Stress Analysis

Stress analysis is an important part of the design and development of any composite part.  There are a number of levels of analysis that can be undertaken to develop a composite part: from coarse to fine modelling techqniues.  Fine modeling is typically associated with Finitie Element Analysis (FEA) which is used to predict stresses in complex composite structures.

Coarse Modeling

Coarse modeling is a technique by which an engineer does hand a first pass, coarse model of a part.  This could include free body diagrams followed by simple beam bending calculations to size up a part.  This is useful when quoting on new projects where the part in question has not previously been designed in composite materials.  This helps with quoting the customer on approximate pricing and product development costs.

A second level of modeling might be an Excel spredsheet where empirical testing has allowed Formtech to develop accurate methodologies for predicting stresses and displacements.  One typical application is the prediction of behaviour of structures in crashes.  The sheet shown below is an example of an analysis formtech has carried out on a Formula One nosebox.

Fine Modeling

Fine modeling is typically associated with Finite Element Analysis (FEA, of FEM).  A CAD model is used to define the surfaces of the structure: see below a rear wing from a Formula One car.

The wing is then broken down into sections where different laminates will be applied as per the final manufacturing sequence.  The image below shows the wing with the laminate areas shown.

An analysis is undertaken with FEA software such as Abaqus, ANSYS, NASTRAN for non-dynamic problems or LS-Dyna3D or PAMCrash for explicit dynamic events like crash testing.

The information can then be post-processed in order for the analyst to make decisions on the safety, stresses and overall displacements that a part will go through in the field.

The wing is shown above with a plot of displacements under load.