As part of an evaluation to determinate the influence of the stress gradient on the stress-life response of a given component, a series of double-notched samples was tested uniaxial stress-controlled fatigue tests. Its results were then compared with the results of similar tests made using single notch specimens. Although the inherent geometrical differences between the sample series, the stress concentration factors are in the range of 2.5 ± 10 % for all series. Nevertheless, the experimental results have shown a very different fatigue response of the double- notched series. To explain the...
Carbon-fibre composite is very popular material in aircraft industry. Application of this material is limited by low fragility and low impact resistance. In flight airplane can be initialy damaged by hailstorm or bird strikes. Vibrations of the engine and turbulence during flight may cause propagation of this damage. This study describes the of laser profilometry to investigate post damage under cycling loading.
This paper outlines two examples of application of close-range photogrammetry, their preliminary results and observations. The first application is identification and measurement of deformations and displacements of the vehicle chassis after a frontal crash-test. This is done by comparison between the pre- and post-crash models and measurements. The second mentioned application is determination of the road pavement macro-texture, where the photogrammetry can serve as an alternative method.
The novelty of this study consists in using drilled cores from a large scale OPC reinforced slab, exposed to a simulated accidental failure of the central support and subsequent vertical loading until collapse, in order to determine the influence of real cracks in concrete structures on the penetration of chlorides. The experimental results were obtained with the non-steady state migration test described in NT BUILD 492, using an electrical field and real cracks. In order to study both the influence of rebars and cracks, reference samples were used. The chloride penetration depth was...
Unlike most metallic materials, some synthetic materials are known to exhibit a very prominent creep behavior. Additionally, among many other variables, this type of effect is highly dependent on the material temperature. The aim of this work is to study the creep behavior of synthetic ropes used in the anchorage of offshore platforms working in deep and ultra-deepwater. In these regions the low temperature of the water affects directly the behavior of the synthetic materials when subjected to permanent tensile loads. These results are shown in a displacement-time graph, in which the three...
In the resent research work a sufficient test method was developed to determine the friction- and wear regimes of POM and PA for different testing conditions. Tribological results show indeed there is a positive influence of the friction modifier in the POM and PA by lowering friction- and wear values. From a failure analytical point of view, different wear processes at the polymer surface are observed related to the presence of the friction modifier.
The paper describes validation of selected multiaxial fatigue criteria in the region of limited lifetime. Used test data and methodology of validation are described. Results of validation are presented.
Hydrogels are attractive materials for many demanding applications (i.e. medical, scaffolds for soft tissue engineering, organic electronics and optics). One of the recent developments in this field is the fabrication of super tough hydrogels by using several modifications of the double-network concept. These hydrogels can show several hundred percent strains without failure under uniaxial tensile loading condition and reveal excellent fracture toughness and notch sensitivity. The measurements have been done with two different types of nanoparticle filled hydrogels which also showed a...
Current research is aimed to create functional material models out of test data to use them in numerical simulations. This process contains several material tests such as tensile tests and dynamic mechanical analyses at different temperatures. All determined test results were used as input data to process model parameters. The selected material models are the hyperelastic Odgen-model, the viscoelastic Prony-series and the hyper-viscoelastic Bergström-Boyce model. After the implementation in ABAQUS/CAE, a comparison of real tensile test data and simulated tensile tests under the same...
This paper presents analytical calculation of stresses in spherical tank which was used during designing of tank, and experimental verification of calculated stresses after the tank was produced. Derivation of equilibrium equations for the shell element is presented as well as procedure for determination of membrane state of stress. Experimental verification of tank is described. Experiments showed concentration of stress at the points of spherical tank support. Maximum equivalent stress exceeds yield stress for material out of which tank was built, but the area with exceeded stress is very...