Deformation modes and crashworthiness energy absorption of sinusoidally corrugated tubes manufactured by direct metal laser sintering

Thin-walled structures are used for crashworthiness energy absorption applications such as automobile vehciles and aircraft. Structures of sinusoidally corrugated profiles were of great interest because of their ability to reduce the peak crushing forces and provide stable energy-absorbing patterns. Studies on structures of sinusoidally corrugated profiles are limited to numerical studies due to manufacturing limitations. Advancement in additive manufacturing enables the fabrication of structures of complex profiles such as corrugated tubes. This could solve the issue of mass productions of such structures for energy absorption applications. This paper aims to additively manufacture and test sinusoidally corrugated tubes experimentally. A sample of 8 sinusoidally corrugated tubes was additively manufactured and tested under a quasi-static displacement rate of 20 mm/min. The results showed that corrugated tubes exhibit lower and stable crushing forces compared to conventional straight tubes. It was found that increasing the wavelength from 10 to 20 mm results in changing deformation mode from ring to diamond, while increasing the amplitude from 1 to 2 mm has no effect when the thickness is 1 mm. Corrugated tubes achieved a maximum peak force reduction of 75%, and a maximum crushing force efficiency increase of 63%. However, they also resulted in a reduction of 46 and 55% in energy absorption and specific energy absorption, respectively. - 2019 Elsevier LtdScopu

Experimental analysis of additively manufactured thin-walled heat-treated circular tubes with slits using AlSi10Mg alloy by quasi-static axial crushing test

In this study, additively manufactured aluminum thin-walled tubes with different slit dimensions are proposed to improve energy absorption efficiency. A total of 18 samples, which varied in the number of slits, slit length, slit width, and slit ends, were tested under quasi-static axial compression at a rate of 20 mm/min. The deformation and failure modes, load-displacement curves, and a number of crashworthiness factors were investigated. The factors considered included, but were not limited to, the specific energy absorption, crushing force efficiency, and energy absorbed per stroke. The results indicated that all the considered physical parameters, except for the slit ends, had an influence on the crashworthiness of the structures. The initial peak load decreases significantly as the number, width, and length of the slits increase. The bulk of the tested tubes exhibited a crushing force efficiency greater than 0.8. Overall, the presence of slits with length 15 mm and width 5 mm resulted in lower and smoother crushing forces than the straight tubes and, therefore, greater crushing force efficiency, validating them as crashworthy structures.The authors are grateful to the Department of Mechanical and Industrial Engineering at Qatar University for the financial support provided to this research project.Scopu

An empirical determination of the whole-life cost of FO-based open-loop wastewater reclamation technologies

Over the past 5–10 years it has become apparent that the significant energy benefit provided by forward osmosis (FO) for desalination arises only when direct recovery of the permeate product from the solution used to transfer the water through the membrane (the draw solution) is obviated. These circumstances occur specifically when wastewater purification is combined with saline water desalination. It has been suggested that, for such an “open loop” system, the FO technology offers a lower-cost water reclamation option than the conventional process based on reverse osmosis (RO). An analysis is presented of the costs incurred by this combined treatment objective. Three process schemes are considered combining the FO or RO technologies with membrane bioreactors (MBRs): MBR-RO, MBR–FO–RO and osmotic MBR (OMBR)-RO. Calculation of the normalised net present value (NPV/permeate flow) proceeded through developing a series of empirical equations based on available individual capital and operating cost data. Cost curves (cost vs. flow capacity) were generated for each option using literature MBR and RO data, making appropriate assumptions regarding the design and operation of the novel FO and OMBR technologies. Calculations revealed the MBR–FO–RO and OMBR-RO schemes to respectively offer a ∼20% and ∼30% NPV benefit over the classical MBR-RO scheme at a permeate flow of 10,000 m3  d−1, provided the respective schemes are applied to high and low salinity wastewaters. Outcomes are highly sensitive to the FO or OMBR flux sustained: the relative NPV benefit (compared to the classical system) of the OMBR-RO scheme declined from 30% to ∼4% on halving the OMBR flux from a value of 6 L m−2. h−1.This work was made possible by the support of a National Priorities Research Programme (NPRP) grant from the Qatar National Research Fund ( QNRF ), grant reference number NPRP10-0118-170191 . The statements made herein are solely the responsibility of the authors. The authors would like to thank Dan Jerry Cortes from Qatar University and Arnold Janson from ConocoPhillips, Qatar for providing useful information for this paper.Scopu

Investigation of thin-film composite hollow fiber forward osmosis membrane for osmotic concentration: A pilot-scale study

The current study applied the forward osmosis (FO) based osmotic concentration (OC) process at the pilot-scale for concentrating synthetic feed solution (FS). The process water (PW) salinity represents effluents from the gas industry, while the draw solution (DS) mimics seawater. Besides, the performance of a hollow fiber (HF) membrane manufactured from polyamide thin film composite (PA-TFC) was evaluated. The effect of operation with various feed recovery rates, flowrates and temperatures on the OC performance was examined. Outcomes reveal that the tested membrane succeeded in recovering up to 90% of FS at water flux of 6.40 LMH. The stability of OC plant was successfully demonstrated for 48 hours long-term run at 75% feed recovery as an optimum condition, where the TFC membrane achieved average water flux of 6.00 LMH, respectively. Higher DS flowrate improved the OC performance by inducing higher water permeation and FS recovery; however, it increased the undesirable reverse solute diffusion. Lastly, the permeability coefficient of the HF membrane was estimated by 2.69 LMH/bar at 25 �C, which significantly enhanced at higher temperatures.This work was made possible by the support of a National Priorities Research Program (NPRP) grant from the Qatar National Research Fund (QNRF), grant reference number NPRP10-0118170191. The statements made herein are solely the responsibility of the authors. The authors would like to thank Dan Jerry Cortes from Qatar University and Arnold Janson from ConocoPhillips, Qatar for providing useful information for this paper.Scopu