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The methodology of criticality assessment is used ever more frequently for the assessment of a system´s resource supply. At present, there are various approaches which differ in the selection of criteria as well as the applied aggregation methods. Mostly, two dimensions are used to assess criticality: “risk or likelihood of supply interruption” and “vulnerability to supply shortages”. However, there is no consensus about the criteria which are used to assess these dimensions. Furthermore, the terms “risk” and “vulnerability” are sometimes used in ways contradicting their general understanding and use in science. This paper presents a further methodological refinement to achieve a more consistent concept of assessing resources. In the presented methodology, vulnerability is determined as a function of sensitivity, exposure and adaptive capacity. It facilitates a clear distinction and allocation of criteria at various organizational levels in order to enable a better interpretation of the results. The presented methodology of vulnerability assessment is exemplarily applied to the automobile industry. So far, no criticality or similar assessment have been conducted for this industry. As a result, of 27 examined metals especially Rh (contained in autocatalysts), Dy, Nd, Tb and Pr (contained in electric motors of electric vehicles) and Eu (contained in emerging LED applications) were identified as the most vulnerable metals of automobile industry. [ABSTRACT FROM AUTHOR]

Gear Transmission Error (TE) is often considered as the main cause of gear whine. TE represents the difference between the perfectly kinematic transmission of motion and the one actually achieved. TE vibrations are extremely small and pose significant measurement challenges. This article demonstrates how low-cost digital encoders can be successfully used together with the Elapsed Time Method to simplify TE measurement with respect to the traditional Direct Method. A precision gear pair test rig is exploited to compare the two methods from a theoretical and an experimental point of view. Following the observations drawn from such comparison, a measuring chain is set up to validate the proposed procedure on a real case all-electric vehicle gearbox. It is shown how TE represents a useful gearbox NVH indicator and how it can be used to support gear microgeometry design. [ABSTRACT FROM AUTHOR]

The increased usage of advanced high strength steels (AHSS) as material for car body parts leads to a continuous reduction of car weight and thus a lowering of CO 2 emissions. This weight reduction results from higher yield and tensile strength of AHSS than conventional steel grades. However, the higher strength of AHSS leads to higher loadings of the forming tools. To increase the wear resistance of the tool surfaces, mechanical surface treatments are used. In this work, the incremental forming of EN-JS2070 deep drawing tools by means of machine hammer peening (MHP) is investigated. In the past, small surface defects were observed after MHP of nodular cast iron EN-JS2070. The cause for the occurrence of these surface defects is unknown. The aim of this work is the investigation and description of the logical relationship between the cause and effect of MHP process parameters and the surface defects on nodular cast iron EN-JS2070. The surface defects occurred independent of the chosen MHP parameter setup at one critical zone on the hammered deep drawing tools and the investigated microstructure showed the existence of shrink holes, which were primarily responsible for the occurrence of the surface defects after MHP. [ABSTRACT FROM AUTHOR]

Tailor-welded blanks (TWBs) are welded sheets consisting of different materials, thicknesses, shapes, and sizes. They are subjected to forming at a particular temperature to achieve the desired shape. One of the problems encountered in TWBs is the undesirable weld line movement which may lead to the formation of wrinkles, tearing, and distortion of components. In order to restrict the weld line movement in TWBs, an experimental setup with a specialized punch is used. The specialized punch is split into two parts separated by insulating material. One part is used for heating the stronger/thicker material and the other part for cooling the weaker/thinner material. With the selective method of heating, the weld line movement reduced drastically as compared to the movement in a single punch. In this work, the influence of thickness ratios on the weld line movement at different temperatures is also studied. Experiments were conducted at room temperature as well as elevated temperature for the same thickness of sheets. Results of experimental work are correlated with numerical analysis. The combined effect of thickness ratio with the selective method of heating has shown a greater effect in controlling the weld line movement. [ABSTRACT FROM AUTHOR]

One of the main goals of modern materials research is obtaining different microstructures and studying their influence on the mechanical properties of metals; aluminum alloys are particularly of interest due to their advanced performance. Traditionally, their required properties are obtained by alloying process, modification, or physical influence during solidification. The present work describes a saturation of the overheated AlSi7Fe1 casting alloy by oxides using oxygen blowing approach in overheated alloy. Changes in metals' microstructural and mechanical properties are also described in the work. An Al10SiFe intermetallic complex compound was obtained as a preferable component to Al2O3 precipitation on it, and its morphology was investigated by scanning electron microscopy. The mechanical properties of the alloy after the oxygen blowing treatment are discussed in this work. [ABSTRACT FROM AUTHOR]

Polymer fuel cells operating above 100 °C (High Temperature Polymer Electrolyte Membrane Fuel Cells, HT-PEMFCs) have gained large interest for their application to automobiles. The HT-PEMFC devices are typically made of membranes with poly(benzimidazoles), although other polymers, such as sulphonated poly(ether ether ketones) and pyridine-based materials have been reported. In this critical review, we address the state-of-the-art of membrane fabrication and their properties. A large number of papers of uneven quality has appeared in the literature during the last few years, so this review is limited to works that are judged as significant. Emphasis is put on proton transport and the physico-chemical mechanisms of proton conductivity. [ABSTRACT FROM AUTHOR]

Carbon fiber manufacturers are adding production capacity to meet an increasing number of high performance applications. Reinforced plastics reports on activities at some leading producers. [ABSTRACT FROM AUTHOR]

The need for accurate material models to simulate the deformation, damage, and failure of polymer matrix composites under impact conditions is becoming critical as these materials are gaining increased usage in the aerospace and automotive industries. There are a variety of material models currently available within commercial transient dynamic finite-element codes to analyze the response of composite materials under impact conditions. However, there are several features that are lacking in the currently available models that could improve the predictive capability of the impact simulations. To address these needs, a combined elasto-plastic model with damage suitable for implementation within transient dynamic finite-element codes has been developed. A key feature of the improved material model is the use of tabulated stress-strain data in a variety of coordinate directions to fully define the stress-strain response of the material. Currently, the model development efforts have focused on creating the plasticity portion of the model. A commonly used composite failure model has been generalized and extended to a strain-hardening-based orthotropic yield function with a non-associative flow rule. The coefficients of the yield function are computed based on the input stress-strain curves using the effective plastic strain as the tracking variable. The coefficients of the flow rule are determined in a systematic manner based on the available stress-strain data for the material. The evolution of the yield surface is examined, in detail, for a sample composite. A numerical algorithm based on the classic radial return method is employed to compute the evolution of the effective plastic strain. A specific laminated composite is examined to demonstrate the process of characterizing and analyzing the response of a composite using the developed model. The developed material model is suitable for use within commercial transient dynamic finite-element codes for use in analyzing the nonlinear response of polymer composites. [ABSTRACT FROM AUTHOR]

The interior sound perceived in an automobile cabin is a very important attribute in vehicle engineering. Therefore, an ever-increasing interest exists to predict the interior acoustic behavior by means of accurate simulation models both to improve the vehicle NVH performance and to reduce the development cycle of a new vehicle. Nevertheless, the current level of accuracy of such models is not sufficient to replace the design prototype phase with an all-digital phase. Experimental methods in which an acoustic characterization is performed play an important role in understanding the modeling challenges, improving the overall modeling know-how and providing a detailed comprehension of the physical behavior. Besides these these longer-term objectives, experimental acoustic methods are also instrumental as part of a vehicle development program and to refine the design; for example, troubleshooting booming noise. By means of a case study on a fully trimmed sedan car, this article discusses acoustic modal analysis equipment requirements and testing procedures. Due to specific challenges, such as high modal damping ratios and the need to use a large number of sound sources spread around the cabin to get a sufficient excitation of the modes, modal parameter estimation is often not a trivial task. The modal parameters (resonance frequencies, damping ratios, mode shapes, and modal participation factors) will be estimated from the measured frequency response functions by the new ML-MM method, a multiple-input, multiple-output frequency-domain maximum likelihood estimator based on a modal model formulation. [ABSTRACT FROM AUTHOR]

Ethylene-propylene-diene monomer rubber (EPDM)-based ground wastes (W-EPDM) are reutilized as rubber matrix in plug material compounds for automotive applications. Production scraps of target product are ground to 35, 40 and 60 mesh in ambient conditions. Effect of particle size and the amount of W-EPDM is studied. A new trial product of maleated ethylene-propylene rubber (EPM) and bitumen are used to improve interphase adhesion of the waste and the virgin EPDM. Cure characteristics, physico-mechanical and aging properties of all compounds are determined. Micro structure of the vulcanizates is studied for explaining dispersion and interaction between different phases. Reutilization of W-EPDM causes some reasonable deterioration in cure characteristics and mechanical properties of the product. However, some systematic and alternative recipes for plug materials are suggested considering cost and environmental benefits. [ABSTRACT FROM PUBLISHER]

A novel vehicle headlamp low beam system is presented. The optical system is composed of three identical cells to ensure enough illumination. A poly-ellipsoid reflector and a aspherical lens are used to concentrate the rays and a baffle is employed to produce the cut-off line. The optical performance shows a good agreement with the requirement for headlamp in Chinese national standard. The smart constant current driver sustains automotive headlamps᾿requirements, moreover it has high power efficiency. The performance of three kinds of cooling systems with different structures are simulated and evaluated by FloTHERM software. Then a loop heat pipes combined with fins cooling system is manufactured for cooling the designed LED headlamp. It can greatly improve the cooling efficiency. Even in the 80°C environmental temperature, it can meet the working requirements of LED headlamp low beam system, so it is a kind of feasible cooling scheme. [ABSTRACT FROM AUTHOR]

Cold-rolled steels are used in every stage of the automotive industry, from engineering design to manufacturing, and advanced numerical studies of these steels require knowledge of their stress–strain behaviour. Existing stress–strain models for these steels either are only capable of accurate predictions over a limited strain range or are defined by many material parameters and the values of some of these parameters are not available in most of the existing design codes. This study presents an analytical approximation of the stress–strain relationship for cold-rolled steels. For this purpose, tensile tests were conducted with some commercial cold-rolled sheets used in the automotive industry. Data were analysed to construct a robust mathematical model. The residual sum of squares was employed as the common analysing parameter for both linear and non-linear models; residual diagnosis was also applied towards achieving robustness of the model. [ABSTRACT FROM AUTHOR]

The present works aims to develop multi-materials such as steel/polymer/steel hybrid system for weight savings in automotive industries. This laminate must be compatible with processing on the industrial line (steel/polymer lamination under 200 °C) and the structure must be flow-resistant during the paint process curing (200 °C for 30 min). Consequently, a yield stress polymer system based on compatibilized PA11/copolymer of ethylene and octene blends has been developed. The yield stress property (for T > 200 °C) depends on the phase concentration and compatibilization strategy. It is observed that an annealing process (heating treatment for 1 h at 200 °C), simulating the painting process, provides a strong benefit for the polymer/steel properties after aging under humidity conditions. [ABSTRACT FROM AUTHOR]

The need for lighter constructional materials in automotive industries has increased the use of high-strength steel alloys. To enhance passenger's safety press hardening may be applied to steel parts. However, as the steel parts are heated up to 950 °C during this process they have to be protected by some kind of coating against the intense oxide formation usually taking place. As the coating systems used so far all have certain disadvantages in this work the ability of nano-particulate thin coatings obtained by the sol-gel process to improve the oxidation resistance of 22MnB5 steel is investigated. The coatings obtained from three sols containing lithium aluminum silicate and potassium aluminum silicate showed the best performance against oxidation. The structural properties of the coating materials were characterized using different methods like XRD and differential thermal analysis. Comparison of the oxidation rate constants proved the ability of the coatings to protect against oxidation at temperatures up to 800 °C. Press-hardening experiments in combination with investigations on the thermal shock resistance of the coated samples also showed the ability of the coatings to stay intact during press hardening with only slight spalling of the coatings in the bending areas. The absence of any secondary intermetallic phases and layer residues during laser beam welding experiments on coated samples proves the suitability of the nano-particulate coatings for further industrial processing. [ABSTRACT FROM AUTHOR]

The history of modern composites begins in the 20th century, when a number of new materials and technologies were invented. New materials are necessary for electrical engineering and computer industry, but their importance rapidly grows in mechanical engineering, especially in aerospace and automotive industry. Industrial demands force to rapidly innovate and bring new materials, with essentially improved properties. Submitted paper deals with the basic overview of manufacturing, processing and main features of the composite materials, based on carbon fibers and their application in the automotive industry. [ABSTRACT FROM AUTHOR]