencipe, Giuseppe; Atahan, Ali O.This paper describes the methodology for the development of a crashworthy heavy containment bridge rail for the Italian Highway System. The current design was determined to be inadequate for heavy vehicle containment and could not be demolished due to damage risk to bridge superstructure. Italian Highway Agency has decided to retrofit the current design. Two different bridge rail models are developed and analysed using 30 ton heavy vehicle according to European EN1317 Test TB71 requirements. Detailed finite element analyses are performed to evaluate the acceptability of retrofit alternatives. A versatile, highly non-linear and widely accepted finite element program LS-DYNA is used to simulate the crash events. Analysis results show that the final bridge rail model successfully contains and redirects the 30 ton vehicle and it is found to be an acceptable retrofit to existing bridge rail design. A full-scale crash test is recommended to substantiate simulation findings.Öğe Testing and comparison of concrete barriers containing shredded waste tire chips(Elsevier Science Bv, 2008) Atahan, Ali O.; Sevim, Umur K.In this study, concrete specimens containing shredded waste tire chips were evaluated using laboratory and field tests. A total of 24 cylindrical specimens, 15 cm x 30 cm in size, were tested to determine the compressive strength of concrete at 7 and 28 days. For the dynamic tests, on the other hand, 6 New Jersey shaped concrete barriers were constructed using the identical mix designs used in the static tests. Results of the study showed that tire addition reduced the compression strength and modulus of elasticity of specimens. Dynamic impact tests show that increase in tire percentage has significant effect on the reduction in vehicle peak deceleration forces and thus impact severity. Based on the static and dynamic test results, it can be concluded that specimens with 20 to 40% aggregate replacement gives the best impact performances without significant reduction in concrete strength. Concrete barriers containing larger amounts of tire can be used at highway applications where concrete fracture is desired for energy dissipation, such as crash cushion and end treatment applications. (C) 2008 Elsevier B.V. All rights reserved.Öğe Vehicle crash test simulation of roadside hardware using LS-DYNA: a literature review(Inderscience Enterprises Ltd, 2010) Atahan, Ali O.A great deal of progress has been achieved during the past several years in integrating advanced non-linear finite element programs into the design and analysis phases of roadside hardware. Most of the progress in this area can be attributed to the pioneering work by Lawrence Livermore National Laboratory (LLNL) along with extensive financial support by the Federal Highway Administration (FHWA) and other institutions. There is still, however, much work remaining before analytical methods achieve their full potential in roadside safety research. The computer software tools are available and computing capabilities continue to improve at a rapid pace making analysis of complex systems possible. The application of Finite Element Analysis (FEA) has evolved from relatively simple impacts to highly realistic interaction problems. With continued progress, FEA is expected to play a vital role in the design and analysis of new generation cost-effective roadside hardware in coming years. This literature review attempts to summarise the major achievements and key developments on crash test simulation of roadside hardware over the past years and inform readers about the current state of knowledge in roadside hardware simulation. Successful crash test simulations on different applications are reviewed based on roadside hardware type. Specific models used in the virtual crash tests are explained. Due to the nature of the paper, many of the details that go into the successful simulations are not discussed herein. References for those details previously discussed in the literature are provided.
