alp karakoc - Academia.edu (original) (raw)

Papers by alp karakoc

Journal of Reinforced Plastics and Composites

The present study concentrates on a series of experiments and numerical analyses for understandin... more The present study concentrates on a series of experiments and numerical analyses for understanding the effects of fiber volume fraction ( VF) and draw ratio ( DR) on the effective elastic properties of unidirectional composites made from an epoxy resin matrix with a continuous fiber reinforcement. Lyocell-type regenerated cellulose filaments (Ioncell) spun with DRs of 3, 6, and 9 were used. In accordance with the specimens in situ, the fibers were modeled as slender solid elements, for which the ratio between the diameter and length was taken to be much less than unity and deposited inside the matrix with the random sequential adsorption algorithm. The embedded element method was thereafter used in the numerical framework due to its computational advantages and reasonable predictions for continuous fiber reinforced composites. Experiments and numerical investigations were carried out, the results of which were compared, and positive trends for both fiber VFs and DRs on the effective...

Inspired by crab exoskeleton, fused deposition modeling (FDM) was used to control local depositio... more Inspired by crab exoskeleton, fused deposition modeling (FDM) was used to control local deposition of acrylonitrile‐butadiene‐styrene (ABS) polymer and local porosity. Effects of four different meso-scale structures on the stochastic mechanical properties were investigated. Tensile tests showed that the biomimetic Bouligand structure increases strength, strain at break, toughness, and mechanical reliability of additively manufactured porous ABS. Change in meso-scale structures impacted variations in mechanical properties. Weibull moduli--as an indication of variation in properties--ranged from 17 to 54 for fracture strength. Variations in strain at break were higher compared to strength with a Weibull modulus between 6 and 16. Finite element simulations captured the experimental fracture behavior of porous structures. Simulations revealed significant damage accumulation in porous Bouligand structures.

Innovations in industrial automation, information and communication technology (ICT), renewable e... more Innovations in industrial automation, information and communication technology (ICT), renewable energy, monitoring and sensing fields have been paving the way for smart devices, which can acquire and convey information to the internet, in every aspect of our lives. Since there is ever-increasing demand for large yet affordable production volumes for such devices, printed electronics has been attracting great attention in both industrial and academic research. In order to understand the potential and future prospects of the printed electronics, the present paper summarizes the basic principles and conventional approaches while providing the recent progresses in the fabrication and material technologies, applications and environmental impacts.

Geotechnical Earthquake Engineering and Soil Dynamics V

Fragility-based seismic performance assessment and design procedures are being refined and adopte... more Fragility-based seismic performance assessment and design procedures are being refined and adopted for many civil structures. With recent advances in computational capabilities as well as broad improvements in ground motion characterization and inelastic modeling of structural and geotechnical systems, large-scale direct models for underground structures—e.g., tunnels, water reservoirs, etc.—can now be devised with relative ease and deployed in engineering practice. In this study, we present a fragility-based seismic performance assessment of a large buried water reservoir. We use existing documents/codes to define the performance criteria and develop fragility functions through a probabilistic seismic demand analysis (PSDA) procedure. The analyses incorporate inelastic/nonlinear behavior of soils and structural components, and account for uncertainties in the expected ground motions. The seismic performance assessment methodology presented herein can be applied to other large underground reservoirs

Juniper Online Journal Material Science, 2017

Sustainability has been a decisive factor in selection of materials for the built environment due... more Sustainability has been a decisive factor in selection of materials for the built environment due to increasing demand of materials despite the limited resources. The present study thus provides an insight into some measures of sustainable building material selection based on various rating systems and international standards.

International Journal of Solids and Structures, 2015

ABSTRACT Rigidity of complex cellular materials, such as wood, depends on multiple geometrical an... more ABSTRACT Rigidity of complex cellular materials, such as wood, depends on multiple geometrical and mechanical parameters of the cell and cell structure. Computational homogenization method gives the effective elastic properties of an infinitely large collection of cells out of a calculation on the representative cell. If the geometric and material properties of the cells are considered constants so that the cell structure can be though to be built from translating and copying the representative cell. Cell shape, cell wall thickness, and anisotropic elastic properties of the cell wall are accounted for in the application, whereas the cell structure is considered regular. The model gives the effective rigidity of a sample of earlywood, transition-/latewood. The effect of the cell shape and cell wall properties on the effective rigidity is illustrated.

Journal of Reinforced Plastics and Composites

The present study concentrates on a series of experiments and numerical analyses for understandin... more The present study concentrates on a series of experiments and numerical analyses for understanding the effects of fiber volume fraction ( VF) and draw ratio ( DR) on the effective elastic properties of unidirectional composites made from an epoxy resin matrix with a continuous fiber reinforcement. Lyocell-type regenerated cellulose filaments (Ioncell) spun with DRs of 3, 6, and 9 were used. In accordance with the specimens in situ, the fibers were modeled as slender solid elements, for which the ratio between the diameter and length was taken to be much less than unity and deposited inside the matrix with the random sequential adsorption algorithm. The embedded element method was thereafter used in the numerical framework due to its computational advantages and reasonable predictions for continuous fiber reinforced composites. Experiments and numerical investigations were carried out, the results of which were compared, and positive trends for both fiber VFs and DRs on the effective...

Inspired by crab exoskeleton, fused deposition modeling (FDM) was used to control local depositio... more Inspired by crab exoskeleton, fused deposition modeling (FDM) was used to control local deposition of acrylonitrile‐butadiene‐styrene (ABS) polymer and local porosity. Effects of four different meso-scale structures on the stochastic mechanical properties were investigated. Tensile tests showed that the biomimetic Bouligand structure increases strength, strain at break, toughness, and mechanical reliability of additively manufactured porous ABS. Change in meso-scale structures impacted variations in mechanical properties. Weibull moduli--as an indication of variation in properties--ranged from 17 to 54 for fracture strength. Variations in strain at break were higher compared to strength with a Weibull modulus between 6 and 16. Finite element simulations captured the experimental fracture behavior of porous structures. Simulations revealed significant damage accumulation in porous Bouligand structures.

Innovations in industrial automation, information and communication technology (ICT), renewable e... more Innovations in industrial automation, information and communication technology (ICT), renewable energy, monitoring and sensing fields have been paving the way for smart devices, which can acquire and convey information to the internet, in every aspect of our lives. Since there is ever-increasing demand for large yet affordable production volumes for such devices, printed electronics has been attracting great attention in both industrial and academic research. In order to understand the potential and future prospects of the printed electronics, the present paper summarizes the basic principles and conventional approaches while providing the recent progresses in the fabrication and material technologies, applications and environmental impacts.

Geotechnical Earthquake Engineering and Soil Dynamics V

Fragility-based seismic performance assessment and design procedures are being refined and adopte... more Fragility-based seismic performance assessment and design procedures are being refined and adopted for many civil structures. With recent advances in computational capabilities as well as broad improvements in ground motion characterization and inelastic modeling of structural and geotechnical systems, large-scale direct models for underground structures—e.g., tunnels, water reservoirs, etc.—can now be devised with relative ease and deployed in engineering practice. In this study, we present a fragility-based seismic performance assessment of a large buried water reservoir. We use existing documents/codes to define the performance criteria and develop fragility functions through a probabilistic seismic demand analysis (PSDA) procedure. The analyses incorporate inelastic/nonlinear behavior of soils and structural components, and account for uncertainties in the expected ground motions. The seismic performance assessment methodology presented herein can be applied to other large underground reservoirs

Juniper Online Journal Material Science, 2017

Sustainability has been a decisive factor in selection of materials for the built environment due... more Sustainability has been a decisive factor in selection of materials for the built environment due to increasing demand of materials despite the limited resources. The present study thus provides an insight into some measures of sustainable building material selection based on various rating systems and international standards.

International Journal of Solids and Structures, 2015

ABSTRACT Rigidity of complex cellular materials, such as wood, depends on multiple geometrical an... more ABSTRACT Rigidity of complex cellular materials, such as wood, depends on multiple geometrical and mechanical parameters of the cell and cell structure. Computational homogenization method gives the effective elastic properties of an infinitely large collection of cells out of a calculation on the representative cell. If the geometric and material properties of the cells are considered constants so that the cell structure can be though to be built from translating and copying the representative cell. Cell shape, cell wall thickness, and anisotropic elastic properties of the cell wall are accounted for in the application, whereas the cell structure is considered regular. The model gives the effective rigidity of a sample of earlywood, transition-/latewood. The effect of the cell shape and cell wall properties on the effective rigidity is illustrated.