Simultaneous Engineering of Aluminum Castings for Chassis Components

<div class="section abstract"><div class="htmlview paragraph">The microcellular foam injection molding process for thermoplastic materials provides design flexibility and cost savings opportunities not found in conventional injection molding. This process allows for plastic part design with material wall thickness optimized for functionality.</div><div class="htmlview paragraph">The combination of density reduction and design for functionality can result in material and weight savings of up to 20%. With the correct equipment configuration, mold design, and processing conditions, these microcellular voids are uniform in size and distribution. The use of microcellular foam molding provides significant reductions in cycle time, material consumption, injection pressure, and clamp tonnage.</div><div class="htmlview paragraph">In this work, a physical foam molding process, MuCell, is applied to a polypropylene (PP) composite. The MuCell injection molding process involves the highly controlled use of gas in supercritical state, as the physical blowing agent, to create millions of micron-sized voids in thin wall molded parts (less than 3mm).</div><div class="htmlview paragraph">The results show that a weight reduction can be achieved without significant degradation in mechanical properties, such as stiffness and impact resistance. MuCell also contributes to faster cooling from the melt as well as the elimination of pack and hold phase, which both result in shorter injection molding cycle times and reduced warpage.</div><div class="htmlview paragraph">Once material tests have been completed, final part tests will also be performed, to validate established design specifications. These results presented here indicate that microcellular foam molding technology has good potential to be applied to interior parts of vehicles, contributing to weight reduction and productivity increase.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The job of a suspension system is to maximize the friction between the tires and the road surface, to provide steering stability with good handling and to act as a cushioning device to ensure the comfort of the driver and passengers. The suspension system also protects the vehicle and any cargo or luggage from damage and wear.</div><div class="htmlview paragraph">Commonly the strength of these suspension systems is evaluated by endurance trials on field or Rig testing which are time consuming and costly. On the other hand, virtual testing methods for strength and stiffness evaluation provide useful information early in the design cycle and save significant time and cost. However, the virtual method also needs validation, which can be achieved by physical co-relations (via rig tests).</div><div class="htmlview paragraph">A study has been done to predict the behavior of Leaf Spring Suspensions entirely through the FEA (Finite Element Analysis) route and correlating those results with physical test. Initially the acceleration data is abstracted via RLDA (Road Load Data Acquisition) pasting the accelerometers at axle points. Strain Gauges are used to acquire strain values with respect to accelerations. This acceleration data is then used as input in rig setup at axle points and relatively strain is measured at same strain gauge locations as done while RLDA. This is done primarily to validate the test rig.</div><div class="htmlview paragraph">After Rig validation, a virtual validation is required. Leaf Spring assemblies modeled in FEA are similar to rig test bed setup. Tests are performed on the rig and gauges are used to extract the data for virtual co-relation. At the time of simulation, various parameters have been modified to achieve realistic behavior. Correlations between Stiffness and Stress have been achieved at these strain gauge locations between the Rig test and CAE (Computer Aided Engineering) results.</div><div class="htmlview paragraph">Correlation (around 90%) has been achieved between Rig test data and FEA results at measured locations. Correlation has helped in reducing product design time and cost of running the rig until crack. This process has also reduced the cost by using soft validation for multiple Leaf Spring Suspensions like Semi-elliptical, Parabolic, Weveller, Bogie and Bell Crank. Hence, this FEA based methodology has facilitated our organization in designing an excellent suspension system which will prove beneficial to our customers.</div></div>

<div class="section abstract"><div class="htmlview paragraph">There is an ever growing demand for blind fastener in the aerospace industry. This demand is driven not only by the advantages of single sided installation, but also by the potential to fully automate their installation process.</div><div class="htmlview paragraph">Blind fasteners can easily be integrated with innovative end-effectors that combine drilling, installation and inspection systems, enabling the reduction of process cycle times and their associated cost savings.</div><div class="htmlview paragraph">Clearly the advantages of single sided installation are a key benefit, but it cannot be forgotten that currently the mechanical performance of these systems is reduced compared with conventional threaded or swaged parallel shank fasteners. There are other important drawbacks existing around them which could penalise significantly the optimised design and performance of the structures.</div><div class="htmlview paragraph">Specific key characteristics that take into account some of these drawbacks have been established by Airbus which will be referenced in this paper.</div><div class="htmlview paragraph">Recently some improvements in new system concepts based on the typical pull and threaded type versions have been achieved by the main aerospace fastener suppliers, based on better mechanical performance, improved cosmetic appearance of the fastener head, etc.</div><div class="htmlview paragraph">This paper will give a global view of the characteristics that are considered more important for evaluation of the next generation of blind systems to allow their optimised implementation on new applications as well as a chance to view some new systems developed by the Suppliers.</div></div>

<div class="section abstract"><div class="htmlview paragraph">A method of fatigue life estimation for the spot-welds of vehicle body structures by means of Finite Element Analysis (FEA) was studied. 6 general forces applied to a nugget of spot-weld under multiaxial loads were determined and the Nominal Structural Stress (σ<sub>ns</sub>) was calculated from them. It was confirmed that fatigue strength of the spot-welds under various multiaxial loads could be estimated universally by using σ<sub>ns</sub>.</div><div class="htmlview paragraph">Based on the theory of elasticity of plates, stress of spot-weld nugget was analyzed. The theoretical equations for determining the principal stress at the nugget edge from6 general forces acting on a nugget were derived. And the principal stress was defined as the σ<sub>ns</sub>.</div><div class="htmlview paragraph">The value of σ<sub>ns</sub> was determined by FEM that used a solid model and compared with the theoretical calculation value. They agreed quite well.</div><div class="htmlview paragraph">Fatigue tests of DC specimens under various multiaxial loads (shear plus cross tension and tensile shear plus torsion) were conducted. The test results fell within a narrow band by using σ<sub>ns</sub> determined according to the above theoretical equations.</div><div class="htmlview paragraph">D-diameters for cross tension and bending moment, that represent the diameter of the constrain position, are required for σ<sub>ns</sub> calculation. A way to decide the value of D-diameter was examined by employing a simple model and guideline to determine it for actual structures was proposed.</div><div class="htmlview paragraph">According to this method and determining optimal D-diameter, fatigue strength of spot-welds can be estimated simply and accurately.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Radars based ADAS solutions are growing at a substantial rate in the automotive market since they play a fundamental role in increasing passengers and pedestrian safety.</div><div class="htmlview paragraph">To support radar designers in reducing time and design cost, to meet the stringent vehicle safety norms, to reduce risks about final installed radar performance etc., more effective and efficient industrial approach have to be devised both in terms of simulation (working at 77 GHz poses several numerical challenges) and testing.</div><div class="htmlview paragraph">This paper presents IDS/Siemens PLM Software technical approach and CAE tools, based on a synergic use of high-fidelity simulation models and measurement set-up’s to support the whole design, optimization and verification cycle, starting from the stand-alone radar antenna performance up to on-car installed radar operational performance verification.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Vibration testing is an essential component of automotive product development, ensuring that components such as engines, transmissions, and electronic systems perform reliably under various operating conditions. The adoption of electronics in the automotive industry, particularly during the 1950s and 1960s, marked a shift in vibration testing approaches, moving from primarily low-frequency tests to methods that could address high-frequency vibrations as well. This evolution highlights the need for effective vibration fixture designs that can simulate real-world conditions, enabling manufacturers to detect potential weaknesses before products are integrated into vehicles. A key aspect of vibration testing is the identification of resonant frequencies within components. The coupled mass-spring-damper system, for example, can exhibit multiple resonances characterized by a Bode Diagram, where the Q factor technique is utilized to assess damping levels. Accurate vibration analysis can be achieved through various methodologies, including modal analysis and frequency response calculations, which help engineers understand how components will behave under different stimulus.</div><div class="htmlview paragraph">Furthermore, the use of advanced analytical tools, such as Finite Element Analysis (FEA) has become increasingly important in the automotive industry. These modern approaches allow for more precise and efficient vibration analysis, providing deeper insights into potential issues and enhancing overall product reliability.</div><div class="htmlview paragraph">By adhering to industry standards such as International Organization for Standardization standard i.e. (ISO) 16750-3, Society of Automotive Engineers standard i.e. (SAE) J1455, and Military standard (MIL-STD)-810G, manufacturers can ensure their products meet rigorous safety and durability requirements, ultimately leading to reduced warranty claims and increased customer satisfaction.</div><div class="htmlview paragraph">Utilizing FEA allows for virtual prototyping, which reduces the reliance on physical prototypes traditionally used to test and refine designs. This approach not only shortens the design-to-production cycle but also allows for comprehensive testing and optimization, ultimately resulting in a more efficient development process and lower costs associated with prototype creation.</div><div class="htmlview paragraph">The design process for vibration fixtures involves a cyclical approach where simulations guide modifications. By continuously analysing and adjusting designs based on performance data, engineers can refine fixtures to meet specific criteria such as cost efficiency, structural performance, and overall functionality. This iterative nature of design helps in exploring multiple configurations and ensuring that the final product achieves all desired performance targets within the constraints of the given package space.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The European Union has defined legally binding CO2-fleet targets for new cars until 2030. Therefore, improvement of fuel economy and carbon dioxide emission reduction is becoming one of the most important issues for the car manufacturers. Today’s conventional car powertrain systems are reaching their technical limits and will not be able to meet future CO2 targets without further improvement in combustion efficiency, using low carbon fuels (LCF), and at least mild electrification.</div><div class="htmlview paragraph">This paper demonstrates a highly efficient and performant combustion engine concept with a passive pre-chamber spark plug, operating at stoichiometric conditions and powered with liquefied petroleum gas (LPG). Even from fossil origin, LPG features many advantages such as low carbon/hydrogen ratio, low price and broad availability. In future, it can be produced from renewables and it is in liquid state under relatively low pressures, allowing the use of conventional injection and fuel supply components.</div><div class="htmlview paragraph">To take advantage of the specific capabilities of LPG a combustion system is designed to increase combustion efficiency and decrease fuel consumption and engine-out emissions. The applied combustion chamber geometry, including the passive pre-chamber, leads to lower exhaust gas temperatures and consequently higher peak power when operating under stoichiometric conditions.</div><div class="htmlview paragraph">The presented combustion system was developed by means of extensive 3D-CFD simulations and experimental single-cylinder engine results by applying advanced combustion diagnosis and analysis tools. The potential of the combustion system is demonstrated over the entire engine map focusing on certification and real operating conditions such as idle, low load and maximum power. The potential of the combustion process will be figured out, both for low and high-power densities, with respect to future emission limitations.</div></div>

<div class="htmlview paragraph">A set of methods is described to calculate boundary conditions for thermal and mechanical finite element (FE) analyses and to assess and present the results of those analyses in a clear and understandable way. The approach utilizes a combination of engine simulation programs and an empirical database of engine measurements developed over many years. The methodology relies on the use of specialized FE pre- and post-processors dedicated to the analyses of engine components.</div> <div class="htmlview paragraph">Gas-side thermal boundary conditions for combustion chamber components are calculated using an engine simulation code for standalone FE analyses or for FE analyses directly coupled to the engine simulation code itself. Coolant side boundary conditions are calculated using multidimensional flow analysis (computational fluid dynamics). Boundary conditions in intake and exhaust manifolds are calculated using a one-dimensional gas dynamics code.</div> <div class="htmlview paragraph">Thermo-mechanical analysis results are assessed and presented using dedicated post-processing tools to determine the effects of temperature on local material strength, and to calculate distributions of safety factor against ultimate strength, yield strength and fatigue strength. New methods of results presentation are described for the analysis of cylinder bore distortion, piston-liner interaction, cylinder liner cavitation and valve seat wear.</div>

<div class="htmlview paragraph">Evaluations were made of the short-term (5 minute) durability at high temperatures of 85 mm outer diameter ceramic radial turbine rotors made of silicon nitride using an improved hot gas spin test rig.</div> <div class="htmlview paragraph">Under no load conditions, the rotors withstood a maximum turbine tip speed (Ut) of 550 m/s without bursting at a turbine inlet gas temperature (TIT) of 1240°C.</div> <div class="htmlview paragraph">Under partially loaded conditions, they withstood up to Ut of 500 m/s at TIT of 1280°C without bursting.</div> <div class="htmlview paragraph">The test results indicated that the knee point temperature in terms of TIT at which the failure tip speed decreased sharply was about 40°C higher under partially loaded condition than under no load condition.</div> <div class="htmlview paragraph">The temperature and stress distribution in the turbine in the hot gas spin test were calculated by the finite element analysis, which supported the dependence of the knee point temperature in terms of TIT at spin test on load condition.</div>

<div class="section abstract"><div class="htmlview paragraph">The Los Angeles City Traffic (LACT) brake test is well known acclaimed procedure used by many vehicle manufacturers to assess the brake pad wear behavior and to investigate the Noise, Vibration and Harness (NVH) performance of the brake system. The LACT driving route consists of a set of real-world driving conditions, which has been considered representative of the US passenger vehicle market.</div><div class="htmlview paragraph">The scope of this study is to mimic the LACT test using finite element analysis (FEA) to calculate the wear displacement based on Rhee’s theory. The Leading-edge and trailing edge of the brake pad’s wear tendency is also predicted from the simulation. The finite element model for wear simulation consists of brake system viz., Rotor, Knuckle, Pads, Anchor bracket, Piston, and Caliper. Various braking scenarios consist of different driving characteristics (Number of brake applications, vehicle speed, brake pressure, rotor temperature, and brake rotor interface friction variation) based on LACT Route traffics are replicated in FEA.</div><div class="htmlview paragraph">The wear displacement results from the finite element analysis are in good agreement with physical test results. Further, based on the wear displacement values, the brake pad’s life span is calculated and correlated well with the test measurements.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Reducing emissions and the carbon footprint of our society have become imperatives requiring the automotive industry to adapt and develop technologies to strive for a cleaner sustainable transport system and for sustainable economic prosperity. Electrified hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV) and range extender powertrains provide potential solutions for reducing emissions, but they present challenges in terms of thermal management. A key requirement for meeting these challenges is accurately to predict the thermal loading and temperatures of an internal combustion engine (ICE) quickly under multiple full-load and part-load conditions.</div><div class="htmlview paragraph">Computational Fluid Dynamics (CFD) and thermal survey database methods are used to derive thermal loading of the engine structure and are well understood but typically only used at full-load conditions. These methods are limited in terms of computational overhead with CFD and the validity of the database when wishing to look at part-load conditions to build up a thermal map of the engine for transient solutions.</div><div class="htmlview paragraph">This paper presents a new analytical Finite Element (FE) based tool for calculating thermal boundary conditions of all the components of the power cylinder using physical models and semi-empirical correlations, without the need for CFD analysis, and which overcomes the limitation of database methods which are not predictive. An iterative solution is used that captures all the heat paths in detail and where each solution runs quickly enough to allow different design variants to be assessed for multiple operating conditions. The calculated temperatures and the corresponding deformations can then be used to predict piston secondary motion and ring dynamics and to better predict friction, wear and oil consumption of the power cylinder and the structural durability of the components.</div><div class="htmlview paragraph">The toolset is applied to a 2.0 liter 4-cylinder Gasoline Turbocharged Direct Injection (GTDI) engine and validated with measurements on the piston, cylinder head and cylinder bore for different full and part-load conditions.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Friction heating in solid cylindrical body contact has been an interesting subject for a long time for physicists (i.e. tribologists) and application engineers. In the current environment where the industry product, such as Diesel Rotary Pump (DRP) which operates at higher speed, the temperature rise from the friction contact is of great importance to the manufacturer for thermal safety and its environment effect.</div><div class="htmlview paragraph">In this paper, a steady-state temperature rise under friction heating is studied on a pump roller to cam ring contact within a cyclic segment of a DRP using quasi steady thermal modeling by both the analytical solution developed to the equations from friction heating and thermal conduction and colling, and the finite element analysis (FEA) method constructed with heat flux data from actual hardware test.</div><div class="htmlview paragraph">In addition to the analytical solution and FEA results, an experimental test was conducted to measure and collect the thermal temperature data adjacent to the contact region to correlate the results from analytical solution and FEA simulation, they are found in good agreement.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Future demands for modern emission free drivetrains using hydrogen or liquid e-fuels also necessitate a fundamental reduction in oil emissions. Entry of lubrication oil into the combustion chamber can lead to pre-combustion phenomena (LSPI) in downsizing or hydrogen engines and is a cause of particle emissions, which play a significant role especially if fuel related particle emissions are already low. A fundamental understanding of the oil film behavior on the piston assembly and cylinder liner surface are crucial to avoid oil ingress into the combustion chamber. The processes involved take place mainly around the piston group. In particular, the area of the piston rings with the prevailing pressure and temperature conditions as well as the component geometries has a high influence on the exchange of media between the crankcase and combustion chamber.</div><div class="htmlview paragraph">The objective of this paper is to increase the understanding of the processes leading to oil ingress into the combustion chamber. In addition, the resulting oil emissions are to be analyzed and put into perspective. An optical accessible “glass-liner” SI- engine is used as a test bench for simultaneous measurements of the oil film by LIF and the oil emission by mass spectrometry to connect and correlate the information gathered into a more profound understanding of the processes involved and their influence on emission behavior.</div><div class="htmlview paragraph">The focus of this paper lies on transitional behavior from fired to motored operation and back to fired operation. The temporal course of the oil flow and its influence on oil-borne emissions in transient phases could be visualized. A non-deterministic behavior of the oil emissions was observed and validated optically.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Aftertreatment durability demonstration is a required validation exercise for on-road medium and heavy-duty diesel engine certification. The demonstration is meant to validate emissions compliance for the engine and aftertreatment system at full useful life or FUL. Current certification practices allow engine manufacturers to complete partial aging and then extrapolate emissions performance results to FUL. While this process reduces the amount of service accumulation time, it does not consider changes in the aftertreatment deterioration rate. Rather, deterioration is assumed to occur at a linear rate, which may lead to false conclusions relating to emissions compliance.</div><div class="htmlview paragraph">With CARB and EPA’s commitment to the reduction of criteria emissions, emphasis has also been placed on revising the existing certification practices. The updated practices would require engine manufacturers to certify with an aftertreatment system aged to FUL. By utilizing an application-specific field cycle, this approach could, theoretically, generate FUL field representative parts. Thus, the requirement would validate field emissions compliance with higher certainty. Establishing a more stringent certification requirement also brings challenges to engine manufacturers. For example, a heavy-duty on-road application would require 9,800 hours of service accumulation time or 14 months. This time commitment poses several issues for engine manufacturers, which include reduced development cycle scheduling and an increased cost burden.</div><div class="htmlview paragraph">To address manufacturer challenges, regulators are proposing accelerated aging as an acceptable alternative to conventional aging. The Diesel Aftertreatment Accelerated Aging Cycle protocol, or DAAAC, is an accelerated aging methodology that considers primary catalyst deterioration mechanisms. This includes exposure to hydrothermal aging, sulfur, and lubricant-derived poisons at accelerated rates. The methodology utilizes application-specific information to derive the aging cycle modes and deterioration mechanism exposure rates. The following work will consider tailpipe emission results from a conventionally aged aftertreatment system and two accelerated aged systems utilizing the DAAAC protocol. The objective of the work was to validate the DAAAC approach on two accelerated aging platforms. The results will consider the performance deterioration utilizing certification cycles like the HD-FTP and RMC.</div></div>

<div class="htmlview paragraph">The GE Operations Services and Solectron Corporation Six Sigma Program improved printed circuit board (PCB) throughput, response time, and capacity through the use of Lean Manufacturing concepts and the application of Lean Manufacturing techniques. This paper illustrates how Lean Manufacturing and Six Sigma complement each other for maximum benefit.</div> <div class="htmlview paragraph">The issues confronting the PCB industry include capacity and responsiveness to customer delivery demands. Rigorous Six Sigma Methods of Measurement and Analysis pointed towards Lean Manufacturing solutions. Lines were unbalanced, WIP clogged the flow and used valuable space, material flow interfered with operations, and non-value added (NVA) time exceeded 95% in some cases. Graphical techniques and time studies pointed toward sensible flow, reduction of bottlenecks and proper allocation of space and human resources.</div> <div class="htmlview paragraph">The resulting improvement allowed for 142% capacity increase and 47% cycle time reduction. Defects were reduced by 93%. Additional revenue significantly increased customer satisfaction.</div>