Mechanical Engineering

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In this study, we investigated and assessed the dependence of dummy head injury mitigation on the side curtain airbag and occupant distance under a side impact of a Dodge Neon. Full-scale finite element vehicle simulations of a Dodge Neon with a side curtain airbag were performed to simulate the side impact. Owing to the wide range of parameters, an optimal matrix of finite element calculations was generated using the design method of experiments (DOE); the DOE method was performed to independently screen the finite element results and yield the desired parametric influences as outputs. Also, analysis of variance (ANOVA) techniques were used to analyze the finite element results data. The results clearly show that the influence of moving deformable barrier (MDB) strike velocity was the strongest influence parameter on both cases for the head injury criteria (HIC36) and the peak head acceleration, followed by the initial airbag inlet temperature. Interestingly, the initial airbag inlet temperature was only a ~30% smaller influence than the MDB velocity; also, the trigger time was a ~54% smaller influence than the MDB velocity when considering the peak head accelerations. Considering the wide range in MDB velocities used in this study, results of the study present an opportunity for design optimization using the different parameters to help mitigate occupant injury. As such, the initial airbag inlet temperature, the trigger time, and the airbag pressure should be incorporated into vehicular design process when optimizing for the head injury criteria. © 2013 Elsevier Ltd. All rights reserved.

World University root node

(SoE) School of Engineering

Accident Analysis and Prevention

Finite element analysis of occupant head injuries: Parametric effects of the side curtain airbag deployment interaction with a dummy head in a side impact crash

The slurry erosion behavior of a zirconium based bulk metallic glass, Zr44Ti11Cu10Ni10Be25, was evaluated in this study. Slurry erosion tests were carried out using a non-circulating type test rig at impingement angles of 30°, 60°, and 90°. Commonly used hydroturbine steel was evaluated under the same test conditions. At 30° impingement angle, the metallic glass demonstrated nearly 2.6 times higher erosion resistance compared to the steel. At normal impingement, the metallic glass was marginally better. Lower erosion rates of the bulk metallic glass at oblique impingement angles was attributed to its significantly higher hardness and deformation induced partial devitrification. For normal impingement, material was removed in the form of fragments from highly strained platelets due to limited plasticity of bulk metallic glasses. The metallic glass demonstrated a brittle mode of erosion with higher erosion rate at higher angle of impingement. In contrast, hydroturbine steel showed ductile mode of erosion under the same test conditions. © 2013 Elsevier B.V.

Wear

Zirconium based bulk metallic glass-Better resistance to slurry erosion compared to hydroturbine steel

Slurry erosion (SE) is commonly observed in almost all kinds of components and machineries involved in fluid (liquid) transfer and delivery. During design and development phase of these components, test rigs are usually required to evaluate their performance; however, only few detailed designs of test rigs are available for SE investigations. Among the existing designs of SE test rigs, most of them belong to rotary type. In the present study, design of a new type of SE test rig has been proposed, which is simpler in construction and working. This newly designed test rig could possibly eliminate some of the limitations (velocity-concentration interdependence and lack of acceleration distance) found in the existing set-ups. Calibration of the test rig was done for jet velocity and erodent concentration. Commissioning of the rig was undertaken by evaluating the effect of operating parameters (concentration and impingement angle) on the erosion rates of aluminum and cast iron. Results show that the rig was able to capture the traditional responses of ductile and brittle erosion behaviors being observed for these materials. Repeatability of the test rig was ensured, and the results were found to be within the acceptable error limits. © 2012 ASM International.

Journal of Materials Engineering and Performance

Design and development of high-velocity slurry erosion test rig using CFD

Hydroturbines and other fluid machineries are generally subjected to cavitation and slurry erosion environment resulting in the degradation of impellers, vanes, nozzle, spear, labyrinth seal, and buckets. Although hydroturbine steel (13Cr4Ni) provides sufficient resistance against cavitation, however, it degrades severely under slurry erosion. Generally thermal spray coatings are used for protection against slurry erosion, however their performance under cavitation erosion is not appreciable. It is generally observed that the material removal process in cavitation and Liquid Impingement erosion is alike. In this paper, Liquid Impingement erosion performance of composite coatings of nickel and alumina, mixed in various proportions, has been investigated and compared with the uncoated 13Cr4Ni steel. Coatings were deposited using the High Velocity Flame Spray (HVFS) technique. Effects of micro hardness, fracture toughness, work-hardening index, residual stresses and porosity of coatings on the Liquid Impingement erosion performance are discussed. In depth study of the erosion mechanism in each coating and their work hardening capabilities were studied using SEM/EDS and micro-hardness tester. It was observed that fracture toughness and work hardening index of coatings correlate well with the erosion resistance. The effect of alumina content on erosion mechanism of the developed coatings was also investigated. The content of alumina was found to be having significant effect on the erosion response and the degradation mechanism of the coatings. © 2013 Elsevier B.V.

Understanding Liquid Impingement erosion behaviour of nickel-alumina based thermal spray coatings

The mass production of printed electronic devices can be achieved by roll-to-roll system that requires highly regulated web tension. This highly regulated tension is required to minimize printing register error and maintain proper roughness and thickness of the printed patterns. The roll-to-roll system has a continuous changing roll diameter and a strong coupling exists between the spans. The roll-to-roll system is a multi-input-multi-output, time variant, and nonlinear system. The conventional proportional-integral-derivative control, used in industry, is not able to cope with roll-to-roll system for printed electronics. In this study, multi-input-single-output decentralized control scheme is used for control of a multispan roll-to-roll system by applying regularized variable learning rate backpropagating artificial neural networks. Additional inputs from coupled spans are given to regularized variable learning rate backpropagating artificial neural network control to decouple the two spans. Experimental results show that the self-learning algorithm offers a solution to decouple speed and tension in a multispan roll-to-roll system. © IMechE 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions. nav.

Fulltext

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

Web tension control of multispan roll-to-roll system by artificial neural networks for printed electronics

In the current investigation, friction stir processing (FSP) of aluminium alloy 6061 alloy was carried out under different cooling conditions to determine its influence on the microstructure evolution and properties of the investigated alloy. It was found that the type and distribution of the strengthening precipitates in the friction stir processed Al 6061 alloy significantly depend on the FSP parameters and working temperatures during FSP. The properties of friction stir processed alloy were evaluated using micro-hardness and bulk hardness tests. It was observed that 6061 alloy friction stir processed under rapid cooling conditions exhibited enhanced hardness which was found to vary between nearly 12 to 33% as compared to the alloy processed under ambient cooling conditions. © (2013) Trans Tech Publications, Switzerland.

Advanced Materials Research

Effect of microstructural evolution on the properties of friction stir processed al 6061 alloy under different cooling conditions

Friction stir processing (FSP) is a material processing technique recognized to enhance the mechanical properties of the material owing to micro-structural refinement. In the present study, the feasibility of the use of FSP for processing of mild steel has been explored. Using FSP, the micro-structural refinement of the steel surface was obtained, resulting in an average grain sizes of the order of 100 nm as confirmed by atomic force microscopy (AFM). Along with grain size refinement, an evolution of various phases was also studied with the help of X-ray diffraction (XRD). It was observed that ferrite was the only phase present in both processed and unprocessed steel.FSP was found to be useful to enhance the micro-hardness of the steel by 50 to 80%, in comparison with that of the un-processed steel. © (2013) Trans Tech Publications, Switzerland.

Friction stir processing of mild steel to enhance its surface hardness

Understanding the erosion mechanism is a key to improve the performance of material subjected to erosive condition. Capability to predict the erosion mechanism could prove to be useful tool. In this work, a parameter named "erosion mechanism identifier," ξ, is proposed to predict the erosion mechanism in materials. Suitability of ξ in predicting erosion mechanism of ductile and brittle materials was evaluated using the data reported in the literature. It was observed that ξ is able to predict the erosion mechanism for both categories of material. The predictability of ξ was not restrained by different operating conditions. © 2013 Springer Science+Business Media New York.

Tribology Letters

Identifying erosion mechanism: A novel approach

The liquid impingement erosion behavior of a zirconium-based bulk metallic glass (BMG), Zr44Ti11Cu10Ni10Be 25, was evaluated in this study. For comparison, commonly used hydroturbine steel was evaluated under the same test conditions. BMG demonstrated more than four times higher resistance against cavitation erosion compared with hydroturbine steel. The unusually high erosion resistance for BMG is attributed to its uniform amorphous structure with no grain boundaries, higher hardness, and ability to accommodate strain through localized shear bands. Copyright © Materials Research Society 2013.

Journal of Materials Research

Unusually high erosion resistance of zirconium-based bulk metallic glass

Friction stir processing (FSP) has proved to be a viable tool for enhancing the mechanical properties of materials, however, the major focus has been upon improving the bulk properties of light metals and their alloys. Hydroturbines are susceptible to damage owing to slurry and cavitation erosion. In this study, FSP of a commonly employed hydroturbine steel, 13Cr4Ni was undertaken. Microstructural characterization of the processed steel was conducted using optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electron back scatter diffraction (EBSD) techniques. Mechanical characterization of the steel was undertaken in terms of microhardness and resistance to cavitation erosion (CE). FSP resulted in the refinement of the microstructure with reduction in grain size by a factor of 10. EBSD results confirmed the existence of submicron and ultrafine grained microstructure. The microhardness of the steel was found to enhance by 2.6 times after processing. The processed steel also showed 2.4 times higher resistance against cavitation erosion in comparison to unprocessed steel. The primary erosion mechanism for both the steels was identical in nature, with plastic deformation responsible for the loss of material. © 2013 Elsevier B.V.