This paper presents three different search engines for the detection of CAD-parts in large databases. The analysis of the contained information is performed by the export of the data that is stored in the structure trees of the CAD-models. A preparation program generates one XML-file for every model, which in addition to including the data of the structure tree, also owns certain physical properties of each part. The first search engine is specializes in the discovery of standard parts, like screws or washers. The second program uses certain user input as search parameters, and therefore has the ability to perform personalized queries. The third one compares one given reference part with all parts in the database, and locates files that are identical, or similar to, the reference part. All approaches run automatically, and have the analysis of the structure tree in common. Files constructed with CATIA V5, and search engines written with Python have been used for the implementation. The paper also includes a short comparison of the advantages and disadvantages of each program, as well as a performance test.
Fused deposition modeling has become the most common 3D printing technology in both the industry and the private sector, due to its easy application and low price. Although some companies provide parameter sets that are perfectly adapted for their machines and filaments, a great variety of materials that can be processed on arbitrary printers are also available. Usually, the operator has to figure out ideal printing parameters in order to achieve high-quality results. In this work, an approach is presented relating the conclusions of differential scanning calorimetry, including the melting and glass transition temperatures and the decomposition points, to the printout quality. To give an overview of the common materials and to correlate the behavior of the printing parameters, 16 different filaments categorized into groups of plastics without additives, metals and carbon, woods, and stones have been investigated. Heat towers have been printed with each filament, whereby the individual floors in 5 °C steps represent the nozzle temperatures and show features for direct comparison. As a main result, it is shown that the optimal printing quality is achieved with temperatures on the colder end of the range between melting and decomposition.
The possibilities of a technical application of the shape memory effect are comprehensive and widespread. Besides the usage of arbitrary geometries, e.g. in the medical sector, especially wires are of great interest for unlocking mechanisms or other kinds of actuators. One of the challenges of the application of shape memory alloys (SMA) is the small deformation factor that prevents actuations with large travels. A second property that is usually seen as a disadvantage is the thermal dependence of the position. It leads to the necessity of comparably high electrical power for holding a location, as the cooling has to be compensated constantly. Therefore, SMA are usually not in use for such applications. For special environments, this effect can still be an advantage. By using an SMA driven positioning actuator in vacuum, the low loss of heat leads to a very precise and low power consuming alignment. Such actuators can be used for example in satellites. This paper presents an analysis of the properties under atmospheric conditions in comparison to the behavior in vacuum. Along with a comprehensive interpretation of the experimental results, further characteristics, like the functional and structural fatigue, are presented in detail.
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