References of "Zuerbes, Arno"
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See detailImproved design of threaded connections by autofrettage in aluminium compounds for cyclic high pressure loading: design calculations and experimental verification
Sellen, Stephan; Maas, Stefan UL; Andreas, Thomas et al

in Fatigue and Fracture of Engineering Materials and Structures (2015)

Threaded connections in an aluminium valve body under high internal swelling pressure are investigated. A static straining process called autofrettage leads to an improved fatigue behaviour of the ... [more ▼]

Threaded connections in an aluminium valve body under high internal swelling pressure are investigated. A static straining process called autofrettage leads to an improved fatigue behaviour of the aluminium component, while normally the threaded connections are unloaded during this autofrettage. But by unloading the thread during autofrettage the first loaded thread flank became the weakest point of this valve component. This effect is analyzed with non-linear finite element simulations, FKM guideline for fatigue assessment and by experimental testing. The analytical and experimental parts match very well and it can be shown that a well-designed autofrettage without unloading the threaded connection is helpful for the aluminium thread and extends its fatigue lifetime, as compressive residual stresses and an equalized stress distribution over the thread flanks can be generated. Finally different materials were chosen for the plug or screw and this effect for cyclic loading is shortly analyzed. [less ▲]

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See detailSome conclusions from the measurements of temperatures and their gradients on eigenfrequencies of bridges
Mahowald, Jean UL; Maas, Stefan UL; Nguyen, Viet Ha UL et al

Scientific Conference (2014, June 30)

The ambient air temperature and solar radiation are affecting the soil and asphalts’ stiffness and hence the eigenfrequencies of a bridge. Very often eigenfrequencies are automatically determined by ... [more ▼]

The ambient air temperature and solar radiation are affecting the soil and asphalts’ stiffness and hence the eigenfrequencies of a bridge. Very often eigenfrequencies are automatically determined by special algorithms from structural response data generated by ambient excitation and measured by permanently installed sensors that is sometimes called “output only analysis” or “operating modal analysis”. Additionally the ambient air temperature is registered and finally the eigenfrequencies are analyzed versus the air temperature. The graph is normally a scatter diagram and each point is one measurement. In general the eigenfrequencies decrease with increasing temperature, whereas often linear regression is used to determine the line of best fit. But the slope of this straight line and the width of the scatter around the regression line differ from bridge to bridge. Especially this scatter field around the mean value at a determined temperature complicates the detection of damage, which is also often based on eigenfrequencies’ reduction. Hence the difficulty among others consists in separating damage from environmental effects. [less ▲]

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See detailDynamic simulations to develop a natural ventilation concept for an office building
Thewes, Andreas UL; Maas, Stefan UL; Scholzen, Frank UL et al

in 8th International Conference on System Simulation in Buildings (2010)

The Sustainability Group of the University of Luxembourg defined for their new buildings a maximum thermal end-energy of 14 kWh/(m3a) and an electricity consumption for HVAC and lighting below 6 kWh/(m3a ... [more ▼]

The Sustainability Group of the University of Luxembourg defined for their new buildings a maximum thermal end-energy of 14 kWh/(m3a) and an electricity consumption for HVAC and lighting below 6 kWh/(m3a). Therefore it was necessary to avoid active cooling loads and mechanical ventilation in the offices and small lecture rooms. The well insulated and air-tight façade, including special outside shading elements which were designed as a grid over the complete building envelope, was an essential given architectural element of the building. Therefore further external shading devices were not applicable. The only possibility to have an influence on solar gains was to optimize the window size, the glazing type and potentially an internal shading device. Furthermore, to prevent the risk of overheating during the summer period, it was necessary to reduce the internal gains from lighting and IT-equipment. Hence detailed dynamic simulations using TRNSYS and TRNFLOW were done to evaluate the thermal comfort without air-conditioning and mechanical ventilation. The effects of optimizations like a state-of-the-art lighting control system or a window-based night ventilation, as well as the influence of the effective thermal inertia of the building were analyzed. The assumed natural ventilation rates were calculated by combining TRNFLOW and TRNSYS simulations and by the software LESOCOOL. [less ▲]

Detailed reference viewed: 210 (8 UL)