Refine
Document Type
- Article (3)
Has Fulltext
- yes (3)
Is part of the Bibliography
- yes (3)
Keywords
- Combined characterisation (1)
- Compression (1)
- Digital image correlation (1)
- Finite element simulation (1)
- Kratzempfindlichkeit (1)
- Kunststoff (1)
- Polymers (1)
- Reibung (1)
- Struktur (1)
- Tension (1)
Institute
This study investigates the validity and applicability of the correlation between scratch and tensile properties for extruded polymer strands. The mechanical properties could be predicted for extruded samples, which allows skipping the step of injection molding and therefore enables a faster material development. Extruded polymer strands and tensile test specimens out of PMMA, PS, POM, PP and PE have been investigated. A correlation of the Young’s modulus and the elastic deformation as well as a correlation of the yield stress and the plastic deformation during scratching is given for both flat molded and cylindrical extruded specimens. SEM images of the scratch grooves are used to analyze the scratch deformation mechanism. The deformation mechanism correlates well to the variation coefficient of the indentation depth. Polarized light microscopy of thin cross sections of both types of specimens provides information about skin layer thickness and morphology. However, the optical analysis could not provide an explanation for the different levels of the indentation depth in the two specimen types. Further investigations should include a study of differences in process induced morphology and the effect of two layers with different mechanical properties, i.e., skin and center, on the stress and strain fields underneath the scratch.
Die Schmierung durch Öle oder Gleitmittel kann zur Minimierung von Verschleiß bei Kunststoffen zum Einsatz kommen – ist allerdings nicht bei allen Anwendungen möglich oder erwünscht. Hier kann die
Strukturierung der Oberflächen von Kunststoffbauteilen helfen. Ein neues Rechenmodell zeigt einen neuen Weg zur Entwicklung tribologisch optimierter Produktoberflächen.
A novel material testing concept is developed in order to provide tensile and compressive properties within a single mechanical test. A new specimen geometry is designed for testing in a universal testing machine. Under tensile load, both a homogeneous tensile stress condition as well as a homogeneous compressive stress condition occur in the specimen. Measurements accompanying the experimental test with digital image correlation provide tensile and compressive Poisson’s ratio as well as tensile modulus. These properties are input parameters for subsequent finite element simulations. The compressive modulus is determined by iteratively adjusting finite element simulations in order to couple experimental and simulated results. For validating the concept, experimental tests are carried out on polyoxymethylene. While the tensile Poisson’s ratio of the new concept shows the best agreement with the reference value, the compressive modulus is approximately 15% higher. Further work should focus on an appropriate material model in order to reduce the deviation.