Experimental Design Analysis Research Articles

Passenger car steering pull and drift reduction considering suspension tolerances

Pull to side, Steering wheel misalignment and Drift leeward are handling anomalies affecting passenger cars travelling on straight paths. They represent a cost factor in the automotive industry, occurring in small but not negligible percentage of the overall car production. The present contribution is aimed at understanding which are their causes in terms of suspension tolerances, and at reducing their extent, in the specific case of vehicles with front Double wishbone suspension and rear Five arms suspension. The most influential parameters on handling irregularities have been identified through a design of experiment analysis. Then, after performing a sensitivity analysis by multibody virtual modelling, a correlation with experimental data from presetting and wheel aligner benches has provided sufficient information for setting tolerance thresholds, able to keep the handling anomalies under study within acceptable bounds. Pull to side and Steering wheel misalignment have been found to be mainly related to the set up phase of wheel angles (front camber angles influencing Pull to side, front and rear toe angles influencing Steering wheel misalignment), while the main cause of Drift leeward has been identified with (rear) ride steer.

Energy recovery through natural gas turboexpander and solar collectors: Modelling and thermoeconomic optimization

This paper presents a novel dynamic simulation model for the analysis of a hybrid turboexpander system coupled with innovative high-vacuum solar thermal collectors. The model is developed in MatLab and it is able to dynamically calculate the energy, exergy, environmental, and economic performances of the investigated system, by taking into account the hourly fluctuation of thermodynamic and economic parameters (e.g. electricity cost, natural gas temperature, and flow rates, etc.). In addition, a computer-based Design of Experiment (DoE) approach was implemented for achieving the optimal design of the proposed system.A suitable case study is presented in order to show the capabilities of the developed simulation tool. Conventional and non-conventional decompression systems located in the weather zone of Messina (South-Italy) are investigated with the aim of assessing the optimal system configuration. By means of the computer-based DoE analysis, the optimal values of several design parameters (such as the number of solar thermal collectors, the volume of the hot water storage tank, and the size of the water loop pump) are calculated. Numerical results show significant primary energy savings (1.36 TWh/year) and avoided carbon dioxide emissions (348 tCO2/year). From the economic point of view, a feasible simple pay-back period of 4.51 years is achieved. The destroyed exergy of the system components are calculated, obtaining the highest value for the turbo-expander, equal to 12.0 TWh/year.

Optimization of the intermediate layer friction stir spot welding process

Friction stir spot welding was performed for joining sheets of 2024 and 6061 aluminum alloys, which is otherwise difficult using conventional welding techniques. The presented approach utilizes an intermediate layer to avoid the keyhole problem. Design of experiment analysis was carried out to evaluate the influence of process parameters. The optimized set of parameters led to the fabrication of sound joints with strength properties exceeding twice the applicable standard requirements as discussed with the evidence of branched hook formations with extensive penetration. Tool rotational speed was determined to be the most significant parameter influencing the mechanical performance. The failure mode revealed itself as sheet tearing-nugget pull out in the joints produced under optimum conditions with various sized dimples apparent on the fracture surface.

Application of environmental friendly and eutectic phase change materials for the efficiency enhancement of household freezers

In this study, a novel freezer consisting of an internal phase change material compartment is compared with an ordinary one. A eutectic mixture of polyethylene glycol has been used which is among the non-flammable and non-toxic phase change materials. The freezer was tested under the standard conditions in the test room both with and without phase change materials loaded in the system and all the temperatures inside the device were monitored for 24 h by the monitoring software. A design of experiment analysis was used and the main goal of this work was to use an optimum amount and temperature of eutectic phase change material inside the freezer. The application of phase change materials in the freezer compartment, located in each tray leads to a significant reduction of temperature fluctuations up to 40.59% with the optimal values of 2 kg of phase change material and melting temperature of −20 °C. Experimental results show that energy consumption of the freezer with phase change material is considerably lower than the ordinary freezer. The results of the novel freezer indicate energy savings of 8.37% with 1.5 kg of phase change material and melting temperature of −20 °C.

A NOVEL STUDY ON SURFACE MODIFICATION OF PALMYRA FIBERS FOR ENHANCING MECHANICAL AND THERMAL PROPERTIES

Natural fiber reinforcing in engineering thermoplastics (Nylon melting point around 230∘C) is challenging, due to the lower degradation temperature ([Formula: see text]C) of lignocellulosic fibers. Further, increasing temperature (beyond 200∘C) results in weakening of its mechanical properties. In this investigation, camphor soot reinforced palmyra fibers (CSRPF) are manufactured by osmosis with the help of design of experiments (DOE) and are examined for different time (4, 8 and 12[Formula: see text]h), temperature (30∘C, 40∘C and 50∘C) and camphor soot concentrations (0.5, 1.0 and 1.5[Formula: see text]wt.%) using L9orthogonal array. The osmosis rate of modified fibers was calculated and tested for their tensile strength as the osmosis rate and tensile strength are the main objective functions. Based on DOE and taguchi-ANOVA analysis, optimal parameters were obtained through main effect plots and Anova results. Further, an optimal combination of parameters for CSRPF was characterized for thermogravimetric analysis (TGA), Fourier transform infrared radiation (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) to inspect and compare it with neat palmyra fibers. There was considerable improvement in the CSRPF tensile strength about 84[Formula: see text]Mpa with respect to neat palmyra fibers which is 58[Formula: see text]MPa. TGA reveals the degradation temperature of neat palmyra fiber is about 225∘C and it is enhanced in case of CSRPF about 265∘C which accounts for 15% enhanced thermal stability. The crystallinity index (CI) of CSRPF was reduced marginally compared to the neat palmyra fibers. FTIR analysis showed the peak drift marginally to the left in CSRPF due to the coating of camphor soot particles. The microstructure of both neat and CSRPF are examined using SEM and EDS which shows that 93.71% carbon was present in the cross section of CSRPF compared to the neat palmyra fiber (62.58%).

Parametric Study of Cyclic Plasticity Behavior in a Directionally Solidified Superalloy with Partial Recrystallization by Crystal Plasticity Finite Element Simulation

To understand the influence of recrystallization on the low-cycle fatigue behavior of directionally solidified nickel-based DZ4 superalloy, crystal plasticity-based finite element (CPFE) analysis was carried out to study the cyclic plastic behaviors. Using the design of experiments (DOE) technique, a series of CPFE simulations were designed and performed for DZ4 superalloy with recrystallized grains to examine the cyclic plastic shear deformation at the carbide/matrix interface, at the recrystallized grain boundary/matrix, and in the matrix. Seven influence factors, i.e., applied strain, strain ratio, carbide modulus, dwell time, misorientation angle, carbide aspect ratio, and carbide size, were considered, and the effects of which were quantitatively evaluated by the maximum accumulated plastic shear strains via CPFE-based DOE analysis. The results showed that carbide and recrystallized grain boundary had competitively significant effects on fatigue crack initiation. Applied strain was the most influential parameter among all the studied parameters.

Evaluation and improvement of promising rubber recycling OT machine using fractional factorial and response surface design

A design of experiment (DOE) is used in many industrial sectors in the development and optimization of manufacturing processes. DOE is a more effective way to determine the impact of two or more factors on a response. In this paper, a Two-Level Fractional Factorial design was employed to develop the important factors that significantly affect new promising OT Rubber recycling machine using a DOEs analysis. Central composite design (CCD) and response surface methodology (RSM) were used to optimize the isolating screen size. The CCD considered five factors with two-level full factorial design. CCD experiments using RSM was proved to be an optimal tool for optimization.

A Factory Analysis on the Proportion of Defects Reduction in The Animal Feed Pellet Production Process using Design of Experiment Analysis

The aim of this research is to reduce a number of defects during a feed pellet production process to improve customer satisfaction. A factory case study produces the feed pellets for several species such as food for pigs, chickens, and ducks. Production data from January to June 2017 manufacturing found that the manufacturing defects rate were about 3.32%. The data showed that the overall defects originated from different problems; 1) cracked or broken food; 2) high humidity; 3) distorted of product color; and 4) an ingredient error, respectively. Statistical methods, design analysis, and cause analysis techniques e.g. the Ishikawa diagram, Pareto chart, and FMEA (Failure Mode and Effects Analysis) were applied to help the factory to identify the main root cause of the defects and the potential failure modes of the factory case study. Due to an increasing number of complaints, this study only concentrated on the duck feed pellet production process. The study was divided into two parts: finding the root cause of the defects, which are the most critical factors for further analysis, and applying an experimental statistical design to decrease the number of defects during the duck pellet production process. The problem with cracked or broken pellets (dust) was found as the main factor affecting the production defects. Results showed that the main factors contributing to the amount of dusk in the duck feed productions came from three factors as follow: the thickness of die, distance between compression rollers and die, and time and temperature of mill machine needed during compressing the duck feed pellet production. Both the fractional factorial experimental design, 2k and 3k, were used to evaluate the influence of each factor on the duck feed production defects. The results by using the factorial 2K experimental show that the most important variable in duck pellets production were thickness of the die, distance between compression rollers and die, and temperature of mill machine needed during compressing the duck feed pellet production while time was not an interaction effect in this problem. The 3k factorial design was used to determine the interaction effects for the duck pellets production process. The experiment was ran and tested for 3 months. The final outcomes showed a significant reduction of defects from 2.51% to 1.09% (P<0.01). The results indicated that thickness -20 mm. of the die, 0.05 mm of distance between compression rollers and die, and 95 degree Celsius of temperature of mill machine needed during compressing the duck feed pellet production would be the most appropriate set of pelleting machine for the duck production process case study.

A one-step residue-free wet etching process of ceramic PZT for piezoelectric transducers

Lead zirconate titanate (PZT) has wide applications in microelectromechanical systems (MEMS) due to its large piezoelectric coefficients. However, there exist serious issues during PZT wet etching even with multiple etching steps, such as residues on etching fronts and large undercut. In this paper, a one-step residue-free wet etching process of ceramic PZT is developed with fluoroboric acid. In this work, the design of experiments (DOE) method is employed to minimize undercut and residues without sacrificing etching rate. The acid concentration, temperature, and agitation are the process parameters considered in the DOE. Through DOE analysis of the experimental data, an optimal recipe is identified as the volume ratio of HBF4:H2O=1:10 at 23 °C. This new PZT etching recipe leads to a high etching rate (1.54 μm/min) with no observable residues and a small undercut (0.78:1) as well as a high selectivity over the photoresist (900:1). This etching recipe can be used for making various piezoelectric transducers.

Experimental investigation into effects of high reactive fuel on combustion and emission characteristics of the Diesel - Natural gas Reactivity Controlled Compression Ignition engine

Reactivity Controlled Compression Ignition (RCCI) engines hold promise for decreasing NOx and particulate emissions. RCCI engines use direct injection (DI) to introduce a high reactivity fuel into the cylinder while a lower reactivity fuel is port fuel injected (PFI). A large reactivity difference between high reactive (diesel) and low reactive (natural gas) fuels provides a strong control variable for phasing and shaping combustion heat release in RCCI engines.Two diesel fuels, a High Reactive Diesel (HRD) fuel with a cetane number (CN) of 85 and a U.S. Ultra-Low Sulfur Diesel (ULSD) fuel with a cetane number of 49 were selected for this study. The effects of these two diesel fuels with methane as the low reactivity premixed fuel were compared in RCCI combustion mode and in Conventional Diesel Combustion (CDC) mode.The hypothesis is that using a HRD fuel in RCCI applications, with a double injection strategy, increases the reactivity of the mixture in the squish region, promoting combustion and consequently reducing unburned hydrocarbons and carbon monoxide. These emissions are generally difficult to control in RCCI combustion at high Blend Ratio (BR). In addition, a larger reactivity difference between the two fuels in RCCI applications, extends the combustion duration and reduces the Maximum Pressure Rise Rate (MPRR) and in-cylinder peak pressure. The reduction in MPRR in RCCI combustion mode makes it possible to operate the engine at higher engine loads without exceeding the MPRR mechanical constraint.The experiments were performed on a 1.9L inline 4 cylinder turbocharged compression ignition (CI) engine modified for dual fuel operation at an engine speed of 1500 RPM and 8 bar IMEP. A full factorial Design of Experiment (DOE) test program and analysis was conducted with four input variables including the diesel fuel reactivity, BR, Exhaust Gas Recirculation (EGR) and Direct Injection (DI) strategy and at two levels of interest. This analysis was used to quantify the impact of the independent input variables on engine out emissions, performance, and MPRR mechanical constraint. Following the DOE testing and analysis the optimum injection strategy to maximize the Brake Thermal Efficiency (BTE) was found for both fuels by sweeping the main Start of Injection timing (SOImain).The results of the DOE analysis showed that the cetane number is the most significant factor that effects HC and CO emissions. The experimental results showed that HRD fuel provides a 2% improvement in brake-thermal efficiency, a 14 g/kW.hr reduction in HC emissions, and 0.5% lower Coefficient of Variation (COV) of Indicated Mean Effective Pressure (IMEP) compared to the baseline diesel-NG RCCI combustion.

Warranty cost sharing policies with preventive maintenance strategy for sensor embedded remanufactured products

With the rapid growth of interest in remanufactured products, offering warranty for remanufactured products and components is becoming necessary for remanufacturer in order to meet customers' requirements mechanism. Furthermore, maintenance policies are of great importance in order to reduce the warranty cost of the remanufacturer. In this paper, a simulation model for remanufactured items sold with one-dimensional non-renewing cost sharing warranty (CSW) and cost limit warranty (CLW) are proposed from the point of view of remanufacturer. In this model, an end-of-life product (EOLP) is subjected to upgrade action at the end of its past life. During the warranty period, preventive maintenance actions are carried out when the remaining life of the product reaches a pre-specified value so that the remanufacturer's expected profit can be maximised. Finally, a numerical example and design of experiment analysis are provided to demonstrate the proposed approach.

Effect of Nickel as Catalyst on the Activation of Titanium Hydride (TiH2) to Titanium Trichloride (TiCl3)

Abstract Titanium hydride (TiH2) uses as a raw material in powder metallurgy method to produce titanium powder. The novel method was introduced to synthesize TiH2 from reaction between titanium (Ⅳ) chloride (TiCl4) and magnesium hydride (MgH2). The critical step in synthesize of TiH2 in this method, is formation of titanium (Ш) chloride (TiCl3) during reactions in the system. The reaction between synthesized TiH2 powder and excess TiCl4 gas in the system can result in the formation of TiCl3. In this study, effect of nickel (Ni) metal and ammonium chloride (NH4Cl) as catalyst was investigated on formation of TiCl3 under hydrogen atmosphere. Statistical design of experiment (DOE) method was applied to examine the effect of catalyst at various conditions. The main including factors were reaction time, temperature and amount of catalyst. It was observed that change in the amount of Ni had the most significant effect on weight loss of TiH2. The results of DOE analysis showed that maximum weight loss reached at temperature of 250 °C, 120 minutes reaction time and 0.1 molar ratio of Ni/NH4Cl. Samples were characterized with X-Ray Diffraction analysis. The results confirmed that excess amount of TiCl4 in the system led to formation of TiH2 to TiCl3, which is not favourable in production of TiH2 powder.

Novel Biobased Textile Fiber from Colombian Agro-Industrial Waste Fiber.

Fique fibers, native to Colombia, are traditionally used for ropes and bags. In the extraction of long fibers for these purposes, the same amount of short fibers is generated; the short fibers are then discarded in the soil or in landfills. This agro-industrial waste is cellulose-rich and can be potentially developed into new biobased products. As an alternative use for these fibers, viscose regenerated fibers with potential applications in the textile industry were developed. Fique waste fibers were pulped (to produce fique cellulose pulp, FCP) using a 33 design of experiment (DOE) to adjust the variables of the whitening treatment, and DOE analysis showed that time and hydrogen peroxide concentration do not have a significant effect on non-cellulosic remotion, unlike temperature. The behavior of this pulp in the production of viscose was compared against that of commercially available wood cellulose pulp (WCP). FCP showed a suitable cellulose content with a high degree of polymerization, which makes it a viable pulp for producing discontinuous viscose rayon filaments. Both pulps showed the same performance in the production of the viscose dope and the same chemical, thermal, and mechanical behavior after being regenerated.

Analysis of dynamic decomposition for barium dimethyl-naphthalene-sulfonate on an Al3Mg (0 0 1) surface from ab-initio molecular dynamics

One important dynamic decomposition pathway for a surface corrosion-inhibitor: barium dimethyl- naphthalene-sulfonate, is investigated on a clean Al3Mg (0 0 1) binary-alloy surface using ab-initio molecular dynamics based upon density functional theory. Each inhibitor molecule is oriented its functional groups of sulfonic-oxygen bases toward the surface, starting at an initial impact velocity. The dynamic decomposition pathway occurs upon molecular collision with the surface, leading to the decomposed fragments that may clearly represent the initial formation stage of additive thin-film on the surface during a plastic substrate deformation. In addition, three important factors: initial impact speed acting on molecule (kinetic effect), substrate temperature (thermal effect) and initial molecular orientation (geometric effect) etc, are employed to analyze their influences on molecular decomposition. An approach of design-of-experiment (DOE) is applied to an analysis of relative importance for each factor and all factor interactions in above, so as to figure out the best way of surface protection. Final DOE analysis indicates that the most significant factor for promoting molecular decomposition on surface is the substrate temperature, i.e., the higher the substrate temperature, the more rapid decomposition of molecule on surface. While initial impact velocity plays a smaller role, and initial molecular orientation performs less importance to molecular decomposition.

Methodology to simulate normalized testing cycles for engines and vehicles via design of experiments with low number of runs

This paper proposes a methodology for simulating engine/vehicle responses of a non-stationary test cycle by means of few steady-state operating modes, which can greatly reduce testing costs and time. The novelty of the proposed methodology is the application of a mapping from the engine working region to a square domain, which allows testing any design of experiments (DoE) regardless of the testing cycle, vehicle or engine. In this new working space (mapped region) it is easy to apply a DoE that satisfies optimality conditions. The validation of the methodology is based on experimental data obtained from the New European Driving Cycle. Firstly, the methodology consists in determining which representative responses can be instantaneously and/or cumulatively approximated via a low degree polynomial function (smooth surfaces) and, secondly, in performing a DoE analysis in the mapped working region where the points defining each DoE are placed. An approach function for each response is developed based on DoE tested points. Subsequently, this model allows simulating vehicle responses during the transient test. For the studied validation case, results show that main engine performance responses can be instantaneously and cumulatively predicted with high accuracy by means of a DoE with few runs. On the other hand, this analysis reveals a cumulative predicted response of confidence for regulated exhaust emissions, but not for the instantaneous values. These findings support future studies to determine the optimal DoE which minimizes testing time and costs with a satisfactory and accurate estimation of engine responses.

Performance Analysis and Improvement of Flat Torque Converters Using DOE Method

Automotive torque converters have recently been designed with an increasingly narrower profile for the purpose of achieving a smaller axial size and reducing weight. Design of experiment (DOE) and computational fluid dynamics (CFD) techniques are applied to improve the performance of a flat torque converter. Four torque converters with different flatness ratios (0.204, 0.186, 0.172, and 0.158) are designed and simulated first to investigate the effects of flatness ratio on their overall performance, including efficiency, torque ratio, and impeller torque factor. The simulation results show that the overall performance tends to deteriorate as the flatness ratio decreases. Then a parametric study covering six geometric parameters, namely, inlet and outlet angles of impeller, turbine, and stator is carried out. The results demonstrate that the inlet and outlet angles play an important role in determining the performance characteristics of a torque converter. Furthermore, the relative importance of the six design parameters is investigated using DOE method for each response (stall torque ratio and peak efficiency). The turbine outlet angle is found to exert the greatest influence on both responses. After DOE analysis, an optimized design for the flat torque converter geometry is obtained. Compared to the conventional product, the width of the optimized flat torque converter torus is reduced by about 20% while the values of stall torque ratio and peak efficiency are only decreased by 0.4% and 1.7%, respectively. The proposed new optimization strategy based on DOE method together with desirability function approach can be used for performance enhancement in the design process of flat torque converters.

Formation of Titanium Hydride from the Reaction Between Magnesium Hydride and Titanium Tetrachloride

The reaction between magnesium hydride (MgH2) and titanium tetrachloride (TiCl4) to produce titanium hydride (TiH2) was carried out at varying temperature, time and Argon (Ar) gas flow rate. The reaction conditions were optimized for increasing the formation of TiH2 by using the statistical design of experiments (DOE). The hydriding temperature was varied from 200 to 300 °C, while the reaction time was changed from 60 to 180 minutes. The flow rate of argon gas was controlled in the range of 20 to 60 mL.min−1 to minimize TiCl4 dilution. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Elemental hydrogen analyzer. From the experiments, the highest weight change (Xw) of the sample produced at 300 °C for 180 minutes with Ar flow rate of 20 mL.min−1 was 0.19 wt.% and the degree of hydriding (Xh) of 38.49% by elemental hydrogen analysis. The DOE analysis inferred that the reaction time was the most significant factor followed by the flow rate of Ar gas and reaction temperature. The SEM/EDX analysis indicated that the product was composed of MgH2, MgCl2, TiCl2.3 and TiH2.The product contained a minor phase of TiO2 that could be due to seepage of ambient moisture into the reaction chamber.

Sensitivity Analysis of BLISK Airfoil Wear

The decreasing performance of jet engines during operation is a major concern for airlines and maintenance companies. Among other effects, the erosion of high-pressure compressor (HPC) blades is a critical one and leads to a changed aerodynamic behavior, and therefore to a change in performance. The maintenance of BLISKs (blade-integrated-disks) is especially challenging because the blade arrangement cannot be changed and individual blades cannot be replaced. Thus, coupled deteriorated blades have a complex aerodynamic behavior which can have a stronger influence on compressor performance than a conventional HPC. To ensure effective maintenance for BLISKs, the impact of coupled misshaped blades are the key factor. The present study addresses these effects on the aerodynamic performance of a first-stage BLISK of a high-pressure compressor. Therefore, a design of experiments (DoE) is done to identify the geometric properties which lead to a reduction in performance. It is shown that the effect of coupled variances is dependent on the operating point. Based on the DoE analysis, the thickness-related parameters, the stagger angle, and the max. profile camber as coupled parameters are identified as the most important parameters for all operating points.

MONEY-BACK GUARANTEE WARRANTY POLICY FOR SENSOR EMBEDDED REMANUFACTURED PRODUCTS

Manufacturers attempt to respond to consumers’ concerns involving environmental issues as well as the more governmentally stringent environmental legislations by establishing facilities which include the minimization of the totality of waste relocated to landfills by recovering materials and components from returned, or End-Of-Life (EOL) products and reuse them to build a remanufactured product, and/or novel components. In this paper, an optimization simulation model for remanufactured items sold with one-dimensional non-renewing Money Back Guarantee (MBG) Warranty policy is proposed from the view of remanufacturer, in which, an End-Of-Life product (EOLP) is subjected to upgrade action at the end of its past life and during the warranty period. Finally, a numerical example and Design of Experiment analysis are provided to demonstrate the proposed approach.

Money-back guarantee warranty policy with preventive maintenance strategy for sensor-embedded remanufactured products

In today’s global environment, technology is constantly evolving. Being able to stay up-to-date with the very latest technological advances can be extremely hard to accomplish. As a result of these changes and developments in technology, which often come unexpectedly, consumers are frequently tempted to update their devices to the very latest model. The result is that the life cycle of a product is becoming shorter and shorter than before. Manufacturers attempt to respond to consumers’ concerns involving environmental issues as well as the more governmentally stringent environmental legislations by establishing facilities which include the minimization of the totality of waste relocated to landfills by recovering materials and components from returned, or End-Of-Life products and reuse them to build a remanufactured product, and/or novel components. With the rapid growth of interest in remanufactured products’ market, offering warranty for remanufactured products and components is becoming a necessity for remanufacturer in order to meet customers’ requirement and as a marketing mechanism. During that process, maintenance policies are of great importance in order to reduce the warranty cost on the remanufacturer. In this paper, an optimization simulation model for remanufactured items sold with one-dimensional non-renewing money-back guarantee (MBG) warranty policy is proposed from the view of remanufacturer, in which, an End-Of-Life product is subjected to upgrade action at the end of its past life and during the warranty period, preventive maintenance actions are carried out when the remaining life of the product reaches a pre-specified value so that the remanufacturer’s expected profit can be maximized. Finally, a numerical example and design of experiment analysis are provided to demonstrate the proposed approach.