다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Additive manufacturing of metallic components – Process, structure and properties

A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

This chapter discusses leading problems linked to energy that the world is now confronting and to propose some ideas concerning possible solutions. Oil deserves special attention among all energy sources. Since the beginning of 1981, it has merely been continuing and enhancing the downward movement in consumption and prices caused by excessive rises, especially for light crudes such as those from Africa, and the slowing down of worldwide economic growth. Densely-populated oil-producing countries need to produce to live, to pay for their food and their equipment. If the economic growth of the industrialized countries were to be 4%, even if investment in the rational use of energy were pushed to the limit and the development of nonpetroleum energy sources were also pursued actively, it would be extremely difficult to prevent a sharp rise in prices. It is evident that it is absolutely necessary to pursue actively the development of coal, natural gas, and nuclear power if a physical shortage of energy is not to block economic growth.

World energy outlook

Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Polymers for 3D Printing and Customized Additive Manufacturing

Berechnung von Kronenrädern für Auslegung und Fertigung

This paper considers heavy duty grinding with resin bonded corundum grinding wheels and without lubrication and cooling. A vertical turning machine redesigned to a grinding machine test bench with a power controlled grinding spindle is used in all of the experiments, allowing high tangential table feed rates up to 480 m/min. This special test-rig emulates the railway grinding usually done by a railway grinding train. The main test-rig components are presented and the resulting kinematics of the experimental set-up is described. A stochastic kinematic grinding model is presented. A wear model that is based on the kinematic description of the grinding process is set up. Grain breakage is identified as the main wear phenomenon, initiated by grain flattening and micro-splintering. The wear model is implemented into the stochastic kinematic modelling. The workpiece material side flow and spring back are considered. The simulation results are validated experimentally. The workpiece surface roughness is compared and a good agreement between simulation and experiment can be found, where the deviation between the experiment and the simulation is less than 15% for single-sided contact between the grinding wheel and the workpiece. Higher deviations between simulation and experiment, up to 24%, for double-sided contact is observed.

Stochastic Kinematic Process Model with an Implemented Wear Model for High Feed Dry Grinding

This paper contributes to the assessment of possible sustainable performance measures from direct data acquisition at shop‐floor level in order to enable the evaluation and further interpretation by the manufacturing management at plant level. Herewith, the possible performance measure related to the CO2 equivalent and energy consumption is evaluated on the basis of the energy consumption of typical machining processes on a conventional lathe. Starting with the machine tool and its components as the lowest acquisition level, this paper proposes a possible conversion and interpretation of the gathered measurement data while simultaneously considering the regional differences in energy generation, which impacts on the CO2 equivalent. The evaluation of the sustainability related manufacturing performance is described exemplarily by calculating the CO2 equivalent based on the energy consumption of a single manufacturing process. Relying on the assumption that it is possible and reasonable to calculate a CO2 equivalent for every other manufacturing process analogously; an approach is Adam Gontarz, Noëlle Jufer, Jens Bathelt, Lukas Weiss and Konrad Wegener presented to connect the thereby gained CO2 equivalents with every single produced product type. Adam Gontarz, Noëlle Jufer, Jens Bathelt, Lukas Weiss and Konrad Wegener

Determination and Evaluation of CO2 as a Sustainable Performance Measure on the Basis of a Typical Lathe

This paper presents a hybrid Smoothed Particle Hydrodynamics (SPH) – Finite Element Method (FEM) solver for metal cutting simulations on Graphics Processing Units (GPU). For the first time in chip formation simulation, the heat transfer between an SPH model of the workpiece, and a transient FEM temperature model for the cutting tool, is established. For validation, the performance of the modeled thermal contact between two numerical domains is compared with a commercial FEM software. The sensitivity of the implemented SPH-FEM contact parameters is investigated for the first time and further insights into the thermal modeling of cutting simulations are generated. Overall, the newly developed hybrid model saves the computational time on the cutting tool side in the pure SPH method and enables more efficient high-fidelity cutting simulations. By clearly defining the thermal contact at the tool-chip interface, the simulated tool surface temperature agrees well with the experimental measurements in the literature. 

Konrad Wegener

Papers

Berechnung von Kronenrädern für Auslegung und Fertigung

Stochastic Kinematic Process Model with an Implemented Wear Model for High Feed Dry Grinding

Determination and Evaluation of CO2 as a Sustainable Performance Measure on the Basis of a Typical Lathe

Hybrid SPH-FEM solver for metal cutting simulations on the GPU including thermal contact modeling

Analysis and relevance of service reports to extend predictive maintenance of large-scale plants