Study of Positive Feed Drilling Parameters for Optimized Drilling in Stackups of Composite/Metallic Materials

<div class="section abstract"><div class="htmlview paragraph">In the present paper, to predict the process relation between laser-assisted machining parameters and machinability characteristics, statistical models are formulated by employing surface response methodology along with artificial neural network. Machining parameters such as speed of cut; the rate of feed; along with the power of laser are taken as model input variables. For developing confidence limit in collected raw experimental data, the full factorial experimental design was applied to cutting force; surface roughness; along with flank wear. Response surface method (RSM) with the least square method is used to develop the theoretical equation. Furthermore, artificial neural network method has been done to model the laser-assisted machining process. Then, both the models (RSM and ANN) are compared for accuracy regarding root mean square error (RMSE); model predicted error (MPE) along with the coefficient of determination (R2). The results show that the ANN model estimates the machinability indices with high accuracy that provides a maximum precision benefit range of about 10% - 22% than RSM model.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Modern automotive powertrains are increasingly adopting engine downsizing and down speeding to meet stringent emission regulations and improving fuel efficiency However, these changes result in higher torsional vibrations excitation amplitudes and NVH (Noise, Vibration, and Harshness) refinement more challenging. With growing customer expectations for premium driving experiences conventional clutch is no longer sufficient. To meet the NVH performance targets of the vehicle Dual Mass Flywheels (DMFs) are used</div><div class="htmlview paragraph">In DMF due to lower stiffness and inertia separation there is a greater advantage on torsional filtration in normal drive and idle condition. But the torsional resonance frequency of the connected DMF is lower than the idle RPM. Engine startup is a key drawback with DMF equipped vehicles. The proper tuning of starter motor performance & DMF stiffness is required to cross the resonance zone faster otherwise it will lead to DMF to stay in the resonance zone for a longer time leading to structural failure over the period.</div><div class="htmlview paragraph">In this paper we focus on DMF resonance crossing during engine startup condition in the 3 Cylinder Gasoline application. Test measurement is done to capture the startability behavior of DMF. AMESIM 1D simulation model is developed to reproduce the DMF resonance behavior and relative displacement between Primary and secondary flywheel is simulated. Optimization of DMF Spring stiffness between stages are proposed based on correlated simulation model. With the new design of DMF, the startability of the vehicle has improved & also the DMF displacement is reduced within the design limit. This evaluation method gives quick assessment on startability improvement in DMF equipped vehicles.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Conventional charging systems for electric and plug-in hybrid vehicles currently use cables to connect to the grid. This methodology creates several disadvantages, including tampering, risk, depreciation and non-value added user efforts. Loose or faulty cables may also create a safety issue. Wireless charging for electric vehicles delivers both a simple, reliable and safe charging process. The system enhances consumer adoption and promotes the integration of electric vehicles into the automotive market. Increased access to the grid enables a higher level of flexibility for storage management, increasing battery longevity.</div><div class="htmlview paragraph">The power class of 3.7kW or less is an optimal choice for global standardization and implementation, due to the readily available power installations for potential customers throughout the world. One of the key features for wireless battery chargers are the inexpensive system costs, reduced content and light weight, easing vehicle integration.</div><div class="htmlview paragraph">This paper demonstrates a wireless charging design with minimal component content. It includes a car pickup coil with 300 mm side length and low volume and mass 1.5 dm<sup>3</sup> power interface electronics. After an overview of its hardware requirements, power transfer and efficiency benefits are presented, providing the anticipated horizontal and lateral deviations.</div><div class="htmlview paragraph">An intense magnetic field is required to transfer the target power at low volumes between the transfer units. This field heats up any metal object over the transfer coil, similar to an induction oven. Consequently, the system should be powered down whenever a metal object is detected in this area. A Foreign Object Detection (FOD) design has been developed to continuously monitor the critical high field area. Device testing results are also provided.</div><div class="htmlview paragraph">Field characteristics are verified alongside the vehicle, ensuring system safety for living beings; compliant with all applicable standards reference limits which is more challenging than the basic limits [<span class="xref">13</span>].</div></div>

<div class="htmlview paragraph">This paper presents a proposal for thermal analysis running cloned models varying the characteristics of the thermal mathematical models. This type of analysis improves the knowledge of the thermal performances of any space segment, anticipating the problems and reducing the critical iterative analysis process.</div> <div class="htmlview paragraph">To perform this type of analysis the stochastic theory and the Monte Carlo method are used. This will be applied to the critical periods like worst case determination, sensitivity analysis, design limits or test correlation.</div> <div class="htmlview paragraph">This methodology has been applied with very nice results and some of them will be shown.</div>

The present paper investigates the cutting parameters pertaining to the turning of X2CrNi18-09 austenitic stainless steel that are studied and optimized using both RSM and desirability approaches. The cutting tool inserts used are the CVD coated carbide. The cutting speed, the feed rate and the depth of cut represent the main machining parameters considered. Their influence on the surface roughness and the cutting force are further investigated using the ANOVA method. The results obtained lead to conclude that the feed rate is the surface roughness highest influencing parameter with a contribution of 89.69%.The depth of cut and the feed rate are further identified as the most important parameters affecting the cutting force with contributions of 46.46% and 39.04% respectively. The quadratic mathematical models presenting the progression of the surface roughness and the cutting force and based on the machining parameters considered (cutting speed, feed rate and depth of cut) were obtained through the application of the RSM method. They are presented and compared to the experimental results. Good agreement is found between the two sections of the investigation. Furthermore, the flank wear of the CVD-coated carbide tool (GC2015) is found to increase with both cutting speed and cutting time. A higher tool life represented by t=44min is observed at cutting speed, feed rate and depth of cut of 280m/min,0.08mm/rev and 0.2mm respectively. Moreover and at low cutting speeds, the formation of micro weld is noticed and leads to an alteration of the surface roughness of the work piece. Finally, optimizing the machining parameters with the objective of achieving an improved surface roughness was accomplished through the application of the Desirability Function approach. This enabled to finding out the optimal parameters for maximal material removal rate and best surface quality for a cutting speed of 350m/min, a feed rate of 0.088 mm/rev and a depth of cut of 0.9mm.

<div class="htmlview paragraph">In the continuous struggle to improve car body properties, and at the same time reduce the weight of the structure, new materials and body concepts are being evaluated. In competition with more self-evident lightweight materials such as aluminium and plastic composites, new and different grades of high-strength steels with various surface coatings are being introduced. From experience it is known that to be able to weld and join these steel grades under high-volume conditions, it is necessary to perform comprehensive testing to establish those assembly parameters which give a superior and reliable weld quality.</div> <div class="htmlview paragraph">To meet the demands of cost-effective low volume production, we can notice a tendency to move away from traditional uni-body concepts and into the direction of space-frame structures. These can preferably be manufactured out of high-strength steels by using production methods like roll-forming, hydro-forming and hot-forming. The challenge arise when these components shall be assembled to form a rigid body structure, as this type of car body architecture favours single-sided joining methods, about which there is still a limited knowledge and experience in modern body shops.</div> <div class="htmlview paragraph">This paper will focus on the gas metal arc welding process as a suitable tool to assemble light weight steel car body structures. It will describe basic weld tests performed on relevant material grades and combinations with different surface coatings, but will also address the problems that occur at complex three-dimensional welding. For that reason advanced assembly fixtures, as well as hydro-forming tools for the manufacture of parts simulating a generic structural node, have been developed at the <i>Volvo Cars Joining Centre</i>. Results from these welding trials, and from static and fatigue testing of such nodes, will be thoroughly described.</div> <div class="htmlview paragraph">At the end follows a discussion on other suitable single-sided welding methods such as laser welding and brazing techniques, and recommendations and guidelines are given about which method to choose in regard to desired product properties and production requirements.</div>

<div class="section abstract"><div class="htmlview paragraph">Body in White (BIW) of an automobile serves as the shell, on which all the components that make up a vehicle, are mounted. The BIW is an assembly of press formed sheet metal components. The sheet metal composition of each component varies based on the form and functionality requirement of that component. The resulting assembly has multiple weld joineries with dissimilar compositions. The weld integrity of the joineries is crucial in maintaining the geometrical and structural integrity of the BIW. The primary welding method used in BIW assembly is Resistance Spot Welding (RSW). The quality of the weld is an outcome of a combination of multiple weld parameters. These parameters are majorly estimated based on the joinery thicknesses and material combinations. Multiple welding and testing iterations are done to fine tune the parameters for an optimum weld joinery. This is a very tedious process which increases the process time of a BIW assembly. This paper studied the impact of critical weld parameters and recommended the optimum parameter combinations. Real world combinations were emulated by evaluating dissimilar material combinations. Advanced high strength steel (DP590) with Extra deep draw (EDD) joineries with varying material thicknesses were considered for the study to represent the commonly used dissimilar composition combination. The optimized parameters for multiple combinations were concluded and results were discussed. The optimized parameters enable quick selection of optimum weld program for a given joinery or weld station and eliminate material wastage and time.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Exhaust Noise attenuation is one of the important functions of exhaust muffler. Transmission Loss (TL) is a measure of noise attenuation used in designing exhaust mufflers for NVH. TL is a logarithmic difference between inlet and outlet pressures for unit velocity input at inlet of the muffler and anechoic termination at outlet of the muffler as boundary conditions. TL amplitude and its frequency tuning depends on a combination of various muffler design parameters like volume, length, muffler cross section, pipe cross sections, pipe perforations, number of chambers, baffle perforations, etc. Achieving the desired TL performance with no valleys over a wide frequency range is very challenging. Manual design iterations with large numbers of permutations and combinations of design variables are difficult and time-consuming. It also needs a highly experienced professional to balance TL performance, design variables and design constraints. The current paper discusses an exhaust muffler TL optimization simulation process that couples modeFRONTIER for DOEs, & GT-POWER, for acoustic simulation. All identified design variables are iterated in batch mode within specified design limits. DOEs are set up using Non-dominated Sorting Genetic Algorithm (NSGA) or Multi Objective Genetic Algorithm (MOGA) in modeFRONTIER. Based upon pre-defined iterative simulation cycles, muffler design is optimized to meet design constraints and TL performance. This optimization helps to reduce manual efforts in building simulation models, to carry out more iterations, to reduce solver time, to reduce manual intervention for post processing, and to give optimized TL performance.</div></div>

<div class="htmlview paragraph">Low-cycle fatigue is a term used to describe the thermal and/or mechanical loading conditions which cause premature failure of materials at less than 20,000 cycles. These cyclic stress conditions are prevalent during engine start-up or shut down and in severe flight maneuvers. From the design standpoint, it is important to assess and predict the behavior of compressor and turbine component materials under these severe conditions.</div> <div class="htmlview paragraph">This paper presents the low cycle fatigue data on six candidate materials which were considered for an advanced engine. The materials were investigated simultaneously by pull-pull and by modified rotating beam fatigue testing techniques. Results indicate that the candidate materials can sustain appreciable cycling at stress levels beyond design limit before fracture occurs by the low cycle fatigue mechanism. Of the materials investigated, Udimet 630 exhibited the optimum low cycle fatigue resistance.</div>

<div class="section abstract"><div class="htmlview paragraph">Lean burn gasoline spark-ignition engines can support the reduction of CO<sub>2</sub> emissions for future hybrid passenger cars. Very high efficiencies and very low NOx raw emissions can be achieved, if relative air/fuel ratios λ of 2 and above can be reached. The biggest challenge here is to assure a reliable ignition process and to enhance the fuel oxidation in order to achieve a short burn duration and a good combustion stability.</div><div class="htmlview paragraph">This article aims at introducing an innovative combustion system fully optimized for ultra-lean operation and very high efficiency. Thereto, a new cylinder head concept has been realized with high peak firing pressure capability and with a low surface-to-volume ratio at high compression ratios. 1D and 3D simulations have been performed to optimize the compression ratio, charge motion and intake valve lift. Numerical calculations also supported the development of the ignition system. Stable ignition and fast flame propagation were achieved thanks to a centrally located active pre-chamber which allows to control the air/fuel ratio independently of the air/fuel ratio in the main combustion chamber.</div><div class="htmlview paragraph">Experimental investigations have then been performed with a single cylinder engine to demonstrate the capabilities of this new combustion system in a sweet spot operating point. A maximal indicated thermal efficiency of 47% was achieved at λ = 2 with optimized injection settings in the pre and main combustion chambers. The fuel efficiency could be maximized thanks to a fast and knock-free combustion process. Compared to the reference operation with stoichiometric air/fuel ratio, only a seventieth of the NOx raw emissions were measured (i. e. 50 ppm), and the particulate mass emissions were halved. The energy balance analysis points out that these promising results could be further improved by working on the reduction of the unburnt hydrocarbon emissions and by jointly optimizing the scavenging process.</div></div>

<div class="section abstract"> <div class="htmlview paragraph">This SAE Standard describes a laboratory test procedure for measuring the vibration damping performance of a system consisting of a damping material bonded to a vibrating cantilevered steel bar. The bar is often called the Oberst bar (named after Dr. H. Oberst) and the test method is often called the Oberst bar test method. Materials for damping treatments may include homogeneous materials, nonhomogeneous materials, or a combination of homogeneous, nonhomogeneous, and/or inelastic (such as aluminum foil) materials. These materials are commonly installed in transportation systems such as ground vehicles, marine products, and aircraft to reduce vibration at resonance, and thus reduce the noise radiation from the vibrating surface. The test method described herein was developed to rank order materials for application on panels using general automotive steel but also may be applicable to other situations or conditions.</div> <div class="htmlview paragraph">Damping performance for most materials and systems varies as a function of both frequency and temperature. Accordingly, this test procedure includes provisions for measuring damping over a range of frequencies and temperatures found applicable to many transportation systems. The measured damping performance will be expressed in terms of composite loss factor, η<sub>c</sub>, within the frequency range of approximately 100 to 1000 Hz, and over the useful temperature range for the given application. The term composite refers to the steel and damping material combination. The composite loss factor is, therefore, dependent upon the thickness, damping, and modulus of both the steel and damping material layer.</div> <div class="htmlview paragraph">The test procedure described here is based on the method described in ASTM E756. However, this SAE document differs from the ASTM E756 method in that the SAE practice specifies the bar material, three bar sizes, the mounting conditions of the test samples, and suggested standard interpolation frequencies. This document provides a means of rank ordering damping materials according to their composite loss factor values from test samples that represent typical sheet metal applications.</div> <div class="htmlview paragraph">The material properties of the damping material alone, including Young’s modulus E, and the material loss factor η, may be computed from the test samples specified in this document if additional conditions are met. ASTM E756 defines these additional conditions as well as the equations to be used to compute the damping material properties for the single layer (Oberst beam) configuration.</div></div>

<div class="section abstract"> <div class="htmlview paragraph">This SAE Recommended Practice describes a laboratory test procedure for measuring the vibration damping performance of a system consisting of a damping material bonded to a vibrating cantilevered steel bar. The bar is often called the Oberst bar (named after Dr. H. Oberst) and the test method is often called the Oberst Bar Test Method. Materials for damping treatments may include homogeneous materials, nonhomogeneous materials, or a combination of homogeneous, nonhomogeneous, and/or inelastic (such as aluminum foil) materials. These materials are commonly installed in transportation systems such as ground vehicles, marine products, and aircraft to reduce vibration at resonance, and thus reduce the noise radiation from the vibrating surface. However, the test method described herein was developed to rank order materials used in PASSENGER VEHICLE APPLICATIONS with steel sheet metal and may not be fully applicable to other situations.</div> <div class="htmlview paragraph">Damping performance for most materials and systems varies as a function of both frequency and temperature. Accordingly, this test procedure includes provisions for measuring damping over a range of frequencies and temperatures found applicable to many transportation systems. The measured damping performance will be expressed in terms of composite loss factor, η<sub>c</sub>, within the frequency range of approximately 100 to 1000 Hz, and over the useful temperature range for the given application. The term composite refers to the steel and damping material combination.</div> <div class="htmlview paragraph">The test procedure described here is based on the method described in ASTM E 756. However, this SAE document differs from the ASTM E 756 method in that the SAE practice specifies the bar material, the bar size, and the mounting conditions of the test samples. This document provides a means of rank ordering damping materials according to their composite loss factor values from test samples that represent typical passenger vehicle applications.</div> <div class="htmlview paragraph">The ASTM E 756 should be followed to determine the damping properties of materials alone, including loss factor η, Young's modulus E, and shear modulus G.</div></div>

In this paper, the empirical research on the effects of cutting parameters on surface roughness when milling 40Cr steel with face mill is conducted. The cutting parameters in this study include the cutting speed, feed rate and depth of cut. The tests are conducted in the form of Central Composite Design. The analysis shows that, for both Ra and Rz: (1) the feed rate has the greatest effect on surface roughness, followed by the degree of influence of the depth of cut, cutting speed with insignificant effects on surface roughness. (2) only the interaction between the feed rate and depth of cut have a significant effect on both Ra and Rz; the interaction between the cutting speed and feed rate, the interaction between the cutting speed and depth of cut have negligible effects on the surface roughness. In addition, the regression equations showing the relationship between Ra, Rz and cutting parameters is developed in this study.

<div class="htmlview paragraph">Detailed finite element modeling of the human body offers a potential major enhancement to the prediction of injury risk during vehicle impacts. Currently, vehicle crash safety countermeasure development is based on a combination of testing with established anthropomorphic test devices (i.e., ATD or dummy) and a mixture of multi-body (dummy) and finite element (vehicle) modeling. If a relatively simple finite element model can be developed to capture additional information beyond the capabilities of the multi-body systems, it would allow improved countermeasure development through more detailed prediction of performance.</div> <div class="htmlview paragraph">A simpler finite element model of human bones could be developed if it were shown that less complex finite element material modeling provides sufficient prediction of long bone macro-level strength. This study investigates the importance of including material anisotropy in the finite element model of a human femur. Four composite femur models were developed: linear orthotropic, linear transversely isotropic, linear isotropic, and non-linear isotropic. Each model was used to simulate anterior-posterior (AP) bending and external-internal rotation. Comparison of the results with physical tests indicates that the global elastic force-deflection response of the whole femur in AP bending is sufficiently described by isotropic material models of the two constituent tissues. The more complex (more detailed anisotropic) material models do not enhance the results of this simulation. However, the global response of the femur in external-internal rotation does indicate that increased material model complexity (or higher degree of detail in material anisotropy) can provide improved prediction capability.</div>

High quality products produced by computerized numerical control machining has a high demand in the industry due to its effect on product appearance, function, and reliability. In order to improve its quality, the application of nano‐cutting fluid system can significantly reduce the cutting forces, surface roughness and cutting temperature as the nanoparticles are known as superior in reducing the friction between the workpiece‐tool. In this study, nano‐cutting fluid containing multi‐wall carbon nanotubes mixed with vegetable oil is developed and applied to the cutting process of aluminium alloy Al6061 which employed minimum quantity lubricant to increase the effectiveness of the nano‐cutting fluid. Surface roughness and cutting forces are analyzed by using signal‐to‐noise response analysis and the analysis of variance (Pareto ANOVA) to determine the optimum parameter of the experiment. The experiment shows the combinations of nanoparticle concentration (A2, 0.2 %), cutting speed (B1, 1000 min‐1), feed rate (C3, 200 mm/min) and depth of cut (D1, 2 mm) for lowest cutting force, nanoparticle concentration (A3, 0.8 %), cutting speed (B1, 1000 min‐1), feed rate (C2, 150 mm/min) and depth of cut (D1, 2 mm) for lowest cutting temperature and nanoparticle concentration (A2, 0.2 %), cutting speed (B2, 2000 min‐1), feed rate (C2, 150 mm/min) and depth of cut (D1, 2 mm) for lowest surface roughness.