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Abstract Wheel chocks are rather simple compliant mechanisms for stabilizing vehicles at rest. However, chocks must be carefully designed given the complex interaction between the chock and the tire/suspension system. Despite their importance for safety, literature is surprisingly limited in terms of what makes a wheel chock efficient. Using simple but reliable quasi-static mechanical models, this study identifies mechanical requirements that help to avoid a number of failure modes associated with many existing wheel chocks. Given that chock grounding is not always possible, a chock’s maximum restraining capacity is only obtained when the wheel is completely supported by the chock. A generic chock profile is proposed to achieve this objective while mitigating undesirable failure modes. The profile is based on fundamental mechanical principles and no assumption is made on the load interaction between the chock and the wheel.

Abstract The ground-effect problems of loss of thrust and fountain-effect instabilities are quantified. Experiments to control and augment ground-effect lift and stability are presented, including jet momentum reflection and fountain redirection using various types of internal and external underbody ventral strakes. By strategically designing the vertical takeoff and landing (VTOL) ventral surface, reflection of the impinging fountain momentum is possible so that instead of losing 10% thrust while in ground-effect, remarkably, thrust is augmented 10% or more to a considerable height above the ground, in addition to stabilizing random pitch and roll moments caused by fountain instability.

Abstract Advanced passenger vehicles are complex dynamic systems that are equipped with several actuators, possibly including differential braking, active steering, and semi-active or active suspensions. The simultaneous use of several actuators for integrated vehicle motion control has been a topic of great interest in literature. To facilitate this, a technique known as control allocation (CA) has been employed. CA is a technique that enables the coordination of various actuators of a system. One of the main challenges in the study of CA has been the representation of actuator dynamics in the optimal CA problem (OCAP). Using model predictive control allocation (MPCA), this problem has been addressed. Furthermore, the actual dynamics of actuators may vary over the lifespan of the system due to factors such as wear, lack of maintenance, etc. Therefore, it is further required to compensate for any mismatches between the actual actuator parameters and those used in the OCAP.

Abstract In this study, a computer-aided design (CAD) geometry system that is linked to each other to create a parametric form of the side rear door’s inner frame sheet piece on a passenger vehicle body in a Siemens NX environment was developed. The system was created in the NX CAD environment, using the program’s unique product development structure. The system was designed and modified for time-consuming parts. At the end of the study, the parameterized vehicle door geometries worked in the NX environment standardized the design process and accelerated the design works.

Abstract Threat identification and security analysis have become mandatory steps in the engineering design process of high-assurance systems, where successful cyberattacks can lead to hazardous property damage or loss of lives. This article describes a novel approach to perform security analysis on embedded systems modeled at the architectural level. The tool, called Security Threat Evaluation and Mitigation (STEM), associates threats from the Common Attack Pattern Enumeration and Classification (CAPEC) library with components and connections and suggests potential defense patterns from the National Institute of Standards and Technology (NIST) Special Publication (SP) 800-53 security standard. This article also provides an illustrative example based on a drone package delivery system modeled in AADL.

Abstract The brake discs are subjected to thermal load due to sliding by the brake pad and fluctuating loads because of the braking load. This combined loading problem requires simulation using coupled thermo-mechanical analysis for design evaluation. This work presents a combined thermal and mechanical finite element analysis (FEA) and evolutionary optimization-based novel approach for estimating the optimal design parameters of the ventilated brake disc. Five parameters controlling the design: inboard plate thickness, outboard plate thickness, vane height, effective offset, and center hole radius were considered, and simulation runs were planned. A total of 27 brake disc designs with design parameters as recommended by the Taguchi method (L27) were modeled using SolidWorks, and the FEA simulation runs were carried out using the ANSYS thermal and structural analysis tool.

Abstract Aircraft cybersecurity efforts have tended to focus at the strategic or tactical levels without a clear connection between the two. There are many excellent engineering tools already in widespread use, but many organizations have not yet integrated and linked them into an overarching “campaign plan” that connects those tactical actions such as process hazard analysis, threat modeling, and probabilistic methods to the desired strategic outcome of secure and resilient systems. This article presents the combined systems security engineering process (CSSEP) as a way to fill that gap. Systems theory provides the theoretical foundation on which CSSEP is built. CSSEP is structured as a control loop in which the engineering team is the controller of the design process. The engineering team needs to have an explicit process model on how systems should be secured, and a control algorithm that determines what control actions should be selected.

Abstract A novel geometry for a six degrees of freedom (6DOF) unmanned aerial vehicle (UAV) rotary wing aircraft is introduced and a flight mechanical analysis is conducted for an aircraft built in accordance to the thrust vectors of the proposed geometry. Furthermore, the necessary mathematical operations and control schemes are derived to fly an aircraft with the proposed geometry. A system identification of the used propulsion system with the necessary thrust reversal in the form of bidirectional motors and propellers was conducted at a whirl tower. The design of the first prototype aircraft is presented as well as the first flight test results. It could be demonstrated that an aircraft with the thrust vectors oriented according to the proposed geometry works sufficiently and offers unique maneuvering capabilities that cannot be reached with a conventional design.

Abstract At hypersonic speed, severe aerodynamic heating is observed, and temperatures are too high to cool by radiation cooling; active cooling such as ablative cooling is helpful in this situation. The Thermal Protection System (TPS) consists of a layer of an ablative material, followed by an insulating material to lower the temperature at the inside wall of the lifting body. The surface area (considering the inside volume of the vehicle constant) of the TPS plays a vital role in heat transfer to the vehicle and heat transferred through the vehicle body. The minimum area sweepback angle (ΛArea-min) is the function of the principal radius (R) and the ratio of the principal radii of the forward bi-curvature stagnation surface (R/r). The ΛArea-min = 80° is obtained for R = 2 m and R/r = 2. The aerothermal analysis of the lifting body is of fundamental interest while designing the TPS.

Abstract Structural optimization evolved as a preferred technique across industries to develop lightweight products. One of the widely studied topics in structural optimization is to develop methods that reduce the radiated noise from a structure, where responses like Equivalent Radiated Power (ERP) and natural frequencies used to indirectly address the noise levels. This article compares freeform optimization with topology optimization technique and investigates their effectiveness for reducing radiated noise and weight. To illustrate the same, Finite Element Method (FEM) and Boundary Element Method (BEM) analysis are performed on a sheet metal flat plate (panel) as an example and correlated the same with experimental data. Further, different optimization problem formulations have been explored on those examples and results have been compared.

Abstract Steering feedback has an important role in good vehicle guidance by the driver. However, the design of the steering feedback usually happens late in the development process of prototype vehicles, when significant changes to the steering system are hardly possible. Hence, a steering system model is developed for the early stages of vehicle development, which is able to predict the transmission behavior of a steering system. Therefore, this article verifies that the steering system can be modeled independently of the tires and axle for relevant amplitudes of the steering feedback. The developed steering system model is a two-mass model consisting of an effective rack mass and a combined steering wheel and steering column inertia. Both are connected via the spring stiffness of the steering column and a steering gear ratio. Friction has a very dominant influence on the transmission behavior of the steering system and is therefore modeled at the column and rack.

Abstract During vehicle development process, it is required to estimate potential thermal risk to vehicle components. Several authors have addressed this topic in earlier studies [1, 2, 3, 4, 5, 6]. For evaluation of potential thermal issues, it is desired to estimate the component temperature profile for a given duty cycle. Therefore, the temperature and exposure time at each temperature have to be estimated for each vehicle duty cycle. The duty cycle represents the customer usage of the vehicle for a variety of vehicle speeds and loadings. In this article, we focus on thermal simulation of rotating components such as prop shaft, drive shaft, and half shaft boots. Though these components temperatures can be measured in drive cell or road trips, the instrumentation is usually a complicated task. Most existing temperature sensors do not satisfy the needs because they either require physical contact or cannot withstand high-temperature environment in the vehicle underhood or underbody.

Abstract Stress-based sheet metal fatigue near nuts welded to thin sheets is one of the necessary design processes for car bodies. In this investigation, the influence of the attachment contact on the localized fatigue mechanism is examined through finite element (FE) models and controlled fatigue experiments. First, a fatigue experimental setup, which includes a thin-sheet closed-hat section with a weld nut bolted to a thick attachment piece, is designed to minimize the uncertainty of the influence of the fixtures on the experimental results. The experiments are carried out on 0.9- and 1.0-mm thick hat sections with a square weld nut under force control conditions with complete reversed loading. Due to the contact, the test specimen performs as a bilinear spring that has a lower stiffness in the upstroke direction when compared to the downstroke direction where full contact of the attachment occurs with the hat section.

Abstract This article concerns an improved vector control model. This model is developed in a phase which comes just before the phase of its integration on electronic boards such as those with FPGA or DSP. The innovative character of this model is based on the replacement of the average model of the Direct Current (DC) to Alternating Current (AC) converter powering a synchronous motor with permanent magnets by a precise model considering the transient model of the power transistors, electromagnetic switches, and diodes. The overall model generates the six DC-AC converter control signals to regulate the speed of the permanent magnet synchronous motor (PMSM) using the technique of back electromotive forces compensation to reduce the power chain energy consumption for variable rectilinear speed operation. This model makes it possible to consider the role of diodes.

Abstract The preliminary gas turbine combustor design process uses a huge amount of empirical correlations to achieve more optimized designs. Combustion efficiency, in relation to the basic dimensions of the combustor, is one of the most critical performance parameters. In this study, semi-empirical correlations for combustion efficiencies are examined and correlation coefficients have been revised using an experimental air-blasted tubular combustor that uses JP8 kerosene aviation fuel. Besides, droplet diameter and effective evaporation constant parameters have been investigated for different operating conditions. In the study, it is observed that increased air velocity significantly improves the atomization process and decreases droplet diameters, while increasing the mass flow rate has a positive effect on the atomization—the relative air velocity in the air-blast atomizer increases and the fuel droplets become finer.

Abstract Uncertainties in design represent a considerable industrial stake. Controlling the reliability and robustness of a mechanical system at the level of design has become necessary in order to control these uncertainties. Using the theory of probabilistic design optimization, the present work reports on the application of the concept of reliability-based robustness on minimizing the weight of a planetary gear train (PGT). The optimum combination of reliability and robustness for the minimum weight of the PGT was found using an optimization algorithm based on Particle Swarm Optimization (PSO) and Monte Carlo Simulation (MCS). The algorithm was developed by combining the propagation of uncertainties with the optimization of the function objective within a single probabilistic model. The results show that a reliability-based robust design offers a better alternative to the traditional deterministic design models.

Abstract Electric powertrains’ astounding recent progress often eclipses comparable energy-saving potential from aggressively reducing tractive load, especially by ambitious lightweighting. Both strategies are valid and important, but their diverse benefits-transcending simple competition for fuel savings-are partly shared, often differentiated and synergistic, and all worth capturing. Far from becoming superfluous once traction is electrified, severalfold-lower tractive load can make electrification much cheaper, easier, and faster, with major side benefits. Yet these two strategies are currently out of balance, misallocating capital, effort, and time. That imbalance is amplified by the standard method for analyzing potential automotive efficiency gains-incremental and technology-by-technology. This highly refined methodology is valid for modest changes in components, but not for major changes in whole vehicles.

Abstract Aerodynamic optimization of the exterior vehicle shape is a highly multidisciplinary task involving, among others, styling and aerodynamics. The often differing priorities of these two disciplines give rise to iterative loops between stylists and aerodynamicists. Reduced-order modeling (ROM) has the potential to shortcut these loops by enabling aerodynamic evaluations in real time. In this study, we aim to assess the performance of ROM via proper orthogonal decomposition (POD) for a real-life industrial test case, with focus on the achievable accuracy for the prediction of fields and aerodynamic coefficients. To that end, we create a training data set based on a six-dimensional parameterization of a Volkswagen passenger production car by computing 100 variants with Detached-Eddy simulations (DES).

Abstract Recent research has demonstrated that gasoline compression ignition (GCI) can improve the soot-oxides of nitrogen (NOx) trade-off of conventional diesel engines due to the beneficial properties of light distillate fuels. In addition to air handling and aftertreatment, fuel systems also require further development to realize the potential efficiency and emissions benefits of GCI. Injector one-dimensional (1-D) hydraulic modeling is an important design tool used for this purpose. The current study is a continuation of prior work that used computed physical fuel properties and hydraulic models to accurately simulate high-pressure injection behavior relevant to GCI. With respect to fuel characteristics for the model, physical properties were validated by direct comparison to measurements at temperatures and pressures reaching 150°C and 2500 bar, respectively.

Abstract In the given work the design and stress–strain calculation of housing parts of large machines during operation are considered. At the same time, both classical electromagnetic forces and technological operations necessary for mechanical processing and assembly of such objects as well as transportation processes are taken into account for the first time. The task of analyzing of the stress–strain state of the framework was solved in the three-dimensional setting using the finite element method by the SolidWorks software complex. The three-dimensional analysis of the stress–strain state of the structure for technological operations, namely tilting, lifting, and moving the large DC machines frame without poles and with poles, showed that the values of mechanical stresses that arise in the connections of the frame exceed the permissible limits, resulting in significant deformation of the structure.