Abstract
Research and/or Engineering Questions/Objective:
Conducting NVH analysis, especially for large models, is a complicated process that imposes hard requirements on pre / post processing as well as on solving itself. The main difficulties that should be overcome are related to the vast amount of data that are created, the long processing / solving times and the complicated procedures involved such as the creation of reduced models, which make the whole process more prone to errors. The objective of this paper is to present an innovative approach based on an integrated simplified environment for streamlining all related actions towards NVH analysis.
Methodology:
All actions related to NVH analysis from pre-processing to post-processing were brought together within a unified environment. Tedious processes are streamlined and automated to a large extent with file / data exchange taking place in the background. One of the innovations of this tool, which is embedded in ANSA pre-processor, is related to representing the whole assembly not only in 3D as FE but also in a simplified diagram view offering a concise overview of the components and connectors that constitute the assembly. All phases of an NVH analysis such as the creation of reduced models, the assembly of multiple components, the creation of multiple and complicated loadcases and the calculation of responses can be fully controlled from within the same environment. The diagram view and the 3D display are synchronised. Each of the components of an assembly can acquire a reduced representation (binary or ascii modal models, for all or just few selected DOFs, test-based FRFs as well as calculated FRFs). The creation of these representations is streamlined. After the assembly and the loadcases are set, various types of responses (acoustic responses, modal and grid participations, panel participations, transfer path analysis, connectors sensitivities) are calculated based on the FRF-substructuring methodology.
Results:
Calculated responses correlate very well with respective Nastran results for the whole assembly. The benefit stems from the fact that more "what-if" studies for actually large and complicated models can be conducted in very short time even on a standard computer. Flexibility is provided also with respect to the parameters that can be changed for the "what-if" studies (modes can be excluded/included, modal mass, modal stiffness and modal damping can be easily modified as well as connectors properties).
Limitations of this study:
The implementation of other methodologies that would enable the use of multi-nodes connectors (eg: the door connected to the BIW). Now only 1-to-1 node connectors are supported. What does the paper offer that is new in the field including in comparison to other work by the authors? The extensive automation and streamlining of all NVH actions from within a single environment combined with capabilities for modifying parameters and calculating various responses lead to better understanding of the NVH behaviour and more complete studies of the influencing parameters, thus to better design. Conclusions: A new environment for orchestrating all NVH actions has been developed with the aim to reduce overall time for multiple "what-if" studies without sacrificing the accuracy of calculated responses.
KEYWORDS – Full vehicle NVH; FRF; FRF-based substructuring; reduced modeling; assembly