In this study, a novel low-cost polishing process is applied on the surface of Fused Deposition Modeling (FDM) products. The developed polishing technique impinges a jet of hot air exit from a nozzle to FDM surfaces. The hot air locally melts the staircase on the surface and leaves it smoother by the effect of sintering phenomenon. Accordingly, the process introduces three main parameters: air jet temperature; air jet velocity; and nozzle translational velocity over the part surface. An experimental test rig was constructed to evaluate the polishing process and its parameters using surfaces with average pre-processed Ra values of 7.5 ∓ 0.5 μm. The process shows significant and reproducible improvements in surface roughness inherent with a glossy surface; whereas, an average reduction ratio up to 88% was reached which corresponds to Ra of 0.85 μm. It was found that there is an allowable range of nozzle translational velocity for every combination between jet velocity and jet temperature; otherwise, lower nozzle velocity than allowable causes overheating and surface deterioration. Furthermore, the study presents in-depth investigation to these deterioration phenomena appeared on the surface. As a result, this investigation demonstrated the possible defects in FDM part surfaces and also evaluated different process parameters. Moreover, it was observed that surface defects are reduced in the polished surfaces. For a concise conclusion, it was found that the condition of low jet velocity and high jet temperature gives the best polishing result over the allowable nozzle velocities.

The present paper presents a heat transfer model to a new polishing process that smoothens the surface of products manufactured by fused deposition modeling (FDM) technology. FDM is one of the most common additive manufacturing techniques which, unfortunately, results in very rough surfaces when compared to similar technologies. This high roughness results from the stepped surface (stair like surface) caused by the technology nature of depositing several 2D layers to form the final 3D product. To smooth the surface, it is heated up till melting which trigger surface tension force to smooth the surface. To achieve surface melting, the surface is exposed to a localized hot air jet with certain temperature and velocity from a moving nozzle with appropriate translational velocity; this introduces three main process parameters: air jet temperature, air jet velocity and air nozzle translational velocity over the product surface. Two analytical heat transfer models were derived using different process parameters and proved to be in agreement with each other. Also, a part of the obtained experimental results verifies model results. Moreover, the effect of entrained air on the heated jet was considered in the model. It can be concluded that we have an analytical model fits the experimental one and represents the modeled process.

The present paper presents a heat transfer model to a new polishing process that smoothens the surface of products manufactured by fused deposition modeling (FDM) technology. FDM is one of the most common additive manufacturing techniques which, unfortunately, results in very rough surfaces when compared to similar technologies. This high roughness results from the stepped surface (stair like surface) caused by the technology nature of depositing several 2D layers to form the final 3D product. To smooth the surface, it is heated up till melting which trigger surface tension force to smooth the surface. To achieve surface melting, the surface is exposed to a localized hot air jet with certain temperature and velocity from a moving nozzle with appropriate translational velocity; this introduces three main process parameters: air jet temperature, air jet velocity and air nozzle translational velocity over the product surface. Two analytical heat transfer models were derived using different process parameters and proved to be in agreement with each other. Also, a part of the obtained experimental results verifies model results. Moreover, the effect of entrained air on the heated jet was considered in the model. It can be concluded that we have an analytical model fits the experimental one and represents the modeled process.

The present paper presents a heat transfer model to a new polishing process that smoothens the surface of products manufactured by fused deposition modeling (FDM) technology. FDM is one of the most common additive manufacturing techniques which, unfortunately, results in very rough surfaces when compared to similar technologies. This high roughness results from the stepped surface (stair like surface) caused by the technology nature of depositing several 2D layers to form the final 3D product. To smooth the surface, it is heated up till melting which trigger surface tension force to smooth the surface. To achieve surface melting, the surface is exposed to a localized hot air jet with certain temperature and velocity from a moving nozzle with appropriate translational velocity; this introduces three main process parameters: air jet temperature, air jet velocity and air nozzle translational velocity over the product surface. Two analytical heat transfer models were derived using different process parameters and proved to be in agreement with each other. Also, a part of the obtained experimental results verifies model results. Moreover, the effect of entrained air on the heated jet was considered in the model. It can be concluded that we have an analytical model fits the experimental one and represents the modeled process.

Fused deposition modeling (FDM) is the most versatile additive manufacturing technology owing to the low-cost materials that handle. However, FDM produce very rough parts which limit its use in molds and other industrial applications owing to stair-case effect. To obtain smoother surfaces, a post-processing phase may be introduced. In this research, a non-contact finishing process to FDM parts using hot air was developed. The hot air is directed locally at the stair-case in the surface till melting it which results after cooling to a smoother surface. An experimental setup was constructed to study the effects of different process parameters including air temperature, air flow rate and the moving velocity of air nozzle over parts surface. An improvement in the Roughness Average of a surfaces measured microscopic peaks and valleys (Ra) down to values of sub-micron was recorded from specimens with average surface roughness from7 to 8 μm.

Fused deposition modeling (FDM) is the most versatile additive manufacturing technology owing to the low-cost materials that handle. However, FDM produce very rough parts which limit its use in molds and other industrial applications owing to stair-case effect. To obtain smoother surfaces, a post-processing phase may be introduced. In this research, a non-contact finishing process to FDM parts using hot air was developed. The hot air is directed locally at the stair-case in the surface till melting it which results after cooling to a smoother surface. An experimental setup was constructed to study the effects of different process parameters including air temperature, air flow rate and the moving velocity of air nozzle over parts surface. An improvement in the Roughness Average of a surfaces measured microscopic peaks and valleys (Ra) down to values of sub-micron was recorded from specimens with average surface roughness from7 to 8 μm.

Fused deposition modeling (FDM) is the most versatile additive manufacturing technology owing to the low-cost materials that handle. However, FDM produce very rough parts which limit its use in molds and other industrial applications owing to stair-case effect. To obtain smoother surfaces, a post-processing phase may be introduced. In this research, a non-contact finishing process to FDM parts using hot air was developed. The hot air is directed locally at the stair-case in the surface till melting it which results after cooling to a smoother surface. An experimental setup was constructed to study the effects of different process parameters including air temperature, air flow rate and the moving velocity of air nozzle over parts surface. An improvement in the Roughness Average of a surfaces measured microscopic peaks and valleys (Ra) down to values of sub-micron was recorded from specimens with average surface roughness from7 to 8 μm.

Fused deposition modeling (FDM) is the most versatile additive manufacturing technology owing to the low-cost materials that handle. However, FDM produce very rough parts which limit its use in molds and other industrial applications owing to stair-case effect. To obtain smoother surfaces, a post-processing phase may be introduced. In this research, a non-contact finishing process to FDM parts using hot air was developed. The hot air is directed locally at the stair-case in the surface till melting it which results after cooling to a smoother surface. An experimental setup was constructed to study the effects of different process parameters including air temperature, air flow rate and the moving velocity of air nozzle over parts surface. An improvement in the Roughness Average of a surfaces measured microscopic peaks and valleys (Ra) down to values of sub-micron was recorded from specimens with average surface roughness from7 to 8 μm.

Fused deposition modeling (FDM) is the most versatile additive manufacturing technology owing to the low-cost materials that handle. However, FDM produce very rough parts which limit its use in molds and other industrial applications owing to stair-case effect. To obtain smoother surfaces, a post-processing phase may be introduced. In this research, a non-contact finishing process to FDM parts using hot air was developed. The hot air is directed locally at the stair-case in the surface till melting it which results after cooling to a smoother surface. An experimental setup was constructed to study the effects of different process parameters including air temperature, air flow rate and the moving velocity of air nozzle over parts surface. An improvement in the Roughness Average of a surfaces measured microscopic peaks and valleys (Ra) down to values of sub-micron was recorded from specimens with average surface roughness from7 to 8 μm.

Post-earthquake damages investigation in past and recent earthquakes has illustrated that the ground motion spatial variation plays an important role in the structural response of long span bridges. For the structural control of seismic-induced vibrations of cable-stayed bridges, it is extremely important to include the effects of the ground motion spatial variation in the analysis for design of an effective control system. The feasibility and efficiency of different vibration control strategies for the cable-stayed bridge under multiple support excitations have been examined to enhance a structure’s ability to withstand earthquake excitations. Comparison of the response due to non-uniform input ground motion with that due to uniform input demonstrates the importance of accounting for spatial variability of excitations. The performance of the optimized designed control systems for uniform input excitations gets worse dramatically over almost all of the evaluation criteria under multiple-support excitations.