xComposites is a powerful tool for various analyses of composites: failure analysis, progressive damage analysis, fatigue analysis, & etc. Using the micromechanics-based multiscale approach, you can unveil the micro mechanisms of composites, design your novel combinations, and test new parts.
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Composites are considered to be combinations of materials differing in composition or form on a macro-scale. The constituents retain their identities in the composite; That is, they do not dissolve or otherwise merge completely into each other although they act in concert. The components can be physically identified and exhibit an interface between one another. This section introduces the concepts about classic laminate composites, different failure criteria, and an exclusive micro-mechanics-based progressive damage prediction method and fatigue life prediction methods.
The applications of braided textile composites have increased rapidly in a variety of industries. They are considered attractive alternatives to conventional prepreg laminates. Two main types of braids are widely used: biaxial braids and triaxial braids. Depending on the interlacement, braids are classified as diamond braid (1/1), regular braid (2/2), and Hercules braid (3/3). This section introduces the FEM modeling approach, and a multi-scale approach to predict the material behavior under different loadings with the variation of the braiding angle.
Woven fabrics are produced by the interlacing of warp fiber tows (90°) and fill fiber tows (0°) in a regular pattern or weave style. They have many advantages such as integral structure design, easier manipulation, better drapability and pliability, and damage tolerance.The weave describes how the warp and fill tows are interlaced. The most popular weaves are plain, twill, and satin. Weave determines drapability and isotropy of strength. This section introduces the FEM modeling approach, and a multi-scale method to predict the material behavior of different types of woven fabrics.
Random short fiber composites have gradually become alternatives to materials used traditionally for structural applications due to the development of new manufacturing technologies. In this section, effective material properties can be predicted using a hybrid approach. By using stress (strain) amplification factors (SAF), the analysis can be expanded from the macro level to the micro level where the mechanical response of the constituents can be observed and therefore further failure analysis can be carried out. A probability distribution is applied to cover the randomness of short fibers.
An RVE, or unit cell, represents micro structure of one ply of unidirectional composites. Based on the idealized fiber arrays, different types of unit cells are developed. All engineering constants of a ply reflect the overall response of this fiber-matrix system to mechanical and thermal loadings. The three-dimensional microscale unit cell model provides fully three-dimensional multi-axial micro stresses of each constituent based on material models. The damages to different constituents were distinguished based on each constituent damage model.
In many cases, there exists another scale between macro and micro scales of composites, which is called "meso scale". Many types of composite fabrics, such as braided fabric composites, woven fabric composites, and non-crimp fabrics (NCFs), can be modeled in the meso scale. For the aforementioned types of fabrics, tow arrangements take the form of repeated patterns. Combining with periodical boundary conditions, a single meso-scale unit cell can be used to predict the engineering constants and simulate the behavior of the entire fabric integrating with micromechanics.
Multi-scale approach has found its way in numerous applications including composite analysis, molecular analysis, and fluid mechanical analysis. It can be a powerful tool for the analysis of composites, since composite materials often have repeatable sub compositions. What’s more, the multi-scale approach is able to provide more detailed mechanical information of the global structure such as the failure behaviour, damage initiation and evolution, and fatigue behaviour. This section will introduce the implementation of the multi-scale approach in the progressive damage analysis of various types of composite materials.
