Suche
Anzeige der Dokumente 81-90 von 143
Aufsatz
Tailoring flow behavior and heat transfer in tempering channels for high-pressure die casting—analysis of potentials of commercial static mixers and prospects of additive manufacturing
(2023-02-16)
Additive manufacturing (AM) opens up manifold possibilities to influence the heat transfer between fluid and die in high-pressure die casting (HPDC), eventually allowing to minimize the total cycle time of the process. AM already has been exploited to establish near-contour temperature control systems in industrial applications. However, AM not only allows to influence the position of tempering channels in dies but it also allows to influence the fluid dynamics itself, e.g., by imprinted static mixers. Up to now, ...
Aufsatz
Data Driven prediction of forced nonlinear vibrations using stabilised Autoregressive Neural Networks
(2023-03-24)
In this work, we propose a novel approach to the data-driven prediction of vibration responses of nonlinear systems. The main idea is based on Autoregressive Neural Networks (ARNN) to model the nonlinear transfer behaviour between an external excitation and the system response. We propose an autoregressive network architecture with embedded symmetry using bias-free tanh activation and guarantee Input-to-State-Stability (ISS) by enforcing a special penalty term to the weights. The resulting training procedure is ...
Aufsatz
An Investigation on Limiting Potentials for Damage Prediction of Viscoelastic Adhesives
(2023-03-24)
In his recent work VOLOKH introduced the energy limiting method as an alternative to continuum damage mechanics developed and envolved by KACHANOV, RABOTNOV, LEMAITRE and many more. In contrast to continuum damage mechanics, the energy limiting method is physically grounded by the process of atomistic debonding and, therefore, motivated on an energy basis. In order to use the energy limiting method within the framework of continuum mechanics, a limiting potential needs to be defined, which can be seen as a macroscopic ...
Aufsatz
Consideration of nonlinear multipoint constraints in finite element analyses based on a master-slave elimination scheme operating at the global level
(2023-03-24)
A method to consider nonlinear multipoint constraints in finite element analysis based on a master-slave elimination scheme operating at the global level is presented. We focus on systems with nonlinear constraints in which the number of constraints is of the same order of magnitude as the number of degrees of freedom. Therefore, we rely on the master-slave elimination which gives us the huge benefit of drastically reducing the problem size. In the literature the presented master-slave elimination schemes for linear ...
Aufsatz
Evaluation of hydraulic efficiency of lined irrigation channels - A case study from Punjab, Pakistan
(2023-04-04)
Indus Basin Irrigation System (IBIS) in Pakistan is the backbone of agriculture in the country. The IBIS provides irrigation support to agricultural lands across the country; however, hydraulic efficiency of the water conveyance system is impacted due to seepage losses. The lining of irrigation channels is considered a potential solution for improving hydraulic efficiency. Therefore, this study explores the impact of canal lining on the hydraulic efficiency of the canals in the Punjab province of Pakistan. Overall, ...
Aufsatz
Experimentelle Untersuchungen von Wärmerohrsystemen für den Einsatz in elektrischen Arbeitskraftmaschinen
(2023-03-01)
Mit dem Ziel die Effizienz elektrischer Arbeitskraftmaschinen durch ein innovatives Kühlsystem zu erhöhen, wird ein Wärmetransportsystem auf Basis von Wärmerohren entwickelt und analysiert. Die Leistungsfähigkeit des Systems bei Variation des Temperaturbereichs und des zugeführten Wärmestroms sowie der Einfluss der Rotation werden experimentell untersucht. Der Wärmewiderstand des Systems wird im Vergleich zu reiner Wärmeleitung um 98 % reduziert. Die Rotation des Systems hat keinen signifikanten Einfluss auf den ...
Aufsatz
Electrostatic Body Forces and their Implications for Cracks
(2023-03-24)
A Griffith-type crack in a dielectric solid under electromechanical loading is investigated by numerically solving the combined boundary value problem. The focus is on the contribution of electrostatically induced body forces, coming along with the still controversially discussed Maxwell stress tensor, to the crack tip loading. A 1/r-singularity of compressive stress is found to evolve at the crack tip, however, just being dominant over the mechanically induced 1/√r-behavior within a very small region
Aufsatz
Effect of Thermo-Mechanically Activated Precipitation on the Hot Deformation Behavior of High Strength Aluminum Alloy AA7075
(2022-09-26)
The present study investigates the effect of two different microstructural conditions on the hot deformation behavior of precipitation-hardenable AA7075 by compression tests ranging from 200 °C to 350 °C and strain rates from 0.1 s-¹ to 10 s-¹. The first condition is solution heat-treated and quenched in water, whereas the second condition is achieved by subsequent artificial aging and stabilization for 24 h at the respective intended deformation temperature. Both conditions indicate an increase in flow stress with ...
Aufsatz
Effect of Combined Forming and Aging Processes on the Mechanical Properties of the Precipitation-Hardenable High-Strength Aluminum Alloys AA6082 and AA7075
(2022-07-25)
The recently increasing demand for hot stamped aluminum components in the automotive and aerospace industries explains the necessity of designing efficient and resource-conserving thermomechanical processes. Within the thermo-mechanical process, the simultaneous effect of deformation and temperature accelerate the precipitation kinetics. Therefore, this study focuses on the combined effect of forming and aging processes on the mechanical properties of high-strength aluminum alloys AA6082 and AA7075. For this aim, two ...
Aufsatz
Comparative Analysis of Resource and Climate Footprints for Different Heating Systems in Building Information Modeling
(2022-10-31)
Buildings play an important role to meet Sustainable Development Goals, especially regarding the use of resources and greenhouse gas emissions. They are increasingly designed with energy-efficient solutions regarding their operations, while the related use of natural resources is still insufficiently considered. In this article, a methodology in Building Information Modeling is proposed to measure the resource and climate footprints of buildings’ heating systems. The methodology is applied to a case study building ...