Makina Mühendisliği

Bu koleksiyon için kalıcı URI

http://hdl.handle.net/11527/25302

Gözat

Konu "additive manufacturing" ile Makina Mühendisliği'a göz atma
  • Öge
    Analytical and numerical modeling on strengths of aluminum and magnesium micro-lattice structures fabricated via additive manufacturing
    (Springer, 2024) Sun, Yeting ; Akçay, Fuzuli Ağrı ; Wu, Dazhong ; Bai, Yuanli ; 0000-0002-5116-0069 ; Makina Mühendisliği
    Bioinspired lattice structures have a wide range of applications in aerospace, automotive, energy, and medical device industries due to their high strength-to-weight ratio. Although experimental and numerical modeling methods have been extensively used to characterize the compressive behavior of lattice structures, an accurate analytical model has great values in material/structure designs and applications. In this study, a new analytical model is developed for two configurations based on limit analysis in the plasticity theory to predict the compressive strengths of micro-lattice structures (MLS). The model is also discussed for determining the amounts of stretching-dominated deformation and bending-dominated deformation. A comparative study is performed between analytical solutions and experimental results of AlSi10Mg (aluminum alloy) and WE43 (magnesium alloy) MLS additively manufactured via selective laser melting (SLM). Finite element simulations using beam elements are conducted to evaluate the accuracy of the analytical solution. Analytical results, finite element simulation results, and the experimental results are in a good agreement with both AlSi10Mg and WE43 MLS. The shear band formation, as a main failure mode of MLS, is also studied and evaluated using the classical Rudnicki–Rice’s criterion, for which a reasonably good accuracy is demonstrated.
  • Öge
    Effects of particle damper design parameters on the damping performance of laser powder bed fused structures
    (Springer, 2024) Özçevik, Birol ; Söylemez, Emrecan ; Bediz, Bekir ; Şimşek, Uğur ; 0000-0003-4003-9287 ; 0000-0003-4827-2606 ; 0000-0002-7925-8228 ; 0000-0002-4405-5420 ; Mechanical Engineering
    Particle dampers (PD), a passive damping technology, absorb energy from particle-particle and particle-cell wall interactions originating from friction and collision. PDs offer advantages such as design simplicity, low cost, applicability in harsh conditions, and flexibility to be used in a wide frequency band range. Additive manufacturing, specifically the powder bed fusion process, can fabricate structures with integrated PDs in a single printing process, eliminating the need to implement external dampers. However, the dynamic behavior of PDs must be determined to utilize their full potential. In this study, we examined 16 cases of integrated PDs by varying specific parameters including size, number, and locations on the structure to understand the effects of these parameters on the dynamic behavior of the first and second modes of the structure. Modal tests were conducted on additively manufactured samples to extract frequency response functions and calculate modal parameters (natural frequency and damping ratio) using the rational fraction polynomial method, studying the effects of PDs. The results showed that the damping performance of the parts was increased by a factor of up to 10 using body-integrated PDs compared with the fully fused specimen. The effectiveness of body-integrated PDs was shown to be strongly dependent on their volume and location. For instance, the damping generally increased as the volume fraction increased, which also reduced the total weight of the specimens by up to 60 g. Furthermore, the damping performance significantly increased for a specific mode when the PDs were located near the maximum displacement regions.
  • Öge
    Evaluation of mechanical properties of additively manufactured beams with lattice structures
    (American Society of Mechanical Engineers, 2024) Pir, İnci ; Şahin, Serhat Arda ; Tüfekci, Mertol ; Tufekci, Ekrem ; Makina Mühendisliği
    The use of lattice structurses is becoming more common day by day. Limitations such as being expensive and time-consuming have led to a search for new solutions in the industry. In light of these limitations, the widespread use of 3D printing technology methods is evaluated. 3D printing technology has advantages in terms of design flexibility, quick prototyping, lightness and the ability to produce complex shapes. 3D printing is used to systematically investigate different geometries in line with the requirements of sustainable product development, leading to the production of auxiliary structures that are both strong and lightweight. This research investigates the mechanical properties of various lattice structures that were previously modelled and analysed through analytical methods in the literature. The samples with five different auxetic structures are manufactured using the Fused Deposition Modelling (FDM) 3D printing technique, with Acrylonitrile Butadiene Styrene (ABS) as the selected material. The manufactured samples are subjected to a three-point bending test to assess their mechanical characteristics, including the flexural modulus, flexural strength, and elongation at break, and the effect of the in-plane geometry on the mechanical behaviour is evaluated.
  • Öge
    The microstructural evolution of material extrusion based additive manufacturing of polyetheretherketone under different printing conditions and application in a spinal implant
    (Wiley, 2024) Irez, Alaeddin Burak ; Dogru, Alperen ; orcid.org/0000-0001-7316-7694 ; orcid.org/0000-0003-3730-3761 ; Makina Mühendisliği
    With the advances in additive manufacturing, polyetheretherketone (PEEK), a biocompatible polymer, can be used in biomedical applications such as spinal implants. This paper aims to investigate the evolution of the microstructure of PEEK parts manufactured by material extrusion (MEX)-based additive manufacturing with different printing parameters. The effect of layer thickness (LT) and nozzle diameter on mechanical properties was investigated using tensile, Charpy impact, and short beam strength (SBS) tests. Two different LTs, 0.1 and 0.2 mm, and two different nozzle diameters, 0.6 and 0.8 mm, were used as printing parameters. By increasing the LT, tensile strength dropped by around 24%, and impact strength by almost 55%. Moreover, altering the LT resulted in a 15% decrease in interlaminar shear strength (ILSS) from the SBS test. In addition, increasing the nozzle diameter also led to a significant reduction in all of the results as tensile strength, Charpy impact strength, and ILSS. The results were also consolidated by scanning electron microscopy. The main findings were that increasing LT leads to an increase in microstructural defects that act as stress concentrators. Following the tests, response surface methodology (RSM) was used to determine optimal printing parameters. In the end, using the optimum printing parameters from the RSM study, a structural analysis of a MEX-printed spinal implant was conducted through finite element method, considering the loading cases mimicking daily human body motions. Highlights As layer thickness increased, tensile and impact strength dropped. Tensile and impact strength dropped truly with increasing nozzle diameter. SEM revealed that increasing layer thickness causes more microstructural flaws. FEM analysis showed that PEEK-based implant provides structural integrity.