ADAMS/Engine Release Notes

ADAMS/Engine Piston

Enables you to analyze secondary motion, that is, the tilting angle and displacement of the piston over time. Essential input data for this analysis is the piston skirt shape and the distorted liner-shape. You can choose from three contact models:

• Dry-contact - Based on a Hertz-contact definition.

• Hydro-2D and Hydro-3D - Hydro-dynamical models that include contact pressure due to the compressed oil film between piston and liner.

ADAMS/Solver (C++) Support

ADAMS/Solver (C++) is now the default solver for all ADAMS/Engine analyses. ADAMS/Solver (C++) is now supported for all analyses, except for linear analyses. Switching the default solver has improved speed for a number of types of models. The improved speed is due to a combination of enhancements:

• The Hilber-Hughes-Taylor integrator (HHT) - A new, stiffly stable, second-order integrator with user-definable numerical damping. For a detailed description see the ADAMS/Solver (C++) Release Notes (Second-Order Integrators: HHT and Newmark).

• An adaptive Jacobian evaluation strategy that minimizes expensive Jacobian evaluations. For a detailed description the ADAMS/Solver (C++) Release Notes (Adaptive Jacobian Pattern).

• Limited Shared Memory Parallel (SMP) processing that can put to use all the processors in your workstation. Chain and belt contact force calculations take advantage of SMP.

Specifically for chain and belt simulations, ADAMS/Engine is taking advantage of exclusive features, such as:

• Planar part, constraint, and force formulations that reduce equation complexity. See 2D Chain and Belt.

• Analytical partial derivatives for belt and chain contact force calculations. This has shown to result in a higher quality integration Jacobian, helping models to converge faster. It is particularly successful in conjunction with the new HHT integrator or the GSTIFF integrator with an adaptive Jacobian pattern.

Our testing shows that certain models are from four to eight times faster with the ADAMS/Solver (C++) when taking advantage of these features.

Solver Settings

The default equilibrium solver setting has changed for max iterations. The new default for Maxit is now 200.

The new HHT integrator has shown to be faster than the GSTIFF integrator for a lot of different types of models.

To set integrator to HHT:

1. From the Settings menu, point to Solver, and then select Dynamics.

2. Set Integrator to HHT.

   Note that Error is changed to 1e-5, which is the default error for HHT integrator.

You can also try an adaptive Jacobian pattern, which has shown some speed up for GSTIFF integrator in conjunction with setting a lower number of max iterations.

To set maxit:

1. From the Settings menu, point to Solver, and then select Dynamics.

2. Select More.

3. Set Maxit to 7.

To set pattern:

1. From the Tools menu select ADAMS/View Interface.

2. From the Settings menu, point to Solver, and then select Dynamics.

3. Set Category to Pattern for Jacobian.

4. Set Number Of Entries to 1.

5. Clear the selection of the check box.

Note:

To get converged results, you must tighten the error tolerance until results do not change significantly between runs.

An easy way to compare results is by plotting the various analyses in one graph.

For cranktrain analyses using the default integrator, GSTIFF, an error tolerance of 1e-3 was found to be a good compromise between reasonable simulation time and result accuracy.

You can set a preference for ADAMS/Engine to use the new HHT integrator as the default integrator from your ADAMS/Engine configuration file by adding the environment variable MDI_AENG_HHT_ERROR. Valid settings are any number. For example:

ENVIRONMENT MDI_AENG_HHT_ERROR 1e-5

This sets the HHT integrator as the default integrator with a default error tolerance of 1e-5 for all ADAMS/Engine analyses, as long as you do not set solver preference to F77. You can still change all solver settings from the Settings menu.

You can set your own solver preferences from the Settings menu or from your configuration file by editing the file (.acar.cfg in your home directory) and adding the environment variable MDI_ACAR_SOLVER_PREF. Valid settings are F77, CXX, and none. For example:

ENVIRONMENT MDI_ACAR_SOLVER_PREF f77

Note also that ADAMS/Engine adds a PREFERENCES/SOLVERBIAS statement to every acf file based on the selected solver. If you remove this statement, or write your own acf file, the solver selected will be based on the registry setting of ADAMS/Solver solver Selection.

2D Chain and Belt

The new 2D links wrapping option enables you to model chains and belts with planar parts. You can use the 2D_Links option only with ADAMS/Solver (C++). This modeling method is faster to simulate than regular links. A 2D_Links chain or belt must have the z-axis of its reference frame parallel to one of the global axes. A 2D_Links chain or belt will constrain the associated sprockets and guides planar to ground.

You can use 2D_Links and Links (3D) chains and belts simultaneously in an assembly. Use Links (3D) for the chains and belts that do not have the z-axis of their reference frame parallel to one of the global axes. You must use Links (3D) for linear analyses because 2D_Links is only supported by ADAMS/Solver (C++), which does not support linear analyses.

Use the HHT integrator and error tolerance of 1.0E-5 and lower.

Curve-flat and Curve-circle Contact Improvements for Initial Static

You can now set the contact to initially use the cam's base radius. All valves in a complete valvetrain will start in a closed position, which will help the assembly find static equilibrium. The contacts will use the true cam profile within the first revolution.

Curve-Circle Contact Stiffness

You can specify a property file with the stiffness of the contact surface as a function of the angle from the circle reference marker.

Sample and Post Requests

Enables you define and auto-generate template-specific processed data.

Flexible Spring Modal Stress

Includes stress modes for flexible spring for improved integration with ADAMS/Durability. New parameter replaces experimental environment variable MDI_AENG_MODALSTRESS.

Torsional Spring Gear

Added torsional flexibility using a torsional spring.

Crowning

In ADAMS/PostProcessor, you can now view stress results, due to crowning, for curve-curve, curve-flat, and curve-circle contact. The cam and roller components have a new crowning radius parameter to simplify parameterization of the contacts.

Hydraulic Lash Adjuster (HLA) and Oil Viscosity Element

Improved HLA, including ability to define user bulk module through solver variable, and expanded oil viscosity element. The oil viscosity component now defines the following oil parameters:

• Oil Density
• Oil Viscosity - temperature dependent
• Oil Bulk Module
• Pressure Coefficient
• Air Fraction

Experimental Features

Several new features are not fully supported, and therefore, have not been enabled in the interface. These include:

• User contact formulation for accessory and trapezoidal toothbelt

• User-entered section connections for accessory belt

• Simplified belt setup for accessory and trapezoidal toothbelt

• Layout assembly for chain and belt timing templates

For information on how to enable these features in the interface and for documentation updates, see Knowledge Base Article 1-KB12440.

Documentation Enhancements

• Updated the online help to include reference information and dialog box help for the additions (2D links, sample and post requests, crowning, and so on).

• Created a tutorial for ADAMS/Engine Piston.

Overall Documentation Improvements

For MSC.ADAMS 2005, we've made improvements to the MSC.ADAMS help:

• Added global search so you can search across the entire set of MSC.ADAMS help. To access the global search, do one of the following:

  • At the top of the help, select Switch Products, and then select the Search tab.

  • In any product, select the Search tab, and then in the window that appears, select Global Search.

  Note that the global search does not include any .pdfs (including getting started guides and ADAMS/Driver).

• Removed any hardcoding of font sizes so you can scale the text of the help to any size. Please note that many of the equations do not scale because they are images, and the help looks the best when viewed with medium (or 100%). In addition, your browser will print the text the same size as it is displayed.

• Documented many of the environment variables for the products to help customize your session. The environment variables are for ADAMS/Controls, ADAMS/Durability, ADAMS/Flex, ADAMS/Solver, ADAMS/View, and the template-based products (ADAMS/Aircraft, ADAMS/Car, ADAMS/Driveline, ADAMS/Rail). For more information, see the Running and Configuring help.

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43284

Some of the analysis dialog boxes interpreted clockwise differently. The correct behavior should be that clockwise is negative rotation around dyno z-axis, and counterclockwise is positive rotation around dyno z-axis.

The following dialog boxes have been changed to have the correct behavior:

• Cam Generation Analysis
• Complete Valve Train Analysis: Rpm Sweep
• Complete Valve Train Analysis: Steady State
• Single Valve Train Analysis: Rpm Sweep
• Single Valve Train Analysis: Steady State

45198

Piston and connection rod lose parameterization of center-of-mass marker when switching Inertia Method from User to Density and back again to User.

44532

44952

Copyright © 2004 MSC.Software Corporation. All rights reserved.