High-Fidelity Modeling of a Backhoe Digging Operation Using an Explicit Multibody Dynamics Code With Integrated Discrete Particle Modeling Capability

2013 ◽  
Author(s):  
Shahriar G. Ahmadi ◽  
Tamer M. Wasfy ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Multibody Dynamics ◽  
Search Algorithm ◽  
Equations Of Motion ◽  
Friction Model ◽  
Rigid Bodies ◽  
Contact Friction ◽  
Contact Detection ◽  
High Fidelity ◽  
Normal Contact ◽  
Contact Search

A high-fidelity multibody dynamics model for simulating a backhoe digging operation is presented. The backhoe components including: frame, manipulator, track, wheels and sprockets are modeled as rigid bodies. The soil is modeled using cubic shaped particles for simulating sand with appropriate inter-particle normal and frictional forces. A penalty technique is used to impose both joint and normal contact constraints (including track-wheels, track-terrain, bucket-particles and particles-particles contact). An asperity-based friction model is used to model joint and contact friction. A Cartesian Eulerian grid contact search algorithm is used to allow fast contact detection between particles. A recursive bounding box contact search algorithm is used to allow fast contact detection between polygonal contact surfaces. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The model can help improve the performance of construction equipment by predicting the actuator and joint forces and the vehicle stability during digging for various vehicle design alternatives.

Coupled Multibody Dynamics and Discrete Element Modeling of Vehicle Mobility on Cohesive Granular Terrains

2014 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Multibody Dynamics ◽  
Search Algorithm ◽  
Soft Soil ◽  
Discrete Element ◽  
Friction Model ◽  
Contact Friction ◽  
Contact Detection ◽  
Normal Contact ◽  
Contact Search ◽  
Contact Surfaces

Multibody dynamics and the discrete element method (DEM) are integrated into one solver for predicting the dynamic response of ground vehicles which run on wheels and/or tracks on cohesive soft soils (such as mud and snow). Multibody dynamics techniques are used to model the various vehicle components and connect those components using various types of joints and contact surfaces. A penalty technique is used to impose joint and normal contact constraints. An asperity-based friction model is used to model joint and contact friction. A soft cohesive soil material model (that includes normal and tangential inter-particle force models) is presented that can account for soil compressibility, plasticity, fracture, friction, viscosity, cohesive strength and flow. A Cartesian Eulerian grid contact search algorithm is used to allow fast contact detection between particles. A recursive bounding box contact search algorithm is used to allow fast contact detection between the particles and polygonal contact surfaces. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. Numerical simulations of a typical vehicle going over a slopped soft soil terrain are presented to demonstrate the integrated solver. The solver can be used in vehicle design optimization.

Coupled Multibody Dynamics and Discrete Element Modeling of Bulldozers Cohesive Soil Moving Operation

2015 ◽  
Author(s):  
Akshay Sane ◽  
Tamer M. Wasfy ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Multibody Dynamics ◽  
Search Algorithm ◽  
Cohesive Soil ◽  
Discrete Element ◽  
Cohesive Strength ◽  
Contact Friction ◽  
Contact Detection ◽  
Normal Contact ◽  
Contact Search ◽  
Contact Surfaces

Multibody dynamics and the discrete element method are integrated into one solver for modeling the excavation and moving operation of cohesive soft soil (such as mud and snow) by bulldozers. A soft cohesive soil material model (that includes normal and tangential inter-particle force models) is presented that can account for soil flow, compressibility, plasticity, fracture, friction, viscosity, gain in cohesive strength due to compression, and loss in cohesive strength due to tension. Multibody dynamics techniques are used to model the various bulldozer components and connect those components using various types of joints and contact surfaces. A penalty technique is used to impose joint and normal contact constraints. An asperity-based friction model is used to model joint and contact friction. A Cartesian Eulerian grid contact search algorithm is used to allow fast contact detection between particles. A recursive bounding box contact search algorithm is used to allow fast contact detection between the particles and polygonal contact surfaces. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. A numerical simulation of a bulldozer performing a shallow digging operation in a cohesive mud-type soil is presented to demonstrate the integrated solver. The solver can be used to improve the design of the various bulldozer components such as the blade geometry, tire design, and track design.

High-Fidelity Modeling of Flexible Timing Belts Using an Explicit Finite Element Code

2011 ◽  
Author(s):  
Tamer M. Wasfy
Keyword(s):  
Finite Element ◽  
Search Algorithm ◽  
Equations Of Motion ◽  
Friction Model ◽  
Rigid Bodies ◽  
Contact Friction ◽  
High Fidelity ◽  
Explicit Finite Element ◽  
Contact Points ◽  
Joint Contact

A time-accurate high-fidelity finite element model for timing belt-drives is presented. The belt is modeled using flexible spatial lumped parameters beam elements. Each finite element belt node can be considered as a rigid body whose contact geometry is used to model the contact surfaces of the belt teeth. The sprockets and pulleys are modeled as rigid bodies. A penalty model is used to impose the joint/contact constraints. An asperity-based friction model is used to model joint/contact friction. A recursive bounding box contact search algorithm is used to allow fast contact detection between contact points on the belt surface (master contact surface) and a polygonal surface representation of the sprockets/pulleys. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The model is partially validated by comparing to a previously published steady-state study where the belt tooth loads over the driven sprocket were experimentally measured. The model can help improve the design of timing belts including increasing the range of operating speeds, reduce the vibrations and noise and increase the drive durability.

Finite Element Modeling of the Dynamic Response of Tracked Vehicles

2009 ◽  
Author(s):  
Tamer M. Wasfy ◽  
James O’Kins
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Search Algorithm ◽  
Equations Of Motion ◽  
Friction Model ◽  
Rigid Bodies ◽  
Contact Friction ◽  
Flexible Bodies ◽  
Tracked Vehicles ◽  
Joint Contact

A time-accurate finite element model for predicting the dynamic response of tracked vehicles is presented. The model supports flexible continuous belt-type tracks and segmented-tracks consisting of rigid and/or flexible links connected using revolute joints. The flexible multibody system representing the tracked vehicle is modeled using rigid bodies, flexible bodies, joints and actuators. Flexible bodies are modeled using total-Lagrangian brick, membrane, beam, truss and linear/rotational spring elements. The penalty method is used to impose the joint/contact constraints. An asperity-based friction model is used to model joint/contact friction. A recursive bounding box contact search algorithm is used to allow fast contact detection between finite elements and other elements as well as general triangular/quadrilateral surfaces. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The model can help improve the design of tracked vehicles including increasing the vehicle’s stability and durability.

Multibody Dynamics Modeling of Sand Flow From a Hopper and Sand Pile Angle of Repose

2013 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Shahriar G. Ahmadi ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Multibody Dynamics ◽  
Flow Rate ◽  
Search Algorithm ◽  
Equations Of Motion ◽  
Friction Model ◽  
Angle Of Repose ◽  
Dynamics Modeling ◽  
Three Dimensional Model ◽  
Normal Contact ◽  
Sand Flow

An explicit time integration multibody dynamics code is used to create a three-dimensional model of sand. Sand is modeled using discrete cubical particles with appropriate normal contact force and tangential friction force models. The model is used to predict the sand angle of repose and flow rate during discharge from a conical hopper. A penalty technique is used to impose normal contact constraints (including particle-particle, particle-hopper and particle-ground contact). An asperity-based friction model is used to model friction. A Cartesian Eulerian grid contact search algorithm is used to allow fast contact detection between particles. The governing equations of motion are solved along with contact constraint equations using a time-accurate explicit solution procedure. Parameter studies are performed in order to study the effects of the particle size and the orifice’s diameter of the hopper on the angle of repose and sand flow rate. The results of the simulations are validated using previously published experimental results.

High-Fidelity Multibody Dynamics Vehicle Model Coupled With a Cohesive Soil Discrete Element Model for Predicting Vehicle Mobility

2015 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Multibody Dynamics ◽  
Soft Soil ◽  
Material Model ◽  
Discrete Element ◽  
Cohesive Strength ◽  
Contact Friction ◽  
Maximum Speed ◽  
High Fidelity ◽  
Ground Vehicles ◽  
Normal Contact

Multibody dynamics and the discrete element method (DEM) are integrated into one solver for predicting the mobility characteristics (including the no-go condition, maximum speed, and required engine torque/power) of ground vehicles on rough off-road soft soil (such as mud and snow) terrains. High fidelity multibody dynamics models are used for the various vehicle systems including: suspension system, wheels, steering system, axle, differential, and engine. A penalty technique is used to impose joint and normal contact constraints. An asperity-based friction model is used to model joint and contact friction. A DEM model of the soil with a cohesive soft soil material model is used. The material model can account for the soil compressibility, plasticity, fracture, friction, viscosity, gain in cohesive strength due to compression, and loss in cohesive strength due to tension. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The model can be used to predict the mobility of ground vehicles as a function of soil type, terrain long slope, and terrain side slope. Typical simulations of a Humvee-type vehicle are provided to demonstrate the model.

Coupled Multibody Dynamics and Smoothed Particle Hydrodynamics for Predicting Liquid Sloshing for Tanker Trucks

2014 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Dynamic Response ◽  
Multibody Dynamics ◽  
Smoothed Particle Hydrodynamics ◽  
Search Algorithm ◽  
Contact Detection ◽  
Contact Search ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Contact Surfaces ◽  
Fluid Particles

Multibody dynamics and smoothed particle hydrodynamics (SPH) are integrated into one solver for predicting the dynamic response of tanker trucks. Multibody dynamics techniques are used to model the various vehicle components and connect those components using various types of joints and contact surfaces. A penalty technique is used to impose joint and normal contact constraints (between the tires and ground, and between the tank and the fluid particles). An asperity-based friction model is used to model joint and contact friction. The liquid in the tanks is modeled using an SPH particle-based approach. A contact search algorithm that uses a moving Cartesian Eulerian grid that is fixed to the tank is used to allow fast contact detection between particles. A recursive bounding box contact search algorithm is used to allow fast contact detection between polygonal contact surfaces and the fluid particles. The governing equations of motion for the solid bodies and the fluid particles are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The integrated solver is used to predict the dynamic response of a typical tanker truck performing a braking test with an empty, half-full and full tank. The solver can be used in vehicle design optimization to simulate and evaluate various vehicle designs.

Coupled Multibody Dynamics and Smoothed Particle Hydrodynamics for Modeling Vehicle Water Fording

2015 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Multibody Dynamics ◽  
Smoothed Particle Hydrodynamics ◽  
Search Algorithm ◽  
Vehicle Body ◽  
Contact Detection ◽  
Water Pool ◽  
Contact Search ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Fluid Particles

Multibody dynamics and smoothed particle hydrodynamics (SPH) are integrated into one solver for predicting the water fording dynamic response of ground vehicles. Multibody dynamics models are used for the various vehicle systems including: suspension system, wheels, steering system, axles, differential, and engine. A penalty technique is used to impose joint and normal contact constraints (between the tires and ground, and between the tires/vehicle body and the fluid particles). An asperity-based friction model is used to model joint and contact friction. Water is modeled using an SPH particle-based approach along with a large eddy-viscosity turbulence model. A contact search algorithm that uses a Cartesian Eulerian grid around the water pool is used to allow fast contact detection between particles. A recursive bounding box contact search algorithm is used to allow fast contact detection between polygonal contact surfaces (representing the tires and vehicle body) and the fluid particles. The governing equations of motion for the solid bodies and the fluid particles are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The integrated solver is used to predict the dynamic response of a Humvee-type vehicle moving through a shallow water pool.

scholarly journals An Efficient Contact Model for the Simulation of Cargo Airdrop Extraction Phase

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Leiming Ning ◽  
Jichang Chen ◽  
Mingbo Tong
Keyword(s):  
Degrees Of Freedom ◽  
Friction Model ◽  
Rigid Bodies ◽  
Contact Dynamics ◽  
Moving Frame ◽  
Contact Friction ◽  
Practical Implementation ◽  
Contact Formulation ◽  
Efficient Code ◽  
Extraction Phase

A high-fidelity cargo airdrop simulation requires the accurate modeling of the contact dynamics between an aircraft and its cargo. This paper presents a general and efficient contact-friction model for the simulation of aircraft-cargo coupling dynamics during an airdrop extraction phase. The proposed approach has the same essence as the finite element node-to-segment contact formulation, which leads to a flexible, straightforward, and efficient code implementation. The formulation is developed under an arbitrary moving frame with both aircraft and cargo treated as general six degrees-of-freedom rigid bodies, thus eliminating the restrictions of lateral symmetric assumptions in most existing methods. Moreover, the aircraft-cargo coupling algorithm is discussed in detail, and some practical implementation details are presented. The accuracy and capability of the present method are demonstrated through four numerical examples with increasing complexity and fidelity.

Effect of Material and Geometric Parameters on the Steady-State Belt Stresses and Belt Slip for Flat Belt-Drives

2015 ◽  
Author(s):  
Cagkan Yildiz ◽  
Tamer M. Wasfy ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Steady State ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Flexible Multibody Dynamics ◽  
Friction Model ◽  
Rigid Bodies ◽  
Geometric Parameters ◽  
Rubber Matrix ◽  
Axial Stiffness ◽  
Belt Drive

In order to accurately predict the fatigue life and wear life of a belt, the various stresses that the belt is subjected to and the belt slip over the pulleys must be accurately calculated. In this paper, the effect of material and geometric parameters on the steady-state stresses (including normal, tangential and axial stresses), average belt slip for a flat belt, and belt-drive energy efficiency is studied using a high-fidelity flexible multibody dynamics model of the belt-drive. The belt’s rubber matrix is modeled using three-dimensional brick elements and the belt’s reinforcements are modeled using one dimensional truss elements. Friction between the belt and the pulleys is modeled using an asperity-based Coulomb friction model. The pulleys are modeled as cylindrical rigid bodies. The equations of motion are integrated using a time-accurate explicit solution procedure. The material parameters studied are the belt-pulley friction coefficient and the belt axial stiffness and damping. The geometric parameters studied are the belt thickness and the pulleys’ centers distance.

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