Directional Response of a B-Train Vehicle Combination Carrying Liquid Cargo

1993 ◽  
Vol 115 (1) ◽  
pp. 133-139 ◽  
Author(s):  
R. Ranganathan ◽  
S. Rakheja ◽  
S. Sankar
Keyword(s):  
Free Surface ◽  
Three Dimensional ◽  
Lateral Acceleration ◽  
Flow Conditions ◽  
Vehicle Model ◽  
Liquid Motion ◽  
Directional Response ◽  
Response Characteristics ◽  
Weight Density ◽  
Liquid Movement

Directional dynamics of a B-train tank vehicle is investigated by integrating the three-dimensional vehicle model to the dynamics associated with the movement of free surface of liquid within the partially filled tanks. The motion of the free surface of liquid due to instantaneous tank roll and lateral acceleration is computed assuming steady state fluid flow conditions. The influence of liquid motion on the dynamic response of the rearmost trailer is investigated for both constant and transient steer inputs, assuming constant forward speed. Directional response characteristics of the B-train tank vehicle are compared to those of an equivalent rigid cargo vehicle to demonstrate the destabilizing effects of the liquid movement within the tank vehicle. Directional response characteristics are further discussed for variation in weight density of liquid and thus the fill height, while the axle loads are held constant around maximum permissible values.

Adapting an Articulated Vehicle to the Drivers

1999 ◽  
Author(s):  
Xiaobo Yang ◽  
Subhash Rakheja ◽  
Ion Stiharu
Keyword(s):  
Open Loop ◽  
Roll Angle ◽  
Driver Model ◽  
Lateral Acceleration ◽  
Vehicle Model ◽  
Response Characteristics ◽  
Performance Potentials ◽  
Compensatory Gain ◽  
Steering Effort ◽  
Control Limits

Abstract A yaw plane model with limited roll DOF of a five-axle tractor semitrailer is developed to study the open-loop directional dynamics of the vehicle. A comprehensive driver model incorporating path preview, low and high frequency compensatory gains and time delays, and prediction of tractor lateral acceleration, articulation rate of the combination and the trailer sprung mass roll angle is developed and integrated with the vehicle model. The coupled driver-vehicle model is analyzed to explore the performance potentials of the vehicle design adapted for control limits of the driver. The data reported in the published studies are reviewed to identify range of control limits of the drivers in terms of preview distance, reaction time and compensatory gain. A comprehensive performance index including the path tracking, vehicle dynamic response characteristics and the driver’s steering effort is formulated and minimized using Gauss-Newton method to derive the desirable ranges of the vehicle parameters, including geometric, inertial, suspension, tire and the fifth wheel. The results of the study revealed that a driver with higher skill can easily adapt the vehicle with large size, soft suspension and relative over-steer nature. The adaptability of the vehicle is further examined for different drivers with varying skills. It is concluded that the adaptability and thus the directional performance of the vehicle can be enhanced through variations in the weights and dimensions, and suspension, tire and the fifth wheel properties. The results further show that the driver-adapted vehicle yields up to 33% reduction in the steering effort demand posed on the driver, while the roll angle and yaw rate response decrease by up to 40%.

Numerical Analysis of 2-D and 3-D Cavitating Hydrofoils Under a Free Surface

2001 ◽  
Vol 45 (01) ◽  
pp. 34-49 ◽  
Author(s):  
Sakir Bal ◽  
Spyros A. Kinnas ◽  
Hanseong Lee
Keyword(s):  
Integral Equation ◽  
Free Surface ◽  
Three Dimensional ◽  
Radiation Condition ◽  
Flow Conditions ◽  
Surface Conditions ◽  
Constant Strength ◽  
Cavitating Hydrofoil ◽  
Upstream Waves ◽  
Transverse Boundary

A method which models two- or three-dimensional cavitating hydrofoils moving with constant speed under a free surface is described. An integral equation is obtained by applying Green's theorem on all surfaces of the fluid domain. This integral equation is divided into two parts:the cavitating hydrofoil problem, andthe free-surface problem. These two problems are solved separately, with the effects of one on the other being accounted for in an iterative manner. The cavitating hydrofoil surface and the free surface are modeled with constant strength dipole and source panels. The source strengths on the free surface are expressed in terms of the second derivative of the potential with respect to the horizontal axis by applying the linearized free-surface conditions. The induced potential by the cavitating hydrofoil on the free surface and by the free surface on the hydrofoil are determined in an iterative sense. In order to prevent upstream waves the source strengths from some distance in front of the hydrofoil to the end of the truncated upstream boundary are enforced to be equal to zero. No radiation condition is enforced at the downstream boundary or at the transverse boundary. The method is applied to 2-D and 3-D hydrofoil geometries in fully wetted or cavitating flow conditions and the predictions are compared with those of other methods in the literature.

Analysis on Usage Comfort of Highway Based on Lateral Acceleration and Lateral Acceleration Change Rate

2013 ◽  
Vol 427-429 ◽  
pp. 320-324 ◽  
Author(s):  
Zheng Yu Wang ◽  
Cheng Bing Li ◽  
Jin Xu
Keyword(s):  
Rigid Body ◽  
Three Dimensional ◽  
Driver Model ◽  
Lateral Acceleration ◽  
Mountainous Area ◽  
Vehicle Model ◽  
Change Rate ◽  
Vehicle Simulation ◽  
Peak Value ◽  
Made In

To control the lateral acceleration of driving vehicle and its rate of growth is always an important part in road geometric design. At present, vehicles are simplified as single rigid body when and are calculated, moreover, the calculation is made in two-dimensional plane, which does not comply with the actuality. In this article, Road-Driver-Vehicle simulation system (RDVS) is applied to get and of driving vehicle on 3 test roads selected from the mountainous area of southwestern China. In RDVS, the dynamic vehicle model is driven on three-dimensional roads under the control of driver model, so it is more close to the real driving. The results show: got from RDVS is bigger than that from single rigid body calculation. As RDVS is more reliable, from single rigid body calculation may cause an insufficient estimation: suppose the driver drives at the designed speed, though the designed speed varies, the peak value of of the three objects range in [2.0m/s2, 2.5m/s2], beyond the limit of comfort but within tolerable scope; as for subject C without application of clothoid, will exceed the limit of 1.0m/s3. So it is suggested using clothoid, considering improving the quality.

Prediction of Ship Motions Via a Three-Dimensional Time-Domain Method Following a Quad-Tree Adaptive Mesh Technique

2020 ◽  
Vol 27 (1) ◽  
pp. 29-38
Author(s):  
Teng Zhang ◽  
Junsheng Ren ◽  
Lu Liu
Keyword(s):  
Free Surface ◽  
Incident Wave ◽  
Time Domain ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Wave Profile ◽  
Time Domain Method ◽  
Ship Motions ◽  
Quad Tree ◽  
Mesh Technique

AbstractA three-dimensional (3D) time-domain method is developed to predict ship motions in waves. To evaluate the Froude-Krylov (F-K) forces and hydrostatic forces under the instantaneous incident wave profile, an adaptive mesh technique based on a quad-tree subdivision is adopted to generate instantaneous wet meshes for ship. For quadrilateral panels under both mean free surface and instantaneous incident wave profiles, Froude-Krylov forces and hydrostatic forces are computed by analytical exact pressure integration expressions, allowing for considerably coarse meshes without loss of accuracy. And for quadrilateral panels interacting with the wave profile, F-K and hydrostatic forces are evaluated following a quad-tree subdivision. The transient free surface Green function (TFSGF) is essential to evaluate radiation and diffraction forces based on linear theory. To reduce the numerical error due to unclear partition, a precise integration method is applied to solve the TFSGF in the partition computation time domain. Computations are carried out for a Wigley hull form and S175 container ship, and the results show good agreement with both experimental results and published results.

Three-dimensional numerical model for open-channels with free-surface variations

2003 ◽  
Vol 41 (1) ◽  
pp. 110-112
Author(s):  
ZhixiaN. Cao ◽  
Rodney Day ◽  
Sarah Liriano
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Three Dimensional ◽  
Open Channels

Truck Suspension Design to Minimize Road Damage

1996 ◽  
Vol 210 (2) ◽  
pp. 95-107 ◽  
Author(s):  
D J Cole ◽  
D Cebon
Keyword(s):  
Three Dimensional ◽  
Fourth Power ◽  
Vehicle Model ◽  
Efficient Procedure ◽  
Suspension Parameters ◽  
Articulated Vehicle ◽  
Suspension Stiffness ◽  
Optimal Values ◽  
Dynamic Components ◽  
Stiffness And Damping

The objective of the work described in this paper is to establish guidelines for the design of passive suspensions that cause minimum road damage. An efficient procedure for calculating a realistic measure of road damage (the 95th percentile aggregate fourth power force) in the frequency domain is derived. Simple models of truck vibration are then used to examine the influence of suspension parameters on this road damage criterion and to select optimal values. It is found that to minimize road damage a suspension should have stiffness about one fifth of current air suspensions and damping up to twice that typically provided. The use of an anti-roll bar allows a high roll-over threshold without increasing road damage. It is thought that optimization in the pitch-plane should exclude correlation between the axles, to ensure that the optimized suspension parameters are robust to payload and speed changes. A three-dimensional ‘whole-vehicle’ model of an air suspended articulated vehicle is validated against measured tyre force histories. Optimizing the suspension stiffness and damping results in a 5.8 per cent reduction in road damage by the whole vehicle (averaged over three speeds). This compares with a 40 per cent reduction if the dynamic components of the tyre forces are eliminated completely.

Base-Vented Hydrofoils of Finite Span Under a Free Surface: An Experimental Investigation

1984 ◽  
Vol 28 (02) ◽  
pp. 90-106
Author(s):  
Jacques Verron ◽  
Jean-Marie Michel
Keyword(s):  
Experimental Investigation ◽  
Free Surface ◽  
Flow Rate ◽  
Cavity Length ◽  
Three Dimensional ◽  
Leading Edge ◽  
Pulsation Frequency ◽  
Cavity Pressure ◽  
Air Flow Rate ◽  
Cavity Configuration

Experimental results are given concerning the behavior of the flow around three-dimensional base-vented hydrofoils with wetted upper side. The influence of planform is given particular consideration so that the sections of the foils are simple wedges with rounded noses. Results concern cavity configuration, the relation between the air flow rate and cavity pressure, leading-edge cavitation, cavity length, pulsation frequency, and force coefficients.

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