ADAMS生成柔性体模态力的流程

ADS Modeling of Flexible Bodies: Texture, Constraints, Contacts, and Arbitrary Loads Using MNF and Modal Forces

Abstract

The Adams software environment provides a comprehensive solution for dynamics simulations, enabling users to directly define constraints, contacts, and forces. Moreover, it supports modal analysis to generate prestressed flexible bodies or to apply dynamic loads defined through modal forces. This paper delineates a systematic method for defining modal forces in flexible bodies using Adams, focusing on the usage of Minimization Neutral File (MNF) and load distributions within a flexible body context. The workflow includes the structured methodology for adding finite element loads from external files to the MNF files, through the Application Programming Interface (API) capabilities offered by the ADAMS Flex Toolkit. This approach facilitates a detailed simulation process, allowing for the customization of actions, impacts, and applied forces across the simulation domain.

1. Introduction

Flexible body simulations in ADMS are pivotal for a wide range of engineering applications, encompassing manufacturing, aerospace, and mechanical engineering. Underpinning this capability is the advanced manipulation of materials and their physical interactions, including but not limited to, forces, contacts, and constraints. This section outlines the essential steps for modeling flexible bodies with orientations, masses, and rigid body simulation (RBS) features, alongside the use of modal computation.

2. CommandSpecific Approach for Modeling Flexible Bodies

This section introduces a project encompassing the "plate.mnf" and "plate.loads" files from the software's example repository, in tandem with specific ADMS commands and processes. The "plate.mnf" file embodies a flexible body MNF lacking modal forces, whereas "plate.loads" serves as an external load file detailing nodelevel forces that can be augmented to the MNF.




2.1 Command Window Outline

FLEXTK Command Overview: The FLEXTK utilities, invoked via `flextk`, are central for myriad tasks. Notably, `mnfload` integrates an external load file into the MNF, thereby enriching it with nodespecific loads.

2.2 Command Syntax Application

Upon navigating to a specified working directory, the following sequence commands the system:

1. MNF Data Integration Command Syntax: `ADAMS_version flextk mnfload old_mnf_file new_mnf_file load_case_file`

This command channels the load information in `plate.loads` to `plate.mnf`, resulting in `plate_load.mnf`.

2.3 Command Execution Workaround

For efficiency and reproducibility, automating the command inputs becomes indispensable. This involves scripting the command in a batch file to circumvent manual repetition.

3. Modeling Flexible Body Modal Forces: A StepbyStep Procedure

Following the MNF and load blending, the `mnf_load` is assimilated into the simulation, enabling the creation of `plate_load.mnf`.

3.1 ABM Overview in ADMS and RMS Integration

Modal Force Definition: Via the `Settings > Runtime > Interface > Fast Track Replacement > Add Modal Forces` parameter, a list generated from the external load file is appended.

Simulated Model Comfort: Confirming that all forces have been accurately applied within the modal force dialog box ensures a smooth simulation process.

4. NodeBased Load Representation

The `plate.loads` file exemplifies a straightforward nodebased load format, delineating nodal forces across predefined lines of action. Load amounts stipulate the force magnitudes, with placeholders such as `FX`, `FY`, or `FZ` indicating axis orientation.

5. Generalization and Future Applications

The outlined methodology is scalable, applicable to any MNF file with a counterpart load file for load distribution. It serves as a versatile framework for the adaptation of simulations to reflect realworld conditions, from manufacturing processes to complex mechanical interactions.

6. Conclusion

This paper has detailed the techniques for modeling flexible bodies within ADMS, emphasizing the adaptability and efficacy of mesh generation, element incorporation, and the subsequent application of load conditions. The integration of modal forces via external load files exemplifies a robust approach, ensuring accurate and realistic simulations across a spectrum of applications. The guidance provided should prove valuable for practitioners aiming to enhance their simulations with precise load definitions and comprehensive load analysis.

Endnotes

ADMS and its adaptive Dynamo and FLEXTK tools constitute an integral part of a simulation engineer’s toolkit, offering unparalleled flexibility and power in the realm of dynamic simulations. The ability to seamlessly integrate external load definitions and to define and restrain flexible bodies with precision underscores the toolkit's utility across multiple engineering disciplines.