This paper experimentally observed at a small level the influence of nozzle temperature change on warping deformation (WD), dimensional Accuracy (DA) and density. The materials chosen are pure PLA and advanced PLA+ specimens of rectangular shape of 63.5 mm × 9.53 mm × 3.2 mm produced by the end-user 3D printer based on fused deposition modeling (FDM). During the printing work, the nozzle temperature was conducted at twelve different values 195°C to 250°C with 5°C increments. Additionally, the infill density was set at 20% along with infill line direction of 0°, 90°, 45° and ±45°. After the fabrication, the FDM 3D printed parts naturally cooled down to room temperature at T = 23±2°C. As a result, the higher the nozzle temperature, the lower the deformed shape errors (with low uncertainty) of the specimens were. Experimental results show that the measured dimensions are always more than the original CAD file dimension along the height but less than the original CAD file dimensions along the width and length. The density measurements of both materials at 90° infill line direction have higher values compared with other directions (0°, 45°, ±45°), which have very similar results. The data and knowledge obtained from this investigation can be helpful for both an academic and an industrial perspective to set optimum nozzle temperature at small scale level and also it can be used to fabricate low-cost functional objects. Furthermore, it will also allow us to redesign the original CAD file in order to compensate the warping deformation encountered when using end-user FDM 3D additive manufacturing.

Abrasive waterjet (AWJ) cutting technology has been used extensively for the cutting and processing of almost all engineering materials because of its precise cutting technique and the lack of damage caused. Currently, the use of abrasive waterjet cutting in the natural stone industry is increasing. However, the effectiveness of abrasive waterjet cutting of natural stones is dependent on the rock properties and machine operating parameters. Consequently, this paper presents the influence of abrasive waterjet machining parameters on the surface texture quality of Carrara marble. The results have shown that the abrasive waterjet cutting process offers better cut surface texture quality of Carrara marble under certain parameter conditions as well as being more environmentally-friendly. The stand-off distance shows the opposite effect on both surface roughness and waviness. With a view to reducing the machining costs, every user tries to select the traverse rate of the cutting head to be as high as possible, but results show that increasing the traverse rate always causes a corresponding increase in terms of inaccuracy, surface roughness, R a ≈ 93.7 µm, and waviness, W a ≈ 92.6 µm. The abrasive mass flow rate is not a significant parameter during the cutting process. In all investigations, it was found that the machined surface of the marble is smoother near the jet entrance, R a ≈ 4 µm, and waviness, W a ≈ 5 µm, and increasingly becomes rougher towards the jet exit. The result also shows that the micro-hardness value of the Carrara marble was in the range of 122 HV to 124 HV.

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The mechanical damage variable, as well as the thermal and mechanical relaxation times, plays essential roles in the thermal quality factor of the resonators, where controls energy damping through the coupling of mechanical and thermal behavior. In this article, we developed a mathematical model in which a static-pre-stress and mechanical damage variable in the context of a two-temperature viscothermoelasticity of silicon resonator has been considered. The effects of static-pre-stress, thermal relaxation time, mechanical relaxation time, mechanical damage variable, isothermal frequency, and length-scale on the quality factor have been discussed in the context of a one-temperature and two-temperature models. The model predicts that significant improvement in terms of quality factors is possible by tuning the static-pre-stress, isothermal frequency, and length-scale of the resonator. Moreover, the thermal and mechanical relaxation times and the mechanical damage variable have impacts on the thermal quality factor.

This paper deals with an assessment of the machined surface created by abrasive waterjet technology regarding its cutting performance versus profile, lagging and waterjet angle assessments. The results of the experiments presented in this study are with regard to Carrara marble. The machined surfaces were measured in seven different locations across a 40 mm depth of cut by a high precision contact-type profilometer and thus assessed using the standardized amplitude parameters of the profile distribution. The lagging and waterjet angle were also evaluated by creating a digital photo of the machined surface together with a reference gauge. The existence of machining marks on the machined surface has been mostly noticeable in the bottom zone around ~20 mm depth of cut down to jet exit. This investigation leads to a conclusion that, stand-off distance and traverse rate play the roles of the utmost importance in considerations of the machined surface quality in contrast to abrasive mass flow rate. In addition, while the striation zone (rough surface) cannot be eliminated entirely, by selecting proper process parameters, a smooth cutting machined surface can be accomplished.