Motorcycle Chassis Design Utilizing Multi-Material Topology Optimization

ABSTRACTA comprehensive solution for bus frame design is proposed to bridge multi-material topology optimization and cross-sectional size optimization. Three types of variables (material, topology and size) and two types of constraints (static stiffness and frequencies) are considered to promote this practical design. For multi-material topology optimization, an ordered solid isotropic material with penalization interpolation is used to transform the multi-material selection problem into a pure topology optimization problem, without introducing new design variables. Then, based on the previously optimal topology result, cross-sectional sizes of the bus frame are optimized to further seek the least mass. Sequential linear programming is preferred to solve the two structural optimization problems. Finally, an engineering example verifies the effectiveness of the presented method, which bridges the gap between topology optimization and size optimization, and achieves a more lightweight bus frame than traditional single-material topology optimization.

<div class="section abstract"><div class="htmlview paragraph">Test methods to evaluate vehicle compatibility are being studied worldwide. Compatibility performance is central in securing mutual protection in collisions between large and small vehicles. To consider compatibility performance, good structural interaction and stiffness matching are important. A test method using a novel moving deformable barrier (MDB) was developed to evaluate compatibility performance that includes consideration of both structural interaction and stiffness matching.</div><div class="htmlview paragraph"> This new barrier has the following features to represent an offset vehicle-to-vehicle collision with a compact car. <ul class="list disc"><li class="list-item"><div class="htmlview paragraph">The barrier width is divided at the lower rail position of the compact car, and the layer that simulates the characteristics of vehicle sections toward the interior is harder than the outward layer. This varying stiffness of the MDB helps simulate the horizontal interaction performance that occurs in real-world crashes.</div></li><li class="list-item"><div class="htmlview paragraph">A bumper structure and a wheel proxy layer are installed at heights corresponding to similar structures of the compact car. These layers are harder than the surrounding layers to evaluate the vertical interaction performance of the evaluated vehicle.</div></li><li class="list-item"><div class="htmlview paragraph">The energy absorption characteristic of this barrier is equivalent to the engine compartment of a compact car to evaluate the stiffness characteristic of the evaluated vehicle.</div></li></ul></div><div class="htmlview paragraph">Vehicle-to-MDB tests were conducted using two large vehicles that have different vertical interaction performance, and the test results were compared to vehicle-to-vehicle test results between prototype SUVs and compact cars.</div><div class="htmlview paragraph">The correlation was verified between the vehicle-to-MDB test and the vehicle-to-compact car test. This MDB test shows promise for the simultaneous evaluation of both the structural interaction and stiffness of vehicles.</div></div>

The algorithms for multi-material topology optimization were developed to solve compliance-minimization problems and applied to engineering problems in automotive concepts and lightweight design. Two small-scale problems of a long cantilever and a control arm were studied initially to verify the effectiveness of the developed algorithms and in-house program. Optimal solutions achieved by the multi-material topology optimization method developed were compared to their counterparts obtained by standard single-material topology optimization. To efficiently solve real-world engineering problems, the algorithms were further advanced to incorporate extrusion constraints and to handle multiple load cases. The effectiveness and the efficiency of the proposed method were demonstrated by the study of two real-world engineering problems: (a) the conceptual design of a cross-member for a chassis frame; and (b) the conceptual design of an automotive engine cradle. The two optimization design problems both involved complex geometries, design and non-design domains, prescribed regions with specific material allocations, multiple load cases, and manufacturing extrusion constraints. It was explicitly demonstrated that, for the same weight, the optimum designs achieved by the multi-material topology optimization method were stiffer than those achieved by standard single-material topology optimization.

<div class="htmlview paragraph">The Aluminum Structured Vehicle Technology (ASVT) program in Alcan is developing technology for the design and manufacture of adhesively bonded aluminum automobile structures. The development of any new vehicle involves a complex balance between package, manufacture, cost and performance constraints, and it is therefore important to be able to give clear guidelines in these areas to support the evaluation of this new technology by the motor industry.</div> <div class="htmlview paragraph">This paper on ASVT structural design demonstrates the important features involved in meeting strength and stiffness needs at minimum weight, and it is intended to complement previous publications which have focused on the core technology and process considerations of ASVT.</div> <div class="htmlview paragraph">The first two sections examine the key elements of ASVT, namely the aluminum and the adhesive bond, with both strength and stiffness being considered. The final two sections examine the large influence of ASVT on the performance of connections between structural members, and the resulting stiffness of structures as a whole.</div>

<div class="htmlview paragraph">The 1975 federal CVS test procedure and emission standards have placed a heavy emphasis on minimizing the time required after engine start up to begin converting exhaust emissions. Four major improvements in catalytic HC/CO converters have been made in the past year to reduce catalyst ignition time:</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">Use of low thermal capacity monolithic catalyst supports.</div> </li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">Locating converter after thermal reactor and/or closer to the exhaust manifold.</div> </li> <li class="list-item"> <span class="li-label">3.</span> <div class="htmlview paragraph">Development of catalysts with superior stability to long exposure at high temperatures.</div> </li> <li class="list-item"> <span class="li-label">4.</span> <div class="htmlview paragraph">Development of catalysts with improved low temperature activity.</div> </li> </ol> </div> <div class="htmlview paragraph">Small laboratory samples of potential HC/CO oxidation catalysts were screened for activity in a “laboratory simulated cold-start” test with exhaust from a 2-cyl engine. Several improved catalyst candidates were evaluated in a full-size converter “cold-start” test with exhaust from a 351 in<sup>3</sup> engine.</div> <div class="htmlview paragraph">Locating the converters closer to the exhaust manifold results in higher catalyst operating temperatures which require greater stability at high temperatures in the presence of trace contaminants. Stability, when exposed to wide temperature variations and changes from oxidation to reduction environments, has been evaluated in a thermal-cycling test for several improved catalysts. Catalyst stability to long-term exposure has also been evaluated in an engine dynamometer mileage accumulation test operated under simulated road conditions.</div> <div class="htmlview paragraph">Unfortunately, the rapid thermal-chemical response of the improved catalyst, operated closer to the exhaust manifold, increases the occurrences of excessive catalyst temperatures. Mathematical model studies of the effect of the improved catalyst properties on thermal response indicate a need to prevent unexpected high CO or HC concentration peaks in the engine exhaust, or to improve properties of existing catalysts. System changes, such as moving the low temperature catalyst farther from the exhaust manifold, may be required to obtain some protection from catalyst overtemperatures. These changes increase emission levels and require a breakthrough in engine control of raw emissions or improved catalysts.</div>

<div class="section abstract"><div class="htmlview paragraph">Topology optimization (TO) represents an invaluable instrument for the structural design of components, with extensive use in numerous industries including automotive and aerospace. TO allows designers to generate lightweight, non-intuitive solutions that often improve overall system performance. Utilization of multiple materials within TO expands its range of applications, granting additional freedom and structural performance to designers. Often, use of multiple materials in TO results in material placement that may not have been previously identified as optimal, providing designers with the ability to produce novel high performance systems. As numerous modern engineering materials possess anisotropic properties, a logical extension of multi-material TO is to include provisions for anisotropic materials. Herein lies the focus of this work.</div><div class="htmlview paragraph">A TO algorithm capable of considering anisotropic material properties is used to investigate a case study on the design of an automotive hood panel. A baseline aluminum hood panel is used to generate stiffness targets for optimization, followed by the generation of a design space model to allow the algorithm to determine optimal material placement. Optimization is undertaken with two types of AS4 continuous carbon fiber reinforced epoxy, each in two orientations. Optimal hood panel solutions that maintain stiffness levels of the conventional baseline are achieved. The mass of the design space is minimized, and constrained through the baseline displacement values. The effect of hood panel thickness and offset distance between panel layers is also investigated.</div><div class="htmlview paragraph">The optimal topologies indicated an overall mass savings of up to 44.5% in relation to the baseline, while maintaining hood panel stiffness. Comparative mass savings decreased as hood panel thickness increased and offset distance decreased. The allocation of stiffer materials was observed near locations of applied loads and constraints, with highly anisotropic materials placed along hood panel extremities. The practicality of anisotropic multi-material TO in lightweight design was thus demonstrated.</div></div>

In this paper the concept of extended optimality, or hyperoptimality, is adopted. By following this idea, a new compliance–volume product is suggested as objective. The volume appearing in the product is also raised to the power of a new design parameter which can be set to different values. In such manner design concepts with different volume fractions can be generated by using the approach of extended optimality. Both manufacturing constraints and unilateral contact constraints are included in the proposed method. The manufacturing constraints are implemented by adjusting the move limits such that the draw directions are satisfied. Both one draw direction as well as split draw constraints are considered. The contact conditions are modeled by the augmented Lagrangian approach such that the Jacobian in the Newton algorithm as well as in the adjoint equation becomes symmetric. The design parametrization is done by the SIMP model and Sigmund’s filter is utilized when the sensitivities are calculated. The proposed method is very robust and efficient. This is demonstrated by solving problems in both 2D and 3D. The numerical results are also compared to solutions obtained by performing compliance optimization with a constraint on the volume fraction.

<div class="htmlview paragraph">Four new 2-cylinder 4-stroke concepts are displayed as design and fitted in vehicles.</div> <div class="htmlview paragraph">These four different concepts comprise</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">a Modular Concept V2- and W3-cylinder</div></li> <li class="list-item"><div class="htmlview paragraph">a MotoGP / Superbike concept with 2 and 3 cylinders,</div></li> <li class="list-item"><div class="htmlview paragraph">a narrow angle V-engine and</div></li> <li class="list-item"><div class="htmlview paragraph">a Building Block System Commuter CVT engine.</div></li> </ul> </div> <div class="htmlview paragraph">Each engine concept is designed to meet the different requirements of the four segments. Specific analysis and simulation concerning 1D thermodynamics, vehicle simulation and delivered performance and tractive force was done for each concept.</div> <div class="htmlview paragraph">The concepts are compared in the aspects of uniform rotation, inertia forces and moments, and the effect on performance by the pulse effects of the manifolded intake and exhaust systems.</div> <div class="htmlview paragraph">The Modular Concept contains an OHC engine with a wide range of displacements and commonality of many parts. Good versatility is obtained as the concepts can be applied for sport- or custom bikes. Also an advanced EMS with additional features is applied and a heated 3-way catalyst and air/fuel sensors are integrated to fulfill the most stringent emission regulations after the year 2006.</div> <div class="htmlview paragraph">The MotoGP / Superbike Concept has an advanced transmission position, which allows to design a very compact motorcycle size comparable to much smaller displacement bikes. The application of a pneumatic valve train allows for aggressive valve timing and high engine output. The concept is compared to engines with higher number of cylinders in terms of race competitiveness.</div> <div class="htmlview paragraph">The narrow-angle V-engine is a sportive and compact engine with newly developed mass balancing.</div> <div class="htmlview paragraph">The Commuter is a medium output design with a continuously variable transmission, featuring an extremely space-saving design</div>

PurposeThis paper aims to present a deep learning–based surrogate model for fast multi-material topology optimization of an interior permanent magnet (IPM) motor. The multi-material topology optimization based on genetic algorithm needs large computational burden because of execution of finite element (FE) analysis for many times. To overcome this difficulty, a convolutional neural network (CNN) is adopted to predict the motor performance from the cross-sectional motor image and reduce the number of FE analysis.Design/methodology/approachTo predict the average torque of an IPM motor, CNN is used as a surrogate model. From the input cross-sectional motor image, CNN infers dq-inductance and magnet flux to compute the average torque. It is shown that the average torque for any current phase angle can be predicted by this approach, which allows the maximization of the average torque by changing the current phase angle. The individuals in the multi-material topology optimization are evaluated by the trained CNN, and the limited individuals with higher potentials are evaluated by finite element method.FindingsIt is shown that the proposed method doubles the computing speed of the multi-material topology optimization without loss of search ability. In addition, the optimized motor obtained by the proposed method followed by simplification for manufacturing is shown to have higher average torque than a reference model.Originality/valueThis paper proposes a novel method based on deep learning for fast multi-material topology optimization considering the current phase angle.

<div class="htmlview paragraph">In Brazil the market for small motorcycles had steadily increased during the last decade. Nowadays about 2 million units are produced every year. Market forecasts show that this trend will remain for many years.</div> <div class="htmlview paragraph">The amount of pollutant gases emitted by the small motorcycles fleet, begin to be significant. For this reason, the government established emissions laws for motorcycles to be effective since 2003.</div> <div class="htmlview paragraph">This law will become stricter over the years up to the point that the use of electronic fuel injection systems for small motorcycles will be a convenient way to adhere to the law.</div> <div class="htmlview paragraph">The cost of ethanol fuel is almost half of the gasoline and therefore is the fuel of choice of the majority of drivers. Moreover the use of ethanol is far better than gasoline in terms of emission of green house effect gases.</div> <div class="htmlview paragraph">The current motorcycle's fuel delivery systems are not suited to use ethanol. The above reasons motivated the development of a flex fuel engine management system for small motorcycles.</div> <div class="htmlview paragraph">With this system, a motorcycle could run with any mixture of ethanol and gasoline, delivering the best performance and fuel economy all the time, while adhering to the emission's laws.</div> <div class="htmlview paragraph">Compared to the carbureted version, the motorcycle using electronic fuel injection has superior fuel consumption, driveability, idle and cold start behaviors. This paper will present this system in detail.</div>

<div class="section abstract"><div class="htmlview paragraph">As part of Nissan’s strategy of electrification and the shift to smart technologies, our powertrain department has two main pillars: zero emissions and ICE Evolution. As a core unit of ICE Evolution, we have developed a brand new 3.5L V6 Twin turbocharged gasoline engine for Nissan’s next generation full-size flagship SUV to deliver luxury and toughness at the highest level.</div><div class="htmlview paragraph">This brand-new engine will be applied to vehicles in all corners of the world and must have strong performance in every corner. More specifically, it has to meet the latest emissions and fuel efficiency regulations, have strong power performance beyond expectation, and provide reliable drivability on rough roads and deserts.</div><div class="htmlview paragraph">To achieve these requirements, the new engine is incorporating many cutting-edge technologies. Stoichiometric combustion range has been expanded by Nissan’s latest high-speed combustion technology, which is enhanced by a higher pressure 35MPa injection system, an increased cooling efficiency combustion chamber, and an advanced exhaust temperature management system. Mirror bore coating, textured valve lifters, and optimized piston ring shaping technology all contribute to reduce friction. Lastly, lubrication performance on rough roads has been improved with a scavenging oil pump.</div><div class="htmlview paragraph">The combination of these technologies results in superior power performance, class-leading fuel efficiency, compliance with LEV4/Tier4 emissions regulations, and amazing off-road capabilities that surpass competitors. They are essential technologies for balancing engine efficiency and environmental considerations, creating a powertrain worthy of a flagship luxury SUV.</div><div class="htmlview paragraph">This paper describes details of this new engine and highlights the applied technologies and development procedures which have contributed to the highly balanced performance of this new engine.</div></div>

<div class="section abstract"><div class="htmlview paragraph">As aircraft programs currently ramp up, productivity of assembly processes needs to be improved while keeping quality, reliability and manufacturing cost requirements. Efficiency of the drilling process still remains an issue particularly in the case of CFRP/metal stacks: hot and long metallic chips are difficult to remove and often damage the surface of CFRP holes.</div><div class="htmlview paragraph">Low frequency axial vibration drilling has been proposed to solve this issue. This innovative drilling process allows breaking up the metallic chips in such a way that jamming is avoided.</div><div class="htmlview paragraph">This paper presents a case of CFRP/Ti6Al4V drilling on a CNC machine where productivity must be increased. A comparison is made between the current regular process and the MITIS drilling process. First the analysis and comparison method is presented. The current process is analyzed and its limits are highlighted. Then the vibration process is implemented and its performances are studied. Both processes are compared according to the following criteria: chip morphology, thrust force, power consumption, tool life, cycle time, holes quality and manufacturing costs.</div><div class="htmlview paragraph">Results show that the vibration drilling process is more productive and reliable, while maintaining the quality as well as reducing manufacturing costs. The paper also shows that the vibration drilling allows simplifying cutting tool design and reducing lubrication.</div></div>

<div class="htmlview paragraph">The use of graphical dynamic system simulation software is becoming more popular as automotive engineers strive to reduce the time to develop new control systems. The use of model-based control methods designed to meet future emission and diagnostic regulations has also increased the need for validated engine models. A previously validated, nonlinear, mean-torque predictive engine model<span class="xref">*</span> is converted to MATLAB / SIMULINK<span class="xref"><sup>†</sup></span> to illustrate the benefits of a graphical simulation environment. The model simulates a port-fuel-injected, spark-ignition engine and includes air, fuel and EGR dynamics in the intake manifold as well as the process delays inherent in a four-stroke cycle engine. The engine model can he used in five ways:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">As a nonreal-time engine model for testing engine control algorithms</div> </li> <li class="list-item"><div class="htmlview paragraph">As a real-time engine model for hardware-in-the-loop testing</div> </li> <li class="list-item"><div class="htmlview paragraph">As an embedded model within a control algorithm or observer</div> </li> <li class="list-item"><div class="htmlview paragraph">As a system model for evaluating engine sensor and actuator models</div> </li> <li class="list-item"><div class="htmlview paragraph">As a subsystem in a powertrain or vehicle dynamics model</div> </li> </ul> </div> <div class="htmlview paragraph">Although developed and validated for a specific engine, the model is generic enough to be used for a wide range of spark-ignition engines. Modular programming techniques reduce model complexity by dividing the engine and control system into hierarchical subsystems.</div>

<div class="section abstract"><div class="htmlview paragraph">High performance vehicles are subjected to a high level of loads during short time intervals. Due this situation, manufacturing procedures that conventionally are used in the automotive industry commonly do not achieve the design specifications defined to maximize the overall performance of the vehicle. This situation is highlighted when the overall performance of the system depends on a compromise between variables. The research developed by a German motorsport team aimed to fix the overheating problem found on the front brake system of a Formula SAE prototype using topology optimization combined with the manufacturing processes called Direct Metal Laser Sintering (DMLS) to develop and fabricate a new 4 piston monoblock brake caliper.</div><div class="htmlview paragraph">The DMLS process is based on powder metallurgy, using an Yb-fibre laser to melt a powder material and generate the product by a progressive deposition of layers. This process stands out from the other due the capability to produce complex geometry, imposing virtually no geometric restriction for the design. Furthermore, this process ensures high relative density to the final product, and eliminates the use of dies, being ideal to the manufacture of prototypes. These advantages allow a design of a new brake caliper through concepts that would not be viable by conventional manufacturing processes. A topologic design optimization was performed in order to identify potential project variables. The average temperature of the new caliper reduced in 11% and the heat transfer mechanism was improved. Furthermore, the new caliper had a 9% of mass reduction for a given stiffness.</div></div>

<div class="htmlview paragraph">In order to allow continued production of the AM General Optimizer 6500 during MY 2007 through 2010 this IDI engine (Indirect Injection - swirl chamber) requires sophisticated aftertreatment controls while maintaining its fuel economy and durability.</div> <div class="htmlview paragraph">The main purpose of the development program was to retain the relatively inexpensive and simple base engine with distributor pump and waste-gated turbocharger, while adding hardware and software components that allow achievement of the phase-in emission standards for 2007 through 2010. The aftertreatment system consists of Diesel Oxidation Catalyst (DOC), NOx Adsorber Catalyst (or DeNOx Trap - DNT) and Diesel Particle Filter (DPF). In addition to the base hardware, an intake air throttle valve and an in-exhaust fuel injector were installed.</div> <div class="htmlview paragraph">The presented work will document the development process for a 2004 certified 6.5 l IDI heavy-duty diesel engine to comply with the 2007 heavy-duty emission standards. The system architecture evaluation proved to be one of the key development items that determined the packaging in the projected vehicle platform. Based on the temperature profile, it was found that the DOC-DPF-DNT configuration is mandatory to achieve NOx and NMHC standards. The development of the DPF regeneration, deNOx and deSOx strategy were strongly based on a multi-variable controls approach using temperature or lambda interventions depending on the system request.</div> <div class="htmlview paragraph">Development results for the HD-FTP and SET (13-mode Supplemental Emissions Test) show that the tailpipe emissions and the NTE (not-to-exceed) limits can be met with a considerable safety margin allowing reasonable degradation factors.</div> <div class="htmlview paragraph">The integrated system was installed in a project vehicle and underwent multiple climate testing trips focusing on DPF regeneration under cold ambient, high altitude and hot ambient conditions.</div> <div class="htmlview paragraph">It could be proven that a concept with a comparably cost-effective base engine which does not utilize direct fuel injection, along with an advanced aftertreatment control system, is capable to meet the U.S. 2007-2010 phase-in emission standards.</div>