Author
Ch. Hartl
Bio: Ch. Hartl is an academic researcher. The author has contributed to research in topics: Hydroforming & Physics. The author has an hindex of 4, co-authored 4 publications receiving 558 citations.
Topics: Hydroforming, Physics, Brittleness, Fusion welding, Renewable energy
Papers
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TL;DR: In this paper, the authors present proceedings and methods to develop process control and highlights the significance of process control for the quality of the forming result of a circular metal tube in a hydroforming process.
209 citations
TL;DR: An overview of the fundamental principles of hydroforming processes and their variants is given in this article, where correlations between the workpiece geometry and the design of tool and process and the forming result are exemplarily illustrated.
209 citations
TL;DR: An overview of the state of the art and important advances of hydroforming regarding the design of process steps, semifinished products, presses and tools is presented in this article, along with new hydroforming technologies like the use of heat energy to improve formability of lightweight materials.
126 citations
TL;DR: In this article, applications of CAx techniques including simulation methods to the development of the hydroformed parts are illustrated using the latest examples, which enable the reduction of process development efforts and costs, and the improvement and optimization of part quality and the process chain.
31 citations
TL;DR: In this paper , the design and testing of hybrid photovoltaics/TEG systems are investigated, which aim to increase the efficiency and improve economic manufacturability of such systems.
Abstract: Photovoltaics (PV) is one of the important technologies for electricity generation from renewable energies today and has an excellent environmental sustainability. It is a fast-growing market worldwide and also offers opportunities for aviation to intensify the use of renewable sources. Although the efficiency of PV systems has increased to a certain extent in recent years, a predominant part of solar radiation acting on a PV system is still lost to the environment through reflection and convection as well as heat radiation from the heated PV system. In addition, the efficiency of these systems decreases with increasing heating. Possible solutions for energy harvesting of this energy loss through thermoelectric (TE) have been investigated theoretically and in part experimentally in various cases but have not yet been transferred to larger PV systems. At the same time, cooling the PV system through thermogenerators (TEG) allows its efficiency to be increased. This contribution presents first results from investigations into the design and testing of hybrid PV/TEG systems, which aim to increase the efficiency and improve economic manufacturability of such systems. Among others, important design aspects of hybrid PV/TEG systems and integration of IoT elements (Internet of Things) are addressed and the development of an analytical model to optimise hybrid systems is presented.
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TL;DR: In this paper, a set of coupled viscoplastic constitutive equations for deformation and damage in hot stamping and cold die quenching of AA6082 panel parts are introduced.
Abstract: This paper introduces a set of coupled viscoplastic constitutive equations for deformation and damage in hot stamping and cold die quenching of AA6082 panel parts The equation set can be used to predict viscoplastic flow and plasticity-induced damage of AA6082 under hot forming conditions Deformation and damage depend upon a coupled set of evolving internal state variables, eg dislocation density, which in turn is affected by thermally activated and deformation-dependent recrystallisation and recovery A phenomenological description of damage is derived based on the expected physical scaling with temperature, strain and strain rate The resulting equations were implemented in the commercial software ABAQUS via the user-defined subroutine VUMAT for carrying out forming process simulations An experimental programme was designed, and specialised testing facilities developed for calibrating and validating the FE process modelling results A good agreement between the process simulation and the experimental results has been achieved This confirms that the physical dependencies in the constitutive equations are correctly formed, and that the equations and FE model can be calibrated and used for hot stamping of AA6082 panel parts Further, forming process optimisation was carried out using the model to identify the optimal forming parameters for a basic panel part with a circular hole in the middle The study concludes with a discussion of the potential impact of the constitutive model, experimental characterisation and modelling results on AA6082 panel parts manufacture
247 citations
TL;DR: In this article, the authors summarized a technological review of the hydroforming process from early years to very recent dates on various topics such as material, tribology, equipment, tooling, etc., so that other researcher at different parts of the world can use it for further investigations in this area.
245 citations
TL;DR: In this article, the state of the art and key technologies concerned with equipment, process control, simulation, etc. are explored in detail, and conclusions are drawn concerning possible future developments in hydroforming technology.
228 citations
TL;DR: An overview of the fundamental principles of hydroforming processes and their variants is given in this article, where correlations between the workpiece geometry and the design of tool and process and the forming result are exemplarily illustrated.
209 citations
TL;DR: In this paper, a comprehensive review of widely used forming processes for aluminium alloys, under cold, warm and hot forming conditions, and the material characteristics and equipment used for each process are presented.
177 citations