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This work evaluates and revisits elements from the depth-sensing indentation literature by means of carefully chosen practical indentation cases, simulated numerically and compared to experiments. The aim is to close a series of debated subjects, which constitute major sources of inaccuracies in the evaluation of depth-sensing indentation data in practice. Firstly, own examples and references from the literature are presented in order to demonstrate how crucial self-similarity detection and blunting distance compensation are, for establishing a rigorous link between experiments and simple sharp-indenter models. Moreover, it is demonstrated, once again, in terms of clear and practical examples, that no more than two parameters are necessary to achieve an excellent match between a sharp indenter finite element simulation and experimental force-displacement data. The clear conclusion is that reverse analysis methods promising to deliver a set of three unique material parameters from depth-sensing indentation cannot be reliable. Lastly, in light of the broad availability of modern finite element software, we also suggest to avoid the rigid indenter approximation, as it is shown to lead to unnecessary inaccuracies. All conclusions from the critical literature review performed lead to a new semi-analytical reverse analysis method, based on available dimensionless functions from the literature and a calibration against case specific finite element simulations. Implementations of the finite element model employed are released as supplementary material, for two major finite element software packages.

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The main purpose of this study is to analyze the fatigue behavior of an industrial (±55°)9 filament-wound glass reinforced epoxy pipe. Fatigue tests are conducted in accordance with ASTM D2992, Standard Practice for Obtaining Hydrostatic or Pressure Design Basis for Fiberglass (Glass-Fiber-Reinforced Thermosetting-Resin) Pipe and Fittings, but instead of the entire pipe, rings cut from the pipe are used in the tests. This standard proposes a frequency of 0.42 Hz and stress ratio of R = 0.05. Tension-tension fatigue tests are performed on the rings at different load levels from 60 to 90 % of the ultimate hoop strength of the pipe. After the tests, the maximum pressure and maximum hoop stress curves versus the number of cycles to fatigue failure are presented. A comprehensive discussion about the importance of substituting the ring test method with ASTM D2992 standard test methods to determine the long-term performance of the composite pipes in the future is presented. The microscopic fatigue failure mechanisms of the rings are also characterized and interpreted using a scanning electron microscope.

In this paper, the ultimate hoop strength of an industrial (±55 deg)9 filament-wound glass-reinforced epoxy (GRE) pipe as a short-term test is determined according to the ASTM D-1599 standard by performing the internal hydrostatic pressure test. After the test, the failure surface of the pipe is photographed by a high magnification camera, and in addition, the explanations are presented about the type of failure. The main purpose of this study is to compare the results obtained for the ultimate hoop strength and failure mechanisms of the pipe by using the internal hydrostatic pressure test with that by the split disk test method according to the ASTM D-2290 standard in the previous work.