# NVH

### FRF for a rectangular plate

This example shows how to setup the keywords for FRF computation. A nodal force excitation is defined. Frequency dependent response amplitudes at nodes are computed. Differences between constant and mode dependent modal damping can be studied. Example 4.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### FRF for a cantilever with pre-stress condition

This cantilever model shows how to run FRF examples with pre-stress condition. The first file shows the usual *FREQUENCY_DOMAIN_FRF setup without pre-stress. In the second file *INTERFACE_SPRINGBACK_LSDYNA is used to create a dynain-file, which is then the basis for pre-stress analysis with *INCLUDE. In addition, usage of intermittent eigenvalue analysis is shown. Example 4.2 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### FRF for a column model with a hole (solid elements)

This example shows a column with a hole using solid elements. *FREQUENCY_DOMAIN_FRF is used to define x-acceleration excitation to the base. Response at different output nodes can be studied. Example 4.3 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Nodal/Resultant force FRF

This example shows a beam model with two layers of solids. *FREQUENCY_DOMAIN_FRF is used to define z-acceleration to the left end and z-direction nodal force output. With *DATABASE_NODAL_FORCE_GROUP resultant force output is defined. Example 4.4 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### FRF of a plate with pressure

This example shows how to use *FREQUENCY_DOMAIN_FRF for a plate with pressure excitation. Example 4.5 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### SSD with a rectangular plate

An example of a rectangular plate shows how to set up keywords for steady state dynamic (SSD) problems and how to start post-processing with *DATABASE_FREQUENCY. Example 5.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### SSD with base and enforced motion

This sequence of two examples shows how to set up an input file for large mass method. In the first file a rectangular plate is computed with base acceleration using *FREQUENCY_DOMAIN_SSD. In the second file for the same structure large mass method is applied with keywords *CONTROL_FREQUENCY_DOMAIN, *ELEMENT_MASS_NODE_SET and *BOUNDARY_SPC. Example 5.2 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### SSD with a wheel rim

This example shows how to run SSD for an industrial problem. A wheel rim model with base acceleration excitation is analysed. Example 5.3 from LS-DYNA training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### ERP for a simplified engine model

This is a simplified engine model with base acceleration. It shows how to run equivalent radiated power (ERP) problems with *FREQUENCY_DOMAIN_SSD_ERP and how to postprocess with *DATABASE_FREQUENCY_BINARY_D3SSD. Example 5.4 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Fatigue analysis based on SSD

This is a simplified bumper model with base acceleration. It shows how to fatigue analysis for sine sweep testing with *FREQUENCY_DOMAIN_SSD_FATIGUE and how to postprocess with *DATABASE_FREQUENCY_BINARY_D3SSD and *DATABASE_FREQUENCY_BINARY_D3FTG. Example 5.5 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Random vibration with pressure load

This is an example of of random vibration with pressure load. A rectangular plate is subjevted to power spectral density load. *DATABASE_FREQUENCY_ASCII_NODOUT_PSD, *DATABASE_FREQUENCY_ASCII_ELOUT_PSD and *DATABASE_FREQUENCY_BINARY_D3PSD are used for post-processing of the results. Example 6.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Cantilever beam I

This is a first example of a cantilever beam with concentrated mass subjected to power spectral density. *DATABASE_FREQUENCY_BINARY_D3PSD and *DATABASE_FREQUENCY_BINARY_D3RMS are defined to get output. Example 6.2 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Cantilever beam II

This is a second example of a cantilever beam subjected to power spectral density. Gravity is used for acceleration. *DATABASE_FREQUENCY_BINARY_D3PSD and *DATABASE_FREQUENCY_BINARY_D3RMS are defined to get output. Example 6.3 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Random vibration with thermal preload I

This is an example of a L-shaped panel subjected to random vibration with thermal preload. The first file shows the usual setup without preload. *INTERFACE_SPRINGBACK_LSDYNA is used to create a dynain-file, which is then the basis for pre-stress analysis with *INCLUDE. In addition, usage of intermittent eigenvalue analysis is shown. In the file domgeom.k the domain decomposition can be studied. Example 6.4 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Random vibration with thermal preload II

This is an example of a L-shaped panel subjected to random vibration with pressure preload. The first file shows the usual setup without preload. *INTERFACE_SPRINGBACK_LSDYNA is used to create a dynain-file, which is then the basis for pre-stress analysis with *INCLUDE. In addition, usage of intermittent eigenvalue analysis is shown. In the file domgeom.k the domain decomposition can be studied. Example 6.5 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### A tube model

This is an example of a tube model under nodal force power spectral density excitation. *DATABASE_FREQUENCY_BINARY_D3PSD and *DATABASE_FREQUENCY_BINARY_D3RMS are used for post-processing of the results. Example 6.6 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### A mass-spring model

This is an example of a mass-spring model under base acceleration power spectral density excitation. *DATABASE_FREQUENCY_BINARY_D3PSD and *DATABASE_FREQUENCY_BINARY_D3RMS are used for post-processing of the results. Example 6.7 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Correlated multiple nodal forces

This is an example of a L-shaped panel subjected to multiple nodal force power spectral density excitation. *DATABASE_FREQUENCY_BINARY_D3PSD and *DATABASE_FREQUENCY_BINARY_D3RMS are used for post-processing of the results. The effect of correlated and uncorrelated excitations can be compared. Example 6.8 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### An aluminium bracket

This is an example of an aluminium bracket subjected to base excitation. Random fatigue analysis is running with *FREQUENCY_DOMAIN_RANDOM_VIBRATION_FATIGUE using Steinberg's three band method. *DATABASE_FREQUENCY_BINARY_D3FTG, *DATABASE_FREQUENCY_BINARY_D3PSD and *DATABASE_FREQUENCY_BINARY_D3RMS are used for post-processing of the results. Example 7.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### An aluminium beam

This is an example of an aluminium beam with pre-determined notch subjected to base acceleration excitation. Random fatigue analysis is running with *FREQUENCY_DOMAIN_RANDOM_VIBRATION_FATIGUE using Dirlik's method. *DATABASE_FREQUENCY_BINARY_D3FTG, *DATABASE_FREQUENCY_BINARY_D3PSD and *DATABASE_FREQUENCY_BINARY_D3RMS are used for post-processing of the results. Example 7.2 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a rectangular plate I

This is a first example of a recangular plate subjected to nodal force excitation. *FREQUENCY_DOMAIN_ACOUSTIC_BEM is used for running a vibro-acoustic problem with variational indirect BEM. In the file domgeom.k the domain decomposition can be studied. Example 8.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a rectangular plate II

This is a second example of a recangular plate subjected to nodal force excitation. *FREQUENCY_DOMAIN_ACOUSTIC_BEM is used for running a vibro-acoustic problem with Rayleigh Method. Example 8.2 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a rectangular plate III

This is a third example of a recangular plate subjected to nodal force excitation. *FREQUENCY_DOMAIN_ACOUSTIC_BEM is used for running a vibro-acoustic problem with Kirchhoff Method. Example 8.3 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a beam subjected to SSD

A rectangular beam is subjected to frequency domain acceleration. BEM acoustic analysis is coupled with SSD excitation via *FREQUENCY_DOMAIN_SSD. *FREQUENCY_DOMAIN_ACOUSTIC_BEM uses variational indirect BEM and raised cosine windowing technique for FFT. In the file domgeom.k the domain decomposition can be studied. Example 8.4 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a simple car model

A simplified car model is subjected to SSD nodal force excitation. BEM acoustic analysis is coupled with SSD excitation via *FREQUENCY_DOMAIN_SSD. *FREQUENCY_DOMAIN_ACOUSTIC_FRINGE_PLOT_SPHERE is used to visualize noise distribution. Example 8.5 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a tunnel model

A simplified tunnel model is subjected to a user defined velocity excitation. *FREQUENCY_DOMAIN_ACOUSTIC_BEM_PANEL_CONTRIBUTION is used for running acoustic panel contribution analysis with variational indirect BEM. Example 8.6 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a simplified compartment model

A simplified auto compartment model is analysed. For FFT, windowing technique raised cosine is used. Differences between collocation BEM and variational indirect BEM can be studied. Example 8.7 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a box with impedance condition

An example of a box shows how to set up an impedance condition. Collocation BEM with different boundary conditions is used Example 8.8 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics of a pulsating sphere in half space

This example of a pulsating sphere in half-space shows how to set up reflection conditions with *FREQUENCY_DOMAIN_ACOUSTIC_BEM_HALF_SPACE. In the files domgeom.k the domain decompositions can be studied. Example 8.9 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics with acoustic transfer vector I

This example shows how to set up an acoustic transfer vector (ATV) computation with *FREQUENCY_DOMAIN_ACOUSTIC_BEM_ATV and how to post-process with *DATABASE_FREQUENCY_BINARY_D3ATV. In the file domgeom.k the domain decomposition can be studied. Example 8.10 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics with acoustic transfer vector II

This example shows how to set up an modal acoustic transfer vector (MATV) computation with *FREQUENCY_DOMAIN_ACOUSTIC_BEM_MATV and how to run several loading cases on SSD with *CASE. Post-processing is done with *DATABASE_FREQUENCY_BINARY_D3SSD. Example 8.11 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### BEM acoustics with incident wave

An example of acoustic pressure scattered from a rigid spherical surface shows how to solve acoustiv scattering problems with *FREQUENCY_DOMAIN_ACOUSTIC_BEM and *FREQUENCY_DOMAIN_ACOUSTIC_INCIDENT_WAVE. Example 8.12 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### FEM acoustics of a simplified compartment model I

This is an example of a simplified compartment model with hexaeder elements and velocity boundary conditions. It is shown how to set up a model for frequency domain FEM acoustics with *FREQUENCY_DOMAIN_ACOUSTIC_FEM and how to post-process with *DATABASE_FREQUENCY_BINARY_D3ACS. Results can be compared with the example ''BEM acoustics of a simplified compartment model''. Example 9.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### FEM acoustics of a simplified compartment model II

This is an example of a simplified compartment model with tetrahedal elements. It is shown how to set up a model for frequency domain FEM acoustics with *FREQUENCY_DOMAIN_ACOUSTIC_FEM and how to post-process with *DATABASE_FREQUENCY_BINARY_D3ACS. Results can be compared with the example ''BEM acoustics of a simplified compartment model'' and ''FEM acoustics of a simplified compartment model I''. Example 9.2 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### FEM acoustics of a simple box model with SSD

This is a simple box model to show how to couple FEM acoustics with steady state dynamics (SSD). Example 9.3 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### FEM acoustics with Impedance boundary conditions

A simple cabin model with seats shows how to set up multiple boundary conditions and how to define impedance boundary conditions. Example 9.4 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Response spectrum analysis of a simple block model

This example shows how to set up a simple brick tower model to run resonse spectrum analysis with *FREQUENCY_DOMAIN_RESPONSE_SPECTRUM. *DEFINE_CURVE and *DEFINE_TABLE are used to define ground acceleration spectra for different damping coefficients. Post-processing is done with *DATABASE_FREQUENCY_BINARY_D3SPCM. Example 10.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Response spectrum analysis of a simplified multi-story building model

This example shows how to run resonse spectrum analysis with *FREQUENCY_DOMAIN_RESPONSE_SPECTRUM for a simplified multi-story building model with shells and beams. *DEFINE_CURVE and *DEFINE_TABLE are used to define ground acceleration spectra for different damping coefficients. Post-processing is done with *DATABASE_FREQUENCY_BINARY_D3SPCM and *DATABASE_NODAL_FORCE_GROUP. Example 10.2 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Simple break

This is a simple break example to show how to set up break squeal problems. A multi-step method with intermittent eigenvalue analysis using *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE_MORTAR_ID, *CONTROL_IMPLICIT_EIGENVALUE, *CONTROL_IMPLICIT_ROTATIONAL_DYNAMICS and *CONTROL_IMPLICIT_SOLVER is presented. Example 11.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Square tube

This is a sequence of problems for running problems with IGA. The first example shows steady state dynamics (SSD) with IGA, *ELEMENT_SHELL_NURBS_PATCH is used to define a shell nurbs element. The second example combines periodical load with IGA. In the third example, results can be compared with classical FEA. Examples 11.2-11.4 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

### Square bar

This is an example for running problems with IGA. Results can be compared with classical FEA. Examples 11.5-11.6 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.