nader zirak - Academia.edu (original) (raw)

Papers by nader zirak

Research paper thumbnail of Optimization of FFF Processing Parameters to Improve Geometrical Accuracy and Mechanical Behavior of Polyamide 6 Using Grey Relational Analysis (GRA)

One of the most widely used additive manufacturing (AM) methods is Fused Filament Fabrication (FF... more One of the most widely used additive manufacturing (AM) methods is Fused Filament Fabrication (FFF), which can produce complex geometry parts. In this process, a continuous filament of thermoplastic material is deposited layer by layer to make the final piece. One of the essential goals in the production of parts with this method is to produce parts with high mechanical properties and excellent geometrical accuracy at the same time. Among the various methods used to improve the desired properties of produced parts is to determine the optimum process parameters in this process. This paper investigates the effect of different process parameters on four essential parameters: chamber temperature, Printing temperature, layer thickness, and print speed on cylindricity, circularity, strength, Young’s modulus, and deformation by Gray Relational Analysis method simultaneously. Taguchi method was used to design the experiments, and the PA6 cylindrical parts were fabricated using a German RepR...

Research paper thumbnail of Fatigue life prediction for amorphous glassy polymers based on cumulative evolution of micro-defects

International Journal of Fatigue

Research paper thumbnail of Effect of build orientation and post-curing of (meth)acrylate‐based photocurable resin fabricated by stereolithography on the mechanical behavior from quasi-static to high strain rate loadings

The International Journal of Advanced Manufacturing Technology

Stereolithography (SLA) is becoming an important fabrication method among the different additive ... more Stereolithography (SLA) is becoming an important fabrication method among the different additive manufacturing (AM) techniques. This study investigates the effect of high strain rate on mechanical behavior, considering the fact that, materials can be shown different mechanical properties under rapid straining compared to quasi-static loading. In addition, the role of polymerization as a determining factor in the nal mechanical properties of the SLA parts is indicated. Regarding, samples based on urethane dimethacrylate resin material were printed in different directions (θ = [0-90]) and post-treatment was performed with respect to the UV and UV with temperature. The effect of high strain rate was analyzed through a servo-hydraulic machine, monotonic, and interrupted tensile tests ranging from 0.3 to 117.4 s-1. Scanning electron microscopy (SEM) was applied to analyze the failure surface characteristics. The results show the important effect of strain rate on mechanical properties such that by increasing the strain rate, yield stress and ultimate stress were increased. Furthermore, investigation of the strain rate sensitivity during the different steps of the failure indicates more sensitivity of the non-linear zone of the stress-strain curve with strain rate.

Research paper thumbnail of An Overview of In Vitro Drug Release Methods for Drug-Eluting Stents

Polymers

The drug release profile of drug-eluting stents (DESs) is affected by a number of factors, includ... more The drug release profile of drug-eluting stents (DESs) is affected by a number of factors, including the formulation, design, and physicochemical properties of the utilized material. DES has been around for twenty years and despite its widespread clinical use, and efficacy in lowering the rate of target lesion restenosis, it still requires additional development to reduce side effects and provide long-term clinical stability. Unfortunately, for analyzing these implants, there is still no globally accepted in vitro test method. This is owing to the stent’s complexity as well as the dynamic arterial compartments of the blood and vascular wall. The former is the source of numerous biological, chemical, and physical mechanisms that are more commonly observed in tissue, lumen, and DES. As a result, universalizing bio-relevant apparatus, suitable for liberation testing of such complex implants is difficult. This article aims to provide a comprehensive review of the methods used for in vit...

Research paper thumbnail of Mechanical strength and shape accuracy optimization of polyamide FFF parts using grey relational analysis

Scientific Reports

This paper investigates the effect of different additive manufacturing process parameters such as... more This paper investigates the effect of different additive manufacturing process parameters such as chamber temperature, Printing temperature, layer thickness, and print speed on five essential parameters that characterize the manufactured components: cylindricity, circularity, strength, and Young’s modulus, and deformation by Gray Relational Analysis method simultaneously. Taguchi method was used to design the experiments, and the PA6 cylindrical parts were fabricated using a German RepRap X500® 3D printer. Then the Gray Relational Grade (GRG) values were calculated for all experiments. In the 8th trial, the highest value of GRG was observed. Then, to discover the optimal parameters, the GRG data were analyzed using ANOVA and S/N analysis, and it was determined that the best conditions for enhancing GRG are 60 °C in the chamber temperature, 270 °C in the printing temperature, 0.1 mm layer thickness, and 600 mm/min print speed. Finally, by using optimal parameters, a verification test...

Research paper thumbnail of Stereolithography of (meth)acrylate‐based photocurable resin: Thermal and mechanical properties

Journal of Applied Polymer Science

Research paper thumbnail of Toward Polymeric and Polymer Composites Impeller Fabrication

Polymers

Impellers are referred to as a core component of turbomachinery. The use of impellers in various ... more Impellers are referred to as a core component of turbomachinery. The use of impellers in various applications is considered an integral part of the industry. So, increased performance and the optimization of impellers have been the center of attention of a lot of studies. In this regard, studies have been focused on the improvement of the efficiency of rotary machines through aerodynamic optimization, using high-performance materials and suitable manufacturing processes. As such, the use of polymers and polymer composites due to their lower weight when compared to metals has been the focus of studies. On the other hand, methods of the manufacturing process for polymer and polymer composite impellers such as conventional impeller manufacturing, injection molding and additive manufacturing can offer higher economic efficiency than similar metal parts. In this study, polymeric and polymer composites impellers are discussed and conclusions are drawn according to the manufacturing method...

Research paper thumbnail of Controlled release from polyurethane films: Drug release mechanisms

Journal of Applied Polymer Science

Research paper thumbnail of Optimization of FFF Processing Parameters to Improve Geometrical Accuracy and Mechanical Behavior of Polyamide 6 Using Grey Relational Analysis (GRA)

One of the most widely used additive manufacturing (AM) methods is Fused Filament Fabrication (FF... more One of the most widely used additive manufacturing (AM) methods is Fused Filament Fabrication (FFF), which can produce complex geometry parts. In this process, a continuous filament of thermoplastic material is deposited layer by layer to make the final piece. One of the essential goals in the production of parts with this method is to produce parts with high mechanical properties and excellent geometrical accuracy at the same time. Among the various methods used to improve the desired properties of produced parts is to determine the optimum process parameters in this process. This paper investigates the effect of different process parameters on four essential parameters: chamber temperature, Printing temperature, layer thickness, and print speed on cylindricity, circularity, strength, Young’s modulus, and deformation by Gray Relational Analysis method simultaneously. Taguchi method was used to design the experiments, and the PA6 cylindrical parts were fabricated using a German RepR...

Research paper thumbnail of Fatigue life prediction for amorphous glassy polymers based on cumulative evolution of micro-defects

International Journal of Fatigue

Research paper thumbnail of Effect of build orientation and post-curing of (meth)acrylate‐based photocurable resin fabricated by stereolithography on the mechanical behavior from quasi-static to high strain rate loadings

The International Journal of Advanced Manufacturing Technology

Stereolithography (SLA) is becoming an important fabrication method among the different additive ... more Stereolithography (SLA) is becoming an important fabrication method among the different additive manufacturing (AM) techniques. This study investigates the effect of high strain rate on mechanical behavior, considering the fact that, materials can be shown different mechanical properties under rapid straining compared to quasi-static loading. In addition, the role of polymerization as a determining factor in the nal mechanical properties of the SLA parts is indicated. Regarding, samples based on urethane dimethacrylate resin material were printed in different directions (θ = [0-90]) and post-treatment was performed with respect to the UV and UV with temperature. The effect of high strain rate was analyzed through a servo-hydraulic machine, monotonic, and interrupted tensile tests ranging from 0.3 to 117.4 s-1. Scanning electron microscopy (SEM) was applied to analyze the failure surface characteristics. The results show the important effect of strain rate on mechanical properties such that by increasing the strain rate, yield stress and ultimate stress were increased. Furthermore, investigation of the strain rate sensitivity during the different steps of the failure indicates more sensitivity of the non-linear zone of the stress-strain curve with strain rate.

Research paper thumbnail of An Overview of In Vitro Drug Release Methods for Drug-Eluting Stents

Polymers

The drug release profile of drug-eluting stents (DESs) is affected by a number of factors, includ... more The drug release profile of drug-eluting stents (DESs) is affected by a number of factors, including the formulation, design, and physicochemical properties of the utilized material. DES has been around for twenty years and despite its widespread clinical use, and efficacy in lowering the rate of target lesion restenosis, it still requires additional development to reduce side effects and provide long-term clinical stability. Unfortunately, for analyzing these implants, there is still no globally accepted in vitro test method. This is owing to the stent’s complexity as well as the dynamic arterial compartments of the blood and vascular wall. The former is the source of numerous biological, chemical, and physical mechanisms that are more commonly observed in tissue, lumen, and DES. As a result, universalizing bio-relevant apparatus, suitable for liberation testing of such complex implants is difficult. This article aims to provide a comprehensive review of the methods used for in vit...

Research paper thumbnail of Mechanical strength and shape accuracy optimization of polyamide FFF parts using grey relational analysis

Scientific Reports

This paper investigates the effect of different additive manufacturing process parameters such as... more This paper investigates the effect of different additive manufacturing process parameters such as chamber temperature, Printing temperature, layer thickness, and print speed on five essential parameters that characterize the manufactured components: cylindricity, circularity, strength, and Young’s modulus, and deformation by Gray Relational Analysis method simultaneously. Taguchi method was used to design the experiments, and the PA6 cylindrical parts were fabricated using a German RepRap X500® 3D printer. Then the Gray Relational Grade (GRG) values were calculated for all experiments. In the 8th trial, the highest value of GRG was observed. Then, to discover the optimal parameters, the GRG data were analyzed using ANOVA and S/N analysis, and it was determined that the best conditions for enhancing GRG are 60 °C in the chamber temperature, 270 °C in the printing temperature, 0.1 mm layer thickness, and 600 mm/min print speed. Finally, by using optimal parameters, a verification test...

Research paper thumbnail of Stereolithography of (meth)acrylate‐based photocurable resin: Thermal and mechanical properties

Journal of Applied Polymer Science

Research paper thumbnail of Toward Polymeric and Polymer Composites Impeller Fabrication

Polymers

Impellers are referred to as a core component of turbomachinery. The use of impellers in various ... more Impellers are referred to as a core component of turbomachinery. The use of impellers in various applications is considered an integral part of the industry. So, increased performance and the optimization of impellers have been the center of attention of a lot of studies. In this regard, studies have been focused on the improvement of the efficiency of rotary machines through aerodynamic optimization, using high-performance materials and suitable manufacturing processes. As such, the use of polymers and polymer composites due to their lower weight when compared to metals has been the focus of studies. On the other hand, methods of the manufacturing process for polymer and polymer composite impellers such as conventional impeller manufacturing, injection molding and additive manufacturing can offer higher economic efficiency than similar metal parts. In this study, polymeric and polymer composites impellers are discussed and conclusions are drawn according to the manufacturing method...

Research paper thumbnail of Controlled release from polyurethane films: Drug release mechanisms

Journal of Applied Polymer Science