WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
Browse
3 results
Search Results
Article Citation - WoS: 12Citation - Scopus: 14The Effect of Different Tabbing Methods on the Damage Progression and Failure of Carbon Fiber Reinforced Composite Material Under Tensile Loading(Elsevier Sci Ltd, 2022-07) Ali, Hafiz Qasim; Yilmaz, Cagatay; Yildiz, MehmetComposites are well-known and widely used materials due to their anisotropic nature and high strength-to-weight ratio; therefore, the mechanical performance of these materials is crucial. Precise tensile testing is essential to obtain material properties that are crucial for the design stage of composite structures. This study is an effort to investigate the effect of adhesive materials used for tabbing process, which is necessary for the tensile testing procedure. Araldite and AF 163-2k film are used as the adhesive film, whereas in the case of AF 163-2k, tabbing is done through two different procedures (Jig and corner holes method). Apart from the tensile per-formance, strain distribution and damage progression are monitored simultaneously using digital image corre-lation (DIC) and acoustic emission (AE) analysis. It is observed that there is no significant difference in the ultimate tensile strength of these composites tabbed with different adhesives and procedures. Nevertheless, the first major failure strength is much higher in Araldite tabbed specimens compared to AF 163-2k film (the first major failure activity is defined as a point at which material loses its integrity, especially when considering structural or aerospace applications). Also, strain distribution throughout the gauge length recorded via DIC is appreciably different, which is attributed to damage accumulation and progression monitored by AE analysis. The frequency-based analysis of AE data is performed to classify the damage, and cumulative energy is correlated with the DIC to navigate the failure activity at different times and stress levels.Article Citation - WoS: 3Citation - Scopus: 4Comparative Study on Bending Performances of 3D-Printed Monolithic and Adhesively Bonded Sandwich Structures With Various Auxetic Cores: An Innovative Production Approach(Sage Publications Ltd, 2025-03-28) Atahan, Mithat Gokhan; Sevim, Caglar; Demirbas, Munise Didem; Apalak, Mustafa KemalThe cores of sandwich structures are typically produced monolithically using lightweight materials and specific geometries. In recent years, the advancements in additive manufacturing have enabled the design and production of novel sandwich core configurations with auxetic behavior and high energy absorption capability. In this study, an innovative production approach, namely adhesively bonded sandwich structures with auxetic cores, was proposed to ensure significant manufacturing advantages for industrial applications. Each part of the sandwich core structures with auxetic core configurations was printed separately and then bonded using an epoxy-based adhesive. To evaluate the mechanical performance of the proposed bonded sandwich structures, three-point and four-point bending tests with DIC (Digital Image Correlation) analyses were conducted. The bending test results of adhesively bonded sandwich structures were compared with those of monolithic sandwich structures and the effectiveness of the proposed innovative production method was evaluated. Re-entrant, star-shaped, and V-shaped auxetic core configurations were compared in terms of the bending performances of the adhesively bonded and monolithic sandwich structures. Monolithic and adhesively bonded sandwich structures showed similar bending behavior as far as load-carrying capacity, deformation stages, and crashworthiness performance are concerned based on three and four-point bending tests. Hence, the proposed innovative production approach can be applied to sandwich structures to enhance their repairability and support sustainable manufacturing.Article Citation - WoS: 10Citation - Scopus: 10Low Velocity Oblique Impact Behavior of Adhesively Bonded Single Lap Joints(Taylor & Francis Ltd, 2019) Atahan, M. Gokhan; Apalak, M. Kemal; Atahan, M. Gokhan; Apalak, M. KemalThis article addresses the low velocity oblique impact behavior of adhesively bonded single lap joints, and the effects of adherend strength and plastic ductility, impact energy, overlap length and oblique impact angle on the damage initiation and propagation in the adhesive layer. The experimental contact force-time, contact force-central displacement variations, axial separation lengths through the adhesive layer and permanent central deflections of overlap region, adhesive fracture surfaces were evaluated in detail. In the explicit finite element analyses, the adhesive layer was divided into three zones: upper and lower adhesive interfaces and the adhesive layer between these interfaces. The adhesive interfaces were modeled with cohesive zone approach to predict the failure initiation and propagation along both upper and lower adhesive-adherend interfaces, whereas the elastic-plastic material model was implemented for the middle adhesive region between the upper and lower adhesive interfaces. The proposed finite element model predicted reasonably the damage initiation and propagation through the adhesive layer, and the contact force-time/central displacement variations. Especially, the test and analysis results were compared with those of the adhesively bonded single lap joints under a normal transverse impact load. Increasing oblique impact angle resulted in lower peak contact forces, shorter contact durations and earlier damage initiation and propagation through the adhesive layer. The peak contact forces increased, the contact duration decreased with increasing impact energy. The strength and plastic deformation capability of adherend materials also affected the damage initiation and propagation through the adhesive layer as well as the after-impact joint geometry.