2 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 2 / 2
Yayın Measurement and assessment of fatigue life of spot-weld joints(Asme-Amer Soc Mechanical Eng, 2009-01) Ertaş, Ahmet Hanifi; Vardar, Öktem; Sönmez, Fazıl Önder; Solim, ZaferSpot-weld joints are commonly used to fasten together metal sheets. Because fatigue fracture is the most critical failure mode for these joints under fluctuating loads, understanding their fatigue failure behavior and assessment of their fatigue lives are crucial from the viewpoint of failure prevention in design. In this study, a series of experiments was conducted to study the fatigue failure of spot-welded modified tensile-shear specimens made of a low carbon steel. Two different types of resistance spot welding were investigated (manual and automated). Tests were repeated under different load ranges, and the corresponding fatigue lives were determined. The specimens were also examined under an optical microscope. In the numerical part of this study, a finite element analysis was carried out using commercial software, ANSYS, to determine the stress and strain states within the specimens. The material nonlinearity, local plastic deformations around the welds during loading, and the residual stresses and strains developed after unloading as a result of plastic deformations were taken into account. Based on the predicted stress and strain states, fatigue analyses were performed using several models for life assessment. Then, the measured and predicted fatigue lives were compared, and the suitability of the models was discussed. Among the strain-based models, Coffin-Manson and Morrow's means stress models yielded the best predictions.Yayın Enhancement of epoxy properties through graphene nanofillers produced in molten salt: morphological, thermal and mechanical characterization(Springer, 2026) Gül, Ayşenur; Kamali, Ali RezaThis research investigates the enhancement of epoxy resin properties through the incorporation of graphene nanoplatelets (GNPs), synthesized via the molten salt exfoliation method, as nanofillers. The study evaluates the morphology, thermal conductivity, and mechanical performance of the resulting nanocomposites. Electron microscopy reveals a high density of reactive edge sites in the graphene material, which enable bonding with epoxy groups during curing. It also shows a uniform dispersion of graphene nanoplatelets (GNPs) within the epoxy matrix, leading to reduced void formation and enhanced interfacial bonding. A notable improvement in the physical and mechanical properties of the epoxy was observed with the addition of GNPs up to 1.0 wt%. At this concentration, Young’s modulus increased by approximately 42% (from 2.9 to 4.2 GPa), while thermal conductivity, compressive strength, and tensile strength improved by around 41%, 9%, and 32%, respectively. These findings indicate that the integration of GNPs into epoxy resin significantly enhances both thermal and mechanical performance, positioning the nanocomposites as strong candidates for advanced structural applications.
