In this work, we apply the radial basis functions for solving the time fractional diffusion-wave equation defined by Caputo sense for (1<a£2). The problem is discretized in the time direction based on finite difference scheme and is continuously approximated by using the radial basis functions in the space direction which achieves the semi-discrete solution. Numerical results show the accuracy and efficiency of the presented method.

In the present study, magnesium aluminate bio-ceramic (MgAl2O4) with particle size of 27 to 40 nm was produced by combustion synthesis method. Also, PLA/MgAl2O4 polymer matrix composites were made using FDM and slurry welding methods and their properties were studied and compared. X-ray diffraction (XRD), scanning electron microscope (FE-SEM), infrared spectrometer (FT-IR) and inductively coupled plasma spectroscopy (ICP) were used to investigate the properties of the produced composites. XRD results showed that in the composite samples synthesized by FDM method, PLA has more crystallinity than the slurry method, which is caused by relatively slow cooling of the polymer melt. To investigate the bioactive properties of this composite, the simulated body solution (SBF) was used and the results of the ICP test showed that the amount of calcium and phosphorus in the fourth week in the PLA/MgAl2O4 printed sample was the highest and equal to 77 mg/L and respectively were 40 mg/L. These results show that the processing of these composites by the 3D printing method brings more degradability than the slurry method and has a higher quality for biological uses.

Additive manufacturing is an advanced manufacturing method, one of which is FDM, which can produce parts from filaments with different materials. One of the most widely used components in various industries is lightweight grid structures that are formed by repeating unit cells and come in different sizes and designs that are also produced from recycled or environmentally friendly materials. In this paper, network structures were made by FDM with two different types of filaments: plain and carbon fiber-reinforced Polylactic Acid (PLA) with square unit cells. The printed samples were placed in three different environments for one week: air, ambient temperature seawater solution, and seawater solution using a plate heater above 45°C, and then a pressure test was performed on them. The results showed that the samples placed in high-temperature seawater solution had the highest compressive force, which was related to better adhesion of the layers due to high temperature, and placing the samples in ambient temperature sea salt solution caused a decrease in compressive force. Also, a higher compressive force was obtained for samples impregnated with plain PLA fibers, and adding carbon fibers to the filament base material caused a decrease in compressive force. The use of variable square hole patterns reduced the compressive strength, with the one-sided pattern showing a 67% reduction in strength in cold brine compared to the plain condition. The compressive strength of samples exposed to hot brine was on average 10% higher than that of similarly shaped samples in cold brine.

FDM 3D printing is one of the fastest growing and expanding 3D printing technologies. However, the materials used in this type of 3D printing are mostly limited to ABS and PLA, but the need for materials with better mechanical properties has led to the production of new filaments in the field of FDM 3D printers. Since various parameters affect the final quality of parts produced with a 3D printer, studying and investigating the effect of these parameters is of particular importance. Stereo lithography and FDM processes have a more limited scope of application due to their low dimensional accuracy compared to the CNC process. In this study, the effect of effective parameters in the stereo lithography process was investigated, which in order of importance include: layer thickness, gate model, and distance between gates, gate loading depth, and gate overload. In addition, the factors related to the dimensional accuracy of the FDM process considered here include, in order of importance: layer thickness, density percentage, nozzle speed, and nozzle diameter. In addition, four samples were made by the FDM process according to different layer thickness and density percentage of stereo lithography and FDM. The aim is to find the effective factors in the stereo lithography process. The results showed that the manufactured parts have 85% of the strength of the original product; therefore, they can be used as functional parts.

In recent years, considerable efforts have been deducted to evaluate the quality of various products. In this regard, quality control of products fabricated by the additive manufacturing methods has become a new interest. In the 3D printing industry, Defect detection could have a vital role in the final evaluation of products. In this study, artificial defects are located in PLA samples printed with different infills via the Fused Deposition Modeling (FDM) method. In order to detection of the mentioned defects in these parts, the Active IR Thermography was employed. Thermal stimulation was selected as excitation method. Two different excitation formation including transmission and reflection mode are used. In order to validate the results, the temperature-pixel diagram for each sample were illustrated. The effect of Gaussian filter on thermal images was also investigated to facilitate the identification of the obtained images. The experimental results indicated the capability of thermally stimulated thermographic inspection in detection of defects in FDM printed parts.

Fused deposition modeling (FDM) is one of the most common 3D printings technologies. Low cost and the ability to produce models using wide range of thermoplastic polymers, makes this process suitable for rapid prototyping and manufacturing some commercial parts. The manufacturing complicated parts and increasing their qualities are possible, using more than three degrees of freedom printers. In this paper, a 5-DOF 3D printer is introduced. The mechanism of this printer is 4-DOF parallel mechanism with one additional degree of freedom resulting from rotation of printer bed about Z-axis. In order to generate tool path for 5-DOF printer, a CAM software was developed with python. For controlling the printer, control software was designed based on open-source Repetier framework. Since original framework only supports 3-axis printers, source code needed to be changed such as extending source code to support 5-axis and adding mechanism inverse kinematics. By using this 5-Dof mechanism, the prints of complicated parts without using the support are possible.

The current research focuses on the fuzzy Delphi technique (FDM) with the aim of introducing a novel approach to modeling Persian vernacular architecture. The main objective of utilizing the Delphi method is to attain the most reliable consensus among a group of expert opinions. This advantage aids in addressing the primary research question: determining the efficacy of the fuzzy Delphi technique in intelligently modeling Persian vernacular architecture. To identify the main factors of the research model, systematic literature reviews were conducted alongside semi-structured interviews with experts. Subsequently, Qualitative Content Analysis (QCA) was employed to extract various themes, which served as the primary factors of the research model. Finally, by applying the fuzzy Delphi technique, the present study examined the degree of certainty and accuracy of these factors in two stages, ultimately identifying 28 factors relevant to the modeling of Persian vernacular architecture.

This paper presents the effect of geogrid tensile strength by calculating the pullout resistance and the geogrid-soil interaction mechanism. In order to investigate this interface, a series of pullout tests have been conducted by a large scale reformed direct shear test apparatus in the both cohesive and granular soils. In numerical, the finite difference software FLAC3D has been carried out on experimental tests and the results are compared with findings from laboratory tests and to complete investigation results. The results show tensile strength of geogrids has an important role in the interface behavior. The effect of the soil type also is discussed. The obtained results show that the geogrids with low tensile strength have higher pullout resistance in the low normal stress on the surface, this effect reversed as the normal applied stress is increased. Numerical analysis only estimates the pullout strength with good agreement in the high normal stresses. Furthermore, it is found that the effective particle size of soil is close to the geogrid thickness by comparing two sands with different grain size.

In this study, the mechanical properties of poly lactic acid samples produced by FDM 3D printing technique were investigated. The 3D printing process parameters were optimized using design of experiment (DOE) Taguchi approach for achieving the optimum mechanical performance. In this regard, infill percentage (at three levels of 30, 50, and 70%), raster angle (at three states of 0/90,-30/30, and-45/45 degree), and layer thickness (at three levels of 200, 250, and 300 μ m) were considered as process parameters for optimization procedure. Their effects on density (as porosity degree), impact strength (as mechanical property), and specific impact strength (the impact strength to density ratio) were investigated. Analysis of variance (ANOVA) was utilized to find the most effective processing parameters. The findings revealed that the infill percentage was the most effective parameter on the density and the impact strength. The density and the impact strength were reduced with the decrease of the infill percentage. These decrements were in a way that their ratio, specific impact strength, was almost constant. The layer thickness had the most influence on the specific impact strength. The specific impact strength was improved by reducing the layer thickness due to the raster entanglement. The optimum conditions to achieve the highest mechanical performance were the raster angle of 30/-30 degrees and the layer thickness of 200 μ m. The optimum infill percentage depended on the application.