# A Modal Model to Simulate Typical Structural Dynamic Nonlinearity

## Abstract

Some initial investigations have been published which simulate nonlinear response with almost traditional modal models: instead of connecting the modal mass to ground through the traditional spring and damper, a nonlinear Iwan element was added. This assumes that the mode shapes do not change with amplitude and there are no interactions between modal degrees of freedom. This work expands on these previous studies. An impact experiment is performed on a structure which exhibits typical structural dynamic nonlinear response, i.e. weak frequency dependence and strong damping dependence on the amplitude of vibration. Use of low level modal test results in combination with high level impacts are processed using various combinations of modal filtering, the Hilbert Transform and band-pass filtering to develop response data that are then fit with various nonlinear elements to create a nonlinear pseudo-modal model. Simulations of forced response are compared with high level experimental data for various nonlinear element assumptions.

- Authors:

- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Univ. of Wisconsin, Madison, WI (United States)

- Publication Date:

- Research Org.:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

- Sponsoring Org.:
- USDOE National Nuclear Security Administration (NNSA)

- OSTI Identifier:
- 1333268

- Report Number(s):
- SAND-2015-8941C

608310

- DOE Contract Number:
- AC04-94AL85000

- Resource Type:
- Conference

- Resource Relation:
- Conference: IMAC, Orlando, FL (United States), 25-28 Jan 2016

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 42 ENGINEERING

### Citation Formats

```
Pacini, Benjamin Robert, Mayes, Randall L., and Roettgen, Daniel R.
```*A Modal Model to Simulate Typical Structural Dynamic Nonlinearity*. United States: N. p., 2015.
Web.

```
Pacini, Benjamin Robert, Mayes, Randall L., & Roettgen, Daniel R.
```*A Modal Model to Simulate Typical Structural Dynamic Nonlinearity*. United States.

```
Pacini, Benjamin Robert, Mayes, Randall L., and Roettgen, Daniel R. Thu .
"A Modal Model to Simulate Typical Structural Dynamic Nonlinearity". United States. https://www.osti.gov/servlets/purl/1333268.
```

```
@article{osti_1333268,
```

title = {A Modal Model to Simulate Typical Structural Dynamic Nonlinearity},

author = {Pacini, Benjamin Robert and Mayes, Randall L. and Roettgen, Daniel R},

abstractNote = {Some initial investigations have been published which simulate nonlinear response with almost traditional modal models: instead of connecting the modal mass to ground through the traditional spring and damper, a nonlinear Iwan element was added. This assumes that the mode shapes do not change with amplitude and there are no interactions between modal degrees of freedom. This work expands on these previous studies. An impact experiment is performed on a structure which exhibits typical structural dynamic nonlinear response, i.e. weak frequency dependence and strong damping dependence on the amplitude of vibration. Use of low level modal test results in combination with high level impacts are processed using various combinations of modal filtering, the Hilbert Transform and band-pass filtering to develop response data that are then fit with various nonlinear elements to create a nonlinear pseudo-modal model. Simulations of forced response are compared with high level experimental data for various nonlinear element assumptions.},

doi = {},

journal = {},

number = ,

volume = ,

place = {United States},

year = {2015},

month = {10}

}