WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394

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Author: search.filters.author.Atahan, M. GokhanPublisher: search.filters.publisher.Springer

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  • Article
    Citation - WoS: 10
    Citation - Scopus: 11
    Finite Element Analysis of Low-Speed Oblique Impact Behavior of Adhesively Bonded Composite Single-Lap Joints
    (Springer, 2023-04-14) Atahan, M. Gokhan; Apalak, M. Kemal
    The development of a realistic numerical model that predicts the impact behavior of adhesively bonded composite joints is important for many industrial sectors such as automotive, aerospace, and marine. In this study, it was aimed to develop a numerical model that can predict the low-velocity oblique impact behavior of composite single-lap joints close to the experimental results. The validation of the proposed numerical model was carried out with the results of the previously experimentally tested joints. In explicit finite element analysis, the orthotropic material model and Hashin's damage criterion were used in the numerical model of composite adherends. The adhesive region was divided into three different regions. The cohesive zone model (CZM) was used to determine the damage initiation and propagation in the upper and lower interface regions of adhesive. The middle region of the adhesive between the two cohesive interfaces was modeled with an elastic-plastic material model to reflect the plastic material behavior of the adhesive in the analysis. The effects of impact angle, fiber orientation, and overlap length on adhesive damage initiation and propagation were investigated in detail. There is a good agreement between the numerical and experimental results, considering the contact force-time variations and composite and adhesive damage. The impact angle and fiber angle had a significant effect on the impact behavior of the composite joints and the adhesive damage initiation and propagation. The increase in impact angle and fiber angle caused a decrease in the maximum contact force value. Adhesive damage propagation patterns varied according to the composite fiber orientation. In addition, since the shear toughness of the adhesive is higher than its tensile toughness, the amount of adhesive damage and damage propagation rate decreased as the impact angle increased.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 12
    Experimental Investigation of Oblique Impact Behavior of Adhesively Bonded Composite Single-Lap Joints
    (Springer, 2022-02-22) Atahan, M. Gokhan; Apalak, M. Kemal
    Determining the impact behavior of adhesive joints allows the designing of high-strength joints. Therefore, the dynamic behavior of adhesive joints has recently become a trending research topic. The study aims to examine the impact behavior and damage mechanism of the adhesively bonded composite joints, taking into account different impact angles. The mechanical behavior of adhesively bonded glass-fiber reinforced laminated composite single-lap joints under bending impact load was experimentally determined via a drop weight impact test machine. The effects of impact angle (theta = 0 degrees, 10 degrees, 20 degrees, 30 degrees), fiber angle (phi = 0 degrees, 45 degrees, 90 degrees), and overlap length (b = 25, 40 mm) on the impact behavior of the joints were investigated. These parameters were determined to affect the impact behavior of the joint and the damage characterization. The highest contact force occurred in the joints with 0 degrees fiber angle having the highest bending strength, and the lowest contact force occurred in the joints with 90 degrees fiber angle having the lowest bending strength. Due to the increase in the impact angle, the maximum contact force value in the joints decreased, while the total contact time increased. The increase in overlap length had little effect on the maximum contact force and total contact time, and the vertical displacement decreased due to the increasing bending stiffness. The unbalanced joint with 45 degrees fiber angle was forced to rotate around its axis due to in-plane unbalanced shear stress distributions induced by the bending impact load. The unbalanced shear stress distribution caused shear damage at the fiber-matrix interface and the top composite-adhesive interfaces. In joints with 0 degrees fiber angle, the impact energy was mostly met with adhesive damage, while the composite adherend was damaged as a result of increased shear stresses in the matrix region for the joints with 90 degrees fiber angle.