This study aims to investigate common fastener implementation methods for parts manufactured with Fused Deposition Modeling (FDM). Although fastener applications for FDM manufactured parts are already in use, the effects of these methods on tensile and bending forces have not been examined. Test samples with different design techniques and infill ratios were produced using Polylactic Acid (PLA), and tensile strength and flexural and tightening torque tests were performed. Four of the of the most preferred fastener applications were studied. Two of the applications use a heat-set insert, and the other two applications use square nuts. Test samples were designed for the applications and printed with three different infill ratios. The production times and material consumption for these different applications were explained and evaluated. Different drawbacks and advantages were investigated for different applications. It has been observed that the strength of the basic heat-set inserts depends on the surface adhesion and is less affected by the filling rate. Advanced heat-set inserts adhere better to the surface, so the infill ratio is the determining factor in strength. The embedded nut methods depend on the infill ratio up to a certain load. As the load increases, the influence of wall thickness becomes increasingly evident. These findings not only contribute to enhancing structural integrity but also offer invaluable insights into optimizing connection methods for diverse applications.

As computer capabilities improve, Molecular Dynamics simulations are becoming more important for solving various flow problems. In this study, Couette and Poiseuille flows at different wall temperatures were investigated using a hard-sphere Molecular Dynamics simulation approach. Although a low spacing ratio was used in the simulations, the results are valid for rarefied gas flows when proper scaling based on the Knudsen number was used because only binary collisions with a hard-sphere model were considered. The main focus of this study was the examination of the effects of various wall speeds, pressure gradients, and wall temperatures. A pressure gradient was generated by developing a modified selective periodicity condition in the flow direction. With the combined effect of the pressure gradient and the wall velocities, subsonic, transonic, and supersonic speeds in nanochannels were examined. With the combination of different parameters, 1260 simulation cases were conducted. The results showed that there are temperature and velocity slips that are dependent on not only the temperature and velocity values but also on the magnitudes of a pressure gradient. The pressure gradient also caused nonlinearities in temperature and velocity profiles.