The Internal Pressure Test in Experiment and Simulation—Influence of the Wall Thickness Variation and the Change of the Packaging Behavior after the Impact of Standard Liquids

The effect of the wall thickness variation of blow‐moulded bodies made of high‐density polyethylene on an internal pressure test after prestoring the packaging with standard liquids was evaluated in experiments and simulations. The objects of the investigation were jerrycans used for the transportation and storage of dangerous goods. The wall thickness was determined using two alternative methods to the magnetostatic measurement. These alternative methods are used for research purpose to get a volumetric model of the jerrycan wall as a geometric model for the simulation. The comparison of the experiments and the simulations of the internal pressure test were performed using the digital image correlation method. The integral strain and deformation of the whole jerrycan was detected by measuring the total mass of the jerrycan being filled with water during the internal pressure test. This is a suitable alternative to the optical measurements of local deformation by the digital image correlation method. Prestorage at 40 °C without the influence of chemicals strengthens the jerrycan, whereas the swelling effect of butyl acetate and hydrocarbon mixture softens the jerrycan. The comparison with the experiment is necessary to verify the accuracy of the simulation. It shows that the deformation can be simulated more precisely by using the actual measured geometry. The weakening of the high‐density polyethylene caused by a hydrocarbon mixture can be simulated using the Arrhenius equation. The aim of the simulation was to discover whether it is possible to use specimens to predict the behaviour of a packaging both after the influence of standard liquids. Copyright © 2012 John Wiley & Sons, Ltd.     

A cross‐cultural comparison of colour emotion for two‐colour combinations

Psychophysical experiments were conducted in the UK, Taiwan, France, Germany, Spain, Sweden, Argentina, and Iran to assess colour emotion for two‐colour combinations using semantic scales warm/cool, heavy/light, active/passive, and like/dislike. A total of 223 observers participated, each presented with 190 colour pairs as the stimuli, shown individually on a cathode ray tube display. The results show consistent responses across cultures only for warm/cool, heavy/light, and active/passive. The like/dislike scale, however, showed some differences between the observer groups, in particular between the Argentinian responses and those obtained from the other observers. Factor analysis reveals that the Argentinian observers preferred passive colour pairs to active ones more than the other observers. In addition to the cultural difference in like/dislike, the experimental results show some effects of gender, professional background (design vs. nondesign), and age. Female observers were found to prefer colour pairs with high‐lightness or low‐chroma values more than their male counterparts. Observers with a design background liked low‐chroma colour pairs or those containing colours of similar hue more than nondesign observers. Older observers liked colour pairs with high‐lightness or high‐chroma values more than young observers did. Based on the findings, a two‐level theory of colour emotion is proposed, in which warm/cool, heavy/light, and active/passive are identified as the reactive‐level responses and like/dislike the reflective‐level response. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2012     

Problems and Benefits of Requirements Gathering With Focus Groups: A Case Study

Focus group interviews are considered as a rather weak, nonquantitative method of assessing user needs, ideas, and reactions in an early stage of the interface design process (Nielsen, 1993). Given this fact, it is relevant to reflect the practical use of focus groups step by step to determine their real strengths and limitations. In this article, we share our experience of planning, running, and analyzing focus groups within the design process of a home automation system. We describe the pre- and postwork in detail so that the pros and cons of gathering requirements with focus groups become apparent.     

Quantifizierungen von Grundwassereintritten in städtische Abwassersysteme mittels stabiler Isotope

Infiltration of groundwater into sewer systems increases the costs for wastewater treatment plant operators. This study explores groundwater infiltration to urban sewer systems in the city of Nuremberg (Germany). Measurements of stable isotopes at the water works, storage tanks, groundwater, and the sewage network were carried out to define input end members for mass balance calculations. Only minor differences in oxygen stable isotopes (δ¹⁸O_H2O) were found between most sewer and drinking water samples which ranged around (??9.5?±?0.1) ‰. One exception was water from a water works at Genderkingen that is situated about 80 km south of Nuremberg. Here, drinking water from bank filtrate of the Lech River had more negative δ¹⁸O_H2O values of ??11.4?‰. This difference of 1.5?‰ revealed maximum possible groundwater contributions of 41?% by mass balance calculations. To obtain more accurate results, we suggest testing the use of deuterium-enriched water (D₂O) added to the sewer system.     

Fatigue assessment of arc welded automotive components using local stress approaches: Application to a track control arm

The applicability of the structural and notch stress approach is examined on the basis of arc welded and dynamically loaded steel structures, taken from the automotive sector. In detail, this is a transverse control arm. Components and specimens with critical regions of failure are tested under cyclic loading with constant and variable amplitudes. With the help of strain gauges, the crack initiation is determined. The specimens are the basis for the application and evaluation of the different approaches for the assessment of fatigue life. The numerical determination of the nominal, structural and notch stresses is performed with finite-element models. Finally the experimental and computational results allow the derivation of structural and notch Woehler S-N curves.     

An analytical solution for geotextile-wrapped soil based on insights from DEM analysis

This paper presents a novel analytical solution for geotextile-wrapped soil based on a comprehensive numerical analysis conducted using the discrete element method (DEM). By examining the soil–geotextile interface friction, principal stress distribution, and stress–strain relations of the constituent soil and geotextile in the DEM analysis, a complete picture of the mechanical characterization of geotextile-wrapped soil under uniaxial compression is first provided. With these new insights, key assumptions are verified and developed for the proposed analytical solution. In the DEM analysis, a near-failure state line that predicts stress ratios relative to the maximums at failure with respect to deviatoric strain is uniquely identified; dilation rates are found to be related to stress ratios via a single linear correlation regardless of the tensile stiffness of the geotextile. From these new findings, the assumptions on the stress-state evolution and the stress–dilatancy relation are developed accordingly, and the wrapped granular soil can therefore be modeled as a Mohr–Coulomb elastoplastic solid with evolving stress ratio and dilation rate. The development of the proposed analytical model also demonstrates an innovative approach to take advantage of multiscale insights for the analytical modeling of complex geomaterials. The analytical model is validated with the DEM simulation results of geotextile-wrapped soil under uniaxial compression, considering a wide range of geotextile tensile stiffnesses. To further examine the predictive capacity of the analytical model, the stress–strain response under triaxial compression conditions is solved analytically, taking both different confining pressures and geotextile tensile stiffnesses into account. Good agreement is obtained between the analytical and DEM solutions, which suggests that the key assumptions developed in the uniaxial compression conditions also remain valid for triaxial compression conditions.