New Composites Analysis Software

30 October 2003

After 4 years of development the Belgian company MATERIAL has launched Composite Star, an entirely new composite material database and design software.

With the support of composite design experts from different universities and the industry, the latest state-of-the-art calculation methods were gathered and integrated into a modern user-friendly software system.

Strength prediction is the most important task of composite design calculation. The calculation is based on the Classical Laminate Theory (CLT), which allows you to determine the laminate's properties as well as the stresses and strains in each layer (ply) of the laminate. Once the stresses in the plies are known the laminate's strength can be calculated by applying a failure criterion to each ply.

Besides common failure criteria Composite Star introduces one of the world's most advanced and sophisticated criterion: Puck's Action Plane Criterion. This criterion distinguishes between 5 different fracture modes (tensile and compressive fiber fracture, tensile, shear and compressive inter fiber fracture). The detailed specification of the fracture modes is vital for the designing engineer since their effects and the techniques to avoid them are completely different. Furthermore Puck's Action Plane Criterion is able to calculate the fracture plane angle, can predict catastrophic wedge effects and considers the interaction between stresses in fiber direction and transverse to the fiber direction.

Together with the Puck Action Plane Criterion, Composite Star uses a new progressive failure analysis and non-linear ply degradation model which allows the simulation of the laminate's failure process after first ply failure. It is based on the physics of the crack building process within the laminate under increasing loads. Composite Star uses this iterative algorithm and calculates all laminate properties, stresses and strains at every important moment of the load increase.

Changes of temperature or moisture content induce thermal or hygroscopic residual stresses inside the laminate. It is essential to take these stresses into account. For this purpose Composite Star introduces the concept of constant and variable loads. Since the constant as well as the variable load can be mechanical, hygrothermal or a combination of both, the designer has all off these possible calculations to work with.

Structural composite parts can be seen as a composition of thin laminate plate elements. There are only a few structural parts (e.g. beams, tubes, plates) for which an exact solution of the elasticity problem can be found. Composite Star calculates their properties and load response (e.g. bending, stresses, failure, buckling) with analytical formulas. More complex structures need to be calculated by Finite Element Analysis (FEA). There is a wide range of FEA software available. Some are more suitable for composite materials, others are less. With its extended FEA interface Composite Star gives the designing engineer all the advantages of the state-of-the-art laminate calculation together with the already existing FEA programs. Any of the fiber, matrix, ply, laminate, stacking sequence, load or structural data can be imported from or exported to any FEA program.

Composite Star stores all data in a state-of-the-art, full featured database. Database features include extensive searching, filtering, sorting and data import/export. The database stores the data of the fibers, the matrices (resins), the plies, the laminates, the load cases and structures. Beside the physical and engineering parameters the database can store comments and text notes, manufacturing guidelines, quality control data as well as material prices. Composite Star's database comes with a set of common fiber and resin data records provided by the material manufactures. Additionally, typical ply data are included. Also the user can enter his own data into the database.

The quality and efficiency of software is only as good as its user interface. Consequently great importance has been given to Composite Star's user interface. The different database tables are shown as grids. As with the so efficient spreadsheet programs, the user can change any value at any time and has to press only one single calculation button to update all calculation results instantly. In spite of its complexity the software can be used intuitively without complicated menus, windows or dialogs.

One of the best ways to present data is a graph. Composite Star's sophisticated graph engine allows the display of any X-Y or polar graph, including any ply's property versus the ply's orientation angle, carpet plots, ply-by-ply stress and strain diagrams and failure process diagrams. An equally important tool for the designer is the 3D model of the failure envelope together with the constant and variable stress vector for each ply. This allows immediate recognition of the stress state and reserve factor in the critical plies.

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