Browse Topic: Camber
Smooth camber morphing aircraft offer increased control authority and improved aerodynamic efficiency. Smart material actuators have become a popular driving force for shape changes, capable of adhering to weight and size constraints and allowing for simplicity in mechanical design. University of Michigan, Ann Arbor, MI Uncrewed aerial vehicles (UAVs) are growing in popularity for both civilian and military applications, which makes improving their efficiency and adaptability for various aerial environments an attractive objective. Many studies pursue this goal using morphing techniques that incorporate shape changes not typically seen in traditional aircraft. Due to weight and volume constraints consistent with smaller flight vehicles, smart materials, such as macro fiber composites (MFCs), have been used to achieve the desired shape changes. Macro fiber composites are low-profile piezoelectric actuators which have gained substantial attention within the morphing aircraft community
This specification covers established inch/pound manufacturing tolerances applicable to carbon steel sheet, strip, and plate ordered to inch/pound dimensions. These tolerances apply to all conditions unless otherwise noted. The term “excl” is used to apply only to the higher figure of the specified range. Tolerances for product sizes not listed herein shall be as agreed upon by purchaser and vendor
With an intense competitive automotive environment, it becomes imperative for any OEM to launch their products into the market in a short span of time & with a ‘First Time Right’ approach. Within the current scenario in the Automotive Industry, the selection of optimum set of hard points and wheel geometry often becomes an iterative or a trial-and-error process which is both time consuming and involves higher development cost as there may be instances where 2 to 3 sets of iterations are needed before specification is finalized for production. Through this paper, an attempt has been made to develop a methodology for deciding wheel geometry parameters (covered in the later section of this paper like Caster, Camber, Mechanical trail, etc.) [1, 2, 3, 4] for a three wheeled vehicle as a First Time Right (FTR) approach to cut down on conventional, expensive & time-consuming iterative approach. In this paper, we have studied the parameters which affects the directional stability and steering
Passengers would always like to reach their destinations with minimum commute time. Generating a higher thrust is a necessity. This implies that the turbomachinery associated with the power plant has to rotate faster and with higher efficiencies. However, high rotational speeds, mainly in the transonic regime, often lead to boundary layer separation, shocks, compressor stall, and surge. The current investigation is an attempt to reduce the abovementioned phenomena. It involves the performance study of a smoothened controlled diffusion airfoil (CDA) blade that has been optimized by “Multi-Objective Genetic Algorithm” (MOGA) by altering maximum camber location and stagger angle. Inlet pressure is varied from 15 kPa to 30 kPa and the angle of attack ranging from 40.4° to 56.4°. C48-S16-BS1 is validated and considered as the baseline profile, and all other blades are collated to this. It is observed that shifting the location of the maximum camber close to the leading edge and increasing
A tire is a prominent part of any vehicle, comprising about 33% of the total aerodynamic drag of a vehicle, and is the only part in contact with the road. In this work, an attempt is made to study the aerodynamic characteristics of a non-pneumatic tire (NPT) with hexagonal spokes (HS) in rotating conditions using SimScale® computational fluid dynamics (CFD). The effect of various parameters like camber angle, steering angle, and velocity on the aerodynamic performance is evaluated through coefficients of drag and lift. The results are compared with that of the static condition at zero yaw and zero camber to understand the effect of a rotating wheel on aerodynamic performance. Results show that the increase in the camber angle or steering angle results in reduced drag and lift coefficients. At a vehicle velocity of 40 km/h, Cd value has reduced by 24.17%, 19.81%, and 31.33% for a 1.5° camber angle, 15° steering angle, and combined case with 1.5° camber and 15° steering angles
Wheel rim is one of the most critical safety parts in a vehicle. Strength in cornering loading is one of the most important durability test requirements for automotive steel wheel rim apart from other loading conditions like vertical and impact loads. Based on the category of vehicle and customer usage pattern, the accelerated cornering test is derived for testing steel wheel rims. The simulation and certification of steel wheel rim for the required dynamic durability testing requirement involves many steps ranging from acceptance criteria derivation to reliably addressing known potential failure zones in steel wheel rims. Nave radius and crown are sensitive to cornering loads, given the pitch circle diameter at the concept stage, the known effects of these key parameters are determined from DOE and used as reliable indicators to arrive at the shape and section of the steel wheel rim. Potential failure zones are typically crown and nave radius from weather side (outer) surface and vent
This paper considers the phenomenon that the self-steer speed when riders bank a motorcycle. This paper points out that this phenomenon originates from capsize mode. Further, it is specified that the first order differential equation representing capsize mode is included in the equation of motion of the steering system. Furthermore, it is specified that this differential equation is the first order differential equation for the roll angle. Therefore, as the roll angle increases, the roll angle further increases and the steering angle also changes, which is the mechanism of capsize mode. Finally, as a result of parameter studies, it is stated that the design parameters that most affect capsize mode were front and rear camber stiffness
This paper presents a coupled numerical and experimental study of an unconventional wing profile such as cp-180-050-gn (Cambered plate C = 18% T = 5% R = 0.78). This wing profile deals with low speeds. It is not currently used on any aircraft model. Otherwise, it presents interesting performances that can be exploited for the design of low-speed STOL or VTOL aircraft by mean of the very high lift that it can generate and can fit with different uses such as VAWT, cyclorotors drones, which are designed explicitly for low-speed operations. After a preliminary CFD assessment of the wing a complete experimental characterisation also at high angles of attack has been performed. The excellent agreement between CFD and experiments has allowed producing a complete analysis of the behaviour of the wing profile both before and after stall conditions. This study has the objective of analysing the viability of such an unconventional wing in traditional or over-stalling conditions. A complete
A vehicle drifts due to several reasons from its intended straight path even in the case of no steering input. Vehicle pull is a condition where the driver must apply a constant correction torque to the steering wheel to maintain a straight-line course of the vehicle. This paper presents an investigation study into the characteristics of a vehicle experiencing steering drift. The aim of the work is to study vehicle stability and the causes of vehicle drift/pull during straight line to minimize vehicle pull level and hence optimize safety measures. A wobble in the steering wheel feels like the steering wheel is shaking to the left and right. This may get worse, if speed increases. This paper focuses on modelling and evaluating effects of suspension parameters, differential friction, brake drag variation, Unbalanced mass in the wheel assembly and C.G. location of the vehicle under multibody dynamic simulation environment. Asymmetry of geometry and compliance between left and right side
Through Adams/Car software, it was developed a complete template of a double wishbone suspension with a single shock absorber per axle for a formula SAE prototype. With this template it is intended to perform a series of simulations to test its kinematics and dynamics in the situations which the vehicle will be submitted at the competition, then the shock absorber’s parameters, double wishbone geometries, camber, caster, toe and kingpin inclination can be improved, validating the system viability and getting a higher performance
Currently, large companies as well as universities have increased the studies into vehicular dynamic behavior, mainly in order to improve driver and passenger safety. Simulations with complete model vehicle have been used for these studies. The tire is one of the most important vehicular component as the only connection with the ground and responsible for transmitting all vertical, longitudinal and lateral forces, consequenetly it is the main component on the model vehicle, being crucial for the correlation between computer simulations results and field tests, This paper presents a methodology, development and construction of a device to obtain lateral forces in any combination of toe and camber angles for different conditions of normal load, the tests can be performed on any type of ground, whether dry or wet. The tire datas used as reference were obtained through an experimental test using “Flat Trac” equipment. Based on these data, the components used to measuare the tire force
In this study, we focus on “camber angle control” and “derivative steering assistance” using “steer-by-wire” as maneuverability and stability improvement techniques that are appropriate for the electric vehicle (EV) era. Movements that produce a negative camber angle generate camber thrust, and vehicle motion performance improvements extend from the fact that the tire side force is increased by the camber thrust effect. In our experimental vehicle, a proportional steering angle system was used to create negative camber angle control via an electromagnetic actuator that allowed us to confirm improvements to both the effectiveness and stability of steering control in restricted cornering areas. More specifically, we determined that it is possible to improve critical cornering performance by executing ground negative camber angle control in proportion to the steering angle. Steer-by-wire refers to an electrical steering technique that allows the steering angle of the entire vehicle to be
In this paper, based on our previously preliminary out-of-plane tire model, a complete out-of-plane flexible tire model is further developed by considering the variation of dimension and parameter values among different slices of the tire model. This tire model is validated via various MSC ADAMS® FTire virtual cleat tests. Especially, the cleat tests with non-zero tire camber angles and non-symmetric cleat shapes, which can better capture the out-of-plane tire properties, are included. By comparing the predicted results of the proposed tire model with FTire for various cleat tests, it shows that the complete out-of-plane flexible ring tire model is better at fully representing the actual tire properties for some complicated cleat testing scenarios
Since the tire inflation pressure has a significant influence on safety, comfort and environmental behavior of a vehicle, the choice of the optimal inflation pressure is always a conflict of aims. The development of a highly dynamic Tire Pressure Control System (TPCS) can reduce the conflict of minimal rolling resistance and maximal traction. To study the influence of the tire inflation pressure on longitudinal tire characteristics under laboratory conditions, an experimental sensitivity analysis is performed using a multivalent usable Corner Module Test Rig (CMTR) developed by the Automotive Engineering Group at Technische Universität Ilmenau. The test rig is designed to analyze suspension system and tire characteristics on a roller of the recently installed 4 chassis roller dynamometer. Camber angle, toe angle and wheel load can be adjusted continuously. In addition, it is possible to control the temperature of the test environment between −20 °C and +45 °C. The results of the
In order to improve robustness of vehicle dynamic performance, a steering mechanism model is proposed with alignment parameters of front wheel based on preference function method. In the steering mechanism model controllable variables include the trapezoid connection length, the base angle of steering trapezoid, the kingpin inclination angle, caster, camber and uncontrollable variables include load and initial braking velocity. Optimization objective is some vehicle dynamic performance. In the preference function method the individual performance preference and preference aggregation in designing variable space and performance variable space are analyzed. The individual performance preference includes the controllable variable preference, noise factor preference and optimization objective preference. The aggregation function is developed by aggregating all the individual performance preferences. The robustness and optimization results are solved based on mean and variance of
In recent years three-wheel camber vehicles, with two wheels in the front and a single rear wheel, have been growing in popularity. We call this kind of vehicle A “Leaning Multi Wheel category Vehicle” (hereinafter referred to as a “LMWV”). A LMWV has various characteristics, but one of them stands out in particular. When a LMWV is cornering, if one of the front wheels passes over a section of road surface with a low friction coefficient, there is very little disturbance to the vehicle’s behavior and can continue to be driven as normal. However, there has been no investigation into why these vehicles have this particular characteristic. Consequently, in this paper an investigation was carried out in order to determine the behavior of a LMWV in this situation. First, measurements were taken using an actual vehicle to confirm the situation described above. As a result, it was confirmed that there is only a small change in the vehicle’s posture and also that the other front tire generates
The tire mechanics characteristics are essential for analysis and control of vehicle dynamics. Basically, the effects of sideslip, longitudinal slip, camber angle and vertical load are able to be represented accurately by current existing tire models. However, the research of velocity effects for tire forces and moments are still insufficient. Some experiments have demonstrated that the tire properties actually vary with the traveling velocity especially when the force and moment are nearly saturated. This paper develops an enhanced brush tire model and the UniTire semi-physical model for tire forces and moments under different traveling velocities for raising need of advanced tire model. The primary effects of velocity on tire performances are the rubber friction distribution characteristics at the tire-road interface. Therefore, in this paper, a simplified analytical tire model considering rubber dynamic friction is established first, which can be used to analyze the effects of
NASA’s Langley Research Center has developed a self-latching piezocomposite actuator. The self-latching nature of this invention allows for piezo actuators that do not require constant power draw. Among other applications, the invention is well suited for use in aerodynamic control surfaces and engine inlets. The technology is a self-latching piezoelectric actuator with power-off, set-and-hold capability. Integrated into an aerodynamic control surface or engine inlet, the self-latching piezocomposite actuator may function as a trim tab, variable camber airfoil, vortex generator, or winglet with adjustable shapes. Deflections could be made in-flight, and set and maintained (latched) without a constant power draw. Current piezo actuators require constant power to control and manage their electric fields. The control device leverages the shape memory behavior (specifically, the remnant stress-strain behavior) to create a morphing actuator that changes and holds the new shape with no
In this research, we examine the three controls inside-outside wheel braking force and driving force, camber angle, and the derivative steering assistance to determine how angle differences affect cornering performance and controllability. This is accomplished by comparing body slip angle area differences in a closed loop examination of the grip to drift area using a driving simulator. The results show that inside-outside wheel braking force and driving force control in the area just before critical cornering occurs has a significant effect on vehicle stability. We also clarified that controlling the camber angle enhances grip-cornering force, and confirmed that the sideslip limit could be improved in the vicinity of the critical cornering area. Additionally, when the counter steer response was improved by the use of derivative steering assistance control in the drift area exceeding the critical cornering limit, corrective steering became easier. Moreover, the effect could be achieved
Research of the past century has demonstrated that wheel camber regulation provides great potential to improve vehicle safety and performance. This led to the development of various prototypes of the camber mechanisms over the last decade. An overview of the existing prototypes is discussed in the presented paper. Most of the investigations related to camber control cover open-loop maneuvers to evaluate a vehicle response. However, a driver’s perception and his reaction can be the most critical factor during vehicle operation. Therefore, the research goal of the presented study is to assess an influence of active camber control on steering feel and driving performance using a driving simulator. In the proposed investigation, a dSPACE ASM vehicle model has been extended by introducing advanced models of steering system and active camber regulation. The steering system describes dynamics of steering components (upper and lower columns, torsion bar, steering rack and others). It is
Kinematic inputs such as camber, caster variation are very important for design of any suspension setup. Usual procedure is to get these inputs from kinematic software. But every designer cannot have this software & one has to learn them too. We have developed a method for kinematic analysis of McPherson strut type suspension which can be implemented on easily available and familiar software like MS Excel. Results obtained are in correlation with results from commercially available mechanism tools such as Pro mechanism. All links in suspension layout are considered as rigid. Vector calculus and other mathematical methods have been used to come up with final solution. Inputs required for mathematical program are suspension hardpoints, Lower arm angle from design orientation as wheel travel input and Rack stroke as steering input. Suspension characteristics which can be derived by using proposed mathematic model are curves for camber, caster, toe change &curves for bump and rebound steer
Vehicle dynamics is the study of response of the vehicle to driver’s input. Various parameters like location of center of gravity (CG), suspension spring stiffness, wheel alignment parameters, etc. determine the handling behavior of the vehicle. This is a study to investigate the effects of aforesaid parameters on handling characteristics of an intercity bus using MSC ADAMS software tool. Handling performance is determined by evaluating various parameters such as understeer gradient, roll gradient, etc. Understeer gradient is influenced by various parameters like location of CG, tire cornering stiffness, etc. Roll gradient of a vehicle depend on various parameters like vertical stiffness of tires, anti-roll bars (ARB) diameter, location of CG, etc. As a part of this study, four different configurations of MBD models were built to investigate the effect of location of ARB on handling behavior of bus. Several vehicle dynamic tests are virtually conducted on the MBD model of the bus. It
The United States Army Tank Automotive Research, Development and Engineering Center (TARDEC) built systems to measure the suspension parameters, center of gravity, and moments of inertia of wheeled vehicles. This is part of an ongoing effort to model and predict vehicle dynamic behavior. The new machines, the Suspension Parameter Identification and Evaluation Rig (SPIdER) and the Vehicle Inertia Parameter Evaluation Rig (VIPER), have sufficient capacity to cover most heavy, wheeled vehicles. The SPIdER operates by holding the vehicle sprung mass nominally fixed while hydraulic cylinders move an “axle frame” in bounce or roll under each axle being tested. Up to two axles may be tested at once. Vertical forces at the tires, displacements of the wheel centers in three dimensions, and steer and camber angles are measured. Contact patch can move in lateral, longitudinal and steer motions of the suspension and the small deflections of the vehicle sprung mass resulting from the contact patch
Vehicle handling is an important attribute that is directly related to vehicle safety. The rapid development of road infrastructure has resulted in a greater focus on safety and stability. Commercial vehicle stability and safety assumes higher significance because of high center of gravity (CG) and heavier loads. A gamut of parameters influence vehicle handling directly and indirectly. However, it is quite difficult to gauge through physical testing, the extent of each parameter's influence on handling. Therefore, this paper examines vehicle handling by way of a sensitivity analysis through numerical simulation. A prototype vehicle is also instrumented and tested to confirm trends and validate the results of the simulation. An Intermediate Commercial Vehicle (ICV) with Gross Vehicle Weight (GVW) of around 13 tonnes is modeled and parameters like wheelbase and tyre stiffness are altered and the effect of these changes on handling parameters (yaw rate, lateral acceleration) is observed
The Learjet 85 is a business jet with an unpowered manual elevator control and is designed for a maximum dive Mach number of 0.89. During the early design, it was found that the stick force required for a 1.5g pull-up from a dive would exceed the limit set by FAA regulations. A design improvement of the tailplane was initiated, using 2D and 3D Navier-Stokes CFD codes. It was discovered that a small amount of positive camber could reduce the elevator hinge moment for the same tail download at high Mach numbers. This was the result of the stabilizer forebody carrying more of the tail download and the elevator carrying less. Consequently, the elevator hinge-moment during recovery from a high-speed dive was lower than for the original tail. Horizontal tails are conventionally designed with zero or negative camber since a positive camber can have adverse effects on tail stall and drag. The tailplane sections for the Learjet 85 were tailored to minimize these adverse effects while achieving
A variation in the camber of an automotive wheel is desired to compensate a side-slip force change owing to normal load transfer when the car is cornering. The camber of a steered wheel can be varied by adjusting caster or lean angle which are the representations of steering axis orientation. Thus, a smart camber can be created by a variable caster or lean angle. Choosing which parameter among the two angles to be variable is very important and dependent on its different effects. Here, homogeneous transformation is employed to establish camber as a function of caster, lean angle, and steering angle in the general case. A comparison between caster and lean angle based on different criteria is then made. The comparison shows that a variable caster is much better and more feasible than a variable lean angle in generating a smart camber
Front bump steer is the steering movement of the front wheels as a result of vertical travel without input from the steering wheel. A requirement for automotive front suspension usually is defined as “as little bump steer as possible” in order to avoid unpredictable vehicle behavior on rough surfaces and also to increase the lifespan of the tire. The aim of this study is support this development without the usage of kinematics software or at least reduce the time spent in the software, since many people does not have access to this engineering tool. Therefore a mathematical model based on 2D kinematics model was developed with the purpose to determine the location of the tie rod inner hardpoint, once that the main suspension geometry parameters was defined (caster, camber, scrub radios, caster offset and Ackerman angle). The mathematical model validation was made in the OptimumKinematics software, where several analyses were run, each with different suspension setups, with the aim of
This paper presents the results of a study about the influence of the suspension manufacturing and assembly induced dimensional variation on the vehicle dynamic behavior for a compound crank rear suspension. A selection of representative vehicle dynamics metrics has been considered for this assessment and each individual dimensional variation has been categorized with respect to its overall effects on the selected metrics. By doing this, it is possible to identify the critical points where the dynamic behavior of the vehicle is more sensitive to the resulting dimensional variation, therefore creating a new criteria to define the appropriate tolerance control for the manufacturing and assembly of the related parts. The analysis procedure is based on a DOE (Design of Experiments) with the position tolerance of the attachment points between the suspension and the body structure defined as variables, as well as the wheel carrier surface tolerance with respect to position and angle (toe and
Nowadays there is a tendency to implement various active vehicle subsystems in a modern vehicle to improve its stability of motion, handling, comfort and other operation characteristics. Since each vehicle subsystem has own limits to generate supporting demand, their potential impact on vehicle dynamics should be analyzed for steady-state and transient vehicle behavior. Moreover, the additional research issue is the assessment of total energy consumption and energy losses, because a stand-alone operation of each vehicle subsystem will provide different impact on vehicle dynamics and they have own energy demands. The vehicle configuration includes (i) friction brake system, (ii) individual-wheel drive electric motors, (iii) wheel steer actuators, (iv) camber angle actuators, (v) dynamic tire pressure system and (vi) actuators generating additional normal forces through external spring, damping and stabilizer forces. A passenger car is investigated using commercial software. The actuator
Body motions of flying animals can be very complex, especially when the body parts are greatly flexible and they interact with the surrounding fluid. The wing kinematics of an animal flight is governed by a large number of variables and thus the measurement of complete flapping flight is not so simple, making it very complex to understand the contribution of each parameter to the performance and hence, to decide the important parameters for constructing the kinematic model of a bat is nearly impossible. In this paper, the influence of each parameter is uncovered and the variables that a specified reconstruction of bat flight should include in order to maximally reconstruct actual dimensional complexity, have been presented in detail. The effects of the different kinematic parameters on the lift coefficient are being resulted. The computation analysis of the lift coefficient for different camber thicknesses and various wing areas is done by unsteady thin airfoil theory and vortex
The modern vehicle suspensions are developed considering several structural and elastokinematics requirements. The elastokinematic behavior and how the suspension responds and transmits the forces and moments from the tires to the chassis have great influence on vehicle dynamics. In a torsion beam suspension, also known as twist beam suspension, parameters such as roll center height, roll stiffness, toe-in and camber variation can be optimized by altering the shape of the torsion beam. The development of a torsion beam that provides an optimal behavior specific to a particular vehicle is a challenge that demands a great amount of time and costs, being developed mainly by the trial and error method. To assist the development process of this study, DOE studies and optimization algorithms are applied. The combination of these methods allow to identify which are the torsion beam shape parameters that most influence the elastokinematic behavior. Then, knowing the effects of each variable
This paper summarizes the complex unsteady, 3-D viscous flow aerodynamics (dominantly laminar) developed in flapping wing generating vortices and intersecting with them. Different flying creatures, (Insects, Birds, and Bats) flapping wing mechanisms are studied and hence being compared based on their wing kinematics and aerodynamic efficiency. The performance of low Reynolds number flyers is highly influenced by the wing shape, wing size, wing camber, aspect ratio, % camber thickness, elastic deformation, wing-beat frequency and wing twisting. The Computation technique used to analyze the wake characteristics of a flapping motion shows that the generation and shedding of vortices dominate the aerodynamic loading on the wing. The periodicity of the wing motion and the resultant vortices leads to conclude that any quantitative model must be based on unsteady aerodynamics and vortex dynamics. The preliminary assessment of the plan form and the airfoils are performed using Modified Blade
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