SEAM acoustic and vibration prediction software

Cambridge Collaborative's SEAM software provides a method of analysis that is particularly well-suited for studying the dynamic response of complex structures at mid and high frequencies. SEAM is used to predict interior noise and vibration in automobiles, aircraft, and construction equipment cabs as well as the radiated noise from ships and the vibroacoustic environments for spacecraft. Other applications include machinery noise, industrial noise, and building acoustics.

SEAM includes a complete implementation of statistical energy analysis (SEA). The complex dynamic system being analyzed is divided into a set of substructures and acoustic elements. The modes of each substructure and acoustic element are grouped into SEA subsystems. The flow of energy between the different subsystems is proportional to the modal energies of the subsystems and the coupling factors. The SEAM program calculates all required coupling factors and performs a power balance for each subsystem. The resulting equations are solved for the modal energy and response of each subsystem.

SEAM software was developed in 1980 to study structure-borne noise in submarines, and was made commercially available in 1983. Since that time SEAM has become an accepted analysis procedure by automobile manufacturers and suppliers, major shipyards, Navy research establishments, and aerospace companies. Cambridge Collaborative continues to advance the state of the art in statistical energy analysis (SEA) through software development and research.

SEAM Technical Features

The SEAM software package provides a complete implementation of statistical energy analysis using vibrational and acoustic energy flow techniques. The following list describes many of the standard features that come with SEAM. Other features are available on request. Please feel free to contact Cambridge Collaborative for more information on any of these features.

- Ability to develop very large models with thousands of SEA subsystems

- Bending and inplane subsystems for all structural elements

- Calculation of coupling loss factors and modal densities

- Transverse shear deformation corrections for bending of all structural elements

- Frequency dependent damping and material properties

- Octave, one-third-octave, narrowband and percentage bandwidth analysis

- Fast sparse matrix solution routines

- Prediction of input power and response mean and variance

- Acoustic duct, layer, and space elements with one, two and three-dimensional modal densities

- Design sensitivity analysis

- Transient analysis

- Interface to structural optimization programs

- Automatic calculation of properties for beam, plate and shell elements from cross-section dimensions and materials

- Readable ASCII input and output files

- Choice of several different metric and English units, including mixed units

- Automatic generation of SEA subsystems from structural and acoustic elements

- Automatic generation of SEA junctions for each degree of freedom from structural and acoustic point, line and area connections

- Parameter studies using symbolic constants and algebraic equations for input parameters

- On-line context sensitive help

- Quick-look plotting for subsystem SEA parameters: modal energy, energy flow, response, transfer functions, acoustic noise reduction, vibration reduction, and sound transmission loss

- Acoustic damping using loss factors, absorption coefficients, or reverberation times

- Algebraic expressions for input parameters

SEAM is the only commercially-available software that provides a complete statistical representation of the SEA response. Predictions of the mean-response can be combined with SEAM predictions of the variance to set upper confidence intervals. Use of the upper confidence interval for product design insures that new products will meet acoustic and vibration design objectives.

Application Platforms

SEAM and visiSEAM are available for both Unix and PC-compatible computers. Sun, Silicon Graphics, and Hewlett Packard workstations are supported.

Training

The rapid spread of SEA in recent years has created a need for engineers trained in this technique. To address this need, Cambridge Collaborative offers SEA training courses. Both public and on-site customer training courses are available.

Services

Cambridge Collaborative also supports clients though an extensive range of engineering services. This work addresses general noise and vibration problems as well as SEA related work. Recent projects for NASA include noise and vibration prediction and test support for the Cassini spacecraft. In the automobile industry, CC has developed advanced techniques for full-vehicle automobile noise predictions. Also, CC continues to make significant contributions to various U.S. Navy and Air Force R&D programs.