Virtual testing of textile reinforcements for composites

From fibre and yarn behaviour to reinforcement design and forming simulations

One use of our virtual fibre models is to predict how textile reinforcements stretch, shear, bend and compress, supporting reinforcement design and composite manufacturing. Developed through studies on different woven architectures, the approach connects fibre and yarn behaviour to the mechanical response of the fabric. These virtual tests allow us to investigate how reinforcement properties can be tuned and provide input data for simulations of forming and compaction.

Textile reinforcements are used in lightweight composite components for applications such as automotive structures, aircraft components and marine structures. During manufacturing, the reinforcement must conform to the component geometry while its yarns rotate, bend and compact. Its response influences the forces required for shaping, the resulting fibre orientations and the thickness reached under pressure.

Understanding these responses is therefore important both when designing a reinforcement and when selecting suitable processing conditions. Physical tests provide essential information, but some properties are difficult to isolate experimentally. Testing many variations of a textile architecture can also require substantial material preparation and characterisation.

Representing the fibrous structure

Our approach represents each yarn as a bundle of virtual fibres. A reduced number of these fibres represents the behaviour of the much larger number of filaments in the real yarn, making the simulations computationally manageable while retaining important mechanisms such as fibre rearrangement, contact and friction.

The yarns are assembled into a model of the textile architecture, which can then be subjected to virtual mechanical tests. Information about fibre and yarn properties, together with the reinforcement geometry, provides the basis for calculating the fabric response. This links the predicted behaviour to the material’s underlying structure and allows us to examine how that structure changes under load.

A range of virtual mechanical tests

Across our research, we have investigated tension in one or two directions, in-plane shear, bending within and out of the fabric plane, and through-thickness compression. Applications include multilayer 3D woven reinforcements, glass-fibre twill fabrics and woven carbon-fibre reinforcements.

Comparisons with mechanical experiments and X-ray CT observations assess both the predicted forces and the accompanying structural changes. For example, tensile and shear simulations capture yarn realignment and the increasing resistance as neighbouring yarns restrict further shearing. Compression simulations describe how yarns flatten and fibres rearrange as pressure increases.

Our recent work addresses in-plane bending, where yarns curve within the fabric surface. This response is challenging to measure because specimens tend to twist or bend out of plane during testing. Virtual tests provide estimates of the bending properties that can subsequently be used in larger-scale forming simulations. In a square-box forming study, including this behaviour for example improved predictions of local yarn orientation and avoided unrealistic abrupt changes in yarn curvature.

Supporting reinforcement and process design

Virtual testing provides a way to investigate how changes in yarn properties or textile architecture affect the reinforcement’s mechanical response. This supports the tuning of properties to an application, for example by assessing the balance between resistance to deformation and the ability to conform to a complex mould.

The calculated responses can also supply material data for models of an entire forming process, where explicitly representing the individual yarns would be computationally demanding. Detailed reinforcement models thus connect material design to predictions at the component scale.

Further information

• Daelemans et al. (2016). Finite element simulation of the woven geometry and mechanical behaviour of a 3D woven dry fabric under tensile and shear loading using the digital element method. Composites Science and Technology, 137, 177–187. https://doi.org/10.1016/j.compscitech.2016.11.003
• Daelemans et al. (2021). Kinematic and mechanical response of dry woven fabrics in through-thickness compression: Virtual fiber modeling with mesh overlay technique and experimental validation. Composites Science and Technology, 207, 108706. https://doi.org/10.1016/j.compscitech.2021.108706
• Zheng et al. (2026). Numerical prediction of the in-plane bending properties of fibrous reinforcements using a mesoscopic virtual fiber finite element approach. Composites Part B, 322, 113771. https://doi.org/10.1016/j.compositesb.2026.113771

Contact

Prof. dr. ir. Lode Daelemans (Lode.Daelemans@ugent.be)