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Working with Composites

Mechanics of composite materials is a fascinating and challenging field of study because of its beauty, richness, diversity and complexity, as those who practice it will confirm. On a more fundamental level, our special interest is concentrated on analytical solutions that are useful for the design and analysis of composite structures. The major challenge is to theoretically predict strength related properties of composite structures, which are generally far more complicated than their stiffness related properties. With a collection of analytical solutions at its core, we attempt to build our software package Crea-Comp step by step, where a lot of attention is paid to the development of a user-friendly graphical interface. At the same time, we have a passion for problem solving with a pragmatic hands-on approach, helping our clients succeed in their projects.

Lamina Database

Laminates and Laminators

Damage and Fracture Mechanics

Composites signify a class of materials that combine two or more distinct materials to form a useful third material. While each component material retains its identity, the new composite material displays macroscopic properties better than its parent constituents, particularly in terms of mechanical properties and economic value. For practical reasons, we restrict us mainly to macro-mechanical analyses. On the lamina level, significant effort has gone into creating a material database of fundamental properties to ensure that the input parameters in the analyses are sufficiently accurate. It is a pragmatic combination of literature survey, data request from material suppliers, simplified micro-mechanical analyses and standard material testing.

The essence of the concept composite is to make all good things come together. From laminae to laminates, it is a step that makes demands on technique, creativity, ingenuity, science, art and intuition. We believe that it is convenient for composite engineers to have digital laminators in their pocket, so that they can easily play with orientation, number and stacking sequence of laminae that make up the laminate. The mechanical performance of the laminate can then be evaluated by means of various analysis modules that are available. What we are trying to do is to put composite and information technologies together and see what happens. Our design philosophy is to combine functionality with simplicity to create the best possible experience for the users.

Our strength calculations on composite structures are all based on the energy balance principle of Griffith, which states that failure occurs when the energy released from the system equals or exceeds the energy dissipated due to the damage formation. We apply the progressive damage methodology in which the damage development process is analyzed step by step, and we believe that accurate and reliable predictions are only possible if the behavior of the main damage mechanisms is clearly understood at each step. From an energetic point of view, critical failure modes that are associated with the catastrophic failure of the structure interact with each other, while non-critical failure modes that do not threaten the structural integrity are non-interactive.

Composite Plates and Shells

Actual and Virtual Testing

Build our Future with Composites

Plates and shells are frequently encountered structures in the composite world. From a mathematical perspective, plates can be considered as a special case of shells, when radii related terms vanish. We follow in the footsteps of the great British mathematician and physicist A.E.H. Love, who derived the shell theory from theory of elasticity and differential geometry in an elegant and concise way. This means that an infinitesimal shell element is essentially a point in the classical sense and the curvature related couplings between different deformations do not exist on the elementary level. We solve the membrane problem with the help of Airy stress function and take the geometrical non-linearity into account. It turns out that the localized snap-through buckling holds the key to the major outstanding problems like buckling and post-buckling of cylindrical shells.

Because of the complex nature of composite materials and structures, we believe that theory and experiment should go hand in hand; in other words, analysis without testing is as bad as testing without analysis. As is known, it can be time-consuming and expensive to design a composite structure that meets stringent stiffness and strength requirements, especially when a large amount of experimental work has to be done to cover the whole range of different loading conditions. In close cooperation with team of designers, we make theoretical calculations to gain more insight into the mechanical behavior of composite structures. This enables us to complement, extend, and if conditions permit, reduce or partly replace the tests with computer simulations. By doing so, we aim to find the right balance between actual and virtual testing, on a case-by-case basis.

In diverse industries ranging from the medical devices, sporting goods, wind energy, construction, shipbuilding to automotive and aerospace, it is beyond all doubt that human ingenuity will find more and more areas where composite materials can be beneficially utilized. We are proud to be one of composite engineers who do their best to make meaningful contributions in this area and to make this world a better place. Mechanics of composite materials is still a relatively new field undergoing rapid changes in methods and focus, and our ideas can also evolve in response to fresh discoveries by our colleagues. We shall keep on doing what we are doing, we place our emphasis on analytical solutions, we promise to bring software development to a successful end, we try to be a growth factor for our clients and grow together with them.