Daum, Benedikt

Rolfes, Raimund

Safdar, Nabeel

Scheffler, Sven

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8th ECCOMAS Thematic Conference on the Mechanical Response of Composites: COMPOSITES 2021M. Fagerström & G. Catalanotti (Editors)PROBABILISTIC FAILURE PREDICTION UNDER COMBINEDIN-PLANE COMPRESSION-SHEAR LOADING FORUNIDIRECTIONAL FIBER REINFORCED COMPOSITESNabeel Safdar1∗, Benedikt Daum1 , Sven Scheffler1 and Raimund Rolfes11 Leibniz University Hannover, Institute of Structural Analysis∗ n.safdar@isd.uni-hannover.deOne of the design limiting failure for fiber reinforced composites (FRC) is under compres-sion loads, showing failure under compression at as low as two thirds of their tensile strengths.Over the past few decades numerous analytical, experimental and numerical investigations haveexplored different dimensions of the problem [1]. It is now widely accepted that the dominantfactors behind compression dominated failure modes are manufacturing induced fiber misalign-ments and the nonlinear matrix material behavior. Uncertainty regarding fiber misalignmentleads to variations in strengths under compression dominated loads [2]. In order to exploit themaximum potential of FRCs, it is essential to predict the failure under axial compression andcompression dominated combined loads reliably.In order to advance the understanding of the problem in this direction, a modeling frameworkis presented where predictions in a probabilistic manner can be performed, leading to develop-ment of numerically calculated probabilistic failure surface under compression and combinedcompression-shear load cases. Figure 1 shows a periodic model schematic where the experi-mentally characterized fiber misalignments, shown as the contour in the figure, are also incor-porated into the model. A resultant failure surface in stress space is also shown. Subsequently,this contribution presents an experimentally obtained failure surface under aforementioned loadcases. The material characterization required for modeling, including fiber misalignment mea-surements is also performed. The differences between the modeling and experimental predic-tions are discussed. Finally, the numerically calculated knock down factors to account for thesedifferences are presented.0-111230Figure 1: The figure shows modeling methodology. 1 is fiber direction whereas 2 and 3 are transversal in-planeand out-of-plane directions respectively.References[1] B. Daum, N. Feld, O. Allix, and R. Rolfes (2019) A review of computational modelingapproaches to compressive failure in laminates. Composite Science and Technology, 181[2] D. Liu, N.A. Fleck, and M.P.F. Sutcliffe (2004) Compressive strength of fibre compositeswith random fibre waviness. Journal of the Mech. and Phy. of Sol., 52(7), 1481-1505

Probabilistic Failure Prediction under Combined in-plane Compression-Shear Loading for Unidirectional Fiber Reinforced Composites

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Probabilistic Failure Prediction under Combined in-plane Compression-Shear Loading for Unidirectional Fiber Reinforced Composites

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