Attachment_0012_-_Vehicle_Dynamics_Data_Sheet_(28JUN2017).xlsx

Cover

V2-28 June 2017

Solicitation Number: W56HZV-18-R-0174

Distribution A: Approved for Public Release; distribution unlimited.

(*Distribution Statement A only applies when form is not filled in)

1. Sprung Vehicle Data

CHASSIS DATA

Chassis mass (sprung mass, excluding turret, gun, and other bodies described below) lbf-sec2/in *

TURRET DATA

Turret mass lbf-sec2/in

WEAPON DATA

Provide finite element model and analysis data for each body that should be considered a compliant structure.

Ver 2.0 Released August 2010

2. Power Train Data

Power Train Data

Property Comment

Engine maximum power (hp)

Curve data of net engine torque (in-lbf) vs. speed (rpm)

Specify gear ratios and efficiencies of the power train

For tracked vehicles, reflected rotational inertia at sprocket (lbf-in-s2) Inertia (lbf-in-sec2) = Inertia (lbm-in2) / 386.088

Engine/Transmission mass (lbf-s2/in) Mass (lbf-sec2/in) = Mass (lbm) / 386.088

Engine/Transmission center-of-mass location (CG) Provide x,y,z coordinates (in); specify coordinate system

Engine/Transmission mount locations Provide x,y,z coordinates of each mount (in); specify coordinate system

Ver 2.0 Released August 2010

P. Jayakumar

3A. Track Data

Ver 1.0 (Original, Unmodified)

Dynamics & Structures Team

3B. Track Suspension Data

Roadwheels are numbered from the idler (if present) to the sprocket

Ver 1.0 (Original, Unmodified)

Dynamics & Structures Team

4. Vehicle Geometry Data

Vehicle Geometry Data

(1) Provide dimensioned drawings showing position*, geometry, connectivity, and layout of the following:

(3) For steering system, specify efficiency and response time.

Ver 2.0 Released August 2010

P. Jayakumar

Microsoft_Word_Document1.docx

VEHICLE DYNAMIC MODELING AND SIMULATION DATA SHEETS

1.0 INTRODUCTION

This package describes the parametric data requirements for high resolution vehicle dynamic analysis using methodologies such as Dynamic Analysis and Design System (DADS). The nature of these methodologies is such that detailed vehicle data are necessary to formulate the models for the simulation to be performed. In order to facilitate the development of dynamic models of modern military vehicle systems, an attempt has been made here to provide generic data sheets to define the system parameters necessary to conduct any desired simulations. These sheets include the minimal requirements necessary to conduct simulations. Special vehicle features or performance characteristics which are not covered by the data sheets need to be described and parameters provided in sufficient detail for high resolution dynamic simulations.

2.0 OBJECTIVES

The purpose of this package is to: 1) define in detail the parameters, drawings, and descriptions that are necessary to perform high resolution vehicle dynamic simulation and 2) provide standardized work sheets which will facilitate wheeled vehicle system description and model development.

3.0 RECOMMENDATIONS

It should be noted that the data defined in this package has a direct effect on the dynamic response of the vehicle. However the parameter values are generally quite difficult to determine. As the model can only be as accurate as the data provided, consideration should be given to collecting accurate and precise data to be used in the modeling process. When accurate data are used correctly in a vehicle dynamic simulation, accurate results can be produced and decisions can be made based on predicted vehicle performance.

As the government deems it necessary, this package will be updated to add data requirements as modeling methodologies and simulation technologies grow.

4.0 DATA SHEETS

In order to determine the dynamic response of military vehicles, parametric data that describes the main subsystems of the vehicle must be known. The following data sheets are included to capture that data.

Models will be developed from each subsystem's parametric data and the models will be combined to create the vehicle model. The level of detail used to describe each subsystem and the accuracy of the parametric data will determine how well the model reflects the true system response.

4.1 Sprung Vehicle Data

For the level of detail required for most analyses, it is sufficient to treat the vehicle sprung mass (chassis) as a single rigid body. However, if the first few mode shapes are known, provide the output from the finite element eigenvalue analysis from ANSYS, MSC/NASTRAN, or COSMIC/NASTRAN. This data can be incorporated into the dynamic model to provide additional accuracy. All spinning components such as the roadwheels should be combined into one. All center-of-gravity location should be given relative to a point located on the ground below the center of the front axle.

4.2 Power Train Data

Vehicle model performance on irregular terrain and over obstacles is highly dependent upon the power train model. Power train models should be capable of dynamically adjusting to varying terrain-induced loads and throttle settings for realistic transient analysis. As in other subsystems, it is difficult to be explicit about all model requirements until the system configuration is known.

As a minimum, curves of maximum torque available at the sprocket versus sprocket speed over the nominal speed range of the vehicle should be provided. Rotational inertia of the drive train, from powerpack to the output sprocket in each gear, should also be provided. Transmission and final drive schematics, with all gear ratios, gear efficiencies and automatic transmission shifting characteristics defined, would make the model even more accurate. Other factors peculiar to a given system, which may substantially affect vehicle performance, should be provided.

Associated with the power train is the vehicle steering system. Tracked vehicles steer by braking or by positive control of differential sprocket speeds. Provide a steering schematic and describe any properties of the steering system such as response time, inefficiencies, etc.

4.3 Tracked Vehicle:

A. Track Data

Track-soil dynamics are the most difficult part of tracked vehicle modeling. Driving and braking forces are transmitted between drive train and the ground via the track. Roadwheels are isolated from terrain irregularities by the bridging of the track. Rolling resistance between wheels and track, ground deformation under the track, and track vibrations account for a significant amount of energy dissipation.

The dimensions and mass of a track segment should be given. Track pad dimensions and material properties can be used for determining displacement between roadwheel, track, and ground. The stiffness and the damping characteristics of the rubber or other material in the roadwheels and track should be provided.

If track tension is dynamically adjusted, the necessary models and parametric data should be supplied in order to include these effects in the track model.

B. Track Suspension Data

Suspension stiffness can be characterized in a number of ways. For example, torsion bar suspensions can be represented by describing torque versus relative angle position between the hull and roadarm, torsional friction versus relative angular velocity, and torsional damping versus relative angular velocity. It is sufficient to provide this data as a table of test points. The data should also characterize jounce and rebound stops, if they exist. If the suspension force data differs between suspension units due to different torsion bar characteristics, indexing, roadarm lengths, etc., separate data for each suspension unit should be provided. Also, provide the index angle for torsion bars and the static position at the nominal vehicle configuration.

If hydro-pneumatic suspension systems are employed, and if they are adjustable, a family of suspension curves or analytical models should be provided. If active suspension compensation devices are employed and if it is expected that they will significantly affect vehicle performance, these systems should be identified and data provided to fully model their performance. Include block diagrams with all parameters listed and defined. If the system is mechanical, the linkage dimensions, geometry, attachment points, etc. should be provided. All dimensions should be provided relative to a well-defined point on the hull such as the center of the sprocket, and for attachment points on the roadarm, with respect to the radar attachment point. If electrohydraulic-mechanical suspension systems are employed, a detailed description of the system, including block diagrams with all parameters defined in sufficient detail to establish a dynamic model, should be provided.

Suspension damping forces also play an important role in dynamic simulation. Force or torque versus relative position and velocity data are required for each damper in the suspension system.

If the suspension system interacts directly with braking, steering, or the drive train, and if these interactions will significantly alter vehicle performance, adequate data to perform detailed simulations of this interaction should be provided.

C. Vehicle Geometry

For the level of detail required for most analyses, it is sufficient to treat the vehicle sprung mass (chassis) as a single rigid body. However, if the first few mode shapes are known, provide the output from the finite element eigenvalue analysis from ANSYS, MSC/NASTRAN, or COSMIC/NASTRAN. This data can be incorporated into the dynamic model to provide additional accuracy. All center-of-gravity location should be given relative to a point located on the ground below the center of the front axle.

image1.emf