Dynamic Modeling of Synchronous Belt-Drives Using an Explicit Finite Element Code

2005 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Michael J. Leamy
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Fixed Number ◽  
Friction Model ◽  
Rigid Bodies ◽  
Finite Element Code ◽  
Tooth Contact ◽  
Friction Forces ◽  
Normal Contact ◽  
Explicit Finite Element

A time-accurate explicit time-integration finite element code is used to simulate the dynamic response of synchronous belts-drives. The belt is modeled using beam or truss elements. The sprockets are modeled as cylindrical rigid bodies. Normal contact between the belt and a sprocket is modeled using the penalty technique and friction is modeled using an asperity-based approximate Coulomb friction model. The belt teeth/grooves are assumed to be located at the belt nodes (every fixed number of belt nodes). The nodes in-between teeth are subjected to the normal contact and tangential friction forces. The belt and sprocket teeth are assumed to be trapezoidal. The equivalent belt-sprocket tooth stiffness and damping coefficients in the normal tooth contact direction are used to calculate a normal tooth contact force at the belt teeth nodes. The tooth contact model also includes the effect of the tooth engagement tolerance. For validation purposes, a two-sprocket drive is modeled and a comparison is made between tooth loads predicted by the finite element model and experimental data available in the literature. Reasonable agreement between the simulation and experimental results is found of the drive’s tooth loads. Also, the dynamic response of a hybrid sprocket – flat pulley belt-drive is studied.

Modeling the Dynamic Frictional Contact of Tires Using an Explicit Finite Element Code

2005 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Michael J. Leamy
Keyword(s):  
Finite Element ◽  
Frictional Contact ◽  
Time Integration ◽  
Friction Model ◽  
Finite Element Code ◽  
Normal Contact ◽  
Explicit Finite Element ◽  
Beam Elements ◽  
Coulomb Friction Model ◽  
Stiffness And Damping

A time-accurate explicit time-integration finite element code is used to simulate the dynamic response of tires including tire/pavement and tire/rim frictional contact. Eight-node brick elements, which do not exhibit locking or spurious modes, are used to model the tire’s rubber. Those elements enable use of one element through the thickness for modeling the tire. The bead, tread and ply are modeled using truss or beam elements along the tire circumference and meridian directions with appropriate stiffness and damping properties. The tire wheel is modeled as a rigid cylinder. Normal contact between the tire and the wheel and between the tire and the pavement is modeled using the penalty technique. Friction is modeled using an asperity-based approximate Coulomb friction model.

Asperity Spring Friction Model With Application to Belt-Drives

2003 ◽  
Author(s):  
Tamer M. Wasfy
Keyword(s):  
Finite Element ◽  
Coulomb Friction ◽  
Friction Model ◽  
Belt Drive ◽  
Finite Element Code ◽  
Time Step ◽  
Stick Slip ◽  
Normal Contact ◽  
Belt Drives ◽  
Coulomb Friction Model

An asperity spring friction model that uses a variable anchor point spring along with a velocity dependent force is presented. The model is incorporated in an explicit timeintegration finite element code. The friction model is used along with a penalty-based normal contact model to simulate the dynamic response of a two-pulley belt-drive system. It is shown that the present friction model accurately captures the stick-slip behavior between the belt and the pulleys using a much larger time-step than a pure velocity-dependent approximate Coulomb friction model.

Numerical Simulation of Blast Loadings on a Thick-Walled Cylindrical Vessel

2007 ◽  
Author(s):  
Guide Deng ◽  
Ping Xu ◽  
Jinyang Zheng ◽  
Yongjun Chen ◽  
Yongle Hu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Dynamic Response ◽  
Rigid Wall ◽  
Cylindrical Vessel ◽  
Finite Element Code ◽  
Explicit Finite Element ◽  
Shell Deformation ◽  
Blast Loadings ◽  
Good Agreement

Determining blast loadings on an explosion containment vessel (ECV) is the foundation to design the ECV. Explosion of TNT centrally located in a thick-walled cylindrical vessel and its impact on the cylinder was simulated using the explicit finite element code LS-DYNA. Blast loadings on the cylinder computed are in good agreement with the corresponding experimental results. Then wall thickness and yield stress of the cylinder were changed in the following simulation to investigate effect of shell deformation on blast loadings. It is revealed that shell deformation during the primary pulses of blast loadings is so slight that it has little influence on the blast loadings. Though the deformation may increase greatly after the primary pulses, the dynamic response of an ECV is mainly affected by the primary pulses. Therefore, decoupled analyses are appropriate, in which the shell of an ECV is treated as a rigid wall when determining blast loadings on it.

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.

Prediction of the Normal and Tangential Friction Forces for Thick Flat Belts Using an Explicit Finite Element Code

2013 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Hatem M. Wasfy ◽  
Jeanne M. Peters
Keyword(s):  
Coulomb Friction ◽  
Friction Model ◽  
Rigid Bodies ◽  
Contact Forces ◽  
Rubber Matrix ◽  
Necessary Condition ◽  
Friction Forces ◽  
Tangential Contact ◽  
Explicit Finite Element ◽  
One Dimensional

A necessary condition for high-fidelity dynamic simulation of belt-drives is to accurately predict the normal and tangential contact forces between the belt and the pulleys. In previous papers those contact forces were predicted using one dimensional thin beam elements and approximate Coulomb friction models. However, typically flat belts have a small thickness and the reinforcements are typically near the top surface of the belt. In this paper the effect of the belt thickness on the normal and tangential contact forces and on the average slip between the belt and the pulleys is studied using a two-pulley belt-drive. The belt rubber matrix is modeled using three-dimensional brick elements. The belt reinforcements are modeled using one dimensional truss elements at the top surface of the belt. 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.

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.

Basic Optimization Methodology for the Design of Friction Damping in Blade Shrouds

2013 ◽  
Author(s):  
Michal Hajžman ◽  
Luděk Pešek ◽  
Jan Brůha ◽  
Vladimír Zeman ◽  
Drahomír Rychecký
Keyword(s):  
Vibration Suppression ◽  
Harmonic Balance Method ◽  
Rigid Bodies ◽  
Geometrical Parameters ◽  
Bending Vibration ◽  
Friction Forces ◽  
Normal Contact ◽  
Friction Element ◽  
Experimental Stand ◽  
Optimization Methodology

This paper is focused on the optimization of friction element parameters in blade shrouds for various types of excitation. In order to create and validate a proper modelling methodology an experimental stand and a numerical simulation of blades interaction by means of a friction element placed in the shrouds were prepared. Mathematical models are based on the finite element method combined with rigid bodies. The interaction of the friction element and blades is described by normal contact and tangential friction forces derived for particular geometrical parameters of the studied mechanical system. The models can be analyzed both in frequency domain (by the harmonic balance method) or in time domain (by the numerical integration). The results of the optimization of friction element parameters with respect to the bending vibration suppression are documented in the paper. Another contact modelling approach intended for more complex contact surfaces is based on the decomposition of a contact surface into a set of elementary areas and on the expression of contact and friction forces between these areas. All methodologies are implemented in the MATLAB system and the results for the chosen test cases are compared with the results obtained by a measurement or by the ANSYS software.

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.

Study on the collapse of tapered tubes subjected to oblique loads

2008 ◽  
Vol 222 (11) ◽  
pp. 2025-2039 ◽  
Author(s):  
P Hosseini-Tehrani ◽  
S Pirmohammad ◽  
M Golmohammadi
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Numerical Models ◽  
Point Of View ◽  
Finite Element Code ◽  
Energy Absorber ◽  
Explicit Finite Element ◽  
Bending Deformation ◽  
Oblique Loading

In this work, several antisymmetric tapered tubes with an inner stiffener under axial and oblique loading are studied and optimum dimensions of the tapered tube are derived from a crashworthiness point of view. The importance of detecting these dimensions is optimizing the weight while the crashworthiness of tube is not damaged. By using an internal stiffener, crashworthiness is improved against oblique loads, and the sensitivity of tubes with respect to oblique loads and bending deformation is diminished. The numerical models have been developed using the explicit finite element code LS-DYNA. The crashworthiness of the optimized tapered tube is compared with that of an octagonal-cross-section tube which is known as the best energy absorber model in the literature. It is shown that an optimized tapered tube has an average of 29.3 per cent less crushing displacement in comparison with octagonal-section tube when both tubes have the same weights and the same peaks of crushing load. Finally, the orientation of loading is changed and the best orientation is proposed.

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