جستجوی مقالات مرتبط با کلیدواژه « fused deposition modeling (fdm) » در نشریات گروه « مکانیک »

Today, the use of additive manufacturing has grown significantly in various industries, including the medical field, and one of its most recent applications in this field is the production of lumbar fusion cage implants. Considering the high impact of interlayer adhesion on the final life of parts made by 3D printing method, in this study, using finite element analysis to predict fatigue failure in lower back vertebra implants made by 3D printing has been studied. In this regard, using the fused deposition modeling (FDM) method, several samples of standard tensile test parts and lower back vertebrae have been made, and mechanical strength tests have been performed. The material used to carry out this research is polylactic acid, with this material, in both horizontal and vertical directions, the standard tensile and fatigue samples with the characteristics of layer thickness of 0.3 mm, nozzle diameter of 0.4 mm, print angle 45/45 and the production speed of 20 mm/s have been printed. The obtained results show that the printing alignment of the parts is very effective in the fatigue life of the parts and the finite element model predicts the fatigue life of the parts with acceptable accuracy.

Fused Deposition Modeling (FDM) 3D printing is one of the fast-growing types of Rapid Prototyping (RP) technology. 3D printing refers to fabricating a physical object from a 3D digital model by laying down successive thin layers of material. The mechanical properties and quality of the printed objects are extensively dependent on various print parameters. This study aimed to find optimized tuning parameters of print such as nozzle diameter and speed and temperature of print to improve accuracy in the prototyped part. For this purpose, the type and material of the employed profiles were first improved during the structural design of the printer, such that the structural vibrations of the device were removed considerably. Secondly, the nozzle vibrations were reduced by the redesign of the printer’s extruder. The stop/start movement of the axes was optimized through the control of the driving stepper motors of the printer’s axes. The effect of these three optimization steps enhanced the accuracy of the printer to a considerable extent. In The experimental tests, various combinations of print parameters have been examined to find the best settings. Printing of the standard model evaluated the accuracy of the printer and confirmed the validity of the results.

Today, due to the importance of reducing the time between design and production, the use of methods such as fused deposition modeling (FDM), is considered as a good alternative compared to reduction production methods. Poly lactic acid (PLA) is used as a biocompatible polymer in many engineering and medical fields. Improving the long-term load bearing capacity of such products is one of the essential criteria to ensure the proper performance of these components. In this study, in order to improve the fatigue life and creep resistance of samples made of poly lactic acid polymer during the fused deposition modeling, to evaluate the effect of layer height, layer thickness, infill percentage and infill pattern on fatigue behavior. And creep resistance of the samples was investigated. Also, in order to benefit from statistical analysis, the response surface methodology has been used. Analysis of variance (ANOVA) showed that the percentage of filling and layer thickness had the greatest effect on increasing the fatigue life and reducing the creep rate of the samples. The results showed that layering based on layer height of 0.1 mm, layer thickness of 0.3 mm, infill percentage of 75% using honeycomb pattern had the highest fatigue life and creep resistance of the samples.

The advancement of AM technologies has resulted in producing parts of high quality and reduced manufacturing time. The purpose of this study is to simultaneously optimize the values of two response variables, build time and surface roughness. In order to achieve the best values for build orientation and other process parameters including raster width, layer thickness, infill percentage, and raster angle, the effects of process parameters and response variables were adopted by the Design of Experiments approach to develop empirical models using Response Surface Methodology. The experimental parts of this research were conducted using an inexpensive and locally assembled FDM machine. Fifty runs for two different geometries, namely cylinder and 3DBenchy, were performed using the Rotatable Central Composite Design, and each process parameters was investigated in two levels in order to develop empirical models. Also, a novel optimization method, namely, the Posterior-Based method, was accomplished to find the best values for the response variables. The results demonstrated that not only build orientation and layer thickness have notable effects on both response variables but also build time is dependent on raster width and infill percentage. This study shows that through adopting the developed model by considering the process parameters, parts of high quality (improved surface finish) with reduced build time could be produced by FDM technology. Optimum process parameters found to be build direction of 0°, raster width of 0.61 mm, layer thickness of 0.22 mm, infill percentage of 20%, and raster angle of 0°.

Due to the increasing need of industries to prototyping with the highest accuracy and lowest cost, the application of rapid prototyping technology as a modern and rapid method has been considered to reduce the time between design to production and market to product. Fused deposition modeling is one of the most common methods in 3D printing and rapid prototyping, but the components produced in this way are usually of poor geometric accuracy and surface quality. Circularity error in the cavities is one of the important geometrical and tolerances errors. In this study, the experimental study the effect of process parameters such as layers thickness, temperature and speed of nozzle on the surface roughness and circularity error of the samples is investigated. The sample is a rectangular that has three holes in three different plates and the measurement of circularity error and surface roughness have been done in three directions and three different plates, respectively.The results showed that the lowest values were obtained for the surface roughness of the holes in the XY plane for a nozzle temperature 270 °C, printing speed 30 mm / s and layer thickness 0.2 mm. Also, the minimum value for the circularity error of the holes was obtained on the XY plate for the nozzle temperature 210 °C, printing speed 30 mm / s and layer thickness 0.4 mm. During the response surface optimization, the model optimized value was 1.174 μm for the surface roughness and 0.114 mm for the circularity error.

3D printing technology is used in a variety of industries without auxiliary tools because it is flexible in producing and reduces the waste of material. In this paper, the laser cutting process of polylactic acid sheets has been investigated by a 3D printer. The fused deposition modeling (FDM) method was used for printing the sheets. Production of sheets with a thickness of 2.3 mm by optimal conditions was conducted (each layer was perfectly solid with a thickness of 0.27 mm, and the extruder temperature of 226.62 °C). The laser used in this paper is a CO2 low-power, continuous-wave laser. Laser input parameters including laser cutting speed, focal point position, and laser power were selected as the variables. By performing several experiments, the effective range of each parameter was evaluated. The upper and lower cut width, the angle of cone and the upper cut width ratio to the lower cut width of the process output parameters were selected. The optical microscope was used to examine the geometric characteristics of cutting kerf of the samples and then the images were measured using ImageJ software. The purpose of this paper is the laser cutting process to achieve cutting kerfs with good quality and proper setting of laser input parameters.