11 - Transverse compression properties of composite reinforcements

Abstract

This chapter discusses transverse compression, one of the dominant deformation modes arising in fibrous reinforcement materials during composites forming and manufacture. A brief review of the experimental procedure to determine fabric compressibility is given and the standard compaction curve is introduced. Various mechanical models (analytical and numerical) used to predict the compressive response of fibrous reinforcements are described and discussed, classified based on the different length scales typically adopted to study this type of material. Microscale models based on individual filaments are examined, including digital chains, spherical particle methods, and models based on imaging techniques. Continuum and non-continuum mesoscale models of fibrous tows are discussed, including tow-tow contact interaction, textile modeling software, stochastic models, constitutive models, numerical issues, and model validation. Methods for constructing mesoscale models directly from micro-CT scans of real fabrics are also discussed. The chapter then discusses the distinctive inelastic properties and response of fibrous materials, including their viscoelasticity and plasticity, and models for predicting the viscoplastic response of reinforcements. The concept of locked energy is introduced, and modeling strategies for its incorporation within a general thermomechanical framework of reinforcement compression is discussed. The chapter ends with a short review of current challenges within transverse compression and possible future trends.