Solid State Phenomena Vol. 294

Abstract: The five stage experiments including without assistance, single and hybrid assisted machining systems on Inconel 718 milling were conducted in this study. First of all, the milling experiment without assistance was performed to investigate the variations of cutting performance and the results were used for a suitable process parameter planning in the subsequent stage experiments. Next, a laser assisted system was introduced in the second stage where the spacing distance between the laser spot and cutting-tool along the cutting direction was modified to test whether laser preheating may effectively reduce the cutting force. A biaxial ultrasonically assisted system with only one-axis oscillation (x or y direction) and with two-axis simultaneous oscillations (x and y directions) were subsequently introduced at the third to fourth stage experiments, respectively. While a biaxial ultrasonically and the laser assisted systems were integrated together to construct a hybrid assisted cutting system at the last stage experiment. Under these assistances, milling experiments of Inconel 718 by cutting-tool of tungsten carbide with nanoSi® coating were conducted. And the full-factorial experiments of process parameter combinations such as spindle speed, radial cutting depth and feed rate were planned. The results indicated that the laser-preheating assisted system could effectively reduce the cutting force as well as enhance the cutting performance. The effect of the biaxial ultrasonic oscillation on tool service life could greatly be promoted. Furthermore, the cutting performance exhibited in the integrated hybrid assisted milling prevails over that in milling without assistance as well as with each single assisted system. Under this hybrid assisted milling, the better surface roughness of 0.216μm was obtained under a combination of spindle speed of 6000 rpm, radial cutting depth of 0.01 mm, and feed rate of 300mm/min, accompanied by a maximum cutting-tool wear of 13.849μm.

Abstract: The current research addresses the effect of impact load on Reinforced Concrete (RC) slabs strengthened by Expanded Polystyrene (EPS) and/ or Glass Fiber Reinforced Polymer (GFRP) sheets. A total of five slabs were tested; one control specimen without EPS or GFRP, two slabs with two EPS panels with different densities on their impact side, one slab with GFRP sheet on impact side and finally one slab with EPS panel on impact side and GFRP on the tension side. To test the effect of the presence of EPS panels and GFRP sheets, the RC slabs were supported on a table centered below a drop tower. A weight of 3.245 kg was dropped freely from the drop tower to hit the slab. The energy that the slab could withstand was calculated based on the weight, height and number of drops. Results varied according to the variation of parameters; the combination of EPS on the impact side and GFRP on the tension side yielded double the energy the specimen could withstand compared to the control specimen. Results also showed that EPS acted like a cushion that is capable of absorbing a portion of the impact energy. Another finding is that the higher the density of the EPS the more energy it can absorb. This paper proves that EPS is a promising material that could be utilized in reducing the effects of impact loads on concrete structures.

Abstract: Compared with natural aggregate concrete (NAC), the cylinder compressive strength and elastic modulus of Recycled aggregate concrete (RAC) are decreased, but the brittleness is increased. The axial compression performance of RAC can be improved by external confinement. In this paper, the effects of Polyvinyl chloride (PVC) pipe confinement and composite confinement of PVC pipe and Carbon Fiber Reinforced Polymer (CFRP) on the axial compression performance of RAC were investigated. The results showed that with the increase of the replacement rate of recycled coarse aggregate, the cylinder compressive strength, peak strain and elastic modulus of RAC were decreased; PVC pipe confinement could significantly improve the cylinder compressive strength, peak strain and elastic modulus of RAC; the CFRP could further improve the cylinder compressive strength and elastic modulus of PVC-RAC to a certain extent, and could significantly enhance the peak strain of PVC-RAC. PVC pipe and CFRP-PVC pipe confinement could improve the axial compression performance of RAC more effectively than NAC. Consequently, PVC pipe and CFRP-PVC pipe confinement could reduce the influence of recycled aggregate (RA) quality on variability of RAC axial compression performance.