DOE Plan Research Articles

Contact force of composite plate impacted at low energy alteration by hygrothermal conditions

Quite recently, considerable attention has been paid to the phenomena of impact. To enrich and give more light on the phenomena, this work is presented to give a comprehensive account of the effect of contact force due to an impact on composite plate subjected to an hygrothermal conditions specially those made of Glass/Polyester.A comparative study between an experimental data obtained by [1] from impact tests to those obtained bysimulations was firstly conducted. Based on the obtained results, it can be concluded that model reproduce very successfully the experimental studies.The obtained numerical forces will be then used in Modde V 5.0 software to establish an DOE plan ‘design of experiments’. Two factors are taken into consideration: the absorbed mass of water by the material and the drop height of the projectile and their effects on the numerical contact force.From the results it has been carried out that the numerical contact force is reduced for aged plates. The mostinfluencing parameter is the drop height of the projectile. An important implication of these findings is that a mathematical model is established which governs the contact force in the domain studied.

Experimental Study of In-Process Heat Treatment on the Mechanical Properties of 3D Printed Thermoplastic Polymer PLA.

The scientific literature regarding additive manufacturing, mainly the material extrusion method, suggests that the mechanical characteristics of the parts obtained by this technology depend on a number of the input factors specific to the printing process, such as printing temperature, printing trajectory, layer height, etc., and also on the post-process operations for parts, which, unfortunately, requires supplementary setups, equipment, and multiple steps that raise the overall costs. Therefore, this paper aims to investigate the influence of the printing direction, the thickness of the deposited material layer, and the temperature of the previously deposited material layer on the part tensile strength, hardness by means of Shore D and Martens hardness, and surface finish by using an in-process annealing method. A Taguchi L9 DOE plan was developed for this purpose, where the test specimens, with dimensions according to ISO 527-2 type B, were analysed. The results showed that the presented in-process treatment method is possible and could lead to sustainable and cost-effective manufacturing processes. The varied input factors influenced all the studied parameters. Tensile strength tended to increase, up to 12.5%, when the in-process heat treatment was applied, showed a positive linear variation with nozzle diameter, and presented considerable variations with the printing direction. Shore D and Martens hardness had similar variations, and it could be observed that by applying the mentioned in-process heat treatment, the overall values tended to decrease. Printing direction had a negligible impact on the additively manufactured parts' hardness. At the same time, the nozzle diameter presented considerable variations, up to 36% for Martens hardness and 4% for Shore D, when higher diameter nozzles were used. The ANOVA analysis highlighted that the statistically significant factors were the nozzle diameter for the part's hardness and the printing direction for the tensile strength.

Experimental Study on the Possibilities of FDM Direct Colour Printing and Its Implications on Mechanical Properties and Surface Quality of the Resulting Parts

The present paper aims to contribute to the methodology of 3D printing in-process colouring and study its implications and impact on the tensile strength and surface quality of the obtained parts. The proposed study was based on a Taguchi L27 DOE plan using standardised EN ISO 527-2 type 1B-shaped specimens, in which four factors on three levels were considered. The obtained results highlight the possibility of using the presented in-process colouring method. Different materials (PLA, PLA+, and PETG) with varying infill densities (15%, 30%, and 50%), colour distribution (33%, 66%, and 99%), and colour pigments (blue, green, and red) were studied and the results highlighted that the most influential parameter on the tensile strength of the parts was infill density, followed by the tested material, colour pigment, and colouring percentage; regarding surface roughness, the most influential parameter was infill density, followed by colouring percentage, colour pigment, and material. Moreover, the values resulting from the Taguchi DOE were compared to uncoloured parts, from which it could be concluded that the colouring of the parts had direct implications (negative for tensile strength and positive for surface roughness).

Modeling of Probeless Friction Stir Spot Welding of AA2024/AISI304 Steel Lap Joint.

In the present study, AA2024 aluminum alloy and AISI304 stainless steel were welded in a lap joint configuration by Probeless Friction Stir Spot Welding (P-FSSW) with a flat surface tool. A full factorial DOE plan was performed. The effect of the tool force (4900, 7350 N) and rotational speed (500, 1000, 1500, 2000 RPM) was analyzed regarding the microstructure and microhardness study. A two-dimensional arbitrary Eulerian-Lagrangian FEM model was used to clarify the temperature distribution and material flow within the welds. The experimental results for the weld microstructures were used to validate the temperature field of the numerical model. The results showed that the tool rotation speed had an extensive influence on the heat generation, whereas the load force mainly acted on the material flow.

Parametric optimization of in-situ heavy oil upgrading using simultaneous microwave radiation and magnetic nanohybrids via Taguchi approach

This study investigated the effect of Fe3O4, Fe3O4-MWCNT, and Fe3O4-NiO nanohybrids on the in-situ heavy oil upgrading using microwave radiation through the Taguchi DOE method. The nanohybrids were synthesized via a co-precipitation method and were characterized using different analyses. Three numerical parameters, including the concentration of nanohybrids, power and time of microwave radiation, and a categorical factor including the type of the nanohybrids, were considered in a DOE plan. Results showed that electrical permeability, loss tangent, and electrical conductivity of Fe3O4-MWCNT nanohybrids are higher than other nanoparticles. Nanoparticle’s concentration (at 0.5 wt%) had the most significant effect on reducing the viscosity and increasing the API degree of crude oil. All three system responses, including viscosity, API, and oil sample temperature, were raised by increasing the power of microwaves from 400 W to 1200 W. The lowest viscosity of crude oil was obtained at low irradiation times (8 min.). The optimal conditions for achieving the greatest reduction in crude oil viscosity were a combination of using 0.5 wt% of Fe3O4-MWCNT nanohybrid under 8 min of 400 W microwave radiation. Finally, it found that microwave radiation has made the oil sample lighter and reduced the sulfur content in the crude oil. So, the use of Fe3O4-MWCNT nanohybrid has reduced the sulfur content in the primary crude oil sample by 16.6%.

Bending Distortion Analysis of a Steel Shaft Manufacturing Chain from Cold Drawing to Grinding

Shafts are usually manufactured from bars that are cold drawn, cut machined, induction hardened, straightened, and finally ground. The main distortion is characterized by bending that appears after induction hardening and is corrected by straightening and/or grinding. In this work, the consequence of the variation of manufacturing parameters on the distortion was analyzed for a complete manufacturing route for production of induction hardened shafts made of Grade 1045 steel. A DoE plan was implemented varying the drawing angle, cutting method, induction hardening layer depth, and grinding penetration depth. The distortion was determined by calculating curvature vectors from dimensional analysis by 3D coordinate measurements. Optical microscopy, microhardness testing, residual stress analysis, and FEM process simulation were used to evaluate and understand effects of the main carriers of distortion potential. The drawing process was identified as the most significant influence on the final distortion of the shafts.

Online Mass Spectrometric Monitoring of Carbon Corrosion in PEMFC Electrodes Subjected to Accellerated Stress Testing

Polymer electrolyte membrane fuel cells (PEMFCs) are considered to be almost market-ready for automotive applications. The main obstacles which decelerate a broad application arise from the high costs for the production of membrane electrode assemblies (MEAs). Another aspect, which is related to operation costs of a fuel cell system, is its lifetime. The lifetime of PEMFCs especially in automotive applications, which include alternating load conditions and frequent start-stop-cycles, is still too short to make them more attractive vehicle power sources than combustion engines. Regarding the lifetime of PEMFCs the US DoE set the durability target of 5000 h by 2017 (with less than 10% loss of initial performance) for automotive applications [1]. Carbon (C) support corrosion was identified as one main contributing mechanism to the degradation of PEMFCs i.e. membrane electrode assemblies (MEAs) [2]. It is known that C support corrosion is dominantly an issue of the fuel cell cathode. It leads to (i) decrease of electrochemically active surface area and (ii) damage of porous electrode structure causing a deterioration of mass transport [2]. Both named phenomena contribute to a decrease of reaction rate and hence fuel cell performance. Beside the applied support material fuel cell operating conditions have a significant influence on C support corrosion rate e.g. high cathode potential conditions during fuel cell start/stop accelerate C support corrosion rates tremendously compared usual equilibrium operating conditions [2-3]. There is still a lack of understanding on how different operating conditions affect the C support corrosion rate. For this reason carbon corrosion rates of PEMFC cathodes were measured by means of inline mass spectrometry. The method is based on a measurement of the release i.e. generation rate of CO2 at the cathode fuel cell exhaust. A correlation to the C corrosion rate is possible since CO2 is known to be final product of the carbon corrosion reaction. The C corrosion rate of fuel cell cathodes was investigated for different conditions. Here, the investigations were focused on cathode potential. On one hand, corrosion rates for cathode potentials corresponding to usual operating potentials were probed and compared to each other. On the other hand, accelerated stress tests (ASTs) [4-5] involving potential cycling at unusually high cathode potentials were applied in order to simulate fuel cell start/stop conditions. It was found that the C corrosion rate during the simulated start/stop conditions is roughly 30-60 times higher compared to usual fuel cell operating conditions. Another focus was put on a separate measurement of C corrosion rate in the catalyst layer (CL) and gas diffusion layer (GDL). From the results of these investigations it can be concluded that the applied AST conditions dominantly accelerate carbon corrosion rates in the CL and hardly in the GDL. [1] US DOE, Multi-Year Research, Development and Demonstration Plan (2012) [2] P.T. Yu et. al, Carbon-Support Requirements for Highly Durable Fuel Cell Operation in F.N. Büchi et. al, Polymer Electrolyte Fuel Cell Durability, Springer (2009). [3] X.-Z. Yuan et. al, A review of polymer electrolyte membrane fuel cell durability test protocols, Journal of Power Sources. 196 (2011), 9107–9116. [4] Cell Component Accelerated Stress Test and Polarization Curve Protocols for PEM Fuel Cells, http://www.uscar.org/commands/files_download.php?files_id=348 (2013). [5] New Energy and Industrial Technology Development Organization (NEDO) - Development of PEFC Technologies for Commercial Promotion - PEFC Evaluation Project - Cell Evaluation and Analysis Protocol Guideline (2014). Figure 1

Comparison of Numerical and Experimental Data in Multi-objective Optimization of a Thermoplastic Molded Part

Abstract Warpage reduction, dimensional tolerance accomplishment and time and cost saving are some of the most important problems in the injection molding production process. In this study, a real case of a thermoplastic injected part is analyzed. The mold for a pipeline connecting element has been designed, according to known technical and economical criterion to fulfill customer requirements. Particularly for this element, warpage of a specified surface and two diameter sizes are fundamental for correct part functionality and assembling. The analysis is centered on the effects of four process parameters, i. e. packing pressure, packing time, melt temperature and cooling time that heavily influence final results. A finite element model has been used to evaluate their effects on four important final objectives that are the geometrical entities and production cycle time. Each variable has been varied into its proper range, in accordance with a central composite design DoE plan; 25 simulations have been executed and results have been represented using response surfaces. Pareto Front for above listed objectives has been extracted using a genetic algorithm and the best set of parameters has been determined after application of specific selection criteria and a weighted objective function. After numerical evaluation, the CCD DoE plan has been experimentally repeated. Results have been measured on real components, and then represented with response surfaces as well. The same algorithm and objective function have been used for optimization, to determine the experimental optimum parameter set. Finally, the two parameter sets have been compared.

TVA TO MAKE TRITIUM FOR ATOMIC WEAPONS

Tritium gas for nuclear weapons will be made in Tennessee Valley Authority (TVA) electricity-producing nuclear reactors under a plan announced on Dec. 22, 1998, by Energy Secretary Bill Richardson. Richardson's decision will expand a 15-month-old Department of Energy pilot project at TVA's Watts Bar reactor in Spring City, Tenn., in which special lithium rods inserted into reactor fuel elements produce and capture tritium. DOE's plan also holds open the option of using TVA Sequoyah's two light-water reactors in Soddy Daisy, Tenn., to produce tritium, if needed. The Watts Bar plan is the cheapest of several proposals DOE was considering for producing the gas, a radioactive hydrogen isotope that decays at a rate of 5.5% per year. It is used to increase the power of nuclear weapons (CE ...

Special Report: Severe Accident Scenarios at Issue in DOE Plan to Restart Reactor

Special Report: Severe Accident Scenarios at Issue in DOE Plan to Restart Reactor

Recent developments in amorphous silicon solar cells.

Since 1976 when Carlson and Wronski demonstrated the amorphous silicon (a-Si) solar cell, it has been on a focus of attention as a low cost solar cell. Aided by the accelerative promotion of the Sunshine Project in Japan, the DOE plan in the U.S, and various countries' plans, numerous research breakthroughs have led to rapid improvement in conversion efficiency. Recently, conversion efficiency of more than 11% was achieved for single-junction structures, and furthermore, more than 13% for multi-junction structures.Since the world's first electronic calculator powered by an a-Si solar cell was put on the market in 1980, consumer electronics and stand-alone systems have been continuously growing in number and in types.This paper reports on recent development in a-Si solar cells. Highly efficient fabrication technologies for a-Si solar cells are mentioned, and the present status of the industrialization of a-Si solar cells is described.