DYNAMIC MODELING AND ANALYSIS OF VEHICLE SMART STRUCTURES FOR FRONTAL COLLISION IMPROVEMENT

A.M. ELMARKBI,J.W. ZU 한국자동차공학회 2004 International journal of automotive technology Vol.5 No.4

The majority of real world frontal collisions involves partial overlap (offset) collision. in which only one of the two longitudinal members is used for energy absorption. This leads to dangerous intrusions of the passenger compartment. Excessive intrusion is usually generated on the impacted side causing higher contact injury risk on the occupants compared with full frontal collision. The ideal structure needs to have extendable length when the front-end structure is not capable to absorb crash energy without violating deceleration pulse requirements. A smart structure has been proposed to meet this ideal requirement. The proposed front-end structure consists of two hydraulic cylinders integrated with the front-end longitudinal members of standard vehicles. The work carried out in this paper includes developing and analyzing mathematical models of two different cases representing vehicle-to-vehicle and vehicle-to-barrier in full and offset collisions. By numerical crash simulations. this idea has been evaluated and optimized. It is proven form numerical simulations that the smart structures bring significantly lower intrusions and decelerations. In addition, it is shown that the mathematical models are valid, flexible, and can be used in an effective way to give a quick insight of real life crashes.

CRASHWORTHINESS IMPROVEMENT OF VEHICLE-TO-RIGID FIXED BARRIER IN FULL FRONTAL IMPACT USING NOVEL VEHICLE'S FRONT-END STRUCTURES

A. M. ELMARAKBI,J. W. ZU 한국자동차공학회 2005 International journal of automotive technology Vol.6 No.5

There are different types of vehicle impacts recorded every year, resulting in many injuries and fatalities. The severity of these impacts depends on the aggressivety and incompatibility of vehicle-to-roadside hardware impacts. The aim of this paper is to investigate and to enhance crashworthiness in the case of full barrier impact using a new idea of crash improvement. Two different types of smart structures have been proposed to support the function of the existing vehicle. The work carried out in this paper includes developing and analyzing mathematical models of vehicle-to-barrier impact for the two types of smart structures. It is proven from analytical analysis that the mathematical models can be used in an effective way to give a quick insight of real life crashes. Moreover, it is shown that these models are valid and flexible, and can be useful in optimization studies.

The effective interfacial shear strength of carbon nanotube fibers in an epoxy matrix characterized by a microdroplet test

Zu, M.,Li, Q.,Zhu, Y.,Dey, M.,Wang, G.,Lu, W.,Deitzel, J.M.,Gillespie, J.W.,Byun, J.H.,Chou, T.W. Pergamon Press ; Elsevier Science Ltd 2012 Carbon Vol.50 No.3

The tensile properties of continuous carbon nanotube (CNT) fibers spun from a CNT carpet consisting of mainly double- and triple-walled tubes, and their interfacial properties in an epoxy matrix, are investigated by single fiber tensile tests and microdroplet tests, respectively. The average CNT fiber strength, modulus and strain to failure are 1.2+/-0.3GPa, 43.3+/-7.4GPa and 2.7+/-0.5%, respectively. A detailed study of strength distribution of CNT fiber has been carried out. Statistical analysis shows that the CNT fiber strength is less scattered than those of MWCNTs as well as commercial carbon and glass fibers without surface treatment. The effective CNT fiber/epoxy interfacial shear strength is 14.4MPa. Unlike traditional fiber-reinforced composites, the interfacial shear sliding occurs along the interface between regions with and without resin infiltration in the CNT fiber. Guidelines for microdroplet experiments are established through probability analysis of variables basic to specimen design.

Stress relaxation in carbon nanotube-based fibers for load-bearing applications

Zu, M.,Li, Q.,Zhu, Y.,Zhu, Y.,Wang, G.,Byun, J.H.,Chou, T.W. Pergamon Press ; Elsevier Science Ltd 2013 Carbon Vol.52 No.-

Carbon nanotube (CNT) based continuous fiber, a CNT assembly that could retain the superb properties of individual CNTs on a macroscopic scale, has emerged as a promising candidate for reinforcement in multifunctional composites. While existing research has extensively examined their short-term mechanical properties based upon quasi-static measurements, the long-term durability of CNT fibers has been largely neglected. Here we report time-dependent behavior of CNT fibers, with a particular focus on tensile stress relaxation. Both the pure CNT fiber and the CNT/epoxy composite fiber exhibited significant stress decay during the relaxation process, and this time-dependent behavior became more significant at a higher initial strain level, a lower strain rate and a greater gauge length. The present approach signifies a fundamental difference in the load-bearing characteristics between CNT fibers and traditional advanced fibers, which has major implications for the long-term durability of CNT fibers in load-bearing multifunctional applications.

CRASHWORTHINESS IMPROVEMENT OF VEHICLE-TO-RIGID FIXED BARRIER IN FULL FRONTAL IMPACT USING NOVEL VEHICLE'S FRONT-END STRUCTURES

ELMARAKBI A. M.,ZU J. W. The Korean Society of Automotive Engineers 2005 International journal of automotive technology Vol.6 No.5

There are different types of vehicle impacts recorded every year, resulting in many injuries and fatalities. The severity of these impacts depends on the aggressivety and incompatibility of vehicle-to-roadside hardware impacts. The aim of this paper is to investigate and to enhance crashworthiness in the case of full barrier impact using a new idea of crash improvement. Two different types of smart structures have been proposed to support the function of the existing vehicle. The work carried out in this paper includes developing and analyzing mathematical models of vehicle-to-barrier impact for the two types of smart structures. It is proven from analytical analysis that the mathematical models can be used in an effective way to give a quick insight of real life crashes. Moreover, it is shown that these models are valid and flexible, and can be useful in optimization studies.

DYNAMIC MODELING AND ANALYSIS OF VEHICLE SMART STRUCTURES FOR FRONTAL COLLISION IMPROVEMENT

Elemarakbi, A.M.,Zu, J.W. The Korean Society of Automotive Engineers 2004 International journal of automotive technology Vol.5 No.4

The majority of real world frontal collisions involves partial overlap (offset) collision, in which only one of the two longitudinal members is used for energy absorption. This leads to dangerous intrusions of the passenger compartment. Excessive intrusion is usually generated on the impacted side causing higher contact injury risk on the occupants compared with full frontal collision. The ideal structure needs to have extendable length when the front-end structure is not capable to absorb crash energy without violating deceleration pulse requirements. A smart structure has been proposed to meet this ideal requirement. The proposed front-end structure consists of two hydraulic cylinders integrated with the front-end longitudinal members of standard vehicles. The work carried out in this paper includes developing and analyzing mathematical models of two different cases representing vehicle-to-vehicle and vehicle-to-barrier in full and offset collisions. By numerical crash simulations, this idea has been evaluated and optimized. It is proven form numerical simulations that the smart structures bring significantly lower intrusions and decelerations. In addition, it is shown that the mathematical models are valid, flexible, and can be used in an effective way to give a quick insight of real life crashes.

Natural dye-sensitized ZnO nano-particles as photo-catalysts in complete degradation of E. coli bacteria and their organic content

Zyoud, A.,Dwikat, M.,Al-Shakhshir, S.,Ateeq, S.,Shteiwi, J.,Zu'bi, A.,Helal, M.H.S.,Campet, G.,Park, D.,Kwon, H.,Kim, T.W.,Kharoof, M.,Shawahna, R.,Hilal, H.S. Elsevier Sequoia 2016 Journal of photochemistry and photobiology Chemist Vol.328 No.-

<P>This communication describes for the first time how nano-size particles, sensitized with natural dye molecules of anthocyanin, can be used as catalysts in photo-degradation of gram negative Escherichia coli bacteria in water. The naked ZnO nano-particles degraded up to 83% of the bacteria under solar simulator light, while the dye-sensitized particles increased the bacterial loss by similar to 10%. Solar simulator light includes about 5% of UV tail (shorter than 400 nm) which means that both UV and visible light (longer than 400 nm) radiations could be involved. When a cut-off filter was used, the naked ZnO caused only 40% bacterial loss, in accordance with earlier literature that described killing of bacteria with ZnO particles both in the dark and under light. With the cut-off filter, the sensitized ZnO particles caused higher than 90% bacterial loss, which confirms sensitization of the ZnO particles to visible light. Moreover, the results show that the catalyzed photo-degradation process causes mineralization of the bacteria and their organic internal components which leach out by killing. The catalyst can be recovered and reused losing similar to 10% of its activity each time due to mineralization of the dye molecules. However, catalyst activity can be totally regained by re-sensitizing it with the anthocyanin dye. The effects of different experimental conditions, such as reaction temperature, pH, bacterial concentration and catalyst amount together with nutrient broth and saline media, will be discussed together with the role of the sensitizer. (C) 2016 Elsevier B.V. All rights reserved.</P>