Probeneinflüsse bei der mechanischen Prüfung von Composites

Translated title of the contribution: Influences of specimen parameters in mechanical testing of composites

Matthias Drvoderic

Research output: ThesisMaster's Thesis

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Abstract

This work investigates sample influences on test specimens made of unidirectional (UD) composites with a fiber orientation of 90°. The aim was to find a test specimen design that is well suited for testing the material properties transverse to fiber direction. There is the problem that with straight specimens, the influences of the clamping often causes the failure to occur near the clamping and the experiment can thus no longer be considered valid. In this thesis mainly the geometrical influences on the risk of failure for shouldered test specimens are considered. These are analyzed using finite element simulations (FE). To perform the calculations, a script was programmed which automatically creates the FEM-model based on input variables. This splits the work into two big blocks. The first block deals with the script for the model and the possibilities it offers. The second block contains the results of the analyzes and their evaluation. At the end, the simulation results are compared to data from tensile tests. The developed script for creating the simulation-model has a modular structure and can also be used for other simulations of tensile specimens. The aim of this first block was to develop a simulation tool to automatically create and analyze models of flat tensile or compressive test specimens. The time for preprocessing can thus be shortened considerably and high-quality simulation results are generated in a short time. In the second block the results of the simulation are presented. An analysis of the geometry influences revealed the direction and the relative magnitude of the influence on the failure risk. The calculated risks are normalized to the failure risk in the testfield, as the samples should fail there to represent a valid test result. In the further course, an attempt is made to optimize the problem areas in such a way that failure occurs in the testfield and not in other areas. As critical areas, the clamping area and the shoulder have been found. Especially in the clamping area the stresses peak at the end of the Tab. In the area of the shoulder there arise stress concentrations due to the taper of the cross section. Here it was tried to intercept these by optimizing the shoulder geometry. Based on the simulation results, two design proposals for UD90 samples are presented, which are also compared with experimental results.
Translated title of the contributionInfluences of specimen parameters in mechanical testing of composites
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Schuecker, Clara, Supervisor (internal)
Award date29 Jun 2018
Publication statusPublished - 2018

Bibliographical note

no embargo

Keywords

  • clamping influence
  • specimen geometry
  • variable model
  • specimen parameters
  • composite specimen

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