Terramechanics-based wheel–terrain interaction model and its applications to off-road wheeled mobile robots

Robotica ◽  
2011 ◽  
Vol 30 (3) ◽  
pp. 491-503 ◽  
Author(s):  
Zhenzhong Jia ◽  
William Smith ◽  
Huei Peng
Keyword(s):  
Mobile Robots ◽  
Soft Soil ◽  
Three Dimensional ◽  
Interaction Model ◽  
Dynamics Simulation ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Wheeled Mobile Robots ◽  
Modular Model ◽  
Reaction Forces

SUMMARYThis paper presents a wheel–terrain interaction model, which enables efficient modeling of wheeled locomotion in soft soil and numerical simulations of off-road mobile robots. This modular model is derived based on wheel kinematics and terramechanics and the main focus is on describing the stress distributions along the wheel–terrain interface and the reaction forces exerted on the wheel by the soil. When the wheels are steered, the shear stresses underneath the wheel were modeled based on isotropic assumptions. The forces and torques contributed by the bulldozing effect of the side surfaces is also considered in the proposed model. Furthermore, the influence of grousers, commonly used on smaller mobile robots, was modeled by (1) averaging the normal pressures contributed by the grousers and the wheel concave portion, and (2) assuming that the shear phenomenon takes places along the grouser tips. By integrating the model with multibody system code for vehicle dynamics, simulation studies of various off-road conditions in three-dimensional environments can be conducted. The model was verified by using field experiment data, both for a single-wheel vehicle and a whole vehicle.

A Three-Dimensional Pedestrian–Structure Interaction Model for General Applications

2018 ◽  
Vol 18 (09) ◽  
pp. 1850107 ◽  
Author(s):  
Yan-An Gao ◽  
Qing-Shan Yang ◽  
Yun Dong
Keyword(s):  
Large Scale ◽  
Damping Ratio ◽  
Three Dimensional ◽  
Interaction Model ◽  
Dynamic Interaction ◽  
Structure Interaction ◽  
Numerical Studies ◽  
Structure Dynamic ◽  
Proposed Model ◽  
Reaction Forces

A three-dimensional (3D) pedestrian–structure interaction (PSI) system based on the biomechanical bipedal model is presented for general applications. The pedestrian is modeled by a bipedal mobile system with one lump mass and two compliant legs, which comprise damping and spring elements. The continuous gaits of the pedestrian are maintained by a self-driven walking kinetic energy, which is a new driven mechanism for the mobile unit. This self-driven mechanism enables the pedestrian to operate at a varying total energy level, as an important component for further modeling of the crowd-structure dynamic interaction. Numerical studies show that the pedestrian walking on the structure leads to a reduction in the natural frequency, but an increase in the damping ratio of the structure. This model can also reproduce the reaction forces between the feet and structure, similar to those measured in the field. In addition, the proposed model can well describe the 3D pedestrian–structure dynamic interaction. It is recommended for use in further study of more complicated scenarios such as the dynamic interaction between a large scale kinetic crowd and slender footbridge.

Influence of Mechanical Behavior of Adhesives on Shear Stress Distributions in the Single-Lap Adhesive Joints

2011 ◽  
Vol 306-307 ◽  
pp. 1126-1129
Author(s):  
Xiao Cong He
Keyword(s):  
Shear Stress ◽  
Mechanical Behavior ◽  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Adhesive Layer ◽  
Adhesive Joints ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Element Analysis ◽  
Three Dimensional Finite Element

This paper deals with the effects of mechanical behavior of adhesives on the shear stress distributions of single-lap adhesive joints under tension using the three-dimensional finite element analysis (FEA) technique. Numerical examples are provided to show the influence on the shear stresses of the joints using adhesives of different characteristics which encompass the entire spectrum of viscoelastic behavior. FEA solutions of the shear stress distributions in the adhesive layer have been obtained for four typical characteristics of adhesives. The results indicate that Young’s modulus and Poisson’s ratios of adhesives strongly affect the shear stress distributions of the joints.

A Novel Wheel-Soil Interaction Model for Off-Road Vehicle Dynamics Simulation

2007 ◽  
Author(s):  
Brendan J. Chan ◽  
Corina Sandu
Keyword(s):  
Vehicle Dynamics ◽  
Three Dimensional ◽  
Interaction Model ◽  
Equilibrium Analysis ◽  
Dynamics Simulation ◽  
Tire Model ◽  
Wheel Load ◽  
Surface Shear ◽  
Modeling Methodology ◽  
Semi Empirical

This work establishes a semi-empirical wheel-soil interaction model, developed in the framework of plasticity theory and equilibrium analysis, to be used in vehicle dynamics simulations. Vehicle-terrain interaction is a complex phenomena governed by soil mechanical behavior and tire deformation. The application of soil load bearing capacity theory is used in this study to determine the tangential and radial stresses on the soil-wheel interface. Using semi-empirical data, the tire deformation geometry is determined to establish the drawbar pull, tractive force, and wheel load. To illustrate the theory developed, two important case studies are presented: a rigid wheel and a flexible tire on deformable terrain; the differences between the two implementations are discussed. The outcome of this work shows promising results which indicate that the modeling methodology presented could form the basis of a three-dimensional off-road tire model. In an off-road three-dimensional tire model, the traction behavior should include shear forces arising from the surface shear with the soil as well as the bulldozing effect during turning maneuvers.

scholarly journals Accurate through-the-thickness stress distributions in thin-walled metallic structures subjected to large displacements and large rotations

2020 ◽  
Vol 42 (3) ◽  
pp. 239-254
Author(s):  
A. Pagani ◽  
R. Azzara ◽  
R. Augello ◽  
E. Carrera ◽  
B. Wu
Keyword(s):  
Three Dimensional ◽  
Path Following ◽  
Higher Order ◽  
Large Displacement ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Displacement Fields ◽  
Isotropic Shell ◽  
Geometrical Nonlinear ◽  
Lagrange Strain

The present paper presents the evaluation of three-dimensional (3D) stress distributions of shell structures in the large displacement and rotation fields. The proposed geometrical nonlinear model is based on a combination of the Carrera Unified Formulation (CUF) and the Finite Element Method (FEM). Besides, a Newton-Raphson linearization scheme is adopted to compute the geometrical nonlinear equations, which are constrained using the arc-length path-following method. Static analyses are performed using refined models and the full Green-Lagrange strain-displacement relations. The Second Piola-Kirchhoff (PK2) stress distributions are evaluated, and lower- to higher-order expansions are employed. Popular benchmarks problems are analyzed, including cylindrical isotropic shell structure with various boundary and loading conditions. Various numerical assessments for different equilibrium conditions in the moderate and large displacement fields are proposed. Results show the distribution of axial and shear stresses, varying the refinement of the proposed two-dimensional (2D) shell model. It is shown that for axial components, a lower-order expansion is sufficient, whereas a higher-order one is needed to accurately predict shear stresses.

Nonlinear Analysis of Flexibility and Local Stress Distribution at Nozzle-Shell Intersection Considering Refractory Lining Rigidity

2004 ◽  
Author(s):  
Takuya Sato ◽  
Shingo Nomura
Keyword(s):  
Finite Element ◽  
Refractory Lining ◽  
Three Dimensional ◽  
Compressive Force ◽  
Design Procedure ◽  
Local Stress ◽  
Contact Boundary ◽  
Stress Distributions ◽  
Reaction Forces ◽  
Nozzle Head

The reactors and re-generators in RFCC and FCC units in refineries are provided with concrete refractory linings. The influence of these linings on the flexibility of the nozzle-shell intersections and the local stress distributions around those intersections is not considered in present designs. In this paper, three-dimensional, nonlinear finite element analyses were performed to evaluate the influence of refractory lining rigidity on the flexibility of nozzle-head intersections. The results of these analyses can be applied to the thermal stress analysis of piping to obtain reaction forces and moments on nozzles. The application of flexibility factors results in a reduction of the reaction forces and moments. The influence of refractory lining rigidity on the local stress distributions around the intersections was also studied. To perform this investigation, three types of finite element models were adopted: • Nozzle-head intersections without refractory lining; • Nozzle-head intersections with refractory lining (adhesive boundary between steel and lining); • Nozzle-head intersections with refractory lining (contact boundary between steel and lining). Shell elements were applied to the nozzle, head and cylindrical shell, and solid elements were applied to the refractory lining. A boundary element was applied to express the contact boundary, which transfers only a compressive force. As a conclusion, a new design procedure for nozzle-head intersections with refractory linings is proposed.

3D CFD Simulation of Water Hammer Through a 90° Bend: Applicability of URANS, 3D Effects and Unsteady Friction

2014 ◽  
Author(s):  
Stefan Riedelmeier ◽  
Stefan Becker ◽  
Eberhard Schlücker
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Water Hammer ◽  
Dynamics Simulation ◽  
Shear Stresses ◽  
Velocity Gradients ◽  
Wall Shear ◽  
The Impact

In most cases, the method of characteristics is used to calculate the propagation of water hammer in hydraulic systems due to the size of those pipings, although three-dimensional effects are known to occur. In order to investigate and quantify these effects, a three-dimensional computational fluid dynamics simulation of water hammer through a bend geometry was performed. For the resolution of the developing high spatial and temporal gradients an adequate mesh and suitable physical model was generated using a commercial code. The applicability of unsteady Reynolds-averaged Navier-Stokes simulation was evaluated considering the turbulent properties of the flow using results from the literature. Furthermore velocity, pressure, wall shear stress and vorticity distributions are presented. The effect of the 90° bend as three-dimensional element was identified and the impact on the flow field is presented. In the end, the annular effect is discussed. Due to the high forces of inertia in the boundary layer and the dominating viscous forces close to the wall, high velocity gradients are developing resulting in high wall shear stresses. It is shown that the viscous and turbulent transport of momentum in the radial direction reduces these velocity gradients and limits the maximum occurring wall shear stress.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

scholarly journals Ultrasonic Deicing Efficiency Prediction and Validation for a Flat Deicing System

2020 ◽  
Vol 10 (19) ◽  
pp. 6640
Author(s):  
Zhonghua Shi ◽  
Zhenhang Kang ◽  
Qiang Xie ◽  
Yuan Tian ◽  
Yueqing Zhao ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Lead Zirconate ◽  
Efficiency Factor ◽  
Zone Model ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Total Energy Density ◽  
Average Shear

An effective deicing system is needed to be designed to conveniently remove ice from the surfaces of structures. In this paper, an ultrasonic deicing system for different configurations was estimated and verified based on finite element simulations. The research focused on deicing efficiency factor (DEF) discussions, prediction, and validations. Firstly, seven different configurations of Lead zirconate titanate (PZT) disk actuators with the same volume but different radius and thickness were adopted to conduct harmonic analysis. The effects of PZT shape on shear stresses and optimal frequencies were obtained. Simultaneously, the average shear stresses at the ice/substrate interface and total energy density needed for deicing were calculated. Then, a coefficient named deicing efficiency factor (DEF) was proposed to estimate deicing efficiency. Based on these results, the optimized configuration and deicing frequency are given. Furthermore, four different icing cases for the optimize configuration were studied to further verify the rationality of DEF. The effects of shear stress distributions on deicing efficiency were also analyzed. At same time, a cohesive zone model (CZM) was introduced to describe interface behavior of the plate and ice layer. Standard-explicit co-simulation was utilized to model the wave propagation and ice layer delamination process. Finally, the deicing experiments were carried out to validate the feasibility and correctness of the deicing system.

Sign in / Sign up

Export Citation Format

Share Document