Zerstörungsfreie in-situ-Detektion von Schädigungsprozessen bei Ermüdungsbelastung zur Charakterisierung von Faserverbundwerkstoffen

Translated title of the contribution: Non-destructive in-situ detection of damage processes during fatigue load for the characterization of fiber composite materials

Clemens Sperling

Research output: ThesisMaster's Thesis

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Abstract

Due to the high stiffness and low density of fibre reinforced polymers, they are commonly used in lightweight applications. To avoid fatigue failure during fatigue loading those constructions are often overdimensioned. To progress with the reduction of cost and material, the damage development during the use has to be better understood. Therefore, in this work fatigue testing with cyclic tensile tests was performed to characterise the damage evolution of multiple laminates, made of glass fibre reinforced epoxy resin. For this purpose, the development of the stiffness and the poisson ratio was evaluated. The used strains were measured with the piston movement of the servo-hydraulic testing machine and additional with digital image correlation. The damage was also recorded through an acoustic emission system. No matrix cracks could be detected with the acoustic emission system. By a plateau in the elastic modulus curve and an evaluation of the acoustic emission data, the start of the delamination within the ±45° laminates could be observed. In addition, also by the acoustic emission system a possible abort criterion for the fatigue test could be detected. The results of the 90° laminate revealed a constant decrease of the Young's modulus until the specimens broke. This was mainly caused by the increasing number of matrix cracks. Apart from this, the results of the digital image correlation and the acoustic emission were correlated. For laminates consisting of 90° layers embedded in 0° layers no significant change in the elastic modulus and poisson ratio could be detected. Although, the beginning of damage could be monitored with signals originating from matrix cracks. Due to the low damping of elastic waves in fibre direction those crossply laminates and other commonly used multiaxial laminates suit the usage of detecting any damage, through acoustic emission systems, well.
Translated title of the contributionNon-destructive in-situ detection of damage processes during fatigue load for the characterization of fiber composite materials
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Pinter, Gerald Gerhard, Supervisor (internal)
Award date25 Jun 2021
Publication statusPublished - 2021

Bibliographical note

embargoed until null

Keywords

  • fiber-reinforced composites
  • damage detection
  • fatigue
  • acoustic emission
  • digital image correlation
  • poisson ratio

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